Subjective cognitive decline and risk of MCI: The Mayo Clinic Study of Aging

Distinct trajectories of subjective cognitive decline before diagnosis of neurocognitive disorders: Longitudinal modelling over 18 years

BACKGROUND

Subjective cognitive decline (SCD) is an established predictor of neurocognitive disorders (NCD) (i.e. mild cognitive impairment and dementia). Yet, its construct remains contentious. Many individuals with SCD do not progress to NCD, leading to an alternative term in the literature - 'functional cognitive disorders' - to describe the SCD experience in these individuals.

OBJECTIVES

To examine the distinct differences in trajectories of SCD between those who did and did not eventually develop NCD.

DESIGN

Case-control study.

SETTING

Alzheimer's Disease Centers across USA.

PARTICIPANTS

A total of 5,167 participants aged ≥50 years were followed up near-annually to evaluate for SCD and NCD (median follow-up=8.1 years; range=1.0-18.0). Cases were defined as those who developed incident NCD during follow-up; controls completed ≥10 years of follow-up and had normal cognition throughout follow-up period.

MEASUREMENTS

SCD was evaluated with a yes/no question based on "perceived decline in memory relative to previously attained abilities". The trajectories of SCD were modelled with mixed-effect logistic regression, using a backward timescale.

RESULTS

Those who developed NCD (cases) had new onset of SCD within past 20 years, which became particularly noticeable 13-14 years before diagnosis, and became even more evident in the last 4 years. Those who did not develop NCD (controls) reported SCD since younger age, with the probability of SCD remaining constant over time. The distinctive trajectories were consistent across Alzheimer's and non-Alzheimer's disease, and among those with higher baseline rates of SCD due to psychiatric conditions.

CONCLUSIONS

SCD exhibits distinctive trajectories among those who do and do not progress to NCD. These distinctive trajectories can inform NCD risk for early interventions, and guide public health messaging to distinguish high-risk SCD from normal ageing. Future SCD scales may possibly need to evaluate symptom changes over a longer, 20-year horizon to better capture the new onset of SCD within this longer timeframe.

Mild cognitive impairment, Alzheimer's disease dementia, and predictors of driving cessation: A 7-year longitudinal prospective study

BackgroundPatients with dementia face driving difficulties and, at some point, cease driving.ObjectiveWe sought to identify predictors of driving cessation among patients with mild cognitive impairment (MCI) or mild Alzheimer's disease dementia (AD).MethodsWe enrolled in this longitudinal study patients with MCI, AD (Clinical Dementia Rating < 2) and cognitively normal (NC) individuals. At baseline evaluation, participants underwent a neurological, neuropsychological and driving simulator assessment. Re-evaluations after 48 and 84 months included a structured interview with the patients and their caregiver. Primary endpoints were driving cessation, death and progression to dementia.Results109 individuals were included (32 NC, mean age 65.8 years/47 MCI, mean age 69.1 years/30 AD, mean age 72.8 years). Dangerous driving events during follow-up were referred for 45% and 59% of MCI and AD patients, respectively. 18 MCI (38%, mean time to cease 35 months) and 25 AD (83%, mean time to cease 15 months) patients ceased driving during follow-up. 36% of MCI patients progressed to dementia during follow-up. Cox Regression multivariate analysis revealed age (Hazard Ratio-HR 1.080), semantic verbal fluency-SVF (HR 0.822) and Tandem Walking Test modified with simultaneous reverse number counting-mTWT (HR 1.099) as significant predictors of driving cessation. Simulator accident probability reached statistical significance only in the univariate model (HR 1.040).ConclusionsAge, SVF and mTWT are significant predictors of driving cessation among MCI and AD patients. Driving simulator may be a promising component of driving evaluation. Large-scale studies are prerequisite for the implementation of a multi-disciplinary driving fitness evaluation protocol.

Towards characterizing subjective cognitive decline in older adults

BackgroundSubjective cognitive decline (SCD), where older adults perceive a persistent decline of cognitive abilities without showing an objective cognitive impairment, may represent a preclinical stage of Alzheimer's disease (AD) in some individuals.ObjectiveThe complex characteristics of SCD cannot only be revealed by existing self-report questionnaires. Rather, it is necessary to involve individuals affected in the research process with methods like focus group discussions (FGDs).MethodsStudy conduction took place in three steps: telephone interview, neuropsychological assessment and questionnaires, four FGDs with 16 older adults (11 female, 5 male) affected by SCD. FGDs were analyzed with qualitative content analysis using an inductive - deductive code system.ResultsAlthough the neuropsychological assessments did not indicate a cognitive impairment, participants reported a decline for all cognitive domains within the FGDs, especially for the memory- and speech domain, with declining word-finding abilities as the most salient symptom. Participants reported strong concerns related to SCD and difficulties in social participation.ConclusionsSCD seems to go beyond age-related cognitive changes, but as individuals do not show an objective cognitive impairment (yet), their symptoms are often not taken seriously enough. The FGDs revealed information that questionnaires or neuropsychological tests do not capture. The gained insight into SCD symptoms, related coping strategies and concerns is important to be able to develop measures for identifying individuals at risk for a transition to AD and to develop intervention measures that aim at delaying a further decline and increasing the quality of life of individuals affected.

Intraindividual variability, subjective cognitive difficulties, and head injury history in former collegiate athletes

Objectives: The association between head injury history and subjective cognitive symptoms among contact sport athletes has been frequently reported, but links between head injury history and performance-based measures have been more variable. Dispersion-based intraindividual variability (IIV) may better align with subjective cognitive concerns and be a more sensitive measure of subtle head injury-related changes. This study investigated the associations among IIV, subjective cognitive symptoms, and head injury history. Methods: Former collegiate football players (N = 57 included in analyses; age = 38 ± 1.5 years) completed evaluations consisting of neuropsychological assessment, subjective rating of cognition (Neuro-QoL Cognitive Functioning-Short Form and Behavior Rating Inventory of Executive Function-Adult; BRIEF-A), and structured interviews of head impact history (i.e. HIEE). Three IIV indices were calculated reflecting degree of dispersion across cognitive domains: Memory-IIV, reaction time/processing speed-IIV (RT/PS-IIV), and attention/executive function-IIV. General linear models were fit to test associations among IIV, subjective measures, concussion history, and Head Impact Exposure Estimate (HIEE). Results: Greater history of concussion and RHI exposure were not significantly associated with levels of cognitive dispersion (IIV indices, p's >.05). Worse general subjective cognition was associated with greater RT/PS-IIV, and worse BRIEF-A metacognition was associated with greater memory-IIV, even when controlling for psychological distress and sleep quality. Conclusions: Results support the assessment of dispersion in cognitive performance as a useful objective measure that complements subjective cognitive symptoms. While IIV is clinically relevant for detecting subtle cognitive difficulties not captured by central tendency methods, it may only indirectly, if at all, relate to changes associated specifically with head injury history.

The Healthy Brain 9 (HB9): A New Instrument to Characterize Subjective Cognitive Decline, and Detect Anosognosia in Mild Cognitive Impairment

Objectives

Subjective cognitive decline (SCD) affects 10% of older adults and may be a risk factor for future mild cognitive impairment (MCI) and dementia. Some individuals with MCI have anosognosia, the denial or lack of awareness of their cognitive deficits. We developed and tested the Healthy Brain 9 (HB9), a self-reported assessment of cognitive performance and everyday functioning, in a diverse community-based cohort of older adults in South Florida.

Design

Cross-sectional study.

Setting

Community-based longitudinal study of brain health.

Participants

A total of 344 participants (mean age of 68.5±9.3y, 70% were female, 62% with 16 or less years of education, 39% ethnoracial minorities) completed the study. The sample included 42% normal cognition, 27% SCD and 30% MCI. Within the MCI group, 62% demonstrated awareness of cognitive deficits and 38% had MCI with anosognosia.

Measurements

The psychometric properties of the HB9 were examined and the performance of the HB9 was compared to Gold Standard comprehensive clinical-cognitive-functional-behavioral evaluations and biomarkers evaluations from the Healthy Brain Initiative at the University of Miami.

Results

The HB9 had strong psychometric properties with a Cronbach α of 0.898 (95%CI: 0.882-0.913) and low floor and ceiling effects. The HB9 performed well across different sociodemographic groups. Lower HB9 scores were associated with greater resilience, better physical performance, and less physical frailty. Higher HB9 scores were associated with more comorbid medical conditions, more mood symptoms, lower resilience, and more functional impairment. A cut-off score of 4 on the HB9 provided a 15-fold ability to detect SCD in cognitively normal individuals, and a 14-fold ability to detect anosognosia in MCI.

Conclusions

The use of the HB9 as an assessment of subjective cognitive complaints may help identify SCD for potential interventions and enrollment into clinical trials. The HB9 may also identify anosognosia which could lead to worse outcomes in MCI.

The impact of depression and anxiety on the correlation between somatic symptom disorder and subjective cognitive decline in the Chinese elderly population: an exploration by simple, serial, and moderated mediation models

Background

Somatic symptom disorder (SSD) exacerbates subjective cognitive decline (SCD). This association can be significantly impacted by the mental well-being of the SSD patients. However, the underlying mechanisms remain obscure.

Methods

A total of 525 elderly patients, who visited the Department of Neurology of Fujian Medical University Union Hospital between October 2017 and August 2024, and the Department of Neurology of Quanzhou First Hospital Affiliated to Fujian Medical University between August 2022 and August 2024, were included in the study. Data of sociodemographics, medical history, somatic symptom disorder, subjective cognitive decline, depression, and anxiety were analyzed by simple, serial and moderated mediation models to evaluate the impact of depression and anxiety on the linkage between SSD and SCD.

Results

SSD significantly affected SCD. Simple mediation analysis showed that depression and anxiety significantly mediated the association between SSD and SCD (βdepression = 0.079, 95% CI: 0.030 to 0.132; βanxiety = 0.058, 95% CI: 0.031 to 0.093). Serial mediation analyses indicated that the worsening of SSD exacerbates anxiety, in turn aggravating depressive symptoms and SCD (β b  = 0.044, 95% CI: 0.026 to 0.069). Moderated mediation model revealed that the depressive symptoms-conferred mediation of the correlation between SSD and SCD was moderated by anxiety symptoms (β = -0.073, 95% CI: -0.131 to -0.014).

