Vascular contributions to cognitive decline: Beyond amyloid and tau in the Harvard aging brain study

In addition to amyloid and tau pathology, elevated systemic vascular risk, white matter injury, and reduced cerebral blood flow contribute to late-life cognitive decline. Given the strong collinearity among these parameters, we proposed a framework to extract the independent latent features underlying cognitive decline using the Harvard Aging Brain Study (N = 166 cognitively unimpaired older adults at baseline). We used the following measures from the baseline visit: cortical amyloid, inferior temporal cortex tau, relative cerebral blood flow, white matter hyperintensities, peak width of skeletonized mean diffusivity, and Framingham Heart Study cardiovascular disease risk. We used exploratory factor analysis to extract orthogonal factors from these variables and their interactions. These factors were used in a regression model to explain longitudinal Preclinical Alzheimer Cognitive Composite-5 (PACC) decline (follow-up = 8.5 ±2.7 years). We next examined whether gray matter volume atrophy acts as a mediator of factors and PACC decline. Latent factors of systemic vascular risk, white matter injury, and relative cerebral blood flow independently explain cognitive decline beyond amyloid and tau. Gray matter volume atrophy mediates these associations with the strongest effect on white matter injury. These results suggest that systemic vascular risk contributes to cognitive decline beyond current markers of cerebrovascular injury, amyloid, and tau.

Early Detection of Amyloid-Related Changes in Memory among Cognitively Unimpaired Older Adults with Daily Digital Testing

OBJECTIVE

This study was undertaken to determine whether assessing learning over days reveals Alzheimer disease (AD) biomarker-related declines in memory consolidation that are otherwise undetectable with single time point assessments.

METHODS

Thirty-six (21.9%) cognitively unimpaired older adults (aged 60-91 years) were classified with elevated β-amyloid (Aβ+) and 128 (78%) were Aβ- using positron emission tomography with 11C Pittsburgh compound B. Participants completed the multiday Boston Remote Assessment for Neurocognitive Health (BRANCH) for 12 min/day on personal devices (ie, smartphones, laptops), which captures the trajectory of daily learning of the same content on 3 repeated tests (Digit Signs, Groceries-Prices, Face-Name). Learning is computed as a composite of accuracy across all 3 measures. Participants also completed standard in-clinic cognitive tests as part of the Preclinical Alzheimer's Cognitive Composite (PACC-5), with 123 participants undergoing PACC-5 follow-up after 1.07 (standard deviation = 0.25) years.

RESULTS

At the cross-section, there were no statistically significant differences in performance between Aβ+/- participants on any standard in-clinic cognitive tests (eg, PACC-5) or on day 1 of multiday BRANCH. Aβ+ participants exhibited diminished 7-day learning curves on multiday BRANCH after 4 days of testing relative to Aβ- participants (Cohen d = 0.49, 95% confidence interval = 0.10-0.87). Diminished learning curves were associated with greater annual PACC-5 decline (r = 0.54, p < 0.001).

INTERPRETATION

Very early Aβ-related memory declines can be revealed by assessing learning over days, suggesting that failures in memory consolidation predate other conventional amnestic deficits in AD. Repeated digital memory assessments, increasingly feasible and uniquely able to assess memory consolidation over short time periods, have the potential to be transformative for detecting the earliest cognitive changes in preclinical AD. ANN NEUROL 2024;95:507-517.

Capturing learning curves with the multiday Boston Remote Assessment of Neurocognitive Health (BRANCH): Feasibility, reliability, and validity

OBJECTIVE

Unsupervised remote digital cognitive assessment makes frequent testing feasible and allows for measurement of learning over repeated evaluations on participants' own devices. This provides the opportunity to derive individual multiday learning curve scores over short intervals. Here, we report feasibility, reliability, and validity, of a 7-day cognitive battery from the Boston Remote Assessment for Neurocognitive Health (Multiday BRANCH), an unsupervised web-based assessment.

METHOD

Multiday BRANCH was administered remotely to 181 cognitively unimpaired older adults using their own electronic devices. For 7 consecutive days, participants completed three tests with associative memory components (Face-Name, Groceries-Prices, Digit Signs), using the same stimuli, to capture multiday learning curves for each test. We assessed the feasibility of capturing learning curves across the 7 days. Additionally, we examined the reliability and associations of learning curves with demographics, and traditional cognitive and subjective report measures.

RESULTS

Multiday BRANCH was feasible with 96% of participants completing all study assessments; there were no differences dependent on type of device used (t = 0.71, p = .48) or time of day completed (t = -0.08, p = .94). Psychometric properties of the learning curves were sound including good test-retest reliability of individuals' curves (intraclass correlation = 0.94). Learning curves were positively correlated with in-person cognitive tests and subjective report of cognitive complaints.

CONCLUSIONS

Multiday BRANCH is a feasible, reliable, and valid cognitive measure that may be useful for identifying subtle changes in learning and memory processes in older adults. In the future, we will determine whether Multiday BRANCH is predictive of the presence of preclinical Alzheimer's disease. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Increased intraindividual variability in reaction time performance is associated with emerging cognitive decline in cognitively unimpaired adults

OBJECTIVE

To investigate whether intraindividual variability (IIV) in reaction time (RT) over monthly administered cognitive tasks is increased in cognitively unimpaired older adults who are at risk for cognitive decline, and whether this is independent of mean RT performance.

METHOD

N = 109 cognitively unimpaired individuals (age 77.4 ± 5.0, 61.5% female, Mini-Mental State Examination 29.1 ± 1.3) from the Harvard Aging Brain Study completed the self-administered Computerized Cognitive Composite (C3) monthly at home for up to 1 year (12.7 ± 3.2 C3 assessments). Baseline C3 assessment coincided with routine in-clinic visits, including amyloid and tau positron emission tomography imaging and standardized cognitive testing, with cognitive testing repeated annually (1.6 ± 1.2 years follow-up). The C3 includes two simple RT tasks and two complex RT tasks. IIV estimates were derived by computing intraindividual standard deviations on residual RT scores after regressing out age and session order effects. Cross-sectional associations of IIV with cognition (global cognition, memory, executive functions [EF], processing speed) and amyloid and tau burden were examined using linear regression analyses correcting for demographics and mean RT. The association between IIV and cognitive decline was assessed using linear mixed models correcting for demographic factors, mean RT, and amyloid burden.

RESULTS

After adjusting for mean RT, increased IIV on complex RT tasks was independently associated with worse EF performance (β = -0.10, 95% CI [-.16, -0.03], p = .004), greater inferior-temporal tau deposition (β = 0.18, 95% CI [0.02, 0.34], p = .024), and faster cognitive decline in those with elevated amyloid (β = -0.62, 95% CI [-1.18, -0.06], p = .033).

