Chronic distress and incidence of mild cognitive impairment

Translating the Post-Mortem Brain Multi-Omics Molecular Taxonomy of Alzheimer's Dementia to Living Humans

Alzheimer's disease (AD) dementia is characterized by significant molecular and phenotypic heterogeneity, which confounds its mechanistic understanding, diagnosis, and effective treatment. In this study, we harness the most comprehensive dataset of paired ante-mortem blood omics, clinical, psychological, and post-mortem brain multi-omics data and neuroimaging to extensively characterize and translate the molecular taxonomy of AD dementia to living individuals. First, utilizing a comprehensive integration of eight complementary molecular layers from brain multi-omics data (N = 1,189), we identified three distinct molecular AD dementia subtypes exhibiting strong associations with cognitive decline, sex, psychological traits, brain morphology, and characterized by specific cellular and molecular drivers involving immune, vascular, and oligodendrocyte precursor cells. Next, in a significant translational effort, we developed predictive models to convert these advanced brain-derived molecular profiles (AD dementia pseudotimes and subtypes) into blood-, MRI- and psychological traits-based markers. The translation results underscore both the promise of these models and the opportunities for further enhancement. Our findings enhance the understanding of AD heterogeneity, underscore the value of multi-scale molecular approaches for elucidating causal mechanisms, and lay the groundwork for the development of novel therapies in living persons that target multi-level brain molecular subtypes of AD dementia.

Multi-omic subtypes of Alzheimer's dementia are differentially associated with psychological traits

Importance

Psychological traits reflecting neuroticism, depressive symptoms, loneliness, and purpose in life are risk factors of AD dementia; however, the underlying biologic mechanisms of these associations remain largely unknown.

Objective

To examine whether one or more multi-omic brain molecular subtypes of AD is associated with neuroticism, depressive symptoms, loneliness, and/or purpose in life.

Design

Two cohort-based studies; Religious Orders Study (ROS) and Rush Memory and Aging Project (MAP), both ongoing longitudinal clinical pathological studies that began enrollment in 1994 and 1997.

Setting

Older priests, nuns, and brothers from across the U.S. (ROS) and older adults from across the greater Chicago metropolitan area (MAP).

Participants

822 decedents with multi-omic data from the dorsolateral prefrontal cortex.

Exposures

Pseudotime, representing molecular distance from no cognitive impairment (NCI) to AD dementia, and three multi-omic brain molecular subtypes of AD dementia representing 3 omic pathways from no cognitive impairment (NCI) to AD dementia that differ by their omic constituents.

Main outcomes and measures

We first ran four separate linear regressions with neuroticism, depressive symptoms, loneliness, purpose in life as the outcomes, and pseudotime as the predictor, adjusting for age, sex and education. We then ran four separate analyses of covariance (ANCOVAs) with Bonferroni-corrected post-hoc tests to test whether the three multi-omic AD subtypes are differentially associated with the four traits, adjusting for the same covariates.

Results

Pseudotime was positively associated (p<0.05) with neuroticism and loneliness. AD subtypes were differentially associated with the traits: AD subtypes 1 and 3 were associated with neuroticism; AD subtype 2 with depressive symptoms; AD subtype 3 with loneliness, and AD subtype 2 with purpose in life.

Conclusions and Relevance

Three multi-omic brain molecular subtypes of AD dementia differentially share omic features with four psychological risk factors of AD dementia. Our data provide novel insights into the biology underlying well-established associations between psychological traits and AD dementia.

Systematic identification and quantification of factors and their interactions with age, sex, and panel wave influencing cognitive function in Korean older adults

Background

Cognitive decline in older adults is influenced by diverse factors, and degrees of influence of these factors may vary depending on sex, age cohorts, and passage of time. Moreover, these factors differ in their responsiveness to general interventions. Thus, identifying these factors including their interactions with age, sex, and panel wave and conducting a systematic quantification of their influences on cognitive function are both necessary for developing efficient intervention strategies.

Methods

To identify the influencing factors and their interactions, we applied a systematic stepwise variable selection using 2,535 community-dwelling older adults who participated in the Korean Longitudinal Study of Aging from Wave 5 (2014) to Wave 8 (2020). These factors were subsequently grouped based on their modifiability to investigate group-wise influences on cognitive function. For handling the longitudinal data, a generalized least squares method was used, and the degrees of influence of these factors were measured using the delta R 2.

Results

Twelve variables had significant main effects on cognitive function in older adults. Among these variables, age interacted with sex, regular exercise, and marital status. Sex interacted with regular exercise, education level, and depressive symptoms. Wave number interacted with depressive symptoms and social activity. In addition, the group-wise delta R 2 values were found to be 10.9, 6.3, and 5.9% in the difficult-to-modify, modifiable, and non-modifiable factor groups, respectively. Afterwards, we provided the delta R 2 for each sub-population divided by the levels of age, sex, and wave number to examine how these factors changed the influences.

Conclusion

Based on the interaction and quantification results, we elucidated the characteristics of the influencing factors and their degrees of influence, and we suggest grouping factors based on their modifiability to systematically prevent cognitive decline in older adults.

Differential associations of neighborhood disadvantage, race/ethnicity, and cognitive status with experiences of psychosocial distress in the HABS-HD cohort

INTRODUCTION

Understanding how contextual socioeconomic factors are associated with psychosocial distress among different ethnoracial groups is important for addressing health disparities in individuals at risk for Alzheimer's disease.

METHODS

Using Health and Aging Brain Study-Health Disparities (HABS-HD) data collected between 2017 and 2023, we examined the association of neighborhood disadvantage with psychosocial distress using demographically adjusted linear regression models, stratified by ethnoracial group and cognitive status.

RESULTS

We included 630 non-Hispanic Black, 1109 Hispanic, and 1068 non-Hispanic White older adults deemed cognitively normal (CN) or diagnosed with mild cognitive impairment (MCI). Residing in areas of greater neighborhood disadvantage was associated with increased chronic stress (CS) among CN White participants, but this relationship was attenuated among White participants with MCI. Regardless of cognitive status, severe levels of disadvantage were associated with increased CS and depression among Black participants.

DISCUSSION

Aging in more disadvantaged neighborhoods was associated with greater CS and depression for Black and White participants.

HIGHLIGHTS

Greater neighborhood disadvantage was associated with increased depression and chronic stress for White and Black individuals. Individuals with mild cognitive impairment reported greater levels of psychosocial distress. These findings are relevant for addressing mental health inequity in aging populations.

Early-Life Parental Affection, Social Relationships in Adulthood, and Later-Life Cognitive Function

OBJECTIVE

Although research has demonstrated the long-term health consequences of childhood adversities, less is known about the long-term impact of positive childhood experiences, such as parental affection.

METHOD

Using longitudinal data (1995-2014) from the Midlife in the United States (MIDUS) study, we analyze structural equation models estimating direct and indirect pathways from early-life parental affection to changes in later-life cognitive function through relationship quality in adulthood among Black and White older adults (N = 1983).

RESULTS

Analyses revealed significant indirect effects of parental affection on better cognitive function through higher levels of social support (both average social support and family social support) in adulthood in the full sample and among Black respondents. Indirect pathways through relationship strain and through friend support were not significant.

DISCUSSION

This work elevates the importance of promoting positive parental relationships during childhood, with implications for better social relationships in adulthood and cognitive function in later life.

Dynamic interplay of cortisol and BDNF in males under acute and chronic psychosocial stress - A randomized controlled study

The neurotrophic protein brain-derived neurotrophic factor (BDNF) plays a pivotal role in brain function and is affected by acute and chronic stress. We here investigate the patterns of BDNF and cortisol stress reactivity and recovery under the standardized stress protocol of the TSST and the effect of perceived chronic stress on the basal BDNF levels in healthy young men. Twenty-nine lean young men underwent the Trier Social Stress Test (TSST) and a resting condition. Serum BDNF and cortisol were measured before and repeatedly after both conditions. The perception of chronic stress was assessed by the Trier Inventory for Chronic Stress (TICS). After the TSST, there was a significant increase over time for BDNF and cortisol. Stronger increase in cortisol in response to stress was linked to an accelerated BDNF decline after stress. Basal resting levels of BDNF was significantly predicted by chronic stress perception. The increased BDNF level following psychosocial stress suggest a stress-induced neuroprotective mechanism. The presumed interplay between BDNF and the HPA-axis indicates an antagonistic relationship of cortisol on BDNF recovery post-stress. Chronically elevated high cortisol levels, as present in chronic stress, could thereby contribute to reduced neurogenesis, and an increased risk of neurodegenerative conditions in persons suffering from chronic stress.