Conclusion

These findings provided new insights into possible avenues for prevention and intervention of SCD through SSD-based treatments with a multifaceted approach to psychiatric disorders.

Managing cognitive impairment in Parkinson's disease: an update of the literature

INTRODUCTION

Cognitive impairment in Parkinson's disease (PD) substantially affects patient outcomes, function, and quality of life. PD-related cognitive dysfunction is often heterogeneous in clinical presentation and rates of progression. As cognitive changes occur in many people with PD, it is essential to evaluate cognition, provide education, and implement management strategies for cognitive symptoms.

AREAS COVERED

This article describes the symptomatology, epidemiology, risk factors, and pathobiology of cognitive impairment in PD. Additionally, the article provides an overview of evidence-based management and other therapeutic and coping strategies for cognitive impairment and dementia in PD. Comment is offered on challenges and opportunities for trials and emerging therapeutics targeting cognitive symptoms or decline.

EXPERT OPINION

While our understanding of cognitive dysfunction in PD has grown, effective and safe therapeutics are still needed to not only treat cognitive impairment and dementia symptomatically but also slow down or prevent cognitive decline. Further research is needed to elucidate the pathobiology of PD cognitive impairment, develop validated biomarkers reflecting cognitive change, and ultimately, integrate clinical and biological frameworks. Consensus regarding cognitive evaluations, definitions, and criteria of cognitive impairment, evaluating functional abilities in the context of cognitive impairment, and determining optimal outcome measures for clinical trials remain unmet needs.

Gait, balance, and physical performance as markers of early Alzheimer's disease and related dementia risk

BACKGROUND

Declining physical functionality is an indicator of cognitive impairment, distinguishing normal cognition (NC) from dementia. Whether this extends to pre-dementia stages is unclear.

OBJECTIVE

Assess physical performance patterns, evaluate relationships with imaging biomarkers, and identify specific measures distinguishing NC, subjective cognitive decline (SCD) and mild cognitive impairment (MCI).

METHODS

Group differences (78 NC, 35 SCD, and 41 MCI) in physical function (global function, balance, gait speed, step length, single leg support) were evaluated with logistic regression while distinguishing between MCI due-to-AD and MCI due-to-vascular etiology. Relationships with imaging biomarkers (cortical atrophy score, white matter hyperintensities volumes) were analyzed with ANCOVA.

RESULTS

Participants were 68.6 ± 9.3 years old, had 16.2 ± 3.0 years of education, and 23% were ethnoracial minorities. Physical performance distinguished MCI from NC and SCD. Greater performance on the Mini Physical Performance Test (mini PPT) and balance were associated with lower odds of being SCD versus NC (ORmini PPT = 0.73; 95% CI:0.56-0.97; ORbalance = 0.35, 95%CI:0.16-0.80). AD etiology accounted for most group differences in physical performance versus vascular etiology. Consistent associations between biomarkers, physical performance, and cognition were found.

CONCLUSIONS

Findings suggest that: 1) changes in mini PPT performance and balance may help detect cognitive impairments, as early as the SCD stage; 2) changes in gait speed, gait cycle parameters, and Timed Up-and-Go may indicate more significant cognitive impairment; 3) neuronal loss is linked to subtle changes in physical functionality as early as SCD. Physical performance may be a valuable tool in early dementia detection in clinical settings and could identify targets for early intervention.

A mobile-based multidomain lifestyle intervention using Cognitive Evergreenland for older adults with subjective cognitive decline: a feasibility study

BACKGROUND

Dementia is a growing public health issue. Non-drug interventions targeting individuals before the onset of overt cognitive decline may be effective. Subjective cognitive decline (SCD) is present in > 50% of older adults and associated with progression to dementia. Here, we tested the compliance and effectiveness of a Multidomain Lifestyle Intervention Program using the mini-program, Cognitive Evergreenland, (MLIP-CE), based on the Health Action Process Approach model to support home-based intervention in older adults with SCD.

METHODS

Cognitive Evergreenland was designed to improve cognitive reserve and maintain brain function in people at high risk of dementia and included: cognitive stimulation, cognitive training, health education, vascular risk monitoring, social support, and functional assessment, among other features. This was an exploratory trial designed to examine participant compliance with the mobile lifestyle intervention and its effectiveness, as well as changes in health-related indicators and cognitive function of older adults with SCD from baseline to 12 and 24 weeks post-intervention.

RESULTS

The retention rate for MLIP-CE was 90.2% (37/41). Mean participant age was 70.93 ± 6.91 years, 73.2% of participants were female, and mean Montreal Cognitive Assessment score was 24.51 ± 2.87. Throughout the 24 weeks of the prescribed intervention, app usage remained consistently high, with over 92% of participants using the mini-program at least once a week and successfully completing corresponding health management tasks. In terms of average usage, cognitive training emerged as the most frequently used functional module (95.73%), closely followed by health education (95.02%). The health behavior levels of older adults with SCD, measured in terms of ability, opportunity, and motivation, were significantly increased relative to baseline (p < 0.001). Regarding cognitive function, Mini-Mental State Examination scores were significantly improved post-intervention, with a moderate effect size (Hedges' g = 0.60).

CONCLUSIONS

These findings suggest that MLIP-CE, which was designed based on a theoretical framework, has potential for implementation, and support ongoing research into use of MLIP-CE for individuals at high risk of SCD or other dementia conditions.

TRIAL REGISTRATION

The trial was prospectively registered at the Chinese Clinical Trials Registry with the registration number ChiCTR2200058665 on 13 April 2022.

Updated Appropriate Use Criteria for Amyloid and Tau PET: A Report from the Alzheimer's Association and Society for Nuclear Medicine and Molecular Imaging Workgroup

The Alzheimer's Association and the Society of Nuclear Medicine and Molecular Imaging convened a multidisciplinary workgroup to update appropriate use criteria (AUC) for amyloid positron emission tomography (PET) and to develop AUC for tau PET. Methods: The workgroup identified key research questions that guided a systematic literature review on clinical amyloid/tau PET. Building on this review, the workgroup developed 17 clinical scenarios in which amyloid or tau PET may be considered. A modified Delphi approach was used to rate each scenario by consensus as "rarely appropriate," "uncertain," or "appropriate." Ratings were performed separately for amyloid and tau PET as stand-alone modalities. Results: For amyloid PET, 7 scenarios were rated as appropriate, 2 as uncertain, and 8 as rarely appropriate. For tau PET, 5 scenarios were rated as appropriate, 6 as uncertain, and 6 as rarely appropriate. Conclusion: AUC for amyloid and tau PET provide expert recommendations for clinical use of these technologies in the evolving landscape of diagnostics and therapeutics for Alzheimer's disease.

Subjective cognitive decline predicts longitudinal neuropsychological test performance in an unsupervised online setting in the Brain Health Registry

BACKGROUNDS

Digital, online assessments are efficient means to detect early cognitive decline, but few studies have investigated the relationship between remotely collected subjective cognitive change and cognitive decline. We hypothesized that the Everyday Cognition Scale (ECog), a subjective change measure, predicts longitudinal change in cognition in the Brain Health Registry (BHR), an online registry for neuroscience research.

METHODS

This study included BHR participants aged 55 + who completed both the baseline ECog and repeated administrations of the CANTAB® Paired Associates Learning (PAL) visual learning and memory test. Both self-reported ECog (Self-ECog) and study partner-reported ECog (SP-ECog), and two PAL scores (first attempt memory score [FAMS] and total errors adjusted [TEA]) were assessed. We estimated associations between multiple ECog scoring outputs (ECog positive [same or above cut-off score], ECog consistent [report of consistent decline in any item], and total score) and longitudinal change in PAL. Additionally we assessed the ability of ECog to identify 'decliners', who exhibited the worst PAL progression slopes corresponding to the fifth percentile and below.

RESULTS

Participants (n = 16,683) had an average age of 69.07 ± 7.34, 72.04% were female, and had an average of 16.66 ± 2.26 years of education. They were followed for an average of 2.52 ± 1.63 visits over a period of 11.49 ± 11.53 months. Both Self-ECog positive (estimate = -0.01, p < 0.001, R²m = 0.56) and Self-ECog consistent (estimate=-0.01, p = 0.002, R²m = 0.56) were associated with longitudinal change in PAL FAMS after adjusting demographics and clinical confounders. Those who were Self-ECog total (Odds ratio [95% confidence interval] = 1.390 [1.121-1.708]) and SP-ECog consistent (2.417 [1.591-3.655]) had higher probability of being decliners based on PAL FAMS.

CONCLUSION

In the BHR's unsupervised online setting, baseline subjective change was feasible in predicting longitudinal decline in neuropsychological tests. Online, self-administered measures of subjective cognitive change might have a potential to predict objective subjective change and identify individuals with cognitive impairments.

Frailty Risk Patterns and Mortality Prediction in Community-Dwelling Older Adults: A 3-Year Longitudinal Study

OBJECTIVES

Frailty is a heterogeneous syndrome with distinct patterns. This study aimed to identify frailty risk patterns and their predictive value for mortality in older adults.

DESIGN

Prospective longitudinal study.

SETTING AND PARTICIPANTS

Data were obtained from a 2017 survey of 609 independently mobile adults aged 65 years and older in suburban Japan, focusing on those at risk for at least 1 frailty dimension.

METHODS

Frailty assessments were extracted from the Kihon checklist, and subgroups were identified using latent class analysis. Associations between frailty patterns and 3-year mortality were assessed using Kaplan-Meier survival analysis and Cox proportional hazards modeling.

RESULTS

Three frailty patterns were identified: "high risk of cognitive impairment" (76.0%), "moderate risk of cognitive, physical, and oral dysfunction" (14.3%), and "high risk of cognitive, physical, and functional decline" (9.7%). We recorded 52 deaths during a mean follow-up time of 25.7 months (standard deviation: 12.6) and a median follow-up time of 26.5 months. Kaplan-Meier analysis showed significant survival differences among the groups (log-rank: P < .001). Compared with the high risk of cognitive impairment group, the moderate risk of cognitive, physical, and oral dysfunction group had a 145% higher mortality risk (adjusted hazard ratio, 2.45; 95% confidence interval, 1.22-4.90), while the high risk of cognitive, physical, and functional decline group exhibited a 220% higher risk of mortality (adjusted hazard ratio, 3.20; 95% confidence interval, 1.53-6.70).