CONCLUSIONS

Increased variability in monthly RT may reflect subtle EF deficits and provide unique information about short-term cognitive decline in preclinical Alzheimer's disease. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Study Partner Report of Apathy in Older Adults is Associated with AD Biomarkers: Findings from the Harvard Aging Brain Study

OBJECTIVES

We examined relationships between apathy (self and study-partner-reported) and markers of Alzheimer's disease (AD) in older adults.

DESIGN

The study utilized a well-characterized sample of participants from the Harvard Aging Brain Study (HABS), a longitudinal cohort study. Participants were cognitively unimpaired without clinically significant neuropsychiatric symptoms at HABS baseline. The dependent variables, apathy evaluation scale-self (AES-S) and informant (AES-I), were administered cross-sectionally between years 6-9 and compared to the independent variables, amyloid and tau PET neuroimaging, from the same year.

SETTING

Community-dwelling participants assessed at research visits in an academic medical center.

PARTICIPANTS

Participants (n = 170) completed assessments within 1.5 years of their neuroimaging visit. At the time of apathy assessment, N = 156 were cognitively unimpaired and 14 had progressed to mild cognitive impairment (n = 8) or dementia (n = 6).

MEASUREMENTS

We utilized linear regression models to assess cross-sectional associations of AES-S and AES-I with AD PET imaging measures (beta-amyloid (Pittsburgh Compound B) and tau (Flortaucipir)), covarying for age, sex, education, and the time between PET scan-apathy assessment.

RESULTS

AES-I was significantly associated with beta-amyloid and temporal lobe tau, and the associations were retained after further adjusting for depressive symptoms. The associations between AES-S and AD biomarkers were not significant. In an exploratory subgroup analysis of cognitively unimpaired individuals with elevated Aβ, we observed an association between AES-I and inferior temporal tau.

CONCLUSIONS

Study-partner-reported, but not self-reported, apathy in older adults is associated with AD pathology, and we observed this relationship starting from the preclinical stage. Our findings highlight the importance of collateral information in capturing AD-related apathy.

Using a digital tool to detect early changes in everyday functioning in older adults: A pilot study of the Assessment of Smartphone Everyday Tasks (ASSET)

INTRODUCTION

To investigate the utility of a new digital tool for measuring everyday functioning in preclinical Alzheimer's disease, we piloted the Assessment of Smartphone Everyday Tasks (ASSET) application.

METHODS

Forty-six participants (50.3 ± 27.1 years; 67% female; 20 young unimpaired, 17 old unimpaired, 9 mildly cognitively impaired) completed ASSET 7 times. ASSET comprises two main tasks, simulating a Patient Portal and a Calendar. We assessed ASSET's internal consistency, test-retest reliability, and user experience.

RESULTS

ASSET main tasks correlated with each other (r = 0.75, 95% confidence interval [CI] = [0.58, 0.86]). Performance on ASSET's Patient Portal related to cognition (r = 0.64, 95% CI = [0.42, 0.79]) and observer ratings of everyday functioning (r = 0.57, 95% CI = [0.24, 0.79]). Test-retest reliability was good (intraclass correlation coefficient = 0.87, 95% CI = [0.77, 0.93]). Most participants rated their experience with ASSET neutrally or positively.

DISCUSSION

ASSET is a promising smartphone-based digital assessment of everyday functioning. Future studies may investigate its utility for early diagnosis and evaluation of treatment of Alzheimer's disease.

Subjective cognitive decline across ethnoracial groups in the A4 study

INTRODUCTION

The associations between subjective cognitive decline (SCD), cognition, and amyloid were explored across diverse participants in the A4 study.

METHODS

Five thousand one hundred and fifty-one non-Hispanic White, 262 non-Hispanic Black, 179 Hispanic-White, and 225 Asian participants completed the Preclinical Alzheimer Cognitive Composite (PACC), self- and study partner-reported Cognitive Function Index (CFI). A subsample underwent amyloid positron emission tomography (18 F-florbetapir) (N = 4384). We examined self-reported CFI, PACC, amyloid, and study partner-reported CFI by ethnoracial group.

RESULTS

The associations between PACC-CFI and amyloid-CFI were moderated by race. The relationships were weaker or non-significant in non-Hispanic Black and Hispanic White groups. Depression and anxiety scores were stronger predictors of CFI in these groups. Despite group differences in the types of study partners, self- and study partner-CFI were congruent across groups.

DISCUSSION

SCD may not uniformly relate to cognition or AD biomarkers in different ethnoracial groups. Nonetheless, self- and study partner-SCD were congruent despite differences in study partner type. Highlights Association between SCD and objective cognition was moderated by ethnoracial group. Association between SCD and amyloid was moderated by ethnoracial group. Depression and anxiety were stronger predictors of SCD in Black and Hispanic groups. Study-partner and self-reported SCD are congruent across groups. Study-partner report was consistent despite difference in study partner types.

Regional cerebral tau predicts decline in everyday functioning across the Alzheimer's disease spectrum

BACKGROUND

Emerging difficulty performing cognitively complex everyday tasks, or 'instrumental activities of daily living' (IADL) may be an early clinical sign of Alzheimer's disease (AD). We aimed to investigate how changes over time in everyday functioning relate to cerebral tau burden across the AD clinical spectrum.

METHODS

We included 581 participants (73.9 ± 7.6 years old; 52% female) from the Alzheimer's Disease Neuroimaging Initiative who underwent tau positron emission tomography (PET) and completed at least two assessments of the Functional Activities Questionnaire (FAQ). Participants were classified as cognitively normal (n = 334) or symptomatic (n = 247). We analyzed the association between longitudinal FAQ scores and baseline tau in six temporal, parietal, and frontal brain regions in mixed-effects models. Models were run in the entire sample, as well as stratified by diagnostic group (cognitively normal or symptomatic). We additionally investigated tau-PET adjusted for, as well as interacting with, amyloid-β.

RESULTS

Greater tau burden in several frontal, temporal, and parietal regions was associated with steeper decline over time in everyday functioning. These findings remained when adjusting for baseline global cortical amyloid-β; amyloid-β itself was only associated with change over time in FAQ scores when tau was not included in the model. When stratifying by diagnostic group, most associations between tau and everyday functioning, adjusted for amyloid-β, were present only in the symptomatic group.

CONCLUSIONS

The rate of change in everyday functioning is related to baseline tau burden in various brain regions, more strongly so than global cortical amyloid-β, specifically in cognitively symptomatic individuals. Longitudinal studies in incident dementia populations are needed to better understand functional changes in response to AD pathology across the disease.

Harmonizing the preclinical Alzheimer cognitive composite for multicohort studies

OBJECTIVES

Studies are increasingly examining research questions across multiple cohorts using data from the preclinical Alzheimer cognitive composite (PACC). Our objective was to use modern psychometric approaches to develop a harmonized PACC.