Looking Back to Move Forward: Research in Stress, Behavior, and Immune Function

BACKGROUND

From the original studies investigating the effects of adrenal gland secretion to modern high-throughput multidimensional analyses, stress research has been a topic of scientific interest spanning just over a century.

SUMMARY

The objective of this review was to provide historical context for influential discoveries, surprising findings, and preclinical models in stress-related neuroimmune research. Furthermore, we summarize this work and present a current understanding of the stress pathways and their effects on the immune system and behavior. We focus on recent work demonstrating stress-induced immune changes within the brain and highlight studies investigating stress effects on microglia. Lastly, we conclude with potential areas for future investigation concerning microglia heterogeneity, bone marrow niches, and sex differences.

KEY MESSAGES

Stress is a phenomenon that ties together not only the central and peripheral nervous system, but the immune system as well. The cumulative effects of stress can enhance or suppress immune function, based on the intensity and duration of the stressor. These stress-induced immune alterations are associated with neurobiological changes, including structural remodeling of neurons and decreased neurogenesis, and these contribute to the development of behavioral and cognitive deficits. As such, research in this field has revealed important insights into neuroimmune communication as well as molecular and cellular mediators of complex behaviors relevant to psychiatric disorders.

Modifiable risk factors for mild cognitive impairment among cognitively normal community-dwelling older adults: A systematic review and meta-analysis

Although numerous studies have investigated modifiable risk factors for mild cognitive impairment (MCI) among community-dwelling seniors, no meta-analysis has summarized these findings. Five databases were searched from January 1, 2000, to December 30, 2023. The protocol was registered with PROSPERO. Data were extracted and reported following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Relevant meta-analyses of modifiable risk factors were performed. The evidence of each factor was assessed by the GRADE for cohort studies. Of 16,651 citations, 87 studies involving 225,584 community-dwelling seniors were included. Fourteen meta-analyses involving 20 studies with 44,199 participants were performed. The analyses revealed low-to-moderate-quality evidence supporting that diabetes, 2 or more comorbidities, anxiety, apathy, depressive symptoms, and physical frailty were risk factors for incident MCI in older adults. Conversely, hypertension, agitation, and irritability might not be risk factors. Additionally, moderate-quality evidence supports the protective effect of engaging in cognitive-demanding activities on the onset of MCI. Collectively, this study constitutes the first extensive compilation of evidence regarding the various risk factors for the development of MCI in older adults. Our findings hold significant potential to guide the formulation of prevention and management strategies to either prevent or potentially reverse the onset of MCI.

Effects of early tooth loss on chronic stress and progression of neuropathogenesis of Alzheimer's disease in adult Alzheimer's model AppNL-G-F mice

Introduction

Alzheimer's disease (AD), the most common neurodegenerative disease, is characterized by accumulated amyloid-β (Aβ) plaques, aggregated phosphorylated tau protein, gliosis-associated neuroinflammation, synaptic dysfunction, and cognitive impairment. Many cohort studies indicate that tooth loss is a risk factor for AD. The detailed mechanisms underlying the association between AD and tooth loss, however, are not yet fully understood.

Methods

We explored the involvement of early tooth loss in the neuropathogenesis of the adult AppNL-G-F mouse AD model. The maxillary molars were extracted bilaterally in 1-month-old male mice soon after tooth eruption.

Results

Plasma corticosterone levels were increased and spatial learning memory was impaired in these mice at 6 months of age. The cerebral cortex and hippocampus of AD mice with extracted teeth showed an increased accumulation of Aβ plaques and phosphorylated tau proteins, and increased secretion of the proinflammatory cytokines, including interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α), accompanied by an increased number of microglia and astrocytes, and decreased synaptophysin expression. AD mice with extracted teeth also had a shorter lifespan than the control mice.

Discussion

These findings revealed that long-term tooth loss is a chronic stressor, activating the recruitment of microglia and astrocytes; exacerbating neuroinflammation, Aβ deposition, phosphorylated tau accumulation, and synaptic dysfunction; and leading to spatial learning and memory impairments in AD model mice.

Multimorbidity, healthy lifestyle, and the risk of cognitive impairment in Chinese older adults: a longitudinal cohort study

BACKGROUND

Evidence on the association between multimorbidity and cognitive impairment in Chinese older population is limited. In addition, whether a healthy lifestyle can protect cognitive function in multimorbid older population remains unknown.

METHODS

A total of 6116 participants aged ≥ 65 years from the Chinese Longitudinal Healthy Longevity Survey were followed up repeatedly. The number of coexisting chronic diseases was used for assessing multimorbidity and cardiometabolic multimorbidity. Three lifestyle statuses (unhealthy, intermediate, and healthy) were defined based on a lifestyle score covering smoking, alcohol drinking, body mass index, outdoor activities, and dietary pattern. Cognitive impairment was defined as the Mini-Mental State Examination score < 24. A modified Poisson regression model with robust error variance was used to assess the associations between multimorbidity, healthy lifestyle, and cognitive impairment.

RESULTS

During a median follow-up period of 5.8 years, 1621 incident cases of cognitive impairment were identified. The relative risk (RR) of cognitive impairment associated with heavy multimorbidity burden (≥ 3 conditions) was 1.39 (95% confidence interval: 1.22-1.59). This association declined with age, with RRs being 3.08 (1.78-5.31), 1.40 (1.04-1.87), and 1.19 (1.01-1.40) in subjects aged < 70 years, ≥ 70 and < 80 years, and ≥ 80 years, respectively (P for interaction = 0.001). Compared to unhealthy lifestyle, a healthy lifestyle was related to an approximately 40% reduced risk of cognitive impairment regardless of multimorbidity burden. Among the 5 lifestyle factors assessed, daily outdoor activities and a healthy dietary pattern showed convincing protective effects on cognitive function.

CONCLUSIONS

The relationship between multimorbidity and cognitive impairment is age-dependent but remains significant in the population aged 80 years or older. A healthy lifestyle may protect cognitive function regardless of the multimorbidity burden. These findings highlight the importance of targeting individuals with heavy multimorbidity burden and promoting a heathy lifestyle to prevent cognitive impairment in Chinese older population.

Association of Anxiety and Unspecified Emotional Distress Obtained from a Medical Records Linkage System with Incident Cognitive Outcomes in a Population-Based Setting

Background

Studies that assess cognition prospectively and study in detail anxiety history in the participants' medical records within the context of brain aging and Alzheimer's disease are limited.

Objective

To examine the associations of anxiety and unspecified emotional distress (UED) acquired throughout a person's life with prospectively collected cognitive outcomes.

Methods

Mayo Clinic Study of Aging participants who were cognitively unimpaired at baseline were included. Anxiety and UED data were abstracted from the medical record using the Rochester Epidemiology Project (REP) resources and were run separately as predictors in our models. The data were analyzed using Cox proportional hazards models for the outcomes of incident mild cognitive impairment (MCI) and dementia and using linear mixed effects models for the outcomes of global and domain specific cognitive z-scores and included key covariates.

Results

The study sample (n = 1,808) had a mean (standard deviation) age of 74.5 (7.3) years and 51.4% were male. Anxiety was associated with increased risk of MCI and dementia and was associated with lower baseline cognitive z-scores and accelerated decline over time in the global, memory, and attention domains. UED was associated with faster decline in all domains except visuospatial but did not show evidence of association with incident cognitive outcomes. These results varied by medication use and timing of anxiety.

Conclusions

Anxiety and UED both showed inverse associations with cognition. Utilization of anxiety and UED data from across the life course, as available, from the REP system adds robustness to our results.