CONCLUSIONS AND IMPLICATIONS

The findings reveal the heterogeneity of frailty among community-dwelling Japanese older adults, with a high prevalence of cognitive impairment risk. The subgroup with risk of cognitive, physical, and functional decline had the highest mortality risk, highlighting the need for multidimensional assessment and intervention.

Association between BrainAGE and Alzheimer's disease biomarkers

INTRODUCTION

The brain age gap estimation (BrainAGE) method uses a machine learning model to generate an age estimate from structural magnetic resonance imaging (MRI) scans. The goal was to study the association of brain age with Alzheimer's disease (AD) imaging and plasma biomarkers.

METHODS

One hundred twenty-three individuals from the Indiana Memory and Aging Study underwent structural MRI, amyloid and tau positron emission tomography (PET), and plasma sampling. The MRI scans were processed using the software program BrainAgeR to receive a "brain age" estimate. Plasma biomarker concentrations were measured, and partial Pearson correlation models were used to evaluate their relationship with brain age gap (BAG) estimation (BrainAGE = chronological age - MRI estimated brain age).

RESULTS

Significant associations between BAG and amyloid and tau levels on PET and in plasma were observed depending on diagnostic categories.

DISCUSSION

These findings suggest that BAG is potentially a biomarker of pathology in AD which can be applied to routine brain imaging.

Highlights

Novel research that uses an artificial intelligence learning tool to estimate brain age.Findings suggest that brain age gap is associated with plasma and positron emission tomography Alzheimer's disease (AD) biomarkers.Differential relationships are seen in different stages of disease (preclinical vs. clinical).Results could play a role in early AD diagnosis and treatment.

Unstable functional brain states and reduced cerebro-cerebellar modularity in elderly individuals with subjective cognitive decline

The preclinical stage of Alzheimer's Disease (AD) holds great potential for intervention, therefore, it is crucial to elucidate the neural mechanisms underlying the progression of subjective cognitive decline (SCD). Previous studies have predominantly focused on the neural changes in the cerebrum associated with SCD, but have relatively neglected the cerebellum, and its functional relationship with the cerebrum. In the current study, we employed dynamic functional connectivity and large-scale brain network approaches to investigate the pathological characteristics of dynamic brain states and cerebro-cerebellar collaboration between SCD (n = 32) and the healthy elderly (n = 29) using resting-state fMRI. Two-way repeated measures ANOVA and permutation t-tests revealed significant group differences, with individuals with SCD exhibiting shorter state duration and more frequent transitions between states compared to the healthy elderly individuals. Additionally, individuals with SCD showed lower levels of intracerebellar functional connectivity, but higher levels of cerebellar-cerebral functional integration. Furthermore, the hub nodes of the functional networks in SCD shifted between the cerebellum and cerebrum across different brain states. These findings indicate that SCD exhibits greater state instability but may compensate for the negative effects of early disease by integrating cerebellar and cerebral networks, thereby maintaining cognitive performance. This study enhances our theoretical understanding of cerebellar-cerebral relationship changes in the early stages of AD and provides evidence for early interventions targeting the cerebellum.

Updated appropriate use criteria for amyloid and tau PET: A report from the Alzheimer's Association and Society for Nuclear Medicine and Molecular Imaging Workgroup

INTRODUCTION

The Alzheimer's Association and the Society of Nuclear Medicine and Molecular Imaging convened a multidisciplinary workgroup to update appropriate use criteria (AUC) for amyloid positron emission tomography (PET) and to develop AUC for tau PET.

METHODS

The workgroup identified key research questions that guided a systematic literature review on clinical amyloid/tau PET. Building on this review, the workgroup developed 17 clinical scenarios in which amyloid or tau PET may be considered. A modified Delphi approach was used to rate each scenario by consensus as "rarely appropriate," "uncertain," or "appropriate." Ratings were performed separately for amyloid and tau PET as stand-alone modalities.

RESULTS

For amyloid PET, seven scenarios were rated as appropriate, two as uncertain, and eight as rarely appropriate. For tau PET, five scenarios were rated as appropriate, six as uncertain, and six as rarely appropriate.

DISCUSSION

AUC for amyloid and tau PET provide expert recommendations for clinical use of these technologies in the evolving landscape of diagnostics and therapeutics for Alzheimer's disease.

HIGHLIGHTS

A multidisciplinary workgroup convened by the Alzheimer's Association and the Society of Nuclear Medicine and Molecular Imaging updated the appropriate use criteria (AUC) for amyloid positron emission tomography (PET) and to develop AUC for tau PET. The goal of these updated AUC is to assist clinicians in identifying clinical scenarios in which amyloid or tau PET may be useful for guiding the diagnosis and management of patients who have, or are at risk for, cognitive decline These updated AUC are intended for dementia specialists who spend a significant proportion of their clinical effort caring for patients with cognitive complaints, as well as serve as a general reference for a broader audience interested in implementation of amyloid and tau PET in clinical practice.

Cognitive, Behavioral, and Functional Outcomes of Suspected Mild Traumatic Brain Injury in Community-Dwelling Older Persons Without Mild Cognitive Impairment or Dementia

BACKGROUND

Traumatic brain injury is associated with greater risk and earlier onset of dementia.

OBJECTIVE

This study investigated whether later-life changes in subjective cognition and behavior - potential markers of Alzheimer disease - could be observed in cognitively unimpaired older persons with a history of suspected mild traumatic brain injury (smTBI) earlier in life and whether changes in cognition and behavior mediated the link between smTBI and daily function.

METHODS

Data for 1392 participants from the Canadian Platform for Research Online to Investigate Health, Quality of Life, Cognition, Behaviour, Function, and Caregiving in Aging were analyzed. A validated self-reported brain injury screening questionnaire was used to determine the history of smTBI. Outcomes were measured using the Everyday Cognition scale (for subjective cognitive decline [SCD]), Mild Behavioral Impairment (MBI) Checklist, and Standard Assessment of Global Everyday Activities (for function). Inverse probability of treatment weighted logistic and negative binomial regressions were used to model smTBI (exposure) associations with SCD and MBI statuses, and Everyday Cognition-II and MBI Checklist total scores, respectively. Mediation analyses were conducted using bootstrapping.

RESULTS

History of smTBI was linked to higher odds of SCD (odds ratio = 1.45, 95% confidence interval: [1.14-1.84]) or MBI (odds ratio = 1.75, 95% confidence interval: [1.54-1.98]), as well as 24% (95% confidence interval: [18%-31%]) higher Everyday Cognition-II and 52% (95% confidence interval: [41%-63%]) higher MBI Checklist total scores. Finally, SCD and MBI mediated approximately 45% and 56%, respectively, of the association between smTBI history and poorer function, as indicated by higher Standard Assessment of Global Everyday Activities total scores.

CONCLUSIONS

smTBI at any point in the life course is linked to poorer cognition and behavior even in community-dwelling older persons without MCI or dementia. Older persons with smTBI may benefit from early dementia risk assessment using tools that measure changes in cognition and behavior. Interventions for declining cognition and behavior may also be beneficial in this population to address functional impairment.

Development of the subjective cognitive function decline scale for middle-aged Koreans

OBJECTIVES

This study developed the Subjective Cognitive Function Decline Scale for Middle-aged South Koreans (SCFD-K), addressing the need for early detection of potential mild cognitive impairment. This study fills a gap in the existing research, which mainly targeted older demographics or generalized cultural differences.

METHOD

We conducted focus group interviews (FGIs) among 36 participants and with nine experts to answer basic questions related to cognitive decline, after which we developed a draft scale using the Delphi with another 15 experts. To examine the reliability and validity of the scale, an online survey of 2,000 people was conducted.

RESULTS

An exploratory factor analysis identified four distinct factors, which are language, visuospatial function, personality/emotion, and memory, with a total of 20 items (Cumulative variance ratio = 57.76), and a confirmatory factor analysis validated the four-factor structure with a good model fit (CFI = 0.932, TLI = 0.921, RMSEA = 0.057, and SRMR = 0.042) and acceptable internal consistency (Cronbach's α = 0.735-0.907).

CONCLUSION

This analysis established the SCFD-K as a reliable and valid tool for assessing cognitive decline among middle-aged South Koreans. The findings have key cultural implications and inform proactive interventions and shaping future healthcare strategies in South Korea.

Memory benefits of daily-living-related contextual cueing for individuals with subjective cognitive decline and mild cognitive impairment

Objective

We aimed to assess how daily-living-related contextual cueing (DLCC) affects memory performance in three groups: healthy older adults (HA), those with subjective cognitive decline (SCD), and mild cognitive impairment (MCI), while accounting for age and education.

Methods

After gathering demographic information, participants underwent neuropsychological assessments including the Montreal Cognitive Assessment (MoCA), Everyday Cognition Scale (ECog-12), Mini Mental State Examination (MMSE), Geriatric Depression Scale (GDS), and Trail Making Test (TMT) to establish baseline characteristics. Participants were categorized into HA (N = 47), SCD (N = 54), and MCI (N = 43) groups based on MoCA and ECog-12 scores. Memory performance was evaluated through two components of the Contextual Memory Test (CMT): one with non-contextual cues and the other with daily-living-related contextual cues.

Results

Interaction effects between contextual cueing and group for immediate recall (p < .001), delayed recall (p < .001), and total recall (p < .001) were found. All recall scores were lower in the MCI group than in the other two groups in the contextual cueing, not non-contextual. The post-hoc results revealed that scores on immediate recall, delayed recall, and total recall were lower in the MCI group than in the other two groups in the contextual cueing condition but not in the non-contextual cueing one.

Conclusions

Daily-living-related contextual cueing benefited HA, SCD, and younger-adult MCI groups more than older-adult MCI group, particularly enhancing delayed and total memory performance.

