Mild behavioral impairment linked to progression to Alzheimer's disease and cortical thinning in amnestic mild cognitive impairment

Structural covariance network patterns linked to neuropsychiatric symptoms in biologically defined Alzheimer's disease: Insights from the mild behavioral impairment checklist

BACKGROUND

The frequent presentation of Alzheimer's disease (AD) with neuropsychiatric symptoms (NPS) in the context of normal or minimally-impaired cognitive function led to the concept of Mild Behavioral Impairment (MBI). While MBI's impact on subsequent cognitive decline is recognized, its association with brain network changes in biologically-defined AD remains unexplored.

OBJECTIVE

To investigate the correlation of structural covariance networks with MBI-C checklist sub-scores in biologically-defined AD patients.

METHODS

We analyzed 33 biologically-defined AD patients, ranging from mild cognitive impairment to early dementia, all characterized as amyloid-positive through cerebrospinal fluid analysis or amyloid positron emission tomography scans. Regional network properties were assessed through graph theory.

RESULTS

Affective dysregulation correlated with decreased segregation and integration in the right inferior frontal gyrus (IFG). Impulse dyscontrol and social inappropriateness correlated positively with centrality and efficiency in the right posterior cingulate cortex (PCC). Global network properties showed a preserved small-world organization.

CONCLUSIONS

This study reveals associations between MBI subdomains and structural brain network alterations in biologically-confirmed AD. The IFG's involvement is crucial for mood dysregulation, while the PCC could be involved in compensatory mechanisms for social cognition and impulse control. These findings underscore the significance of biomarker-based neuroimaging for the characterization of NPS across the AD spectrum.

Empirical Classification of Neuropsychiatric Symptoms and Association of Classes With Diagnostic Progression and Cognitive Decline in Mild Cognitive Impairment and Alzheimer's Disease Populations

BACKGROUND

The current study aimed to identify classes of cognitively impaired older individuals based on their neuropsychiatric symptoms (NPSs) and to investigate the contribution of NPS class to cognitive decline and Alzheimer's disease (AD) risk in mild cognitive impairment (MCI).

METHODS

Our study included 1472 participants (age range 55-91 years) from the ADNI (Alzheimer's Disease Neuroimaging Initiative) who were diagnosed with MCI or mild AD and completed the Neuropsychiatric Inventory at their baseline visit. We used latent class analysis to categorize groups by NPS patterns. Linear mixed models of repeated measures were used to compare changes in cognitive performance across 5 years as a function of NPS class. Subsequently, Cox proportional hazards models were used in individuals with MCI to assess whether the rate of conversion to AD differed across the NPS groups.

RESULTS

We identified 3 latent classes of NPSs: no NPS (n = 799, 51.7%), apathy/affective NPS (n = 572, 39.8%), and complex NPS (n = 108, 8.5%). In longitudinal analyses, we observed interactions between class and time, indicating accelerated cognitive decline in memory and executive function in the apathy/affective class. In MCI, hazard ratios for conversion to AD were 1.39 (95% CI, 1.10-1.76) for the apathy/affective class and 2.03 (95% CI, 1.33-3.10) for the complex class compared with the no NPS group after adjusting for age, sex, education, global cognition, and APOE ε4 positivity.

CONCLUSIONS

Among cognitively impaired older adults, empirically derived clusters of NPS profiles were associated with cognitive decline and risk of conversion from MCI to AD. Such NPS classes may reflect specific neurobiological mechanisms within or related to AD-related neurodegeneration. Further studies with biological markers are needed to clarify these neurobiological mechanisms.

Associations of Traumatic Brain Injury and Mild Behavioral Impairment With Cognitive Function and Dementia

OBJECTIVE

Traumatic Brain Injury (TBI) may contribute additional complexity to the clinical picture of mild behavioral impairment (MBI). MBI, a behavioral analog to mild cognitive impairment (MCI), is comprised of five neuropsychiatric domains: decreased motivation, affective dysregulation, impulse dyscontrol, social inappropriateness, and abnormal perception/thought content. We investigated (1) if cross-sectional associations of cognitive status with MBI symptoms differ by TBI status and (2) if prospective associations of MBI domain positivity with incident dementia risk differ by TBI status.