METHOD

We used longitudinal data from the Alzheimer's Disease Neuroimaging Initiative (ADNI), Harvard Aging Brain Study (HABS), and Australian Imaging, Biomarker and Lifestyle Study of Ageing (AIBL) cohorts (n = 2,712). We further demonstrated our method with the Anti-Amyloid Treatment of Asymptomatic Alzheimer's Disease (A4) Study prerandomized data (n = 4,492). For the harmonization method, we used confirmatory factor analysis (CFA) on the final visit of the longitudinal cohorts to determine parameters to generate latent PACC (lPACC) scores. Overlapping tests across studies were set as "anchors" that tied cohorts together, while parameters from unique tests were freely estimated. We performed validation analyses to assess the performance of lPACC versus the common standardized PACC (zPACC).

RESULTS

Baseline (BL) scores for the zPACC were centered on zero, by definition. The harmonized lPACC did not define a common mean of zero and demonstrated differences in baseline ability levels across the cohorts. Baseline lPACC slightly outperformed zPACC in the prediction of progression to dementia. Longitudinal change in the lPACC was more constrained and less variable relative to the zPACC. In combined-cohort analyses, longitudinal lPACC slightly outperformed longitudinal zPACC in its association with baseline β-amyloid status.

CONCLUSIONS

This study proposes procedures for harmonizing the PACC that make fewer strong assumptions than the zPACC, facilitating robust multicohort analyses. This implementation of item response theory lends itself to adapting across future cohorts with similar composites. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Linking self-perceived cognitive functioning questionnaires using item response theory: The subjective cognitive decline initiative

OBJECTIVE

Self-perceived cognitive functioning, considered highly relevant in the context of aging and dementia, is assessed in numerous ways-hindering the comparison of findings across studies and settings. Therefore, the present study aimed to link item-level self-report questionnaire data from international aging studies.

METHOD

We harmonized secondary data from 24 studies and 40 different questionnaires with item response theory (IRT) techniques using a graded response model with a Bayesian estimator. We compared item information curves to identify items with high measurement precision at different levels of the self-perceived cognitive functioning latent trait. Data from 53,030 neuropsychologically intact older adults were included, from 13 English language and 11 non-English (or mixed) language studies.

RESULTS

We successfully linked all questionnaires and demonstrated that a single-factor structure was reasonable for the latent trait. Items that made the greatest contribution to measurement precision (i.e., "top items") assessed general and specific memory problems and aspects of executive functioning, attention, language, calculation, and visuospatial skills. These top items originated from distinct questionnaires and varied in format, range, time frames, response options, and whether they captured ability and/or change.

CONCLUSIONS

This was the first study to calibrate self-perceived cognitive functioning data of geographically diverse older adults. The resulting item scores are on the same metric, facilitating joint or pooled analyses across international studies. Results may lead to the development of new self-perceived cognitive functioning questionnaires guided by psychometric properties, content, and other important features of items in our item bank. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Associations of the Harvard Automated Phone Task and Alzheimer's Disease Pathology in Cognitively Normal Older Adults: Preliminary Findings

BACKGROUND

Detecting clinically meaningful changes in instrumental activities of daily living (IADL) at the earliest stages of Alzheimer's disease (AD) is critical.

OBJECTIVE

The objective of this exploratory study was to examine the cross-sectional relationship between a performance-based IADL test, the Harvard Automated Phone Task (APT), and cerebral tau and amyloid burden in cognitively normal (CN) older adults.

METHODS

Seventy-seven CN participants underwent flortaucipir tau and Pittsburgh Compound B amyloid PET. IADL were assessed using the three Harvard APT tasks: prescription refill (APT-Script), health insurance company call (APT-PCP), and bank transaction (APT-Bank). Linear regression models were used to determine associations between each APT task and entorhinal cortex, inferior temporal, or precuneus tau with or without an interaction with amyloid.

RESULTS

Significant associations were found between APT-Bank task rate and interaction between amyloid and entorhinal cortex tau, and APT-PCP task and interactions between amyloid and inferior temporal and precuneus tau. No significant associations were found between the APT tasks and tau or amyloid alone.

CONCLUSION

Our preliminary findings suggest an association between a simulated real-life IADL test and interactions of amyloid and several regions of early tau accumulation in CN older adults. However, some analyses were underpowered due to the small number of participants with elevated amyloid, and findings should be interpreted with caution. Future studies will further explore these associations cross-sectionally and longitudinally in order to determine whether the Harvard APT can serve as a reliable IADL outcome measure for preclinical AD prevention trials and ultimately in the clinic setting.

Monthly At-Home Computerized Cognitive Testing to Detect Diminished Practice Effects in Preclinical Alzheimer's Disease

Introduction: We investigated whether monthly assessments of a computerized cognitive composite (C3) could aid in the detection of differences in practice effects (PE) in clinically unimpaired (CU) older adults, and whether diminished PE were associated with Alzheimer's disease (AD) biomarkers and annual cognitive decline. Materials and Methods: N = 114 CU participants (age 77.6 ± 5.0, 61% female, MMSE 29 ± 1.2) from the Harvard Aging Brain Study completed the self-administered C3 monthly, at-home, on an iPad for one year. At baseline, participants underwent in-clinic Preclinical Alzheimer's Cognitive Composite-5 (PACC5) testing, and a subsample (n = 72, age = 77.8 ± 4.9, 59% female, MMSE 29 ± 1.3) had 1-year follow-up in-clinic PACC5 testing available. Participants had undergone PIB-PET imaging (0.99 ± 1.6 years before at-home baseline) and Flortaucipir PET imaging (n = 105, 0.62 ± 1.1 years before at-home baseline). Linear mixed models were used to investigate change over months on the C3 adjusting for age, sex, and years of education, and to extract individual covariate-adjusted slopes over the first 3 months. We investigated the association of 3-month C3 slopes with global amyloid burden and tau deposition in eight predefined regions of interest, and conducted Receiver Operating Characteristic analyses to examine how accurately 3-month C3 slopes could identify individuals that showed >0.10 SD annual decline on the PACC-5. Results: Overall, individuals improved on all C3 measures over 12 months (β = 0.23, 95% CI [0.21-0.25], p < 0.001), but improvement over the first 3 months was greatest (β = 0.68, 95% CI [0.59-0.77], p < 0.001), suggesting stronger PE over initial repeated exposures. However, lower PE over 3 months were associated with more global amyloid burden (r = -0.20, 95% CI [-0.38 - -0.01], p = 0.049) and tau deposition in the entorhinal cortex (r = -0.38, 95% CI [-0.54 - -0.19], p < 0.001) and inferior-temporal lobe (r = -0.23, 95% CI [-0.41 - -0.02], p = 0.03). 3-month C3 slopes exhibited good discriminative ability to identify PACC-5 decliners (AUC 0.91, 95% CI [0.84-0.98]), which was better than baseline C3 (p < 0.001) and baseline PACC-5 scores (p = 0.02). Conclusion: While PE are commonly observed among CU adults, diminished PE over monthly cognitive testing are associated with greater AD biomarker burden and cognitive decline. Our findings imply that unsupervised computerized testing using monthly retest paradigms can provide rapid detection of diminished PE indicative of future cognitive decline in preclinical AD.