Structural disruption in subjective cognitive decline and mild cognitive impairment

Subjective cognitive decline (SCD) marks the initial stage in Alzheimer's disease continuum. Nonetheless, current research findings regarding brain structural changes in the SCD are inconsistent. In this study, 37 SCD patients, 28 mild cognitive impairment (MCI) patients, and 42 healthy controls (HC) were recruited to investigate structural alterations. Morphological and microstructural differences among the three groups were analyzed based on T1- and diffusion-weighted images, correlating them with neuropsychological assessments. Additionally, classification analysis was performed by using support vector machines (SVM) categorize participants into three groups based on MRI features. Both SCD and MCI showed decreased volume in left inferior parietal lobe (IPL) compared to HC, while SCD showed altered morphologies in the right inferior temporal gyrus (ITG), right insula and right amygdala, and microstructures in fiber tracts of the right ITG, lateral occipital cortex (LOC) and insula relative to MCI. Moreover, the volume in the left IPL, right LOC, right amygdala and diffusivity value in fiber tracts of right LOC were significantly correlated with cognitive functions across all subjects. The classification models achieved an accuracy of > 0.7 (AUC = 0.8) in distinguishing the three groups. Our findings suggest that SCD and MCI share similar atrophy in the IPL but show more differences in morphological and microstructural features of cortical-subcortical areas.

A short version of the Everyday Cognition scale can predict clinical progression and cognitive decline

BACKGROUND

The Everyday Cognition scale (ECog-39) scores are associated with future cognitive decline. We investigated whether the 12-item ECog (ECog-12), which is being collected in Alzheimer's Disease Neuroimaging Initiative (ADNI)4, can predict progression.

METHODS

Baseline self (PT)- and study partner (SP)-ECog-12 data were extracted from the 39-item version collected in the ADNI. Weibull analysis examined the relationship between baseline ECog-12 and future clinical progression (change in Clinical Dementia Rating Sum of Boxes [CDR-SB] scores and diagnostic conversion).

RESULTS

Higher PT- and SP-ECog-12 scores were associated with faster CDR-SB worsening, with hazard ratios in cognitively unimpaired (CU) 3.34 and 9.61, mild cognitive impairment (MCI) 1.44 and 2.82, and dementia 0.93 and 1.82. They were associated with conversion from CU to MCI 3.01 and 6.24 and MCI to dementia 1.61 and 3.07.

DISCUSSION

SP-ECog-12 provided a higher prognostic value for predicting clinical progression, so this can help identify and monitor patients at risk in research and health-care settings.

HIGHLIGHTS

The 12-item Everyday Cognition scale (ECog-12) data obtained from both raters increased diagnostic conversion risk from cognitively unimpaired to mild cognitive impairment (MCI) and from MCI to dementia. ECog-12, rated by study partners, was associated with an increased risk of Clinical Dementia Rating Sum of Boxes worsening in all diagnostic groups. Our results provide novel information about the specific scoring outputs and rater types (participant vs. study partner) of ECog-12 that can facilitate screening, prioritization, and longitudinal monitoring of the clinical progression of participants in Alzheimer's Disease Neuroimaging Initiative 4 and other Alzheimer's disease clinical studies, clinical trials, and in health-care settings.

Exploring easily accessible neurophysiological biomarkers for predicting Alzheimer's disease progression: a systematic review

Alzheimer disease (AD) remains a significant global health concern. The progression from preclinical stages to overt dementia has become a crucial point of interest for researchers. This paper reviews the potential of neurophysiological biomarkers in predicting AD progression, based on a systematic literature search following PRISMA guidelines, including 55 studies. EEG-based techniques have been predominantly employed, whereas TMS studies are less common. Among the investigated neurophysiological measures, spectral power measurements and event-related potentials-based measures, including P300 and N200 latencies, have emerged as the most consistent and reliable biomarkers for predicting the likelihood of conversion to AD. In addition, TMS-based indices of cortical excitability and synaptic plasticity have also shown potential in assessing the risk of conversion to AD. However, concerns persist regarding the methodological discrepancies among studies, the accuracy of these neurophysiological measures in comparison to established AD biomarkers, and their immediate clinical applicability. Further research is needed to validate the predictive capabilities of EEG and TMS measures. Advancements in this area could lead to cost-effective, reliable biomarkers, enhancing diagnostic processes and deepening our understanding of AD pathophysiology.

Racial discrimination predicts subjective cognitive decline: Perceived relationship support buffers the association

OBJECTIVES

Recent studies show that chronic exposure to racial discrimination increases the occurrence of subjective cognitive decline (SCD) among Black Americans. Little research, however, has examined potential for protective factors, such as perceived partner support, to buffer these effects.

METHODS

This study utilized longitudinal data over a 10-year period from the Family and Community Health Study (FACHS) to examine the associations between experiences of racial discrimination, marital status, partner support, and SCD, measured by the Everyday Cognition (ECog) Scale, among 286 middle-aged Black American women. Regression analysis and internal moderator analyses were employed to analyze the data.

RESULTS

About 31% were in married relationships. Thirty-four percent reported cognitive decline, especially in forgetting object locations and dates. Chronic discrimination predicted SCD, and for those in couple relationships, partner support buffered the adverse effects of discrimination, with those in warm and supportive relationships experiencing less SCD than those in relatively unsupportive relationships or not in a relationship.

CONCLUSIONS

The study's findings support the idea that racism influences SCD and underscores the importance of supportive couple relationships in promoting resilience. The results also highlight the potential value of culturally relevant family interventions and support strategies to reduce the impact of discrimination-induced stress on cognitive health.

Self-reported hearing loss is associated with faster cognitive and functional decline but not diagnostic conversion in the ADNI cohort

INTRODUCTION

Hearing loss is identified as one of the largest modifiable risk factors for cognitive impairment and dementia. Studies evaluating this relationship have yielded mixed results.

METHODS

We investigated the longitudinal relationship between self-reported hearing loss and cognitive/functional performance in 695 cognitively normal (CN) and 941 participants with mild cognitive impairment (MCI) enrolled in the Alzheimer's Disease Neuroimaging Initiative.

RESULTS

Within CN participants with hearing loss, there was a significantly greater rate of cognitive decline per modified preclinical Alzheimer's cognitive composite. Within both CN and MCI participants with hearing loss, there was a significantly greater rate of functional decline per the functional activities questionnaire (FAQ). In CN and MCI participants, hearing loss did not significantly contribute to the risk of progression to a more impaired diagnosis.

DISCUSSION

These results confirm previous studies demonstrating a significant longitudinal association between self-reported hearing loss and cognition/function but do not demonstrate an increased risk of conversion to a more impaired diagnosis.

CLINICAL TRIAL REGISTRATION INFORMATION

NCT00106899 (ADNI: Alzheimer's Disease Neuroimaging Initiative, clinicaltrials.gov), NCT01078636 (ADNI-GO: Alzheimer's Disease Neuroimaging Initiative Grand Opportunity, clinicaltrials.gov), NCT01231971 (ADNI2: Alzheimer's Disease Neuroimaging Initiative 2, clinicaltrials.gov), NCT02854033 (ADNI3: Alzheimer's Disease Neuroimaging Initiative 3, clinicaltrials.gov).

HIGHLIGHTS

Hearing loss is a potential modifiable risk factor for dementia. We assessed the effect of self-reported hearing loss on cognition and function in the ADNI cohort. Hearing loss contributes to significantly faster cognitive and functional decline. Hearing loss was not associated with conversion to a more impaired diagnosis.

Subjective cognitive decline and cognitive change among diverse middle-aged and older Hispanic/Latino adults: Results from the Study of Latinos-Investigation of Neurocognitive Aging (SOL-INCA)

INTRODUCTION

The potential utility of subjective cognitive decline (SCD) as an early risk marker of Alzheimer's disease and related dementias is under consideration. We examined associations between SCD and cognitive change among middle-aged and older Hispanic/Latino adults living in the United States.

METHODS

The short-form Everyday Cognition Scale (ECog-12) was assessed to generate global, executive function, and memory-related SCD scores. We used survey generalized regressions to model the change in learning, memory, verbal fluency, executive function, and global cognitive performance over 7 years as a function of SCD (at Visit 2).

RESULTS

The mean age was 56.37 ± 8.10 years at Visit 1 (n = 6225). Higher ECog-12 was associated with greater decline in global cognitive performance (ECog-12 global: B = -0.17, standard error [SE] = 0.02; ECog-12 executive: B = -0.15, SE = 0.02; ECog-12 memory: B = -0.14, SE = 0.02, p's < 0.001).

DISCUSSION

These results support the link between subjective reports of cognitive decline and objectively measured 7-year cognitive decline in community-dwelling, middle-aged, and older Hispanic/Latino adults.

HIGHLIGHTS

We found that nearly two-thirds of diverse middle-aged and older Hispanics/Latinos reported cognitive concerns in a large and representative population study. Self-reported subjective experiences of cognitive decline reflect objective cognitive decline in US Hispanics/Latinos. The relationship is stronger among men compared to women. The relationship between subjective and objective changes to memory are stronger in those with cognitive concerns, and remain even in cognitively healthy individuals.

Accelerated long-term forgetting: from subjective memory decline to a defined clinical entity

Subjective memory decline (SMD) might represent the preclinical phase of Alzheimer's disease (AD), and has been reported in epileptic amnesia associated with accelerated long-term forgetting (ALF). We investigated ALF in SMD subjects by means of RAVLT recall and recognition and ROCF recall after 1-week retention and compared with a control group. Two-way ANOVAs for RAVLT and ROCF were conducted, and stepwise regression analysis was administered considering EMQ and DASS-21 as factors. SMD subjects performed significantly worse than controls at 1-week delay on RAVLT recall and recognition, but not on ROCF, and not associated with depression or memory complaints. SMD patients showed ALF, which is usually associated with temporomesial dysfunctions, representing a cognitive marker to assess objectively memory problems in SMD, and to undisclose initial neurodegenerative disease involving temporal structures usually compromised in AD. Therefore, SMD might no longer be "subjective," but rather a specific and defined clinical entity.

Association Between Dietary Diversity and Subjective Cognitive Decline in the Middle-Aged and Elderly Chinese Population: A Cross-Sectional Study

BACKGROUND

This cross-sectional study aimed to examine the association between dietary diversity and risk of subjective cognitive decline (SCD), a precursor of dementia, in middle-aged and elderly Chinese populations residing in eastern China.