Association of Self-Reported Psychological Stress with Cognitive Decline: A Systematic Review

Psychological stress is a potential modifiable risk factor for cognitive decline. However, the extent to which self-reported psychological stress is differentially associated with decline in specific cognitive domains remains unclear. Differences may be due to heterogeneity in the aspects of psychological stress investigated, for example, neuroticism (which is linked to vulnerability to stress), perceived stress, or exposure to stressful life events. This review aims to establish the associations between these aspects of self-reported psychological stress and cognitive decline. PsychINFO, Embase and MEDLINE were searched from database inception to September 2021. Studies were included if they were observational, prospective, and if they investigated the association between self-reported psychological stress and cognitive decline in adults with a minimum mean age of 40 years at baseline. Thirty studies satisfied the inclusion criteria, with most examining neuroticism (n = 17) as a predictor of cognitive decline. Fewer examined perceived stress (n = 7) or stressful life events (n = 6). There was evidence of an association between neuroticism and cognitive decline, particularly in the domain of memory. Similarly, across studies, perceived stress was also associated with memory decline. Research investigating the relationship between stressful life events and cognitive decline had fewer outcomes to interpret. Overall, the findings highlight that memory may be particularly susceptible to high levels of neuroticism and perceived stress. We identified a lack of research into some cognitive domains, such as executive function, which should be addressed by future studies.

Association of Cerebrovascular Imaging Biomarkers, Depression, and Anxiety, with Mild Cognitive Impairment

The study included 1,738 Mayo Clinic Study of Aging participants (≥50 years old; 1,460 cognitively unimpaired and 278 with mild cognitive impairment (MCI)) and examined the cross-sectional association between cerebrovascular (CVD) imaging biomarkers (e.g., white matter hyperintensities (WMH), infarctions) and Beck Depression Inventory-II (BDI-II) and Beck Anxiety Inventory (BAI) scores, as well as their association with MCI. High (abnormal) WMH burden was significantly associated with having BDI-II>13 and BAI > 7 scores, and both (CVD imaging biomarkers and depression/anxiety) were significantly associated with MCI when included simultaneously in the model, suggesting that both were independently associated with the odds of MCI.

Stress, depression, and risk of dementia - a cohort study in the total population between 18 and 65 years old in Region Stockholm

BACKGROUND

Chronic stress and depression are potential risk factors for mild cognitive impairment and dementia, including Alzheimer disease. The aim was to investigate whether any such risk is additive.

METHODS

Cohort study including 1 362 548 people (665 997 women, 696 551 men) with records in the Region Stockholm administrative healthcare database (VAL). Exposure was a recorded ICD-10 diagnosis of chronic stress, depression, or both, recorded in 2012 or 2013. Outcome was a diagnosis of Alzheimer disease, other dementia, or mild cognitive impairment recorded from 2014 through 2022. Odds ratios with 99% confidence intervals (CI) adjusted for age, sex, neighborhood socioeconomic status, diabetes, and cardiovascular disorders were calculated.

RESULTS

During the exposure period, 4 346 patients were diagnosed with chronic stress, 40 101 with depression, and 1 898 with both. The average age at baseline was around 40 years in all groups. In the fully adjusted model, the odds ratio of Alzheimer disease was 2.45 (99% CI 1.22-4.91) in patients with chronic stress, 2.32 (99% CI 1.85-2.90) in patients with depression, and 4.00 (99% CI 1.67-9.58) in patients with chronic stress and depression. The odds ratio of mild cognitive impairment was 1.87 (99% CI 1.20-2.91) in patients with chronic stress, 2.85 (99% CI 2.53-3.22) in patients with depression, and 3.87 (99% CI 2.39-6.27) in patients with both. When other dementia was analyzed, the odds ratio was significant only in patients with depression, 2.39 (99% CI 1.92-2.96).

CONCLUSIONS

Documented chronic stress increased the risk of mild cognitive impairment and Alzheimer disease. The same was seen with depression. The novel finding is the potential additive effect of chronic stress to depression, on risk of MCI and AD.

Openness to experience and cognitive functioning and decline in older adults: The mediating role of cognitive reserve

OBJECTIVE

Openness to experience has been consistently associated with better cognitive functioning in older people, but its association with cognitive decline is less clear. Cognitive reserve has been proposed as a mechanism underlying this relationship, but previous studies have reported mixed findings, possibly due to the different ways of conceptualizing cognitive reserve. We aimed to analyze the potential mediating role of cognitive reserve in the association between openness and cognitive functioning and decline in healthy older people.

METHOD

In Wave 1 and at the four-year follow-up (Wave 2), 87 healthy older people (49.4% women; M age = 65.08, SD = 4.54) completed a neuropsychological battery to assess cognitive functioning and a questionnaire to assess cognitive reserve. Openness was measured with the NEO- Five-Factor Inventory. Mediation models were proposed to investigate the relationship between openness and cognitive function or decline through cognitive reserve or its change.

RESULTS

Cognitive reserve mediated the openness-cognitive functioning association. Thus, individuals with higher openness showed greater cognitive reserve, and this greater cognitive reserve was associated with better cognitive functioning. Moreover, greater cognitive reserve at baseline also mediated the association between higher openness and slower cognitive decline. However, change in cognitive reserve did not mediate the association between openness and change in cognitive functioning.

CONCLUSIONS

Cognitive reserve is a mechanism underlying the association between openness and cognitive functioning and decline. These findings support the differential preservation hypothesis, suggesting that healthy older adults who engage in more cognitively stimulating activities would show less age-related cognitive decline.

Depressive and Biopsychosocial Frailty Phenotypes: Impact on Late-life Cognitive Disorders

 In older age, frailty is a detrimental transitional status of the aging process featuring an increased susceptibility to stressors defined by a clinical reduction of homoeostatic reserves. Multidimensional frailty phenotypes have been associated with all-cause dementia, mild cognitive impairment (MCI), Alzheimer's disease (AD), AD neuropathology, vascular dementia, and non-AD dementias. In the present article, we reviewed current evidence on the existing links among depressive and biopsychosocial frailty phenotypes and late-life cognitive disorders, also examining common pathways and mechanisms underlying these links. The depressive frailty phenotype suggested by the construct of late-life depression (LLD) plus physical frailty is poorly operationalized. The biopsychosocial frailty phenotype, with its coexistent biological/physical and psychosocial dimensions, defines a biological aging status and includes motivational, emotional, and socioeconomic domains. Shared biological pathways/substrates among depressive and biopsychosocial frailty phenotypes and late-life cognitive disorders are hypothesized to be inflammatory and cardiometabolic processes, together with multimorbidity, loneliness, mitochondrial dysfunction, dopaminergic neurotransmission, specific personality traits, lack of subjective/objective social support, and neuroendocrine dysregulation. The cognitive frailty phenotype, combining frailty and cognitive impairment, may be a risk factor for LLD and vice versa, and a construct of depressive frailty linking physical frailty and LLD may be a good dementia predictor. Frailty assessment may enable clinicians to better target the pharmacological and psychological treatment of LLD. Given the epidemiological links of biopsychosocial frailty with dementia and MCI, multidomain interventions might contribute to delay the onset of late-life cognitive disorders and other adverse health-related outcomes, such as institutionalization, more frequent hospitalization, disability, and mortality.

Xanthine oxidase mediates chronic stress-induced cerebrovascular dysfunction and cognitive impairment

Xanthine oxidase (XO) mediates vascular function. Chronic stress impairs cerebrovascular function and increases the risk of stroke and cognitive decline. Our study determined the role of XO on stress-induced cerebrovascular dysfunction and cognitive decline. We measured middle cerebral artery (MCA) function, free radical formation, and working memory in 6-month-old C57BL/6 mice who underwent 8 weeks of control conditions or unpredictable chronic mild stress (UCMS) with or without febuxostat (50 mg/L), a XO inhibitor. UCMS mice had an impaired MCA dilation to acetylcholine vs. controls (p < 0.0001), and increased total free radical formation, XOR protein levels, and hydrogen peroxide production in the liver compared to controls. UCMS increased hydrogen peroxide production in the brain and cerebrovasculature compared to controls. Working memory, using the y-maze test, was impaired (p < 0.05) in UCMS mice compared to control mice. However, blocking XO using febuxostat prevented the UCMS-induced impaired MCA response, while free radical production and hydrogen peroxide levels were similar to controls in the liver and brain of UCMS mice treated with febuxostat. Further, UCMS + Feb mice did not have a significant reduction in working memory. These data suggest that the cerebrovascular dysfunction associated with chronic stress may be driven by XO, which leads to a reduction in working memory.

The more the neuroticism, the more the susceptibility to Alzheimer's disease. What inspiration can neuroticism provide?

Study of neuroticism can provide important insights. Before the inclusion of neuroticism in the study of Alzheimer's disease (AD), clinical and scientific researchers used relatively fixed models to treat AD, such as prescribing fixed doses of drugs and fixed research strategies. However, taking neuroticism into account affects drug use, the direction of scientific research, and even the mental health of the population, which translates into more immediate economic benefits.