Everyday Functioning and Entorhinal and Inferior Temporal Tau Burden in Cognitively Normal Older Adults

BACKGROUND

Performance of cognitively complex "instrumental activities of daily living" (IADL) has previously been related to amyloid deposition in preclinical Alzheimer's disease.

OBJECTIVES

We aimed to investigate the relationship between IADL performance and cerebral tau accumulation in cognitively normal older adults.

DESIGN

Cross-sectional.

SETTING

Data was collected in the Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4) and Longitudinal Evaluation of Amyloid Risk and Neurodegeneration (LEARN) studies.

PARTICIPANTS

Participants (n = 447, age 71.9±4.9 years, 57.5% female) who underwent tau positron emission tomography were selected from the A4 and LEARN studies.

MEASUREMENTS

IADL performance was measured using the self- and study partner-reported versions of the Alzheimer's Disease Cooperative Study Activities of Daily Living - Prevention Instrument (ADCS ADL-PI). We also investigated discordance between participants and their study partners. Cross-sectional associations between entorhinal and inferior temporal tau (independent variables) and ADCS ADL-PI total scores, item-level scores and discordance (dependent variables) were investigated in linear and logistic regressions. Analyses were adjusted for age, sex and education and a tau by amyloid interaction was also included.

RESULTS

Participants and their study partners reported high levels of IADL performance. Entorhinal and inferior temporal tau were related to study partner but not to self-reported total ADCS ADL-PI scores. The association was not retained after adjustment for global cerebral amyloid burden. At the item level, greater entorhinal tau was associated with study partner-reported difficulties remembering important dates (odds ratio (OR) = 1.24, 95% confidence interval (95%CI) = [1.06, 1.45], p = 0.008) and difficulties remembering the details of TV programs and movies (OR = 1.32, 95%CI = [1.08, 1.61], p = 0.007). Greater inferior temporal tau was associated with self-reported difficulties managing to find personal belongings (OR = 1.23, 95%CI = [1.04, 1.46], p = 0.018) and study partner-reported difficulties remembering the details of TV programs and movies (OR = 1.39, 95%CI = [1.11, 1.75], p = 0.005). Discordance between participant and study partner-report was more likely with greater entorhinal (OR = 1.18, 95%CI = [1.05, 1.33], p = 0.005) and inferior temporal tau burden (OR = 1.29, 95%CI = [1.10, 1.51], p = 0.002).

DISCUSSION

We found a cross-sectional relationship between study partner-reported everyday functioning and tau in cognitively normal older adults. Participants were more likely to self-report difficulties differently from their study partners when tau burden was higher. This may hint at an altered early-disease awareness of functional changes and underscores the importance of self-report of IADL functioning in addition to collateral report by a study partner.

Subjective Cognitive Decline in a Registry Sample: Relation to Psychiatric History, Loneliness, and Personality

BACKGROUND

With the increasing focus on prevention of Alzheimer's disease, there is need for characterization of preclinical populations. Local participant registries offer an opportunity to facilitate research engagement via remote data collection, inform recruitment, and characterize preclinical samples, including individuals with subjective cognitive decline.

OBJECTIVES

We sought to characterize subjective cognitive decline in a registry sample, as related to psychiatric history and related variables, including personality and loneliness, quality of life, and factors related to dementia risk (e.g., family history of dementia).

DESIGN, SETTING, PARTICIPANTS

Participants were 366 individuals (mean age=67.2 (range 50-88), 65% female, 94% white, 97% non-Hispanic or Latino, 82% with at least a bachelor's degree) with no reported history of mild cognitive impairment or dementia. All participants had expressed interest in research, primarily via community outreach events and prior research involvement. Data was collected via electronic surveys, distributed using REDCap. Electronic questionnaires included questions on demographic variables, subjective cognitive decline, quality of life, loneliness, and personality.

RESULTS

There was a high prevalence of risk factors for dementia in the registry sample (68% with family history of dementia, 31% with subjective cognitive decline). Subjective cognitive decline was more common in women and associated with history of depression, but not with family history of dementia. Subjective cognitive decline was also associated with lower conscientiousness and lower emotional stability, as well as higher loneliness and lower quality of life. Among participants who endorsed a psychiatric history, most reported onset more than 10 years prior, rather than within the last 10 years.

CONCLUSIONS

Subjective cognitive decline in a registry sample may be more strongly associated with longstanding psychiatric and personality variables, rather than family history of dementia, adding to the literature on characterization of subjective cognitive decline across different settings. These findings highlight the acceptability of remote data collection and the potential of registries to inform recruitment by characterizing registrants, which may help to stratify dementia risk and match participants to eligible trials.

Neuroimaging correlates of Stages of Objective Memory Impairment (SOMI) system

INTRODUCTION

To assess the relationship between memory performance defined by the Stages of Objective Memory Impairment (SOMI) system and the Alzheimer's disease (AD) ATN (amyloid beta [A], pathologic tau [T], and neurodegeneration [N]) biomarker system.

METHODS

We used data from the Harvard Aging Brain Study cohort to estimate the level of ATN biomarkers: amyloid beta (C-Pittsburgh compound B-positron emission tomography [PET]), tau (F-18-flortaucipir [FTP] PET), and neurodegeneration (magnetic resonance imaging volumetrics). We assessed the cross-sectional relationship of SOMI classification with global amyloid levels, entorhinal and inferior temporal tau deposition, and hippocampal atrophy.

RESULTS

Participants with both memory storage and retrieval deficits (SOMI-3, -4) had smaller hippocampal volumes and higher entorhinal and inferior temporal tau burden than participants with no memory impairment (SOMI-0) or mild retrieval difficulty (SOMI-1). Amyloid burden did not differ among SOMI stages.

DISCUSSION

This pilot supports the close relationship between tau pathology and memory impairment across the AD continuum.  SOMI may be useful to determine eligibility for randomized controlled trials prior to the assessment of biomarker status.