METHODS

Participants aged ≥ 45 years were recruited from a community in an eastern Chinese city after excluding potential objective cognitive impairment using the Mini-Cognitive Assessment Instrument (Mini-Cog). SCD was assessed using the Subjective Cognitive Decline Questionnaire-9 (SCD-Q9). Dietary data were collected using the Dietary Quality Questionnaire (DQQ), and the Food Group Diversity Score (FGDS) and the Consumed All Five Recommended Food Score (All-5) were calculated as indicators of dietary diversity. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed to evaluate the associations of FGDS and All-5 scores with SCD after adjusting for age, sex, socioeconomic status, lifestyle factors, and health status.

RESULTS

Among the 871 participants, 358 (41.1%) were classified as having SCD. Compared with participants with the highest FGDS (≥8) and those with the highest All-5 score (5), those with the lowest FGDS (≤4) and the lowest All-5 score (≤3) exhibited 85% (OR = 1.85; 95% CI: 1.10-3.13; p = 0.02) and 90% (OR = 1.90; 95% CI: 1.21-2.97; p < 0.01) higher risk of SCD, respectively, after adjusting for all covariates. Fruits were the only food group among the All-5 components that demonstrated a significant association with SCD risk.

CONCLUSIONS

Poor dietary diversity was associated with an elevated risk of SCD in middle-aged and older adults, and fruits were the food group with the most substantial effect.

Cognitive synaptopathy: synaptic and dendritic spine dysfunction in age-related cognitive disorders

Cognitive impairment is a leading component of several neurodegenerative and neurodevelopmental diseases, profoundly impacting on the individual, the family, and society at large. Cognitive pathologies are driven by a multiplicity of factors, from genetic mutations and genetic risk factors, neurotransmitter-associated dysfunction, abnormal connectomics at the level of local neuronal circuits and broader brain networks, to environmental influences able to modulate some of the endogenous factors. Otherwise healthy older adults can be expected to experience some degree of mild cognitive impairment, some of which fall into the category of subjective cognitive deficits in clinical practice, while many neurodevelopmental and neurodegenerative diseases course with more profound alterations of cognition, particularly within the spectrum of the dementias. Our knowledge of the underlying neuropathological mechanisms at the root of this ample palette of clinical entities is far from complete. This review looks at current knowledge on synaptic modifications in the context of cognitive function along healthy ageing and cognitive dysfunction in disease, providing insight into differential diagnostic elements in the wide range of synapse alterations, from those associated with the mild cognitive changes of physiological senescence to the more profound abnormalities occurring at advanced clinical stages of dementia. I propose the term "cognitive synaptopathy" to encompass the wide spectrum of synaptic pathologies associated with higher brain function disorders.

Linking cognitive and behavioral reserve: Evidence from the CAN-PROTECT study

INTRODUCTION

Changes to the brain due to Alzheimer's disease and other age-related neuropathologies may present with cognitive and behavioral symptoms, even during preclinical and prodromal stages. While cognitive reserve is known to mitigate cognitive decline in the preclinical stages of Alzheimer's disease, links between cognitive reserve and behavioral symptoms remain unclear. This study investigates the relationship between cognitive reserve and mild behavioral impairment (MBI), a neurodegenerative behavioral prodrome.

METHODS

We analyzed cross-sectional data from 1204 participants in the Canadian Platform for Research Online to Investigate Health, Quality of Life, Cognition, Behavior, Function, and Caregiving in Aging (CAN-PROTECT) study. A cognitive reserve score (CRS) was generated based on education, occupation, and personal cognitive reserve proxies. MBI presence (MBI+) and MBI global and domain symptom severity were evaluated using the self-reported MBI Checklist. Initial analyses examined the convergent validity of the CRS through associations with objective neuropsychological test performance and self-reported cognitive symptoms (Everyday Cognition [ECog-II] scale). Models were also fitted to assess MBI status and severity as functions of the CRS.

RESULTS

Higher CRS was associated with better neuropsychological test scores, lower odds of subjective cognitive decline (OR = 0.86, 95% CI: [0.76, 0.98], p = .03), and lower ECog-II total score. Likewise, higher CRS was associated with lower odds of MBI+ (OR = 0.81, 95% CI: [0.71, 0.93], p = .003), and lower MBI symptom severity globally, and in impulse dyscontrol and social inappropriateness domains.

DISCUSSION

We provide preliminary evidence that engagement in activities known to preserve cognitive function in aging and disease may also preserve behavioral function. Future research should disentangle possible pathways through which cognitive reserve may preserve both cognition and behavior, explore common etiologies for these symptoms, and observe outcomes longitudinally to better understand these relationships.

Highlights

Education, occupation, and personal activities are cognitive reserve proxies.Cognitive reserve is linked to lower subjective cognitive decline in older persons.Cognitive reserve is linked to lower mild behavioral impairment odds and severity.

Specific Association of Worry With Amyloid-β But Not Tau in Cognitively Unimpaired Older Adults

OBJECTIVE

Anxiety disorders and subsyndromal anxiety symptoms are highly prevalent in late life. Recent studies support that anxiety may be a neuropsychiatric symptom during preclinical Alzheimer's disease (AD) and that higher anxiety is associated with more rapid cognitive decline and progression to cognitive impairment. However, the associations of specific anxiety symptoms with AD pathologies and with co-occurring subjective and objective cognitive changes have not yet been established.

METHODS

Baseline data from the A4 and Longitudinal Evaluation of Amyloid Risk and Neurodegeneration studies were analyzed. Older adult participants (n = 4,486) underwent assessments of anxiety (State-Trait Anxiety Inventory-6 item version [STAI]), and cerebral amyloid-beta (Aβ; 18F-florbetapir) PET and a subset underwent tau (18F-flortaucipir) PET. Linear regressions estimated associations of Aβ in a cortical composite and tau in the amygdala, entorhinal, and inferior temporal regions with STAI-Total and individual STAI item scores. Models adjusted for age, sex, education, marital status, depression, Apolipoprotein ε4 genotype, and subjective and objective cognition (Cognitive Function Index-participant; Preclinical Alzheimer Cognitive Composite).

RESULTS

Greater Aβ deposition was significantly associated with higher STAI-Worry, adjusting for all covariates, but not with other STAI items or STAI-Total scores. In mediation analyses, the association of Aβ with STAI-Worry was partially mediated by subjective cognition with a stronger direct effect. No associations were found for regional tau deposition with STAI-Total or STAI-Worry score.

CONCLUSION

Greater worry was associated with Aβ but not tau deposition, independent of subjective and objective cognition in cognitively unimpaired (CU) older adults. These findings implicate worry as an early, specific behavioral marker and a possible therapeutic target in preclinical AD.

An effective screening model for subjective cognitive decline in community-dwelling older adults based on gait analysis and eye tracking

Objective

To evaluate the effectiveness of multimodal features based on gait analysis and eye tracking for elderly people screening with subjective cognitive decline in the community.

Methods

In the study, 412 cognitively normal older adults aged over 65 years were included. Among them, 230 individuals were diagnosed with non-subjective cognitive decline and 182 with subjective cognitive decline. All participants underwent assessments using three screening tools: the traditional SCD9 scale, gait analysis, and eye tracking. The gait analysis involved three tasks: the single task, the counting backwards dual task, and the naming animals dual task. Eye tracking included six paradigms: smooth pursuit, median fixation, lateral fixation, overlap saccade, gap saccade, and anti-saccade tasks. Using the XGBoost machine learning algorithm, several models were developed based on gait analysis and eye tracking to classify subjective cognitive decline.

Results

A total of 161 gait and eye-tracking features were measured. 22 parameters, including 9 gait and 13 eye-tracking features, showed significant differences between the two groups (p < 0.05). The top three eye-tracking paradigms were anti-saccade, gap saccade, and median fixation, with AUCs of 0.911, 0.904, and 0.891, respectively. The gait analysis features had an AUC of 0.862, indicating better discriminatory efficacy compared to the SCD9 scale, which had an AUC of 0.762. The model based on single and dual task gait, anti-saccade, gap saccade, and median fixation achieved the best efficacy in SCD screening (AUC = 0.969).

Conclusion

The gait analysis, eye-tracking multimodal assessment tool is an objective and accurate screening method that showed better detection of subjective cognitive decline. This finding provides another option for early identification of subjective cognitive decline in the community.

Influence of human gut microbiome on the healthy and the neurodegenerative aging

The gut microbiome plays a crucial role in host health throughout the lifespan by influencing brain function during aging. The microbial diversity of the human gut microbiome decreases during the aging process and, as a consequence, several mechanisms increase, such as oxidative stress, mitochondrial dysfunction, inflammatory response, and microbial gut dysbiosis. Moreover, evidence indicates that aging and neurodegeneration are closely related; consequently, the gut microbiome may serve as a novel marker of lifespan in the elderly. In this narrative study, we investigated how the changes in the composition of the gut microbiome that occur in aging influence to various neuropathological disorders, such as mild cognitive impairment (MCI), dementia, Alzheimer's disease (AD), and Parkinson's disease (PD); and which are the possible mechanisms that govern the relationship between the gut microbiome and cognitive impairment. In addition, several studies suggest that the gut microbiome may be a potential novel target to improve hallmarks of brain aging and to promote healthy cognition; therefore, current and future therapeutic interventions have been also reviewed.