Psychological distress in later life and incident dementia: The Ohsaki Cohort 2006 Study

BACKGROUND

The role of reverse causation in the association between psychological distress and incident dementia remains unclear. We investigated whether psychological distress is a risk factor for, or prodromal symptom of, dementia.

METHODS

A longitudinal analysis of psychological distress with incident dementia was conducted among 12,076 Japanese individuals (age ≥65 years) followed for 5.7 years. Psychological distress was measured using the Kessler 6-item psychological distress scale (0-24 points) at baseline, with participants categorized into four psychological distress groups: no (0-4), mild (5-9), moderate (10-12), and serious (13-24). Dementia cases were retrieved from the public Long-term Care Insurance database. Cox proportional hazards model was used to estimate the multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (95%CIs) for incident dementia. Stratified analysis was conducted by cognitive function (higher or lower) at baseline.

RESULTS

During 60,240 person-years of follow-up, 997 individuals developed dementia. A dose-response association was found between psychological distress and dementia; however, the stratified analysis indicated that this association depended on cognitive function at baseline. Among those with higher cognitive function at baseline, a significantly elevated dementia risk was observed only for serious psychological distress (HR: 2.04, 95%CI: 1.24-3.36). Among those with lower cognitive function, both moderate (HR: 1.30, 95%CI: 1.00-1.68) and serious (HR: 1.79, 95%CI: 1.37-2.34) psychological distress showed an increased dementia risk.

CONCLUSION

The association between late-life psychological distress and incident dementia is partly explained by reserve causation, whereby mild and moderate distress could be a prodromal symptom of dementia.

Tarooneh extract relieves anxiety-like behaviors and cognitive deficits by inhibiting synaptic loss in the hippocampus and frontal cortex in rats subjected to chronic restraint stress

In traditional medicine, Tarooneh (a hardcover of the date palm; Phoenix dactylifera) has known as a sedative and relaxant medicine. In this study, we evaluated the protective effects of Tarooneh in the anxiety-like behavior, cognitive deficit, and neuronal damages in the CA1, CA3, and dentate gyrus (DG) regions of the hippocampus and frontal cortex neurons employing a rat model of chronic restraint stress. The animal received Tarooneh extract for 14 consecutive days in water, and chronic restraint stress was performed daily during this period. The results of the Barnes maze test showed that treatment with Tarooneh significantly improves spatial memory parameters such as latency time to find the target hole, number of errors, and distance traveling compared to the stress group. The EPM results showed that Tarooneh significantly increased the time spent in open arms and the percentage of entries into open arms and significantly decreased the frequency of head dipping behavior compared to animals in the stress group. Golgi-Cox staining indicates that loss of neural spine density in DG, CA1, CA3, and frontal cortex due to chronic restraint stress, was prevented with daily administration of Tarooneh. The results of cresyl-violet staining indicate that Tarooneh significantly increased the number of CV-positive neurons in the frontal cortex and CA1 region of the hippocampus compared to the stress group. Our results suggest that Tarooneh potentially prevented and improved effects in anxiety-like behavior, memory impairment, and synaptic plasticity loss in frontal and hippocampal neurons induced by chronic restraint stress. In conclusion, our results suggest that Tarooneh prevented and improved anxiety-like behavior, cognitive deficit, and neuronal damages in the CA1, CA3, and DG regions of the hippocampus and frontal cortex neurons induced by chronic restraint stress.

Correlates of Person-Specific Rates of Change in Sensor-Derived Physical Activity Metrics of Daily Living in the Rush Memory and Aging Project

This study characterized person-specific rates of change of total daily physical activity (TDPA) and identified correlates of this change. TDPA metrics were extracted from multiday wrist-sensor recordings from 1083 older adults (average age 81 years; 76% female). Thirty-two covariates were collected at baseline. A series of linear mixed-effect models were used to identify covariates independently associated with the level and annual rate of change of TDPA. Though, person-specific rates of change varied during a mean follow-up of 5 years, 1079 of 1083 showed declining TDPA. The average decline was 16%/year, with a 4% increased rate of decline for every 10 years of age older at baseline. Following variable selection using multivariate modeling with forward and then backward elimination, age, sex, education, and 3 of 27 non-demographic covariates including motor abilities, a fractal metric, and IADL disability remained significantly associated with declining TDPA accounting for 21% of its variance (9% non-demographic and 12% demographics covariates). These results show that declining TDPA occurs in many very old adults. Few covariates remained correlated with this decline and the majority of its variance remained unexplained. Further work is needed to elucidate the biology underlying TDPA and to identify other factors that account for its decline.

Five-Factor Model Personality Traits and the Trajectory of Episodic Memory: Individual-Participant Meta-Analysis of 471,821 Memory Assessments from 120,640 Participants

OBJECTIVES

Five-factor model (FFM) personality traits are associated with concurrent memory function and risk of incident dementia but are less consistently associated with the change in episodic memory. The present research analyzes multiple large-scale studies with a consistent analytic approach to evaluate the association between personality and change in episodic memory over time.

METHOD

Across nine public longitudinal data sets, 120,640 participants provided 471,821 memory assessments over up to 26 years (age range 18-108). FFM traits were tested as predictors of the average level (intercept) and change over time (slope) of episodic memory. Results from the individual samples were meta-analyzed to summarize the associations.

RESULTS

Consistent with expectations for the intercept, higher neuroticism was associated with worse memory performance, whereas higher openness and conscientiousness were associated with better performance; extraversion and agreeableness were also associated with better performance. Higher neuroticism and lower conscientiousness were related to declines in memory only in samples with more than two assessments of memory. The other three traits were unrelated to memory slope. The pattern was similar when participants with dementia were excluded from the analysis, and the association with the slope was not moderated by age.

DISCUSSION

FFM traits have a robust association with average memory performance. Higher neuroticism and lower conscientiousness were associated with declines in memory performance only among samples with more than two memory assessments. The heterogeneity across studies suggests that multiple memory assessments are needed to reliably detect change over time, which may be one reason for past inconsistencies across studies.

Predictors of cognitive functioning trajectories among older Americans: A new investigation covering 20 years of age- and non-age-related cognitive change

Despite the extensive study of predictors of cognitive decline in older age, a key uncertainty is how much these predictors explain both the intercept and age- and non-age-related change in cognitive functioning (CF). We examined the contribution of a broad range of life course determinants to CF trajectories. Data came from 7,068 participants in the 1996-2016 Health and Retirement Study. CF was measured as a summary score on a 27-point cognitive battery of items. We estimated multilevel growth curve models to examine the CF trajectories in individuals ages 54-85. We found that the variation in CF level at age 54 was three times as much as the variation in age slope. All the observed individual predictors explained 38% of the variation in CF at age 54. Personal education was the most important predictor (25%), followed by race, household wealth and income, parental education, occupation, and depression. The contributions of activity limitations, chronic diseases, health behaviors (obesity, smoking, vigorous activity), childhood conditions (childhood health, nutrition, financial situation), gender, marital status, and religion were rather small (<5%). Even though the age slope varied with many adulthood factors, they only explained 5.6% of the between-person variation in age slope. Moreover, age explained 23% of within-person variation in CF from age 54 to 85. The rest non-age-related within-person variation could not be explained by the observed time-varying factors. These findings suggest that future research is urgently needed to discover the main determinants of the slope of cognitive decline to slow down the progression of cognitive impairment and dementia.

Social isolation is linked to classical risk factors of Alzheimer's disease-related dementias

Alzheimer's disease and related dementias is a major public health burden-compounding over upcoming years due to longevity. Recently, clinical evidence hinted at the experience of social isolation in expediting dementia onset. In 502,506 UK Biobank participants and 30,097 participants from the Canadian Longitudinal Study of Aging, we revisited traditional risk factors for developing dementia in the context of loneliness and lacking social support. Across these measures of subjective and objective social deprivation, we have identified strong links between individuals' social capital and various indicators of Alzheimer's disease and related dementias risk, which replicated across both population cohorts. The quality and quantity of daily social encounters had deep connections with key aetiopathological factors, which represent 1) personal habits and lifestyle factors, 2) physical health, 3) mental health, and 4) societal and external factors. Our population-scale assessment suggest that social lifestyle determinants are linked to most neurodegeneration risk factors, highlighting them as promising targets for preventive clinical action.