METHODS

2246 participants without dementia from the Atherosclerosis Risk in Communities Study were included (mean age = 75.6 years, 59.0% female). TBI was defined by self-report/ICD-9/10 codes, MBI via an established algorithm based on the Neuropsychiatric Inventory Questionnaire, and baseline cognitive status/incident dementia using neuropsychological tests, informant interviews, and hospital/death certificate codes.

RESULTS

Cross-sectionally, although MCI status was associated with greater odds of MBI, this did not differ based on TBI status (MCI with TBI: OR = 2.04, 95% CI = 1.44-2.88, MCI without TBI: OR = 1.60, 95% CI = 1.20-2.14). Individuals with MCI (with or without TBI) were more likely to have decreased motivation, affective dysregulation, and impulse dyscontrol. Prospectively, positivity in 1+ MBI domains was associated with increased risk of incident dementia, not differing by TBI status (no TBI and MBI: HR = 2.15, 95% CI = 1.55-2.99, TBI and MBI: HR = 2.62, 95% CI = 1.81-3.80).

CONCLUSIONS

Neither cross-sectional associations between cognitive status and MBI domain positivity nor prospective associations of MBI domain positivity with incident dementia risk differed by TBI status. How TBI may relate to neuropsychiatric symptomatology in the context of neurodegenerative processes requires further clarification.

Associations of Mild Behavioral Impairment Domains with Brain Volumes: Cross-sectional Analysis of Atherosclerosis Risk in Community (ARIC) Study

BACKGROUND

Mild behavioral impairment (MBI) has been associated with global brain atrophy, but the regional neural correlates of MBI symptoms are less clear, particularly among community-dwelling older individuals without dementia.

OBJECTIVE

Our objective was to examine the associations of MBI domains with gray matter (GM) volumes in a large population-based sample of older adults without dementia.

METHODS

We performed a cross-sectional study of 1445 community-dwelling older adults in the Atherosclerosis Risk in Communities Study who underwent detailed neurocognitive assessment and brain magnetic resonance imaging in 2011-2013. MBI domains were defined using an established algorithm that maps data collected from informants on the Neuropsychiatric Inventory Questionnaire to the 5 MBI domains of decreased motivation, affective dysregulation, impulse dyscontrol, social inappropriateness, and abnormal perception/thought content. We performed voxel-based morphometry analyses to investigate associations of any MBI domain symptoms with GM volumes. We additionally performed region-of-interest analyses using adjusted linear regression models to examine associations between individual MBI domains with a priori-hypothesized regional GM volumes.

RESULTS

Overall, the mean age of participants was 76.5 years; 59% were female, 21% were of Black race, and 26% had symptoms in at least one MBI domain. Participants with normal cognition comprised 60% of the population, and 40% had mild cognitive impairment. Compared to individuals without any MBI domain symptoms, voxel-based morphometry analyses showed that participants with symptoms in at least one MBI domain had consistently lower GM volumes in the cerebellum and bilateral temporal lobes, particularly involving the hippocampus. In adjusted region-of-interest models, affective dysregulation domain symptoms were associated with lower GM volume in the inferior temporal lobe (β = -0.34; 95% confidence interval = -0.64, -0.04), and impulse dyscontrol domain symptoms were associated with lower GM volume in the parahippocampal gyrus (β = -0.06; 95% confidence interval = -0.11, 0.00).

CONCLUSIONS

In this community-dwelling population of older adults without dementia, MBI symptoms were associated with lower GM volumes in regions commonly implicated in early Alzheimer's disease pathology. These findings lend support to the notion that MBI symptoms may be useful in identifying individuals at risk for future dementia.