Altered functional connectivity of primary olfactory cortex-hippocampus-frontal cortex in subjective cognitive decline during odor stimulation

Subjective cognitive decline (SCD) is a high-risk population in the preclinical stage of Alzheimer's disease (AD), and olfactory dysfunction is a risk factor for dementia progression. The present study aimed to explore the patterns of functional connectivity (FC) changes in the olfactory neural circuits during olfactory stimulation in SCD subjects. A total of 56 SCD subjects and 56 normal controls (NCs) were included. All subjects were assessed with a cognitive scale, an olfactory behavior test, and olfactory task-based functional magnetic resonance imaging scanning. The FC differences in olfactory neural circuits between the two groups were analyzed by the generalized psychophysiological interaction. Additionally, we calculated and compared the activation of brain regions within the olfactory neural circuits during odor stimulation, the volumetric differences in brain regions showing FC differences between groups, and the correlations between neuroimaging indicators and olfactory behavioral and cognitive scale scores. During odor stimulation, the FC between the bilateral primary olfactory cortex (bPOC) and the right hippocampus in the SCD group was significantly reduced; while the FC between the right hippocampus and the right frontal cortex was significantly increased in the SCD group. The bPOC of all subjects showed significant activation, but no significant difference in activation between groups was found. No significant differences were observed in the volume of the brain regions within the olfactory neural circuits or in olfactory behavior between groups. The volume of the bPOC and right frontal cortex was significantly positively correlated with olfactory identification, and the volume of the right frontal cortex and right hippocampus was significantly correlated with cognitive functions. Furthermore, a significant correlation between the activation of bPOC and the olfactory threshold was found in the whole cohort. These results suggested that while the structure of the olfactory neural circuits and olfactory behavior in SCD subjects remained stable, there were significant changes observed in the FC of the olfactory neural circuits (specifically, the POC-hippocampus-frontal cortex neural circuits) during odor stimulation. These findings highlight the potential of FC alterations as sensitive imaging markers for identifying high-risk individuals in the early stage of AD.

Development of a machine learning algorithm to predict the residual cognitive reserve index

Elucidating the mechanisms by which late-life neurodegeneration causes cognitive decline requires understanding why some individuals are more resilient than others to the effects of brain change on cognition (cognitive reserve). Currently, there is no way of measuring cognitive reserve that is valid (e.g. capable of moderating brain-cognition associations), widely accessible (e.g. does not require neuroimaging and large sample sizes), and able to provide insight into resilience-promoting mechanisms. To address these limitations, this study sought to determine whether a machine learning approach to combining standard clinical variables could (i) predict a residual-based cognitive reserve criterion standard and (ii) prospectively moderate brain-cognition associations. In a training sample combining data from the University of California (UC) Davis and the Alzheimer's Disease Neuroimaging Initiative-2 (ADNI-2) cohort (N = 1665), we operationalized cognitive reserve using an MRI-based residual approach. An eXtreme Gradient Boosting machine learning algorithm was trained to predict this residual reserve index (RRI) using three models: Minimal (basic clinical data, such as age, education, anthropometrics, and blood pressure), Extended (Minimal model plus cognitive screening, word reading, and depression measures), and Full [Extended model plus Clinical Dementia Rating (CDR) and Everyday Cognition (ECog) scale]. External validation was performed in an independent sample of ADNI 1/3/GO participants (N = 1640), which examined whether the effects of brain change on cognitive change were moderated by the machine learning models' cognitive reserve estimates. The three machine learning models differed in their accuracy and validity. The Minimal model did not correlate strongly with the criterion standard (r = 0.23) and did not moderate the effects of brain change on cognitive change. In contrast, the Extended and Full models were modestly correlated with the criterion standard (r = 0.49 and 0.54, respectively) and prospectively moderated longitudinal brain-cognition associations, outperforming other cognitive reserve proxies (education, word reading). The primary difference between the Minimal model-which did not perform well as a measure of cognitive reserve-and the Extended and Full models-which demonstrated good accuracy and validity-is the lack of cognitive performance and informant-report data in the Minimal model. This suggests that basic clinical variables like anthropometrics, vital signs, and demographics are not sufficient for estimating cognitive reserve. Rather, the most accurate and valid estimates of cognitive reserve were obtained when cognitive performance data-ideally augmented by informant-reported functioning-was used. These results indicate that a dynamic and accessible proxy for cognitive reserve can be generated for individuals without neuroimaging data and gives some insight into factors that may promote resilience.

Brain structure, amyloid, and behavioral features for predicting clinical progression in subjective cognitive decline

As a potential preclinical stage of Alzheimer's dementia, subjective cognitive decline (SCD) reveals a higher risk of future cognitive decline and conversion to dementia. However, it has not been clear whether SCD status increases the clinical progression of older adults in the context of amyloid deposition, cerebrovascular disease (CeVD), and psychiatric symptoms. We identified 99 normal controls (NC), 15 SCD individuals who developed mild cognitive impairment in the next 2 years (P-SCD), and 54 SCD individuals who did not (S-SCD) from ADNI database with both baseline and 2-year follow-up data. Total white matter hyperintensity (WMH), WMH in deep (DWMH) and periventricular (PWMH) regions, and voxel-wise grey matter volumes were compared among groups. Furthermore, using structural equation modelling method, we constructed path models to explore SCD-related brain changes longitudinally and to determine whether baseline SCD status, age, and depressive symptoms affect participants' clinical outcomes. Both SCD groups showed higher baseline amyloid PET SUVR, baseline PWMH volumes, and larger increase of PWMH volumes over time than NC. In contrast, only P-SCD had higher baseline DWMH volumes and larger increase of DWMH volumes over time than NC. No longitudinal differences in grey matter volume and amyloid was observed among NC, S-SCD, and P-SCD. Our path models demonstrated that SCD status contributed to future WMH progression. Further, baseline SCD status increases the risk of future cognitive decline, mediated by PWMH; baseline depressive symptoms directly contribute to clinical outcomes. In conclusion, both S-SCD and P-SCD exhibited more severe CeVD than NC. The CeVD burden increase was more pronounced in P-SCD. In contrast with the direct association of depressive symptoms with dementia severity progression, the effects of SCD status on future cognitive decline may manifest via CeVD pathologies. Our work highlights the importance of multi-modal longitudinal designs in understanding the SCD trajectory heterogeneity, paving the way for stratification and early intervention in the preclinical stage. PRACTITIONER POINTS: Both S-SCD and P-SCD exhibited more severe CeVD at baseline and a larger increase of CeVD burden compared to NC, while the burden was more pronounced in P-SCD. Baseline SCD status increases the risk of future PWMH and DWMH volume accumulation, mediated by baseline PWMH and DWMH volumes, respectively. Baseline SCD status increases the risk of future cognitive decline, mediated by baseline PWMH, while baseline depression status directly contributes to clinical outcome.

Prospective exploration of the role of combined internalizing symptoms in self-reported memory among older adults during the COVID-19 pandemic

OBJECTIVES

A growing literature suggests depression and anxiety increase risk of cognitive decline. However, few studies have examined their combined effects on cognition, among older adults, especially during periods of high stress.

METHOD

Based on a sample of community dwelling older adults (N = 576), we evaluated the effects of pre-pandemic anxiety and depressive symptoms, obtained in September 2018, to changes in self-reported memory (SRM) assessed 3 months into the COVID-19 pandemic.

RESULTS

In separate models, we found participants with depression scores at least 1-SD above the mean and participants with anxiety scores at least 2-SD above the mean to report a significant decline in SRM. Moderation analyses revealed those with high depressive symptoms (at or above the mean) showed a decrease in SRM regardless of anxiety. The extent to which high pre-pandemic anxiety symptoms influenced SRM is dependent on whether pre-pandemic depression was at or above the mean.

CONCLUSIONS

Pre-pandemic depression predicted a decline in SRM regardless of anxiety. Moderation analyses revealed that the extent to which anxiety symptoms influenced SRM was dependent on depression being at or above the mean. Those with high anxiety and depression are at highest risk of experiencing cognitive consequences related to stressful exposures like COVID-19.

Rural-Urban mild cognitive impairment comparison in West Michigan through EHR

INTRODUCTION

Mild cognitive impairment (MCI) is a significant public health concern and a potential precursor to Alzheimer's disease (AD). This study leverages electronic health record (EHR) data to explore rural-urban differences in MCI incidence, risk factors, and healthcare navigation in West Michigan.

METHODS

Analysis was conducted on 1,528,464 patients from Corewell Health West, using face-to-face encounters between 1/1/2015 and 7/31/2022. MCI cases were identified using International Classification of Diseases (ICD) codes, focusing on patients aged 45+ without prior MCI, dementia, or AD diagnoses. Incidence rates, cumulative incidences, primary care physicians (PCPs), and neuropsychology referral outcomes were examined across rural and urban areas. Risk factors were evaluated through univariate and multivariate Cox regression analyses. The geographic distribution of patient counts, hospital locations, and neurology department referrals were examined.

RESULTS

Among 423,592 patients, a higher MCI incidence rate was observed in urban settings compared to rural settings (3.83 vs. 3.22 per 1,000 person-years). However, sensitivity analysis revealed higher incidence rates in rural areas when including patients who progressed directly to dementia. Urban patients demonstrated higher rates of referrals to and completion of neurological services. While the risk factors for MCI were largely similar across urban and rural populations, urban-specific factors for incident MCI are hearing loss, inflammatory bowel disease, obstructive sleep apnea, insomnia, being African American, and being underweight. Common risk factors include diabetes, intracranial injury, cerebrovascular disease, coronary artery disease, stroke, Parkinson's disease, epilepsy, chronic obstructive pulmonary disease, depression, and increased age. Lower risk was associated with being female, having a higher body mass index, and having a higher diastolic blood pressure.

DISCUSSION

This study highlights rural-urban differences in MCI incidence and access to care, suggesting potential underdiagnosis in rural areas likely due to reduced access to specialists. Future research should explore socioeconomic, environmental, and lifestyle determinants of MCI to refine prevention and management strategies across geographic settings.

Highlights

Leveraged EHRs to explore rural-urban differences in MCI in West Michigan.Revealed a significant underdiagnosis of MCI, especially in rural areas.Observed lower rates of neurological referrals and completions for rural patients.Identified risk factors specific to rural and urban populations.

Studying the Alzheimer's disease continuum using EEG and fMRI in single-modality and multi-modality settings

Alzheimer's disease (AD) is a biological, clinical continuum that covers the preclinical, prodromal, and clinical phases of the disease. Early diagnosis and identification of the stages of Alzheimer's disease (AD) are crucial in clinical practice. Ideally, biomarkers should reflect the underlying process (pathological or otherwise), be reproducible and non-invasive, and allow repeated measurements over time. However, the currently known biomarkers for AD are not suitable for differentiating the stages and predicting the trajectory of disease progression. Some objective parameters extracted using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are widely applied to diagnose the stages of the AD continuum. While electroencephalography (EEG) has a high temporal resolution, fMRI has a high spatial resolution. Combined EEG and fMRI (EEG-fMRI) can overcome single-modality drawbacks and obtain multi-dimensional information simultaneously, and it can help explore the hemodynamic changes associated with the neural oscillations that occur during information processing. This technique has been used in the cognitive field in recent years. This review focuses on the different techniques available for studying the AD continuum, including EEG and fMRI in single-modality and multi-modality settings, and the possible future directions of AD diagnosis using EEG-fMRI.