Hypothalamic-pituitary-adrenal (HPA) axis activity and anxiety-like behavior during aging: A test of the glucocorticoid cascade hypothesis in amyloidogenic APPswe/PS1dE9 mice

Alzheimer's disease (AD) is a progressive, dementing, whole-body disorder that presents with decline in cognitive, behavioral, and emotional functions, as well as endocrine dysregulation. The etiology of AD is not fully understood but stress- and anxiety-related hormones may play a role in its development and trajectory. The glucocorticoid cascade hypothesis posits that levels of glucocorticoids increase with age, leading to dysregulated negative feedback, further elevated glucocorticoids, and resulting neuropathology. We examined the impact of age (from 2 to 10 months) and stressor exposure (predator odor) on hormone levels (corticosterone and ghrelin), anxiety-like behavior (open field and light dark tests), and memory-related behavior (novel object recognition; NOR), and whether these various measures correlated with neuropathology (hippocampus and cortex amyloid beta, Aβ) in male and female APPswe/PS1dE9 transgenic and non-transgenic mice. Additionally, we performed exploratory analyses to probe if the open field and light dark test as commonly used tasks to assess anxiety levels were correlated. Consistent with the glucocorticoid cascade hypothesis, baseline corticosterone increased with age. Predator odor exposure elevated corticosterone at each age, but in contrast to the glucocorticoid cascade hypothesis, the magnitude of stressor-induced elevations in corticosterone levels did not increase with age. Overall, transgenic mice had higher post-stressor, but not baseline, corticosterone than non-transgenic mice, and across both genotypes, females consistently had higher (baseline and post-stressor) corticosterone than males. Behavior in the open field test primarily showed decreased locomotion with age, and this was pronounced in transgenic females. Anxiety-like behaviors in the light dark test were exacerbated following predator odor, and female transgenic mice were the most impacted. Compared to transgenic males, transgenic females had higher Aβ concentrations and showed more anxiety-like behavior. Performance on the NOR did not differ significantly between genotypes. Lastly, we did not find robust, statistically significant correlations among corticosterone, ghrelin, recognition memory, anxiety-like behaviors, or Aβ, suggesting outcomes are not strongly related on the individual level. Our data suggest that despite Aβ accumulation in the hippocampus and cortex, male and female APPswePS1dE9 transgenic mice do not differ robustly from their non-transgenic littermates in physiological, endocrine, and behavioral measures at the range of ages studied here.

Interactions Between Neuropsychiatric Symptoms and Alzheimer's Disease Neuroimaging Biomarkers in Predicting Longitudinal Cognitive Decline

Objective

To examine interactions between Neuropsychiatric symptoms (NPS) with Pittsburgh Compound B (PiB) and fluorodeoxyglucose positron emission tomography (FDG-PET) in predicting cognitive trajectories.

Methods

We conducted a longitudinal study in the setting of the population-based Mayo Clinic Study of Aging in Olmsted County, MN, involving 1581 cognitively unimpaired (CU) persons aged ≥50 years (median age 71.83 years, 54.0% males, 27.5% APOE ɛ4 carriers). NPS at baseline were assessed using the Neuropsychiatric Inventory Questionnaire (NPI-Q). Brain glucose hypometabolism was defined as a SUVR ≤ 1.47 (measured by FDG-PET) in regions typically affected in Alzheimer's disease. Abnormal cortical amyloid deposition was measured using PiB-PET (SUVR ≥ 1.48). Neuropsychological testing was done approximately every 15 months, and we calculated global and domain-specific (memory, language, attention, and visuospatial skills) cognitive z-scores. We ran linear mixed-effect models to examine the associations and interactions between NPS at baseline and z-scored PiB- and FDG-PET SUVRs in predicting cognitive z-scores adjusted for age, sex, education, and previous cognitive testing.

Results

Individuals at the average PiB and without NPS at baseline declined over time on cognitive z-scores. Those with increased PiB at baseline declined faster (two-way interaction), and those with increased PiB and NPS declined even faster (three-way interaction). We observed interactions between time, increased PiB and anxiety or irritability indicating accelerated decline on global z-scores, and between time, increased PiB and several NPS (e.g., agitation) showing faster domain-specific decline, especially on the attention domain.

Conclusions

NPS and increased brain amyloid deposition synergistically interact in accelerating global and domain-specific cognitive decline among CU persons at baseline.

The Role of Incarceration as a Risk Factor for Cognitive Impairment

OBJECTIVES

The objective of this study was to understand disparities in cognitive impairment between middle-aged formerly incarcerated (FI) and nonincarcerated individuals.

METHODS

The 1979 National Longitudinal Survey of Youth is a nationally representative longitudinal data set containing information on incarceration, cognitive functioning, and other health conditions. Using a modified version of the Telephone Interview for Cognitive Status (TICS-m), adapted from the Health and Retirement Study, we analyzed the association between incarceration and cognitive impairment, cognitive impairment-not dementia and dementia. Multivariable regression models were estimated, including prior incarceration status and covariates associated with incarceration and cognitive functioning.

RESULTS

FI individuals had lower unadjusted scores on TICS-m (-2.5, p < .001) and had significantly greater unadjusted odds ratios (OR) for scoring in the cognitive impairment (OR = 2.4, p < .001) and dementia (OR = 2.7, p < .001) range. Differences were largely explained by a combination of risk factors associated with incarceration and cognition. Education and premorbid cognition (measured by Armed Forces Qualification Test) separately and completely explained differences in the odds of dementia. Regardless of incarceration status, Blacks and Hispanics had significantly greater odds of cognitive impairment and dementia relative to Whites, holding other factors constant.

DISCUSSION

The association between prior incarceration and cognitive impairment in middle age was largely explained by differences in educational attainment and premorbid cognitive functioning, supporting the cognitive reserve hypothesis. Greater prevalence of cognitive impairment and dementia among the FI could create challenges and should be considered in reentry planning. Structural and institutional factors should be considered when addressing health disparities in Alzheimer's Disease and Related Dementias.

APOE alleles are associated with sex-specific structural differences in brain regions affected in Alzheimer's disease and related dementia

Alzheimer's disease is marked by intracellular tau aggregates in the medial temporal lobe (MTL) and extracellular amyloid aggregates in the default network (DN). Here, we examined codependent structural variations between the MTL's most vulnerable structure, the hippocampus (HC), and the DN at subregion resolution in individuals with Alzheimer's disease and related dementia (ADRD). By leveraging the power of the approximately 40,000 participants of the UK Biobank cohort, we assessed impacts from the protective APOE ɛ2 and the deleterious APOE ɛ4 Alzheimer's disease alleles on these structural relationships. We demonstrate ɛ2 and ɛ4 genotype effects on the inter-individual expression of HC-DN co-variation structural patterns at the population level. Across these HC-DN signatures, recurrent deviations in the CA1, CA2/3, molecular layer, fornix's fimbria, and their cortical partners related to ADRD risk. Analyses of the rich phenotypic profiles in the UK Biobank cohort further revealed male-specific HC-DN associations with air pollution and female-specific associations with cardiovascular traits. We also showed that APOE ɛ2/2 interacts preferentially with HC-DN co-variation patterns in estimating social lifestyle in males and physical activity in females. Our structural, genetic, and phenotypic analyses in this large epidemiological cohort reinvigorate the often-neglected interplay between APOE ɛ2 dosage and sex and link APOE alleles to inter-individual brain structural differences indicative of ADRD familial risk.

The Impact of Marital Quality as Older Couples Adjust to Dementia Onset

OBJECTIVES

A burgeoning literature links being married to better cognitive health, but less attention has been paid to how couples view their marital relationships. Couples do not always concur in their assessments, and such discrepancies affect both partners' health. We present a dyadic study on whether and how overall and discrepant views of marital quality predicted (a) dementia onset and (b) changes in older adults' depressive symptoms with spousal dementia.

METHODS

A pooled sample of couples aged 50+ (dyad N = 3,936) from the Health and Retirement Study rated positive and negative marital quality at baseline (2006/2008). Each participant reported whether they had been told of having dementia and their depressive symptoms once every other year (2006/2008-2014/2016).

RESULTS

Cox proportional hazards regression revealed that older adults who rated their marriages either more positively or more negatively than their spouses were more likely to develop dementia. We applied multiphase growth curve modeling to older adults whose spouses developed dementia, finding that those in marriages that were more negative overall reported more depressive symptoms but exhibited a smaller increase in these symptoms in response to spousal dementia.