Neurodegeneration in the cortical sulcus is a feature of chronic traumatic encephalopathy and associated with repetitive head impacts

Neurodegeneration is a seminal feature of many neurological disorders. Chronic traumatic encephalopathy (CTE) is caused by repetitive head impacts (RHI) and is characterized by sulcal tau pathology. However, quantitative assessments of regional neurodegeneration in CTE have not been described. In this study, we quantified three key neurodegenerative measures, including cortical thickness, neuronal density, and synaptic proteins, in contact sport athletes (n = 185) and non-athlete controls (n = 52) within the sulcal depth, middle, and gyral crest of the dorsolateral frontal cortex. Cortical thickness and neuronal density were decreased within the sulcus in CTE compared to controls (p's < 0.05). Measurements of synaptic proteins within the gyral crest showed a reduction of α-synuclein with CTE stage (p = 0.002) and variable changes in PSD-95 density. After adjusting for age, multiple linear regression models demonstrated a strong association between the duration of contact sports play and cortical thinning (p = 0.001) and neuronal loss (p = 0.032) within the sulcus. Additional regression models, adjusted for tau pathology, suggest that within the sulcus, the duration of play was associated with neuronal loss predominantly through tau pathology. In contrast, the association of duration of play with cortical thinning was minimally impacted by tau pathology. Overall, CTE is associated with cortical atrophy and a predominant sulcal neurodegeneration. Furthermore, the duration of contact sports play is associated with measures of neurodegeneration that are more severe in the cortical sulcus and may occur through tau-dependent and independent mechanisms.

Mild behavioral impairment in people with mild cognitive impairment: Are the two conditions related?

BACKGROUND

Mild cognitive impairment (MCI) and mild behavioral impairment (MBI) are both considered potential prodromal stages of dementia, especially Alzheimer's disease. Previous literature has lacked specific information about MBI in individuals with MCI and associations of several aspects of both, MBI and MCI.

OBJECTIVE

Our aim was to investigate whether associations exist between aspects of MBI and aspects of cognitive performance in certain dimensions of the Montreal Cognitive Assessment (MoCA).

METHODS

We used baseline data from the double-blind randomized controlled intervention MCI-CCT-study. Current cognitive performance of individuals with MCI was measured with the MoCA. MBI was assessed with the MBI Shortscale (MBI short), which was administered through a self-report interview. Associations were assessed with Pearson correlations. Sensitivity analyses were conducted for gender and cognition. Group differences were examined with independent samples t-tests or Welch test. Significant correlations were considered in binary logistic regressions under control of covariates.

RESULTS

There was no significant correlation between the current MoCA and MBI short scores in the total sample or in the gender-related analysis. Using dichotomized cognitive performance, significant correlations between MCI and MBI were revealed for individuals with lower MoCA scores. On the task level, several significant associations were identified between MoCA dimensions and MBI dimensions in the total sample and in the sensitivity analyses, also under control of covariates.

CONCLUSIONS

Our findings support the hypothesis that with increasing cognitive decline, the association between MCI and MBI becomes stronger. Furthermore, a certain cut-off on the MoCA must be reached to identify a correlation.

Mild behavioral impairment in the general population aged 55+ and its association with incident dementia

This study aimed to investigate the dementia risk associated with mild behavioral impairment (MBI) and its domains in older community-dwelling individuals. A total 4803 community-dwelling individuals aged over 55 years were followed for 4.5 years (ZARADEMP study). MBI was assessed according to the International Society to Advance Alzheimer's Research and Treatment (ISTAART) diagnostic criteria using the Geriatric Mental State (GMS). Odds ratios (OR) for incident dementia and Alzheimer's disease (AD) were determined using logistic regression models adjusted for potential confounders (such as age, disability, or vascular disease). In cognitively normal individuals, decreased motivation was the only MBI domain that was associated with an increased risk of all-cause dementia (OR: 2.30 [95% confidence interval {CI}: 1.16-4.61]) in multivariable analyses, although the increase in the risk of AD was not statistically significant. Our findings suggest that decreased motivation may be a phenotypic marker for individuals at risk of dementia. Further research is required to evaluate the association between MBI domains and different types of dementia.

Neuropsychiatric symptoms: Risk factor or disease marker? A study of structural imaging biomarkers of Alzheimer's disease and incident cognitive decline