Greater psychological resilience during the COVID‐19 pandemic is associated with lower tau burden in cognitively unimpaired individuals

Background

The outbreak of the 2019 novel coronavirus SARS‐CoV‐2, causing the COVID‐19 pandemic, along with the global measures used to control the spread of the disease, have been particularly stressful for older individuals. Robust evidence suggests that stress‐related physiological processes may play a significant role in the onset of age‐related cognitive decline and dementia, such as Alzheimer’s disease (AD). For example, previous animal and human research have shown that stress exacerbates tau pathology and subsequent cognitive impairment. One important factor determining a person’s level of stress is psychological resilience, which refers to a person’s ability to return to equilibrium when difficulties occur. As such, resilience may buffer and protect individuals against the deleterious effects of stress. The objectives of this study were to examine the relationship between psychological resilience and tau burden in cognitively unimpaired individuals, and to evaluate whether amyloid (Aß) pathology modifies this relationship.

Method

A total of 114 older adults (mean age=74.5;66 females (57.9%)) enrolled in the Harvard Aging Brain Study or the Instrumental Activities of Daily Living study completed an electronic survey online including measures of psychological resilience (Connor‐Davidson Resilience Scale‐10, where a higher score indicates greater resilience) during the COVID‐19 pandemic period (May 2020). We used previously collected (mean time from survey=1.75 year) PET imaging data to assess Aß and tau burden.

Results

Overall, participants demonstrated high levels of resilience (mean=29.5,range=9‐40). Multiple regression analyses (correcting for age, gender and time difference between survey and PET) demonstrated an interaction between resilience and amyloid on tau pathology (ß=‐0.01,p=0.015, Figure1). Specifically, in Aß+ individuals (SUVR>1.324), those with higher psychological resilience also had lower tau pathology. No relationship was seen in Aß‐ individuals.

Conclusion

Our findings suggest that greater resilience during the pandemic is associated with lower tau burden in individuals at higher risk of cognitive decline (i.e. preclinical AD). Future studies are needed to determine the impact of stress and psychological resilience on prospective pathological brain changes and subsequent cognitive decline. Furthermore, resilience may be an important target for interventions to support older adults navigating stressful situations and to lessen the influence of stressors on AD pathological processes.

Development and Validation of a Deep Learning Model for Earlier Detection of Cognitive Decline From Clinical Notes in Electronic Health Records

IMPORTANCE

Detecting cognitive decline earlier among older adults can facilitate enrollment in clinical trials and early interventions. Clinical notes in longitudinal electronic health records (EHRs) provide opportunities to detect cognitive decline earlier than it is noted in structured EHR fields as formal diagnoses.

OBJECTIVE

To develop and validate a deep learning model to detect evidence of cognitive decline from clinical notes in the EHR.

DESIGN, SETTING, AND PARTICIPANTS

Notes documented 4 years preceding the initial mild cognitive impairment (MCI) diagnosis were extracted from Mass General Brigham's Enterprise Data Warehouse for patients aged 50 years or older and with initial MCI diagnosis during 2019. The study was conducted from March 1, 2020, to June 30, 2021. Sections of notes for cognitive decline were labeled manually and 2 reference data sets were created. Data set I contained a random sample of 4950 note sections filtered by a list of keywords related to cognitive functions and was used for model training and testing. Data set II contained 2000 randomly selected sections without keyword filtering for assessing whether the model performance was dependent on specific keywords.

MAIN OUTCOMES AND MEASURES

A deep learning model and 4 baseline models were developed and their performance was compared using the area under the receiver operating characteristic curve (AUROC) and area under the precision recall curve (AUPRC).

RESULTS

Data set I represented 1969 patients (1046 [53.1%] women; mean [SD] age, 76.0 [13.3] years). Data set II comprised 1161 patients (619 [53.3%] women; mean [SD] age, 76.5 [10.2] years). With some overlap of patients deleted, the unique population was 2166. Cognitive decline was noted in 1453 sections (29.4%) in data set I and 69 sections (3.45%) in data set II. Compared with the 4 baseline models, the deep learning model achieved the best performance in both data sets, with AUROC of 0.971 (95% CI, 0.967-0.976) and AUPRC of 0.933 (95% CI, 0.921-0.944) for data set I and AUROC of 0.997 (95% CI, 0.994-0.999) and AUPRC of 0.929 (95% CI, 0.870-0.969) for data set II.

CONCLUSIONS AND RELEVANCE

In this diagnostic study, a deep learning model accurately detected cognitive decline from clinical notes preceding MCI diagnosis and had better performance than keyword-based search and other machine learning models. These results suggest that a deep learning model could be used for earlier detection of cognitive decline in the EHRs.

Item-Level Investigation of Participant and Study Partner Report on the Cognitive Function Index from the A4 Study Screening Data

BACKGROUND

Greater subjective cognitive changes on the Cognitive Function Index (CFI) was previously found to be associated with elevated amyloid (Aß) status in participants screening for the A4 Study, reported by study partners and the participants themselves. While the total score on the CFI related to amyloid for both sources respectively, potential differences in the specific types of cognitive changes reported by either participants or their study partners was not investigated.

OBJECTIVES

To determine the specific types of subjective cognitive changes endorsed by participants and their study partners that are associated with amyloid status in individuals screening for an AD prevention trial.

DESIGN, SETTING, PARTICIPANTS

Four thousand four hundred and eighty-six cognitively unimpaired (CDR=0; MMSE 25-30) participants (ages 65-85) screening for the A4 Study completed florbetapir (Aß) Positron Emission Tomography (PET) imaging. Participants were classified as elevated amyloid (Aß+; n=1323) or non-elevated amyloid (Aß-; n=3163).

MEASUREMENTS

Prior to amyloid PET imaging, subjective report of changes in cognitive functioning were measured using the CFI (15 item questionnaire; Yes/Maybe/No response options) and administered separately to both participants and their study partners (i.e., a family member or friend in regular contact with the participant). The impact of demographic factors on CFI report was investigated. For each item of the CFI, the relationship between Aß and CFI response was investigated using an ordinal mixed effects model for participant and study partner report.

RESULTS

Independent of Aß status, participants were more likely to report 'Yes' or 'Maybe' compared to the study partners for nearly all CFI items. Older age (r= 0.06, p<0.001) and lower education (r=-0.08, p<0.001) of the participant were associated with higher CFI. Highest coincident odds ratios related to Aß+ for both respondents included items assessing whether 'a substantial decline in memory' had occurred in the last year (ORsp= 1.35 [95% CI 1.11, 1.63]; ORp= 1.55 [95% CI 1.34, 1.79]) and whether the participant had 'seen a doctor about memory' (ORsp= 1.56 [95% CI 1.25, 1.95]; ORp =1.71 [95% CI 1.37, 2.12]). For two items, associations were significant for only study partner report; whether the participant 'Repeats questions' (ORsp = 1.30 [95% CI 1.07, 1.57]) and has 'trouble following the news' (ORsp= 1.46[95% CI 1.12, 1.91]). One question was significant only for participant report; 'trouble driving' (ORp= 1.25 [95% CI 1.04, 1.49]).