DISCUSSION

This study adds to the literature by showing how discrepant marital assessments shape cognitive aging and offers new insights into identifying older adults with greater dementia risk. Findings also revealed the impact of overall negative marital quality on older adults' psychological adjustment to spousal dementia, which could inform interventions intended to help couples better cope with early-stage dementia from a relational perspective.

Mediation of perceived stress and cortisol in the association between neuroticism and global cognition in older adults: A longitudinal study

Neuroticism has been associated with a greater dementia risk, but its association with cognitive decline in healthy older adults remains unclear. Stress has been proposed as one of the mechanisms that could explain this relationship. Our aim was to analyse, in healthy older people, the mediating role of perceived stress and the Hypothalamic-Pituitary-Adrenal (HPA) axis in the association between neuroticism and global cognition. At Waves 1 and 2 (4-year follow-up), 87 older people (49.4% women; M age = 65.08, SD = 4.54 at Wave 1) completed a neuropsychological battery and the Perceived Stress Scale (PSS), and provided saliva samples on two (Wave 1) and three (Wave 2) consecutive days to measure the wake-to-bed slope. In Wave 2, neuroticism was assessed with the NEO-Five-Factor Inventory. PSS, but not the wake-to-bed slope, mediated the negative associations between neuroticism and global cognition (Waves 1, 2 and change). Regarding gender differences, PSS (Waves 1, 2 and change) and the wake-to-bed slope (Wave 2 and change) mediated these associations in men. Our results suggest that perceived stress and HPA-axis dysregulation could act as mechanisms underlying the association between neuroticism and cognitive functioning and decline, at least in older men.

Non-Pharmacological Treatments of Neuropsychiatric Symptoms in Mild Cognitive Impairment (MCI)

Mild cognitive impairment (MCI) is a syndrome defined by objective cognitive deficits that do not impact functional independence. Individuals with MCI develop dementia at an annual rate of 10 to 15%. Neuropsychiatric symptoms (NPS) are common non-cognitive features of neurocognitive disorders and have a major impact on the wellbeing and quality of life of affected individuals and their families. Non-pharmacological interventions for NPS are considered the first-line treatment because of the limited efficacy and side-effect potential of current pharmacological agents. This article summarizes the literature on non-pharmacological treatments for NPS in MCI. The limited number of studies specific to individuals with MCI and its various etiologies, as well as the overall heterogeneity of research design and methodologies, make the evidence base inconclusive. Nevertheless, some studies support psychosocial interventions aimed at individuals with MCI and their caregivers.

Childhood Stressors, Relationship Quality, and Cognitive Health in Later Life

OBJECTIVES

The rising prevalence of cognitive impairment, Alzheimer's disease, and related disorders signals the need for a better understanding of how social factors may affect cognitive health for millions of Americans. Drawing from cumulative inequality theory, we aim to understand the implications of a stressful childhood on social relationships and cognitive health in later life.

METHODS

This study utilizes longitudinal data (2006-2016) from the Health and Retirement Study to examine pathways, both direct and indirect through social relationships in adulthood, from childhood stressors to cognitive health trajectories over time.

RESULTS

Respondents reporting a greater number of stressors in childhood had worse cognitive health over time, but those negative effects were not as steep as time progressed. Early-life stressors are also associated with less social support and more social strain in adulthood which, in turn, are associated with initial cognitive health. Finally, pathway analyses confirm that childhood stressors are indirectly associated with initial cognitive health through social strain and social support.

DISCUSSION

Findings reveal that a stressful childhood creates chains of risks that have lifelong implications for cognitive health, both directly and indirectly by creating obstacles for developing healthy and supportive social relationships.

Correlation between Gut Microbiota and Six Facets of Neuroticism in Korean Adults

A person high in neuroticism is more likely to experience anxiety, stress, worry, fear, anger, and depression. Previous studies have shown that the gut microbiota can influence personality and mental disorders, including stress, anxiety, and depression, through the gut-brain axis. Here, we investigated the correlations between the sub-facet of neuroticism and gut microbiota using the Revised NEO Personality Inventory and the 16S rRNA gene sequencing data 784 adults. We found that the high anxiety and vulnerability group showed significantly lower richness in microbial diversity than a group with low anxiety and vulnerability. In beta diversity, there was a significant difference between the low and high groups of anxiety, self-consciousness, impulsiveness, and vulnerability. In taxonomic compositions, Haemophilus belonging to Gammaproteobacteria was correlated with the Neuroticism domain as well as N1 anxiety and N6 vulnerability facets. The high N1 anxiety and N6 vulnerability group was correlated with a low abundance of Christensenellaceae belonging to Firmicutes Clostridia. High N4 self-consciousness was correlated with a low abundance of Alistipes and Sudoligranulum. N5 impulsiveness was correlated with a low abundance of Oscillospirales. Our findings will contribute to uncovering the potential link between the gut microbiota and neuroticism, and the elucidation of the correlations of the microbiome-gut-brain axis with behavioral changes and psychiatric cases in the general population.

Gender Differences in the Link Between Marital Quality and Cognitive Decline Among Older Adults in Korea

OBJECTIVE

This study aimed to investigate the association between positive marital quality and cognitive health over time and to examine gender differences in this association.

METHODS

Drawing on 2006-2018 Korean Longitudinal Study of Aging data (n=7,427 respondents, 35,066 person-year observations), a series of hybrid mixed-effects models were used to estimate the effects of time-invariant (gender) and time-variant (marital quality) variables on within-person changes and on between-person differences in cognitive decline over the observation period.

RESULTS

The results showed that individuals' likelihood of having higher cognitive health grew when their spousal relationship became more positive and that, compared with those with lower levels of marital quality, people with higher levels of marital quality were more likely to have higher cognitive health. Interestingly, improvements in marital quality were more beneficial for men than for women, whereas level of marital quality had similar effects on men's and women's cognitive health.

CONCLUSION

Couple-based intervention programs aiming to improve marital quality should be encouraged, especially among older adults.

Female specific risk factors for the development of Alzheimer's disease neuropathology and cognitive impairment: Call for a precision medicine approach

Alzheimer's disease (AD) includes a long asymptomatic stage, which precedes the formal diagnosis of dementia. AD biomarker models provide a framework for precision medicine approaches during this stage. However, such approaches have ignored the possible influence of sex on cognition and brain health, despite female sex noted as a major risk factor. Since AD-related changes may emerge in midlife, intervention efforts are being redirected around this period. Midlife coincides with several endocrinological changes, such as the menopausal transition experienced by women. In this narrative review, we discuss evidence for sex-differences in AD neuropathological burden and outline key endocrinological mechanisms for both sexes, focussing on hormonal events throughout the lifespan that may influence female susceptibility to AD neuropathology and dementia onset. We further consider common non-modifiable (genetic) and modifiable (lifestyle and health) risk factors, highlighting possible sex-dependent differential effects for the AD disease course. Finally, we evaluate the studies selected for this review demonstrating sex-differences in cognitive, pathological and health factors, summarising the state of sex differences in AD risk factors. We further provide recommendations for targeted research on female-specific risk factors, to inform personalised strategies for AD-prevention and the promotion of female brain health.

Reducing Your Risk of Alzheimer's Dementia: Building a Better Brain as We Age

Alzheimer' dementia is a large and growing public health problem. Of utmost importance for limiting the impact of the disease on society is the prevention of dementia, that is, delay onset either by years whereby death ensues prior to dementia onset. The Religious Orders Study and the Rush Memory and Aging Project are two harmonized cohort studies of aging and dementia that include organ donation at death. Ongoing since 1994 and 1997, respectively, we published on the association of numerous experiential, psychological, and medical risk factors for dementia, many of which are potentially modifiable. Here, selected findings are reviewed based on a presentation at the 2020 National Academy of Neuropsychology given virtually in Chicago in October of 2020.

Mindfulness-Based Training Does Not Improve Neuropsychological Outcomes in Mild Cognitive Impairment More Than Spontaneous Reversion Rates: A Randomized Controlled Trial

BACKGROUND

Current pharmacological and behavioral treatment options for mild cognitive impairment (MCI) are limited, motivating a search for alternative therapies that might slow the progression of cognitive decline.

OBJECTIVE

We investigated the effectiveness of a cognition-focused mindfulness-based intervention.