Neuropsychiatric symptoms (NPS) are risk factors for Alzheimer's disease (AD) but can also manifest secondary to AD pathology. Mild behavioral impairment (MBI) refers to later-life emergent and persistent NPS that may mark early-stage AD. To distinguish MBI from NPS that are transient or which represent psychiatric conditions (non-MBI NPS), we investigated the effect of applying MBI criteria on NPS associations with AD structural imaging biomarkers and incident cognitive decline. Data for participants (n = 1273) with normal cognition (NC) or mild cognitive impairment (MCI) in the National Alzheimer's Coordinating Center Uniform Data Set were analyzed. NPS status (MBI, non-MBI NPS) was derived from the Neuropsychiatric Inventory Questionnaire and psychiatric history. Normalized measures of bilateral hippocampal (HPC) and entorhinal cortex (EC) volume, and AD meta-region of interest (ROI) mean cortical thickness were acquired from T1-weighted magnetic resonance imaging scans. Multivariable linear and Cox regressions examined NPS associations with imaging biomarkers and incident cognitive decline, respectively. MBI was associated with lower volume and cortical thickness in all ROIs in both NC and MCI, except for EC volume in NC. Non-MBI NPS were only associated with lower HPC volume in NC. Although both of the NPS groups showed higher hazards for MCI/dementia than No NPS, MBI participants showed more rapid decline. Although both types of NPS were linked to HPC atrophy, only NPS that emerged and persisted in later-life, consistent with MBI criteria, were related to AD neurodegenerative patterns beyond the HPC. Moreover, MBI predicted faster progression to dementia than non-MBI NPS.

Neuropsychiatric symptoms as a prodromal factor in Alzheimer's type neurodegenerative disease: A scoping review

Objective: Identifying neuropsychiatric symptoms (NPS) can aid in the early detection of Alzheimer's disease (AD); however, there is still a need for a greater consensus. This review aims to delineate the predominant NPS, compile a comprehensive list of the most commonly employed NPS assessment tools, and corroborate the principal findings regarding the link between NPS and neuropsychological assessment and neurobiological substrates. Methods: To conduct this scoping review, we followed the Preferred Reporting Items for Systematic Reviews guidelines and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). We searched for relevant articles published between 2017 and 2023 in MEDLINE, PsycINFO, PubMed, Web of Science, and Cochrane Library. Results: Of the 61 eligible articles, depression, anxiety, and apathy were the main NPSs. The Neuropsychiatric Inventory Questionnaire and Neuropsychiatric Inventory were the primary assessment tools used to evaluate NPS. Correlations between NPS severity and neurobiological markers were considered clinically significant. Furthermore, clinical procedures prioritized the use of global cognitive screening tools, assessments of executive functions, and functionality evaluations. Conclusion: Standardization of procedures is necessary because of the diversity of methods. The data show that NPS can predict the etiology, severity, form, and type of disease progression, serving as a precursor sign of AD. The results of the most common cognitive screening tools and NPS instruments provided an interesting overview of future clinical approaches.

White Matter Microstructural Underpinnings of Mild Behavioral Impairment in Parkinson's Disease

BACKGROUND

Patients with Parkinson's disease (PD) experience changes in behavior, personality, and cognition that can manifest even in the initial stages of the disease. Previous studies have suggested that mild behavioral impairment (MBI) should be considered an early marker of cognitive decline. However, the precise neurostructural underpinnings of MBI in early- to mid-stage PD remain poorly understood.

OBJECTIVE

The aim was to explore the changes in white matter microstructure linked to MBI and mild cognitive impairment (MCI) in early- to mid-stage PD using diffusion magnetic resonance imaging (dMRI).

METHODS

A total of 91 PD patients and 36 healthy participants were recruited and underwent anatomical MRI and dMRI, a comprehensive neuropsychological battery, and the completion of the Mild Behavioral Impairment-Checklist. Metrics of white matter integrity included tissue fractional anisotropy (FAt) and radial diffusivity (RDt), free water (FW), and fixel-based apparent fiber density (AFD).

RESULTS

The connection between the left amygdala and the putamen was disrupted when comparing PD patients with MBI (PD-MBI) to PD-non-MBI, as evidenced by increased RDt (η2 = 0.09, P = 0.004) and both decreased AFD (η2 = 0.05, P = 0.048) and FAt (η2 = 0.12, P = 0.014). Compared to controls, PD patients with both MBI and MCI demonstrated increased FW for the connection between the left orbitofrontal gyrus (OrG) and the hippocampus (η2 = 0.22, P = 0.008), augmented RDt between the right OrG and the amygdala (η2 = 0.14, P = 0.008), and increased RDt (η2 = 0.25, P = 0.028) with decreased AFD (η2 = 0.10, P = 0.046) between the right OrG and the caudate nucleus.