CONCLUSIONS

Elevated Aβ is associated with greater reporting of subjective cognitive changes as measured by the CFI in this cognitively unimpaired population. While participants were more likely than study partners to endorse change on most CFI items, unique CFI items were associated with elevated Aß for participants and their study partners, supporting the value of both sources of information in clinical trials.

Unsupervised mobile cognitive testing for use in preclinical Alzheimer's disease

INTRODUCTION

Unsupervised digital cognitive testing is an appealing means to capture subtle cognitive decline in preclinical Alzheimer's disease (AD). Here, we describe development, feasibility, and validity of the Boston Remote Assessment for Neurocognitive Health (BRANCH) against in-person cognitive testing and amyloid/tau burden.

METHODS

BRANCH is web-based, self-guided, and assesses memory processes vulnerable in AD. Clinically normal participants (n = 234; aged 50-89) completed BRANCH; a subset underwent in-person cognitive testing and positron emission tomography imaging. Mean accuracy across BRANCH tests (Categories, Face-Name-Occupation, Groceries, Signs) was calculated.

RESULTS

BRANCH was feasible to complete on participants' own devices (primarily smartphones). Technical difficulties and invalid/unusable data were infrequent. BRANCH psychometric properties were sound, including good retest reliability. BRANCH was correlated with in-person cognitive testing (r = 0.617, P < .001). Lower BRANCH score was associated with greater amyloid (r = -0.205, P = .007) and entorhinal tau (r = -0.178, P = .026).

DISCUSSION

BRANCH reliably captures meaningful cognitive information remotely, suggesting promise as a digital cognitive marker sensitive early in the AD trajectory.

Diminished Learning Over Repeated Exposures (LORE) in preclinical Alzheimer's disease

INTRODUCTION

We determine whether diminished Learning Over Repeated Exposures (LORE) identifies subtle memory decrements in cognitively unimpaired (CU) older adults with Alzheimer's disease (AD) biomarker burden.

METHODS

Ninety-four CU participants (mean age = 77.6 ± 5.02) completed a challenging associative memory test, at home, monthly, for up to 1 year (mean = 9.97 months) on a study-issued iPad. Learning curves for face-name memory were computed for two versions completed monthly: same face-name pairs (A-A-A) and alternate face-name pairs (B-C-D). Positron emission tomography (PET) imaging characterized global amyloid (Pittsburgh Compound-B (PiB); amyloid beta (Aβ)+/-) and regional tau burden (flortaucipir).

RESULTS

Diminished LORE for same (but not alternate) face-name pairs was associated with greater amyloid and tau burden. Aβ+/- group differences for same face-name pairs emerged by the fourth exposure and was of medium-to-large magnitude (Cohen's d = 0.66; 95% confidence interval [CI] = 0.25-1.08).

DISCUSSION

Subtle decrements in learning related to AD pathological burden in CU are detectable over short time-intervals (ie, months). Implications for prevention trial design are discussed.

Financial Capacity and Regional Cerebral Tau in Cognitively Normal Older Adults, Mild Cognitive Impairment, and Alzheimer's Disease Dementia

BACKGROUND

Financial capacity is often one of the first instrumental activities of daily living to be affected in cognitively normal (CN) older adults who later progress to amnestic mild cognitive impairment (MCI) and Alzheimer's disease (AD) dementia.

OBJECTIVE

The objective of this study was to investigate the association between financial capacity and regional cerebral tau.

METHODS

Cross-sectional financial capacity was assessed using the Financial Capacity Instrument -Short Form (FCI-SF) in 410 CN, 199 MCI, and 61 AD dementia participants who underwent flortaucipir tau positron emission tomography from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Linear regression models with backward elimination were used with FCI-SF total score as the dependent variable and regional tau and tau-amyloid interaction as predictors of interest in separate analyses. Education, age, sex, Rey Auditory Verbal Learning Test Total Learning, and Trail Making Test B were used as covariates.

RESULTS

Significant associations were found between FCI-SF and tau regions (entorhinal: p < 0.001; inferior temporal: p < 0.001; dorsolateral prefrontal: p = 0.01; posterior cingulate: p = 0.03; precuneus: p < 0.001; and supramarginal gyrus: p = 0.005) across all participants. For the tau-amyloid interaction, significant associations were found in four regions (amyloid and dorsolateral prefrontal tau interaction: p = 0.005; amyloid and posterior cingulate tau interaction: p = 0.005; amyloid and precuneus tau interaction: p < 0.001; and amyloid and supramarginal tau interaction: p = 0.002).

CONCLUSION

Greater regional tau burden was modestly associated with financial capacity impairment in early-stage AD. Extending this work with longitudinal analyses will further illustrate the utility of such assessments in detecting clinically meaningful decline, which may aid clinical trials of early-stage AD.

Instrumental activities of daily living, amyloid, and cognition in cognitively normal older adults screening for the A4 Study

INTRODUCTION

We examined the associations among instrumental activities of daily living (IADL), cortical amyloid, and cognition in cognitively normal (CN) older adults.

METHODS

CN participants screening for the A4 Study (n = 4486) underwent florbetapir (amyloid) positron emission tomography. IADL were assessed using the Alzheimer's Disease Cooperative Study Activities of Daily Living Prevention Instrument. Separate logistic regression models were run with cortical amyloid or cognition as independent variable and IADL as dependent variable, adjusting for age and sex.

RESULTS

IADL difficulties were endorsed infrequently (≤16%). Overall IADL and four select IADL item difficulties ("remembering appointments," "finding belongings," "following TV programs," and "remembering current events") reported by both participant and study partner were significantly associated with greater amyloid burden and worse cognition.

DISCUSSION

Although IADL deficits were infrequent in this CN cohort, greater participant and study partner report of overall IADL deficits and subtle difficulties in specific IADL items were associated with mildly higher amyloid burden and worse cognition.

Decline in cognitively complex everyday activities accelerates along the Alzheimer's disease continuum

BACKGROUND

Impairment in daily functioning is a clinical hallmark of dementia. Difficulties with "instrumental activities of daily living" (IADL) seem to increase gradually over the course of Alzheimer's disease (AD), before dementia onset. However, it is currently not well established how difficulties develop along the preclinical and prodromal stages of AD. We aimed to investigate the trajectories of decline in IADL performance, as reported by a study partner, along the early stages of AD.

METHODS

In a longitudinal multicenter study, combining data from community-based and memory clinic cohorts, we included 1555 individuals (mean age 72.5 ± 7.8 years; 50% female) based on availability of amyloid biomarkers, longitudinal IADL data, and clinical information at baseline. Median follow-up duration was 2.1 years. All amyloid-positive participants (n = 982) were classified into the National Institute on Aging-Alzheimer's Association (NIA-AA) clinical stages ranging from preclinical AD (1) to overt dementia (4+). Cognitively normal amyloid-negative individuals (n = 573) served as a comparison group. The total scores of three study-partner reported IADL questionnaires were standardized.