Electroencephalographic slowing during REM sleep in older adults with subjective cognitive impairment and mild cognitive impairment

STUDY OBJECTIVES

In older adults with Alzheimer's disease, slowing of electroencephalographic (EEG) activity during REM sleep has been observed. Few studies have examined EEG slowing during REM in those with mild cognitive impairment (MCI) and none have examined its relationship with cognition in this at-risk population.

METHODS

Two hundred and ten older adults (mean age = 67.0, SD = 8.2 years) underwent comprehensive neuropsychological, medical, and psychiatric assessment and overnight polysomnography. Participants were classified as subjective cognitive impairment (SCI; n = 75), non-amnestic MCI (naMCI, n = 85), and amnestic MCI (aMCI, n = 50). REM EEG slowing was defined as (δ + θ)/(α + σ + β) power and calculated for frontal, central, parietal, and occipital regions. Analysis of variance compared REM EEG slowing between groups. Correlations between REM EEG slowing and cognition, including learning and memory, visuospatial and executive functions, were examined within each subgroup.

RESULTS

The aMCI group had significantly greater REM EEG slowing in the parietal and occipital regions compared to the naMCI and SCI groups (partial η2 = 0.06, p < 0.05 and 0.06, p < 0.05, respectively), and greater EEG slowing in the central region compared to SCI group (partial η2 = 0.03, p < 0.05). Greater REM EEG slowing in parietal (r = -0.49) and occipital regions (r = -0.38 [O1/M2] and -0.33 [O2/M1]) were associated with poorer visuospatial performance in naMCI.

CONCLUSIONS

REM EEG slowing may differentiate older adults with memory impairment from those without. Longitudinal studies are now warranted to examine the prognostic utility of REM EEG slowing for cognitive and dementia trajectories.

Gardening and subjective cognitive decline: a cross-sectional study and mediation analyses of 136,748 adults aged 45+ years

BACKGROUND

Given the benefits of gardening for physical and psychological health, we explored whether gardening was associated with lower risks of subjective cognitive decline (SCD), a precursor of dementia, and SCD-related functional limitations.

METHODS

Included in this cross-sectional study were 136,748 participants aged 45 + years old from the Behavioral Risk Factor Surveillance System 2019 survey, who were then categorized into three groups according to self-reported exercise status: non-exercisers, gardeners, and other exercisers. SCD was assessed via a questionnaire, and SCD-related functional limitations were referred to as having difficulties in engaging in household or social activities due to SCD. The odds ratio (OR) and 95% confidence interval (CI) were calculated to assess the associations of gardening with SCD and SCD-related functional limitations, adjusted for age, sex, socioeconomic status, lifestyle factors, and health status. Mediation analyses were conducted to examine whether the observed association between gardening and SCD was mediated by energy expenditure (MET-hours/week), depression status, and consumption of fruits and vegetables.

RESULTS

Overall, 11.1% and 5.4% of participants self-reported experiencing SCD and SCD-related functional limitations, respectively. The adjusted OR for gardeners vs. non-exercisers, was 0.72 (95% CI 0.62-0.83) for SCD and 0.57 (95% CI 0.44-0.73) for SCD-related functional limitations. The observed association between gardening and SCD was explained by higher energy expenditure (39.0%), lower likelihood of having depression (21.5%), and higher consumption of fruits and vegetables (3.4%) (P<0.05 for all). Similar patterns were observed for SCD-related functional limitations.

CONCLUSION

In this nationally representative sample, gardening was associated with better cognitive status, which may be mainly attributed to better depression status and energy expenditure.

Psychometric properties and normative data of the Italian version of the Cognitive Function at Work Questionnaire: a screening tool for detecting subjective cognitive complaints at work

INTRODUCTION

Considering the extension of working life due to socioeconomic and political factors, many people may experience cognitive complaints (CC) at their workplace, with severe consequences on their quality of life. The identification of workers reporting significative SCC is crucial to eventually address them to an objective neuropsychological evaluation and implement cognitive interventions to guarantee workers' well-being. Since no Italian questionnaires for detecting CC were designed for occupational settings, the aim of the study was to validate the Italian version of the Cognitive Function at Work Questionnaire (CFWQ) and to provide its normative data.

MATERIALS AND METHODS

Internal consistency, convergent and divergent validity, and factorial structure of the CFWQ were evaluated. A regression-based procedure served to compute percentiles of CFWQ and its subscales.

RESULTS

Four hundred twenty-one participants without psychiatric and/or neurological disorders completed the survey. We found that the Italian CFWQ included 26 items, with a good internal consistency (Cronbach's alpha = 0.897) and a six-factor structure (memory, language, processing speed, abstract thinking/behavioral control, behavioral inertia, planning ability). CFWQ score did not correlate with empathy but correlated strongly with memory scores and moderately with anxiety and depression scores.

CONCLUSIONS

The Italian CFWQ showed good psychometric properties, in analogy with the original English scale. Therefore, it can be successfully employed in organizational contexts to possibly identify workers with CC and therefore with possible co-occurrent psychological, behavioral, and cognitive consequences.

The influence of APOE status on rate of cognitive decline

BACKGROUND

Apolipoprotein (APOE) ɛ4 positivity and subjective cognitive decline (SCD) both increase risk of Alzheimer's disease (AD) development. However, few studies have examined the relationship between SCD and APOE status, especially using longitudinal data. The current study examined whether APOE is associated with the rate of cognitive change in SCD and mild cognitive impairment (MCI).

METHODS

A sample of 3494 older adults (1990 normal controls, NC, 775 SCD, and 729 MCI) with a mean follow-up of 9.09 years were included from the Rush Alzheimer's Disease Center Research Sharing Hub. Linear mixed effects models examined the relationship between APOE status and cognitive change in older adults with SCD normal controls, and people with MCI.

RESULTS

The presence of at least one ɛ2 allele in SCD and MCI results in cognitive change rates similar to a NC with the ɛ3ɛ3 genotype. Older adult SCD-ɛ4 individuals exhibited increased rate of cognitive decline compared to all groups, including NC-ɛ4 and MCI-ɛ4.

CONCLUSION

People with SCD with at least one ɛ4 allele experience increased rates of cognitive decline compared to cognitively healthy older adults and people with MCI. These findings have important implications for treatments and interventions and can improve future research and clinical trials by targeting people in the preclinical AD phase (i.e., SCD) who also possess at least one APOE ɛ4 allele.

Cognitive and neuroscientific perspectives of healthy ageing

With dementia incidence projected to escalate significantly within the next 25 years, the United Nations declared 2021-2030 the Decade of Healthy Ageing, emphasising cognition as a crucial element. As a leading discipline in cognition and ageing research, psychology is well-equipped to offer insights for translational research, clinical practice, and policy-making. In this comprehensive review, we discuss the current state of knowledge on age-related changes in cognition and psychological health. We discuss cognitive changes during ageing, including (a) heterogeneity in the rate, trajectory, and characteristics of decline experienced by older adults, (b) the role of cognitive reserve in age-related cognitive decline, and (c) the potential for cognitive training to slow this decline. We also examine ageing and cognition through multiple theoretical perspectives. We highlight critical unresolved issues, such as the disparate implications of subjective versus objective measures of cognitive decline and the insufficient evaluation of cognitive training programs. We suggest future research directions, and emphasise interdisciplinary collaboration to create a more comprehensive understanding of the factors that modulate cognitive ageing.

White matter alterations and their associations with biomarkers and behavior in subjective cognitive decline individuals: a fixel-based analysis

BACKGROUND

Subjective cognitive decline (SCD) is an early stage of dementia linked to Alzheimer's disease pathology. White matter changes were found in SCD using diffusion tensor imaging, but there are known limitations in voxel-wise tensor-based methods. Fixel-based analysis (FBA) can help understand changes in white matter fibers and how they relate to neurodegenerative proteins and multidomain behavior data in individuals with SCD.

METHODS

Healthy adults with normal cognition were recruited in the Northeastern Taiwan Community Medicine Research Cohort in 2018-2022 and divided into SCD and normal control (NC). Participants underwent evaluations to assess cognitive abilities, mental states, physical activity levels, and susceptibility to fatigue. Neurodegenerative proteins were measured using an immunomagnetic reduction technique. Multi-shell diffusion MRI data were collected and analyzed using whole-brain FBA, comparing results between groups and correlating them with multidomain assessments.

RESULTS

The final enrollment included 33 SCD and 46 NC participants, with no significant differences in age, sex, or education between the groups. SCD had a greater fiber-bundle cross-section than NC (pFWE < 0.05) at bilateral frontal superior longitudinal fasciculus II (SLFII). These white matter changes correlate negatively with plasma Aβ42 level (r = -0.38, p = 0.01) and positively with the AD8 score for subjective cognitive complaints (r = 0.42, p = 0.004) and the Hamilton Anxiety Rating Scale score for the degree of anxiety (Ham-A, r = 0.35, p = 0.019). The dimensional analysis of FBA metrics and blood biomarkers found positive correlations of plasma neurofilament light chain with fiber density at the splenium of corpus callosum (pFWE < 0.05) and with fiber-bundle cross-section at the right thalamus (pFWE < 0.05). Further examination of how SCD grouping interacts between the correlations of FBA metrics and multidomain assessments showed interactions between the fiber density at the corpus callosum with letter-number sequencing cognitive score (pFWE < 0.01) and with fatigue to leisure activities (pFWE < 0.05).

CONCLUSION

Based on FBA, our investigation suggests white matter structural alterations in SCD. The enlargement of SLFII's fiber cross-section is linked to plasma Aβ42 and neuropsychiatric symptoms, which suggests potential early axonal dystrophy associated with Alzheimer's pathology in SCD. The splenium of the corpus callosum is also a critical region of axonal degeneration and cognitive alteration for SCD.