CONCLUSION

MBI is associated with abnormal microstructure of connections involving the orbitofrontal cortex, putamen, and amygdala. To our knowledge, this is the first assessment of the white matter microstructure in PD-MBI using dMRI. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Exploring the Relationship between Behavioral and Neurological Impairments Due to Mild Cognitive Impairment: Correlation Study between Virtual Kiosk Test and EEG-SSVEP

Amnestic mild cognitive impairment (aMCI) is a transitional stage between normal aging and Alzheimer's disease, making early screening imperative for potential intervention and prevention of progression to Alzheimer's disease (AD). Therefore, there is a demand for research to identify effective and easy-to-use tools for aMCI screening. While behavioral tests in virtual reality environments have successfully captured behavioral features related to instrumental activities of daily living for aMCI screening, further investigations are necessary to establish connections between cognitive decline and neurological changes. Utilizing electroencephalography with steady-state visual evoked potentials, this study delved into the correlation between behavioral features recorded during virtual reality tests and neurological features obtained by measuring neural activity in the dorsal stream. As a result, this multimodal approach achieved an impressive screening accuracy of 98.38%.

The mind and motion: exploring the interplay between physical activity and Mild Behavioral Impairment in dementia-free older adults

Physical inactivity in mid-life is a modifiable risk factor for dementia. Mild behavioral impairment (MBI) is a marker of potential neurodegenerative disease. We investigated the association between physical activity and MBI. Baseline data from the Canadian Platform for Research Online to Investigate Health, Quality of Life, Cognition, Behaviour, Function, and Caregiving in Aging (CAN-PROTECT) were used. Four categories of weekly physical activity (cardiovascular, mind-body, strength training, and physical labour) were derived from the Community Healthy Activities Model Program for Seniors questionnaire. MBI was measured using the MBI-Checklist. Multivariable negative binomial regressions modelled the association between the standardized physical activity duration and MBI severity, adjusted for age, sex, education, marital status, ethno cultural origin, occupation, hypertension, dyslipidemia, mobility, and body mass index. Every 1 SD increase in cardiovascular activity was associated with 8.42% lower MBI severity. In contrast, every 1 SD increase in physical labor duration was associated with 5.64% greater MBI severity. These associations were neither moderated by the frequency engaging in each physical activity nor by sex. Cardiovascular physical activity in older persons may reduce levels of non-cognitive dementia markers like MBI, comparable to effects seen in cognition, potentially modulating dementia risk.

Applying the Consensus Criteria for Traumatic Encephalopathy Syndrome Retrospectively to Case Studies of Boxers from the 20th Century

There are no validated diagnostic criteria for traumatic encephalopathy syndrome (TES). During the early and middle 20th century, TES was described as a clinical condition that was experienced by some high-exposure boxers-and it was believed to reflect chronic traumatic brain injury. Consensus criteria for the diagnosis of TES were published in 2021. We applied the consensus criteria for TES retrospectively to cases of chronic brain damage in boxers described in articles published in the 20th century that were obtained from narrative and systematic reviews. The sample included 157 boxers identified in 21 articles published between 1929 and 1999. Two authors reviewed each case description and coded the criteria for TES. For the core clinical features, cognitive impairment was noted in 63.1%, and in 28.7% of cases the person's cognitive functioning appeared to be broadly normal. Neurobehavioral dysregulation was present in 25.5%. One third (34.4%) were identified as progressive, 30.6% were not progressive, and the course could not be clearly determined in 35.0%. In total, 29.9% met the TES consensus criteria, 28.0% did not, and 42.0% had insufficient information to make a diagnostic determination. TES, in the 20th century, was described as a neurological condition, not a psychiatric disorder-and this supports the decision of the 2021 consensus group to remove primary and secondary psychiatric diagnoses from being a core diagnostic feature. Future research is needed to determine whether, or the extent to which, cognitive impairment or neurobehavioral dysregulation described as characterizing TES are associated with chronic traumatic encephalopathy neuropathological change.