METHODS

An open-label, three arm randomized controlled trial was conducted at a public tertiary medical center. Older persons (ages 45-75; N = 76) diagnosed with MCI were recruited and randomized into either mindfulness-based training (MBT), cognitive rehabilitation therapy (CRT), or treatment as usual (TAU). Participants in the intervention arms received 8 weekly 2-h sessions delivered in a group setting and engaged in home practice. Primary outcomes measures included changes in index scores for attention, immediate memory, and delayed memory as measured using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Depression was a secondary outcome.

RESULTS

Using intent-to-treat analysis, we found that participants receiving MBT showed significant improvements in global cognition (d = 0.26; [95%CI 0.03-0.56]) and delayed memory (d = 0.36; [95%CI 0.17-0.57]), with significantly greater improvements in delayed memory than CRT (ηp2 = 0.10). However, there was no benefit of MBT over TAU. No change in depression was observed in the MBT group. Reductions in depression were associated with improvements in cognitive functioning in the MBT group only.

CONCLUSION

Our results suggest that a cognition-focused MBT did not improve cognitive functioning in MCI patients substantially more than spontaneous reversion rates, possibly as mood symptoms were not significantly alleviated in this group.

Neuropsychiatric symptoms and the outcome of cognitive trajectories in older adults free of dementia: The Mayo Clinic Study of Aging

OBJECTIVE

Neuropsychiatric symptoms (NPS) are associated with the risk of incident mild cognitive impairment (MCI) and dementia. We examined associations between NPS and the outcomes of global and domain-specific cognitive trajectories.

METHODS

In this longitudinal study conducted in the setting of the population-based Mayo Clinic Study of Aging, 5081 community-dwelling, nondemented individuals aged ≥50 years (51% males) underwent NPS assessment using Neuropsychiatric Inventory Questionnaire (NPI-Q), and Beck Depression and Anxiety Inventories (BDI-II, BAI). Global and domain-specific (memory, language, attention, and visuospatial skills) cognitive performance was assessed through neuropsychological testing every 15 months. Associations between baseline NPS and trajectories for individual yearly change in cognitive z-scores were calculated using linear mixed-effect models.

RESULTS

Cognition declined regardless of NPS status over the median follow-up of 4.5 years. Presence of NPS was associated with increased cognitive decline. Differences in annualized change in global cognition z-scores for participants with NPS compared to without NPS ranged from -0.018 (95% CI -0.032, -0.004; p = 0.011) for irritability to -0.159 (-0.254, -0.065; p = 0.001) for hallucinations. Associations between NPS and annual decline in global cognition were significant for most NPI-Q-assessed NPS and clinical depression (BDI-II≥13). Participants with NPI-Q-assessed depression, apathy, nighttime behavior, and clinical depression had greater decline in all domain-specific z-scores; presence of delusions and anxiety was associated with more pronounced decline in language, attention and visuospatial skills.

CONCLUSION

NPS were associated with a more accelerated cognitive decline. Clinical assessment and potential treatment of NPS is warranted even in a community setting as NPS may impact cognitive decline in nondemented individuals.

Association of Stress with Risk of Dementia and Mild Cognitive Impairment: A Systematic Review and Meta-Analysis

BACKGROUND

Although many studies have investigated the association between stress and risk of dementia, findings are inconsistent due to the variation in the measures used to assess stress.

OBJECTIVE

We conducted a systematic review and meta-analysis to investigate the association between psychological stress (including neuroticism, stressful life events, and perceived stress) and the risk of incident dementia and mild cognitive impairment in adults.

METHODS

PsycINFO, Embase, and MEDLINE were searched to October 2020 for eligible observational, prospective studies. Of the 1,607 studies screened, 26 (24 unique cohorts) were included in the qualitative analysis and 16 (15 unique cohorts) were included in the quantitative analysis.

RESULTS

Across studies, higher perceived stress was significantly associated with an increased risk of mild cognitive impairment (Cases/Total N = 207/860: hazard ratio [HR] = 1.19, 95% confidence interval [CI] = 1.03-1.38) and all-cause dementia (Cases/Total N = 203/1,882: HR = 1.44, 95% CI = 1.07-1.95). Exposure to two or more stressful life events (versus none) was significantly associated with an increased risk of all-cause dementia (Cases/Total N = 3,354/11,597: HR = 1.72, 95% CI = 1.14-2.60), while one or more stressful life events was not. Higher neuroticism was significantly associated with an increased risk of Alzheimer's disease dementia (Cases/Total N = 497/4,771: HR = 1.07, 95% CI = 1.01-1.12), but not all-cause dementia.

CONCLUSION

This review suggests that psychological stress in adulthood is associated with an increased risk of dementia. Further research is needed to clarify the mechanisms underlying these associations.

Cerebral amyloid accumulation is associated with distinct structural and functional alterations in the brain of depressed elders with mild cognitive impairment

BACKGROUND

Elderly patients with late-life depression (LLD) often report mild cognitive impairment (MCI), so Alzheimer's disease (AD) is hard to identify in these patients. We aimed to identify the structural and functional differences between prodromal AD and LLD-related MCI.

METHODS

We performed voxel-based morphometry and functional connectivity (FC) analyses in elderly patients with both LLD and MCI to compare alterations between those with cerebral amyloidopathy and those without. We subdivided patients into subthreshold depression (STD) and major depressive disorder (MDD) groups. Using florbetaben positron emission tomography (PET), we compared volume and connectivity between healthy controls and four STD and MDD groups with or without amyloid deposition(A): STD-MCI-A(+), MDD-MCI-A(+), STD-MCI-A(-), and MDD-MCI-A(-).

RESULTS

Subjects with MDD or amyloid deposition showed greater volume reduction in the left middle temporal gyrus. MDD groups had lower FC than STD groups in the frontal, cortical, and limbic areas. The STD-MCI-A(+) group showed greater FC reduction than the MDD-MCI-A(-) and STD-MCI-A(-) groups, particularly in the hippocampus, parahippocampus, and frontal and temporal cortices. The functional differences associated with amyloid plaques were more evident in the STD group than in the MDD group.

LIMITATIONS

Limitations include disproportional sex ratios, inability to determine the longitudinal effects of amyloidopathy in large populations.

CONCLUSIONS

Regional gray matter loss and alterations in brain networks may reflect impairments caused by amyloid deposition and depression. Such changes may facilitate the detection of prodromal AD in elderly patients with both depression and cognitive dysfunction, allowing earlier intervention and more appropriate treatment.

Brain Regional Glucose Metabolism, Neuropsychiatric Symptoms, and the Risk of Incident Mild Cognitive Impairment: The Mayo Clinic Study of Aging

OBJECTIVE

The authors conducted a prospective cohort study to examine the risk of incident mild cognitive impairment (MCI) as predicted by baseline neuropsychiatric symptoms (NPS) and brain regional glucose metabolic dysfunction.

METHODS

About 1,363 cognitively unimpaired individuals (52.8% males) aged ≥50 years were followed for a median of 4.8 years to the outcome of incident MCI. NPS were assessed using Beck Depression and Anxiety Inventories and Neuropsychiatric Inventory Questionnaire. Glucose hypometabolism was measured by fluorodeoxyglucose positron emission tomography and defined as standardized uptake value ratio ≤ 1.47 in regions typically affected in Alzheimer disease. Cox proportional hazards models were adjusted for age, sex, education, and APOE ε4 status.

RESULTS

Participants with regional glucose hypometabolism and depression (Beck Depression Inventory-II ≥13) had a more than threefold increased risk of incident MCI (hazard ratio [95% confidence interval], 3.66 [1.75, 7.65], p <0.001, χ² = 11.83, degree of freedom [df] = 1) as compared to the reference group (normal regional glucose metabolism and no depression), and the risk was also significantly elevated (7.21 [3.54, 14.7], p <0.001, χ² = 29.68, df = 1) for participants with glucose hypometabolism and anxiety (Beck Anxiety Inventory ≥10). Having glucose hypometabolism and ≥1 NPS (3.74 [2.40, 5.82], p <0.001, χ² = 34.13, df = 1) or ≥2 NPS (3.89 [2.20, 6.86], p <0.001, χ² = 21.92, df = 1) increased the risk of incident MCI by more than three times, and having ≥3 NPS increased the risk by more than four times (4.12 [2.03, 8.37], p <0.001, χ² = 15.39, df = 1).