RESULTS

The rate of decline in cognitively normal (stage 1) individuals with and without abnormal amyloid did not differ (p = .453). However, from stage 2 onwards, decline was significantly faster in individuals on the AD continuum (B [95%CI] = - 0.32 [- 0.55, - 0.09], p = .007). The rate of decline increased with each successive stage: one standard deviation (SD) unit per year in stage 3 (- 1.06 [- 1.27, - 0.85], p < .001) and nearly two SD units per year in stage 4+ (1.93 [- 2.19, - 1.67], p < .001). Overall, results were similar between community-based and memory clinic study cohorts.

CONCLUSIONS

Our results suggest that the rate of functional decline accelerates along the AD continuum, as shown by steeper rates of decline in each successive NIA-AA clinical stage. These results imply that incremental changes in function are a meaningful measure for early disease monitoring. Combined with the low-cost assessment, this advocates the use of these functional questionnaires for capturing the effects of early AD-related cognitive decline on daily life.

The Latin American Spanish version of the Face-Name Associative Memory Exam is sensitive to cognitive and pathological changes in preclinical autosomal dominant Alzheimer's disease

BACKGROUND

To determine whether performance on the Latin American Spanish version of the Face-Name Associative Memory Exam (LAS-FNAME) can differentiate between cognitively intact carriers of an autosomal dominant Alzheimer's disease mutation (E280A) in Presenilin-1, who are genetically determined to develop early-onset dementia, from matched non-carriers. We also sought to examine whether LAS-FNAME performance is associated with amyloid-β and regional tau burden in mutation carriers.

METHODS

A total of 35 cognitively intact mutation carriers (age range 26-41), 19 symptomatic carriers, and 48 matched non-carriers (age range 27-44) completed a neuropsychological assessment including the LAS-FNAME. A subset of participants (31 carriers [12 symptomatic] and 35 non-carriers) traveled from Colombia to Boston to undergo positron emission tomography (PET) using Pittsburgh compound B to measure mean cortical amyloid-β and flortaucipir for regional tau. ANOVA analyses and Spearman correlations were used to examine group differences and relationships among LAS-FNAME performance and amyloid-β and tau accumulation.

RESULTS

Compared to non-carriers, cognitively intact mutation carriers had lower scores on the LAS-FNAME Total Scores (p = .040). Across all carriers (including symptomatic carriers), higher levels of amyloid-β (r = - .436, p = .018) and regional tau in the entorhinal (r = - .394, p = .031) and inferior temporal cortex (r = - .563, p = .001) were associated with lower LAS-FNAME Total Scores.

CONCLUSIONS

Performance on the LAS-FNAME differentiated between cognitively intact mutation carriers from non-carriers and was associated with greater amyloid and tau burden when examining all carriers. Findings suggest that the LAS-FNAME is sensitive to early clinical and pathological changes and can potentially help track disease progression in Spanish-speaking individuals.

Sex Mediates Relationships Between Regional Tau Pathology and Cognitive Decline

OBJECTIVE

The goal of this study was to examine sex differences in tau distribution across the brain of older adults, using positron emission tomography (PET), and investigate how these differences might associate with cognitive trajectories.

METHODS

Participants were 343 clinically normal individuals (women, 58%; 73.8 [8.5] years) and 55 individuals with mild cognitive impairment (MCI; women, 38%; 76.9 [7.3] years) from the Harvard Aging Brain Study and the Alzheimer's Disease Neuroimaging Initiative. We examined ¹⁸ F-Flortaucipir (FTP)-positron emission tomography (PET) signal across 41 cortical and subcortical regions of interest (ROIs). Linear regression models estimated the effect of sex on FTP-signal for each ROI after adjusting for age and cohort. We also examined interactions between sex*Aβ-PET positive / negative (+ / -) and sex*apolipoprotein ε4 (APOEε4) status. Linear mixed models estimated the moderating effect of sex on the relationship between a composite of sex-differentiated tau ROIs and cognitive decline.

RESULTS

Women showed significantly higher FTP-signals than men across multiple regions of the cortical mantle (p < 0.007). β-amyloid (Aβ)-moderated sex differences in tau signal were localized to medial and inferio-lateral temporal regions (p < 0.007); Aβ + women exhibited greater FTP-signal than other groups. APOEε4-moderated sex differences in FTP-signal were only found in the lateral occipital lobe. Women with higher FTP-signals in composite ROI exhibited faster cognitive decline than men (p = 0.04).

INTERPRETATION

Tau vulnerability in women is not just limited to the medial temporal lobe and significantly contributed to greater risk of faster cognitive decline. Interactive effects of sex and Aβ were predominantly localized in the temporal lobe, however, sex differences in extra-temporal tau highlights the possibility of accelerated tau proliferation in women with the onset of clinical symptomatology. ANN NEUROL 2020;88:921-932.

Multiple markers contribute to risk of progression from normal to mild cognitive impairment

OBJECTIVE

To identify a parsimonious set of markers that optimally predicts subsequent clinical progression from normal to mild cognitive impairment (MCI).

METHODS

250 clinically normal adults (mean age = 73.6 years, SD = 6.0) from the Harvard Aging Brain Study were assessed at baseline on a wide set of markers, including magnetic resonance imaging markers of gray matter thickness and volume, white matter lesions, fractional anisotropy, resting state functional connectivity, positron emission tomography markers of glucose metabolism and β-amyloid (Aβ) burden, and a measure of vascular risk. Participants were also tested annually on a battery of clinical and cognitive tests (median follow-up = 5.0 years, SD = 1.66). We applied least absolute shrinkage and selection operator (LASSO) Cox models to determine the minimum set of non-redundant markers that predicts subsequent clinical progression from normal to MCI, adjusting for age, sex, and education.

RESULTS

23 participants (9.2%) progressed to MCI over the study period (mean years of follow-up to diagnosis = 3.96, SD = 1.89). Progression was predicted by several brain markers, including reduced entorhinal thickness (hazard ratio, HR = 1.73), greater Aβ burden (HR = 1.58), lower default network connectivity (HR = 1.42), and smaller hippocampal volume (HR = 1.30). When cognitive test scores were added to the model, the aforementioned neuroimaging markers remained significant and lower striatum volume as well as lower scores on baseline memory and processing speed tests additionally contributed to progression.

CONCLUSION

Among a large set of brain, vascular and cognitive markers, a subset of markers independently predicted progression from normal to MCI. These markers may enhance risk stratification by identifying clinically normal individuals who are most likely to develop clinical symptoms and would likely benefit most from therapeutic intervention.