Tau-PET in early cortical Alzheimer brain regions in relation to mild behavioral impairment in older adults with either normal cognition or mild cognitive impairment

Mild Behavioral Impairment (MBI) leverages later-life emergent and persistent neuropsychiatric symptoms (NPS) to identify a high-risk group for incident dementia. Phosphorylated tau (p-tau) is a hallmark biological manifestation of Alzheimer disease (AD). We investigated associations between MBI and tau accumulation in early-stage AD cortical regions. In 442 Alzheimer's Disease Neuroimaging Initiative participants with normal cognition or mild cognitive impairment, MBI status was determined alongside corresponding p-tau and Aβ. Two meta-regions of interest were generated to represent Braak I and III neuropathological stages. Multivariable linear regression modelled the association between MBI as independent variable and tau tracer uptake as dependent variable. Among Aβ positive individuals, MBI was associated with tau uptake in Braak I (β =0.45(0.15), p<.01) and Braak III (β =0.24(0.07), p<.01) regions. In Aβ negative individuals, MBI was not associated with tau in the Braak I region (p=.11) with a negative association in Braak III (p=.01). These findings suggest MBI may be a sequela of neurodegeneration, and can be implemented as a cost-effective framework to help improve screening efficiency for AD.

Optimizing detection of Alzheimer's disease in mild cognitive impairment: a 4-year biomarker study of mild behavioral impairment in ADNI and MEMENTO

BACKGROUND

Disease-modifying drug use necessitates better Alzheimer disease (AD) detection. Mild cognitive impairment (MCI) leverages cognitive decline to identify the risk group; similarly, mild behavioral impairment (MBI) leverages behavioral change. Adding MBI to MCI improves dementia prognostication over conventional approaches of incorporating neuropsychiatric symptoms (NPS). Here, to determine if adding MBI would better identify AD, we interrogated associations between MBI in MCI, and cerebrospinal fluid biomarkers [β-amyloid (Aβ), phosphorylated-tau (p-tau), and total-tau (tau)-ATN], cross-sectionally and longitudinally.

METHODS

Data were from two independent referral-based cohorts, ADNI (mean[SD] follow-up 3.14[1.07] years) and MEMENTO (4.25[1.40] years), collected 2003-2021. Exposure was based on three-group stratification: 1) NPS meeting MBI criteria; 2) conventionally measured NPS (NPSnotMBI); and 3) noNPS. Cohorts were analyzed separately for: 1) cross-sectional associations between NPS status and ATN biomarkers (linear regressions); 2) 4-year longitudinal repeated-measures associations of MBI and NPSnotMBI with ATN biomarkers (hierarchical linear mixed-effects models-LMEs); and 3) rates of incident dementia (Cox proportional hazards regressions).

RESULTS

Of 510 MCI participants, 352 were from ADNI (43.5% females; mean [SD] age, 71.68 [7.40] years), and 158 from MEMENTO (46.2% females; 68.98 [8.18] years). In ADNI, MBI was associated with lower Aβ42 (standardized β [95%CI], -5.52% [-10.48-(-0.29)%]; p = 0.039), and Aβ42/40 (p = 0.01); higher p-tau (9.67% [3.96-15.70%]; p = 0.001), t-tau (7.71% [2.70-12.97%]; p = 0.002), p-tau/Aβ42 (p < 0.001), and t-tau/Aβ42 (p = 0.001). NPSnotMBI was associated only with lower Aβ42/40 (p = 0.045). LMEs revealed a similar 4-year AD-specific biomarker profile for MBI, with NPSnotMBI associated only with higher t-tau. MBI had a greater rate of incident dementia (HR [95%CI], 3.50 [1.99-6.17; p < 0.001). NPSnotMBI did not differ from noNPS (HR 0.96 [0.49-1.89]; p = 0.916). In MEMENTO, MBI demonstrated a similar magnitude and direction of effect for all biomarkers, but with a greater reduction in Aβ40. HR for incident dementia was 3.93 (p = 0.004) in MBI, and 1.83 (p = 0.266) in NPSnotMBI. Of MBI progressors to dementia, 81% developed AD dementia.

CONCLUSIONS

These findings support a biological basis for NPS that meet MBI criteria, the continued inclusion of MBI in NIA-AA ATN clinical staging, and the utility of MBI criteria to improve identification of patients for enrollment in disease-modifying drug trials or for clinical care.