Clinical predictors of Alzheimer's disease-like brain atrophy in individuals with memory complaints

OBJECTIVES

The definition and assessment methods for subjective cognitive decline (SCD) vary among studies. We aimed to investigate which features or assessment methods of SCD best predict Alzheimer's disease (AD)-related structural atrophy patterns.

METHODS

We assessed 104 individuals aged 55+ with memory complaints but normal cognitive screening. Our research questions were as follows: To improve the prediction of AD related morphological changes, (1) Would the use of a standardized cognitive screening scale be beneficial? (2) Is conducting a thorough neuropsychological evaluation necessary instead of relying solely on cognitive screening tests? (3) Should we apply SCD-plus research criteria, and if so, which criterion would be the most effective? (4) Is it necessary to consider medical and psychiatric comorbidities, vitamin deficiencies, vascular burden on MRI, and family history? We utilized Freesurfer to analyze cortical thickness and regional brain volume meta-scores linked to AD or predicting its development. We employed multiple linear regression models for each variable, with morphology as the dependent variable.

RESULTS

AD-like morphology was associated with subjective complaints in males, individuals with advanced age, and higher education. Later age of onset for complaints, complaints specifically related to memory, excessive deep white matter vascular lesions, and using medications that have negative implications for cognitive health (according to the Beers criteria) were predictive of AD-related morphology. The subjective cognitive memory questionnaire scores were found to be a better predictor of reduced volumes than a single-question assessment. It is important to note that not all SCD-plus criteria were evaluated in this study, particularly the APOE genotype, amyloid, and tau status, due to resource limitations.

CONCLUSIONS

The detection of AD-related structural changes is impacted by demographics and assessment methods. Standardizing SCD assessment methods can enhance predictive accuracy.

Impaired lexical access for unique entities in individuals with subjective cognitive decline

Subjective cognitive decline (SCD) may serve as an early indicator of Alzheimer's disease (AD). However, accurately quantifying cognitive impairment in SCD is challenging, mainly because existing assessment tools lack sensitivity. This study examined how tasks specifically designed to assess knowledge of famous people, could potentially aid in identifying cognitive impairment in SCD. A total of 60 adults with SCD and 60 healthy controls (HCs) aged 50 to 82 years performed a famous people verbal fluency task and a famous people naming task. In the famous people fluency task, the results showed that the individuals with SCD produced significantly fewer famous names in the total time allowed than the HCs, and this difference was also found in the first and the second time interval. In the famous people naming task, the performance of the SCD group was significantly lower than that of the HC group only in the more recent period of fame. Overall, these results suggest that retrieving the names of famous people was more difficult for people with SCD than for people without cognitive complaints. They also suggest that famous people verbal fluency and naming tasks could be useful in detecting cognitive decline at the preclinical stage of AD.

Numerosity comparison, cognitive strategies, and general cognitive functioning in older people

Introduction

Studies have shown age-related differences in numerical cognition, for example, in the level of numerosity comparison ability. Moreover, some studies point out individual differences in the cognitive strategies employed during the performance of numerosity comparison tasks and reveal that they are related to the aging process. One probable cause of these differences is the level of cognitive functioning. The aim of our study was to determine the relationships among numerosity comparison ability, the cognitive strategies utilized in the performance of numerosity comparison tasks and the general cognitive functioning in older people.

Methods

Forty-seven elderly people participated in the study. The participants were examined using overall cognitive functioning scales and computerized numerosity comparison task.

Results

The results showed many correlations between the participants' level of cognitive functioning and the percent of correct responses (PCR) and response time (RT) during numerosity comparison, as well as with the cognitive strategies applied by the participants. Task correctness was positively related to the level of performance in the attention and executive function tasks. In contrast, the long-term memory resources index and visuospatial skills level were negatively correlated with RT regarding numerosity comparison task performance. The level of long-term memory resources was also positively associated with the frequency of use of more complex cognitive strategies. Series of regression analyses showed that both the level of general cognitive functioning and the cognitive strategies employed by participants in numerosity comparison can explain 9-21 percent of the variance in the obtained results.

Discussion

In summary, these results showed significant relationships between the level of cognitive functioning and proficiency in numerosity comparison measured in older people. Moreover, it has been shown that cognitive resources level is related to the strategies utilized by older people, which indicates the potential application for cognitive strategy examinations in the development of new diagnostic tools.

Research hotspots and nursing inspiration in research of older adults with subjective cognitive decline from 2003 to 2023: A bibliometric analysis

Objectives

There has been a significant increase in subjective cognitive decline (SCD) studies in older adults over the years. A bibliometric analysis was conducted to demonstrate the current hotspots and emerging trends in SCD research in older adults and provide references for further research in this field.

Methods

The study conducted a bibliometric analysis based on co-citation analysis. From the Web of Science Core Collection database, this study obtained 1,436 manuscripts regarding SCD in older adults published from 2003 to 2023. Software CiteSpace was used to analyse the results for countries, institutions, authors, journals, keywords, top-cited papers, and burst citations scientifically and intuitively.

Results

Our result showed an overall upward trend in the volume of publications on SCD in the elderly population, suggesting that the study of SCD in older adults has attracted the attention of researchers. The United States dominates this research field, followed by China and France. The top three institutions were the University of California System, Institut National de la Sante et de la Recherche Medicale (Inserm), and UDICE-French Research Universities. Frank Jessen, Han Ying, and Kathryn Ellis were the top three researchers. The top three cited journals were Neurology, Alzheimers & Dementia, and Journal of Alzheimer's Disease. The keywords clustering were "depression", "functional connectivity", "cognitive reserve", "cognitive function", "physical activity", "recommendations", "dementia prevention", " behavioral disorders", "primary care", "early diagnosis", and "community-based study". Keywords with the highest citation bursts include "physical activity", "framework", "preclinical Alzheimer's disease", "future dementia", and "late life depression".

Conclusions

Parallel to the growth trend, the range of research scopes and topics is expanding steadily, focusing on early screening and prevention, negative emotion, and symptom management, broadening researchers' perspectives, which can provide reference and guidance for nursing researchers to conduct research.

Nutrition, Exercise, and Cognitive Rehabilitation for Dementia Prevention

Dementia is one of the most significant global challenges in medical and social care in the 21st century. It affects not only the patients themselves, but also their families, caregivers, and society in general, causing physical, psychological, and socioeconomic effects. As of 2020, there are approximately 6 million people in Japan aged 65 or older with dementia, and this number is expected to increase to around 7 million by 2025, meaning that one out of every five elderly people will have dementia. To prevent the onset and progression of dementia, it is crucial to have a proper understanding of its risks and adopt a healthy lifestyle. Leading an active life from an early stage can also aid in delaying or preventing the onset of dementia. Livingston has identified 12 risks that can lead to dementia, including physical inactivity, smoking, excessive alcohol consumption, air pollution, head injury, social isolation, poor educational history, obesity, hypertension, diabetes, depression, and hearing loss. Modifying one's lifestyle and leading an active life can be crucial in reducing these risks. The Mediterranean diet is gaining attention as a good practice for dementia prevention due to its diversity, richness in omega-3 fatty acids and vitamins. Exercise has been shown to prevent dementia on biological, behavioral, and socio-psychological levels. Repetitive transcranial magnetic stimulation is a non-invasive brain stimulation method that can alter brain plasticity and is being studied for clinical applications as a non-drug therapy for preventing dementia progression.

Individual and dual trajectories of insomnia symptoms and body mass index before and after retirement and their associations with changes in subjective cognitive functioning

BACKGROUND

We examined individual and dual trajectories of insomnia symptoms and body mass index (BMI) before and after retirement, and their associations with changes in subjective cognitive functioning after retirement.

METHODS

We used the Helsinki Health Study's (n = 2360, 79% women, aged 40-60 at baseline, Finland) repeated surveys to identify the developmental patterns of insomnia symptoms and BMI (2000-2017) and changes in subjective cognitive functioning (2017-2022). We analysed the data using latent group-based dual trajectory modelling and logistic regression analysis.

RESULTS

Three latent groups were identified for insomnia symptoms (stable low, decreasing and increasing symptoms) and BMI (stable healthy weight, stable overweight and stable obesity). Insomnia symptoms were associated with declining subjective cognitive functioning and largely explained the effects in the dual models.

CONCLUSION

The association between dual trajectories of insomnia symptoms and BMI with subjective cognitive decline is dominated by insomnia symptoms.

Symptomatic Clusters Related to Amyloid Positivity in Cognitively Unimpaired Individuals

Background

The NIA-AA Research Framework on Alzheimer's disease (AD) proposes a transitional stage (stage 2) characterized by subtle cognitive decline, subjective cognitive decline (SCD) and mild neurobehavioral symptoms (NPS).

Objective

To identify participant clusters based on stage 2 features and assess their association with amyloid positivity in cognitively unimpaired individuals.

Methods

We included baseline data of N = 338 cognitively unimpaired participants from the DELCODE cohort with data on cerebrospinal fluid biomarkers for AD. Classification into the AD continuum (i.e., amyloid positivity, A+) was based on Aβ42/40 status. Neuropsychological test data were used to assess subtle objective cognitive dysfunction (OBJ), the subjective cognitive decline interview (SCD-I) was used to detect SCD, and the Neuropsychiatric Inventory Questionnaire (NPI-Q) was used to assess NPS. A two-step cluster analysis was carried out and differences in AD biomarkers between clusters were analyzed.

Results

We identified three distinct participant clusters based on presented symptoms. The highest rate of A+ participants (47.6%) was found in a cluster characterized by both OBJ and SCD. A cluster of participants that presented with SCD and NPS (A+:26.6%) and a cluster of participants with overall few symptoms (A+:19.7%) showed amyloid positivity in a range that was not higher than the expected A+ rate for the age group. Across the full sample, participants with a combination of SCD and OBJ in the memory domain showed a lower Aβ42/ptau181 ratio compared to those with neither SCD nor OBJ.

Conclusions

The cluster characterized by participants with OBJ and concomitant SCD was enriched for amyloid pathology.