An UNC5C Allele Predicts Cognitive Decline and Hippocampal Atrophy in Clinically Normal Older Adults

BACKGROUND

The UNC5C rs3846455G allele has been linked to poor cognitive resilience against age-related neuropathologies, but this association remains to be replicated, and the allele's effect on hippocampal neurodegeneration needs to be examined.

OBJECTIVE

To further validate the association between rs3846455G and faster cognitive decline, especially among cognitively normal older adults, and to assess whether rs3846455G predicts accelerated hippocampal volume loss in older adults.

METHODS

We assessed participants in the Harvard Aging Brain Study (HABS), a longitudinal cohort study of older adults who were clinically normal at baseline. To avoid bias from population admixture, analyses were limited to participants of European descent with longitudinal neuroimaging data (n = 174). Linear mixed effect models were used to examine the effect of rs3846455G on longitudinal change of the Preclinical Alzheimer Cognitive Composite (PACC) and MRI-measured bilateral hippocampal volume, adjusting for baseline amyloid-β (Aβ) measured by the cortical Pittsburgh Compound B PET distributed volume ratio. We also tested whether hippocampal atrophy mediates the association between rs3846455G and greater PACC decline through a mediation analysis.

RESULTS

rs3846455G was associated with greater PACC decline (β= -0.087/year, 95% CI -0.169 to -0.005, p = 0.039) after controlling for baseline Aβ. Further, rs3846455G predicted accelerated hippocampal atrophy after controlling for baseline Aβ (β= -57.3 mm3/year, 95% CI -102.8 to -11.9, p = 0.014). The association between rs3846455G and greater PACC decline was partially mediated by accelerated hippocampal atrophy (mediated effect (relative scale) = -0.014, 95% CI -0.032 to -6.0×10-4, p = 0.039).

CONCLUSION

UNC5C rs3846455G predicts greater cognitive decline and accelerated hippocampal atrophy in clinically normal older adults.

The presubiculum links incipient amyloid and tau pathology to memory function in older persons

OBJECTIVE

To identify the hippocampal subregions linking initial amyloid and tau pathology to memory performance in clinically normal older individuals, reflecting preclinical Alzheimer disease (AD).

METHODS

A total of 127 individuals from the Harvard Aging Brain Study (mean age 76.22 ± 6.42 years, 68 women [53.5%]) with a Clinical Dementia Rating score of 0, a flortaucipir tau-PET scan, a Pittsburgh compound B amyloid-PET scan, a structural MRI scan, and cognitive testing were included. From these images, we calculated neocortical, hippocampal, and entorhinal amyloid pathology; entorhinal and hippocampal tau pathology; and the volumes of 6 hippocampal subregions and total hippocampal volume. Memory was assessed with the selective reminding test. Mediation and moderation analyses modeled associations between regional markers and memory. Analyses included covariates for age, sex, and education.

RESULTS

Neocortical amyloid, entorhinal tau, and presubiculum volume univariately associated with memory performance. The relationship between neocortical amyloid and memory was mediated by entorhinal tau and presubiculum volume, which was modified by hippocampal amyloid burden. With other biomarkers held constant, presubiculum volume was the only marker predicting memory performance in the total sample and in individuals with elevated hippocampal amyloid burden.

CONCLUSIONS

The presubiculum captures unique AD-related biological variation that is not reflected in total hippocampal volume. Presubiculum volume may be a promising marker of imminent memory problems and can contribute to understanding the interaction between incipient AD-related pathologies and memory performance. The modulation by hippocampal amyloid suggests that amyloid is a necessary, but not sufficient, process to drive neurodegeneration in memory-related regions.

Regional Tau Correlates of Instrumental Activities of Daily Living and Apathy in Mild Cognitive Impairment and Alzheimer's Disease Dementia

BACKGROUND

Instrumental activities of daily living (IADL) impairment and apathy occur in early-stage Alzheimer's disease (AD) and are associated with regional atrophy and hypometabolism in vivo and greater tau burden at autopsy.

OBJECTIVE

To explore the association between IADL impairment, apathy, and in vivo regional tau in mild cognitive impairment (MCI) and AD dementia.

METHODS

Forty participants (24 MCI, 16 AD dementia) underwent assessments of IADL (Functional Activities Questionnaire, FAQ) and apathy (Apathy Evaluation Scale Informant report, AES-I). Regional tau was assessed using flortaucipir positron emission tomography (PET) and amyloid using Pittsburgh Compound B PET. Regions with unadjusted associations of p≤0.01 were entered into regression models assessing the relationship between tau and FAQ or AES-I, adjusting for age, sex, and cognition, with/without a tau by amyloid interaction.

RESULTS

Unadjusted IADL impairment but not apathy was associated with greater tau in multiple regions. After adjusting for covariates, for medial orbitofrontal and entorhinal cortex the interaction between tau and amyloid was associated with IADL impairment and for anterior cingulate it was not but independent associations with both tau and amyloid were retained. With whole brain analyses, similar results were seen for IADL, while for apathy tau in small clusters within the right anterior cingulate and dorsolateral prefrontal cortices were seen, which were more pronounced in individuals with greater amyloid.

CONCLUSIONS

This exploratory study suggests that IADL impairment in AD is associated with medial temporal and frontal tau, especially in individuals with elevated amyloid, while apathy may be associated with right frontal tau.

Clinical meaningfulness of subtle cognitive decline on longitudinal testing in preclinical AD

INTRODUCTION

Demonstrating the "clinical meaningfulness" of slowing early cognitive decline in clinically normal (CN) older adults with elevated amyloid-β (Aβ+) is critical for Alzheimer's disease secondary prevention trials and for understanding early cognitive progression.

METHODS

Cox regression analyses were used to determine whether 3-year slopes on the preclinical Alzheimer's cognitive composite predicted MCI diagnosis and global Clinical Dementia Rating>0 in 267 Aβ+ CN individuals participating in the Harvard Aging Brain Study, Australian Imaging, Biomarker and Lifestyle Study, and Alzheimer's Disease Neuroimaging Initiative.

RESULTS

Steeper preclinical Alzheimer's cognitive composite decline over 3 years was associated with increased risk for MCI diagnosis and global Clinical Dementia Rating>0 in the following years across all cohorts. Hazard ratios using meta-analytic estimates were 5.47 (95% CI: 3.25-9.18) for MCI diagnosis and 4.49 (95% CI: 2.84-7.09) for Clinical Dementia Rating>0 in those with subtle decline (>-.14 to -.26 preclinical Alzheimer's cognitive composite standard deviations/year) on longitudinal cognitive testing.

DISCUSSION

Early "subtle cognitive decline" among Aβ+ CN on a sensitive cognitive composite demonstrably increases risk for imminent clinical disease progression and functional impairment.