CONCLUSION

Combined presence of NPS with regional glucose hypometabolism is associated with an increased risk of incident MCI, with fluorodeoxyglucose positron emission tomography appearing to be a stronger driving force of cognitive decline than NPS.

Interactions between Personality, Depression, Anxiety and Cognition to Understand Early Stage of Alzheimer's Disease

The multifaceted nature of Alzheimer's disease (AD) and Mild cognitive impairment (MCI) can lead to wide inter-individual differences in disease manifestation in terms of brain pathology and cognition. The lack of understanding of phenotypic diversity in AD arises from a difficulty in understanding the integration of different levels of network organization (i.e. genes, neurons, synapses, anatomical regions, functions) and in inclusion of other information such as neuropsychiatric characteristics, personal history, information regarding general health or subjective cognitive complaints in a coherent model. Non-cognitive factors, such as personality traits and behavioral and psychiatric symptoms, can be informative markers of early disease stage. It is known that personality can affect cognition and behavioral symptoms. The aim of the paper is to review the different types of interactions existing between personality, depression/anxiety, and cognition and cognitive disorders at behavioral and brain/genetic levels.

A Multilevel View of the Development of Alzheimer's Disease

Every year the Alzheimer's Association publishes a report that provides facts and figures indicating the public health, social and economic impact of Alzheimer's disease (AD). In addition, there are a number of reviews on the disease for general readers. Also, at congresses, AD is analyzed at different but not always related levels, leading to an "elephant as seen by blind men situation" for many of the participants. The review presented herein seeks to provide readers with a holistic view of how AD develops from various perspectives: the whole human organism, brain, circuits, neurons, cellular hallmarks, and molecular level.

Can Adults with Mild Cognitive Impairment Build Cognitive Reserve and Learn Mindfulness Meditation? Qualitative Theme Analyses from a Small Pilot Study

BACKGROUND/OBJECTIVE

High levels of chronic stress negatively impact the hippocampus and are associated with increased incidence of mild cognitive impairment (MCI) and Alzheimer's disease. While mindfulness meditation may mitigate the effects of chronic stress, it is uncertain if adults with MCI have the capacity to learn mindfulness meditation.

METHODS

14 adults with MCI were randomized 2:1 to Mindfulness Based Stress Reduction (MBSR) or a wait-list control group. We conducted qualitative interviews with those who completed MBSR. Transcribed interviews were: a) coded using an emergent themes inductive approach informed by grounded theory; b) rated 0-10, with higher scores reflecting greater perceived benefit from, and understanding of, mindfulness meditation. Ratings were correlated with daily home practice times and baseline level of cognitive function.

RESULTS

Seven themes emerged from the interviews: positive perceptions of class; development of mindfulness skills, including meta-cognition; importance of the group experience; enhanced well-being; shift in MCI perspective; decreased stress reactivity and increased relaxation; improvement in interpersonal skills. Ratings of perceived benefit and understanding ranged from 2-10 (mean = 7) and of 0-9.5 (mean = 6), respectively. Many participants experienced substantial benefit/understanding, some had moderate, and a few had minimal benefit/understanding. Understanding the key concepts of mindfulness was highly positively correlated with ≥20 minutes/day of home practice (r = 0.90) but not with baseline cognitive function (r = 0.13).

CONCLUSIONS

Most adults with MCI were able to learn mindfulness meditation and had improved MCI acceptance, self-efficacy, and social engagement. Cognitive reserve may be enhanced through a mindfulness meditation program even in patients with MCI.

The relationship between cognitive reserve and personality traits: a pilot study on a healthy aging Italian sample

BACKGROUND

Exploring the role of different individual factors in affecting the cognitive reserve levels is crucial step for aging research. Several studies explored the relationship between personality traits and aging, but a specific focus on the cognitive reserve is missing.

AIMS

This study aimed at collecting more direct evidence about possible relationships between cognitive reserve and personality traits.

METHODS

A sample of 100 healthy aging participants was involved in the study. They completed the Big Five personality inventory and a test to assess the cognitive reserve.

RESULTS

Results returned a positive relationship between the personality traits and participants' cognitive reserve. The only factor that did not return a significant correlation was Emotional stability (which overlaps with Neuroticism).

DISCUSSION

This study provides additional evidence to the existing literature and also adds relevant information and a critical reading regarding the role of personality traits that has been neglected in the aging literature, Friendliness and Conscientiousness.

CONCLUSION

The ability to measure and identify personality traits could be important in future research for developing interventions or activities that could target specific personality characteristics.

Effect of Mental Fatigue on Postural Sway in Healthy Older Adults and Stroke Populations

The aim of this study was to examine the effect of mental fatigue on postural sway under different sensory conditions in healthy older adults and in persons with chronic stroke (PwCS). Thirty healthy older adults (> 60 years old), randomly separated into experimental and control groups, as well as 15 PwCS participated in this study. Experimental groups were asked to stand on a force platform wearing seven inertial sensors while performing the Sensory Organization Test (SOT) under two cognitive conditions (single- and dual-task) before and after a mental fatigue task (stop-signal task for 60 min). The control group performed the same protocol before and after watching a movie for 60 min. Changes in subjective fatigue was assessed by the NASA Task Load Index and psychophysiological workload was assessed by heart rate variability (HRV). Postural sway was assessed by calculating the Jerk and root mean square (RMS) of center of mass (COM). Higher Jerk and RMS of COM (p < 0.05) were observed after the mental fatigue task in both healthy older adults and PwCS during SOT, which was not observed in the control group (p > 0.05). Additionally, postural sway increased in the three groups as the SOT conditions became more challenging. Our results indicate that mental fatigue, induced by sustained cognitive activity, can impair balance during SOT in older adult and stroke populations.

Neuropsychiatric symptoms as prognostic makers for the elderly with mild cognitive impairment: a meta-analysis

BACKGROUND

Although several neuropsychiatric symptoms (NPSs) have been demonstrated to have value in the prediction of the progression of mild cognitive impairment (MCI) to dementia, these symptoms are less studied for the prediction of the transition from normal cognition (NC) to MCI.

METHODS

Prospective cohort studies were included if they reported on at least one NPS at baseline and had MCI as the outcome.

RESULTS

We obtained 13 cohort studies with a total population of 33,066. Depression was the most common neuropsychiatric symptom and could significantly predict transition to MCI (RR = 1.49, 95% CI: 1.13-1.86). However, depression was more capable of predicting amnestic MCI (RR=1.43, 95% CI: 1.04-1.83) than non-aMCI (RR= 0.96, 95% CI 95% CI: 0.60-1.33). Subgroup analysis suggested that the association between depression and MCI changed with depression severity, depression criteria, apolipoprotein-E-adjusted status, age, the percentage of females, and follow-up times, but some data were too sparse for a reliable estimate. Regarding other NPSs, there were insufficient data to assess their effect on the development of MCI. However, apathy, anxiety, sleep disturbances, irritability, and agitation might be risk factors for the prediction of NC-MCI transition with strong predictive value.

CONCLUSIONS

Depression was associated with an approximately 1.5-fold sincreased risk of the progression to MCI in the population with normal cognition. Other NPSs with underlying predictive value deserve more attention.

The mediating effect of psychological distress on cognitive function and physical frailty among the elderly: Evidence from rural Shandong, China

BACKGROUND

Few studies have explored the underlying mechanism between physical frailty and cognitive function. The aim of this study is to explore the mediating role of psychological distress (PD) for the association between cognitive function and physical frailty among the elderly in rural China.

METHODS

A total of 3,242 rural older adults were included in the analysis. Logistic regression and Bootstrap analyses were employed to explore the association between cognitive function, PD and frailty, and the mediating role of PD.

RESULTS

This study found that the prevalence of frailty and cognitive impairment among the elderly in rural China was 18.0%, 22.4%. After adjusted for controlling variables, cognitive function was significantly associated with high level of PD, and elderly with higher level of PD had a higher probability of suffering from frailty. PD played a partially mediating effect in cognitive function and frailty and the mediating effect of PD can explain the 11.0% of the total effect of cognitive function on frailty.

LIMITATIONS

The data were cross-sectional, thus the causal relationship between variables could not be determined. The main variables in this study were measured by self-report information, which might result in recall bias.

CONCLUSIONS

This study provide evidence that the effect of cognitive function on physical frailty was partially mediated by PD among the elderly in rural China. Primary health care should strengthen the screening of PD characterized by depression and anxiety, and strive to improve the physical and psychological well-being of rural elderly in China.