Limited Longitudinal Change in Self-reported Spatial Navigation Ability in Preclinical Alzheimer Disease.

Subtle changes in objective spatial navigation ability have been observed in the preclinical stage of Alzheimer disease (AD) cross-sectionally and have been found to predict clinical progression. However, longitudinal change in self-reported spatial navigation ability in preclinical AD has yet to be examined. The current study examined whether AD biomarkers suggestive of preclinical AD at baseline spatial navigation assessment and APOE genotype predicted decline in self-reported spatial navigation ability and whether APOE genotype moderated the association of AD biomarkers with change in self-reported spatial navigation. Clinically normal (Clinical Dementia Rating Scale=0) adults aged 56 to 90 completed the Santa Barbara Sense of Direction Scale (SBSOD) annually for an average of 2.73 years. Biomarker data was collected within +/-2 years of baseline (ie, cerebrospinal fluid Aß42, p-tau181, p-tau181/Aß42 ratio, positron emission tomography imaging with Florbetapir or Pittsburgh Compound-B, and hippocampal volume). APOE genotyping was obtained for all participants. SBSOD demonstrated a nonsignificant trend toward a decline over time (P=0.082). AD biomarkers did not predict change in self-reported spatial navigation (all Ps>0.163). APOE genotype did not moderate the relationship between AD biomarkers and self-reported spatial navigation in planned analyses (all Ps>0.222). Results suggest that self-reported spatial navigation ability, as estimated with the SBSOD, may be limited as a measure of subtle cognitive change in the preclinical stage of AD.

The complex relationship between depression and progression to incident cognitive impairment across race and ethnicity.

INTRODUCTION: We examined baseline differences in depression and antidepressant use among cognitively normal older adults in five ethnoracial groups and assessed whether depression predicted a faster progression to incident cognitive impairment across groups. METHODS: Data from the National Alzheimer's Coordinating Center (n = 8168) were used to examine differences between non-Hispanic Whites (nHW), African Americans (AA), Hispanics, Asians, and American Indian and Alaskan Natives in cross-sectional and longitudinal models. RESULTS: AA had a lower risk of depression compared to nHW at baseline. No statistical interactions were noted between ethnoracial groups and depression. However, depression independently predicted a faster progression to incident cognitive impairment. Hispanics and Asian participants had a higher hazard for progression compared to nHW. DISCUSSION: Previously established risk factors between depression and dementia were not found among AA and nHW participants. The relationship between depression and ethnoracial groups is complex and suggests differential effects on progression from cognitive normality to impairment.

The impact of the COVID-19 pandemic on radiotherapy services in England, UK: a population-based study.

BACKGROUND: The indirect impact of the COVID-19 pandemic on cancer outcomes is of increasing concern. However, the extent to which key treatment modalities have been affected is unclear. We aimed to assess the impact of the pandemic on radiotherapy activity in England. METHODS: In this population-based study, data relating to all radiotherapy delivered for cancer in the English NHS, between Feb 4, 2019, and June 28, 2020, were extracted from the National Radiotherapy Dataset. Changes in mean weekly radiotherapy courses, attendances (reflecting fractions), and fractionation patterns following the start of the UK lockdown were compared with corresponding months in 2019 overall, for specific diagnoses, and across age groups. The significance of changes in radiotherapy activity during lockdown was examined using interrupted time-series (ITS) analysis. FINDINGS: In 2020, mean weekly radiotherapy courses fell by 19·9% in April, 6·2% in May, and 11·6% in June compared with corresponding months in 2019. A relatively greater fall was observed for attendances (29·1% in April, 31·4% in May, and 31·5% in June). These changes were significant on ITS analysis (p<0·0001). A greater reduction in treatment courses between 2019 and 2020 was seen for patients aged 70 years or older compared with those aged younger than 70 years (34·4% vs 7·3% in April). By diagnosis, the largest reduction from 2019 to 2020 in treatment courses was for prostate cancer (77·0% in April) and non-melanoma skin cancer (72·4% in April). Conversely, radiotherapy courses in April, 2020, compared with April, 2019, increased by 41·2% in oesophageal cancer, 64·2% in bladder cancer, and 36·3% in rectal cancer. Increased use of ultra-hypofractionated (26 Gy in five fractions) breast radiotherapy as a percentage of all courses (0·2% in April, 2019, to 60·6% in April, 2020; ITS p<0·0001) contributed to the substantial reduction in attendances. INTERPRETATION: Radiotherapy activity fell significantly, but use of hypofractionated regimens rapidly increased in the English NHS during the first peak of the COVID-19 pandemic. An increase in treatments for some cancers suggests that radiotherapy compensated for reduced surgical activity. These data will assist health-care providers in understanding the indirect consequences of the pandemic and the role of radiotherapy services in minimising these consequences. FUNDING: None.

Recruitment of African American and Non-Hispanic White Older Adults for Alzheimer Disease Research Via Traditional and Social Media: a Case Study.

The increasing prevalence of Alzheimer disease (AD), higher risk among certain ethnoracial groups, and lack of effective therapies highlights the need to recruit and enroll diverse populations in prospective, observational studies and clinical trials. However, there is little known about the effectiveness of traditional media vs. social media outreach on recruitment in aging study studies. This study retrospectively examined the effectiveness and differences in using both traditional and social media materials for the recruitment of African American (AA) versus non-Hispanic white (NHW) participants for a prospective, longitudinal study examining preclinical AD and driving outcomes. Participants needed to be at least 65 years old, drive at least an average of once weekly, own a vehicle that was manufactured in 1996 or later, and agree to cognitive testing, psychometric testing, brain magnetic resonance imaging (MRI), brain amyloid positron emission tomography (PET), and cerebrospinal fluid collection via lumbar puncture. A total of 546 individuals contacted the study coordinator by phone or email. Of those individuals, 97 enrolled and 192 were not contacted secondary to filling enrollment capacity. Sixteen participants (16.5%) were AA and the remainder were NHW. Of the 354 individuals whom the coordinator contacted back, approximately 73% declined or did not return calls. Social media was more effective with recruiting NHW participants, while traditional advertisement (newspaper) was more successful in recruiting AA participants in this urban setting. Prospective studies should balance participant burden and enrollment with a targeted, multi-tiered recruitment plan and sufficient budget to reach the population of interest.

Incident cognitive impairment: longitudinal changes in molecular, structural and cognitive biomarkers.

Longer periods are needed to examine how biomarker changes occur relative to incident sporadic cognitive impairment. We evaluated molecular (CSF and imaging), structural, and cognitive biomarkers to predict incident cognitive impairment and examined longitudinal biomarker changes before and after symptomatic onset. Data from participants who were cognitively normal, underwent amyloid imaging using Pittsburgh compound B and/or CSF studies, and at least two clinical assessments were used. Stepwise Cox proportional hazards models tested associations of molecular (Pittsburgh compound B; CSF amyloid-ß42, tau, ptau181, tau/amyloid-ß42, ptau181/amyloid-ß42), structural (normalized hippocampal volume, normalized whole brain volume), and cognitive (Animal Naming, Trail Making A, Trail Making B, Selective Reminding Test - Free Recall) biomarkers with time to Clinical Dementia Rating (CDR) > 0. Cognitively normal participants (n = 664), aged 42 to 90 years (mean ± standard deviation = 71.4 ± 9.2) were followed for up to 16.9 years (mean ± standard deviation = 6.2 ± 3.5 years). Of these, 145 (21.8%) participants developed a CDR > 0. At time of incident cognitive impairment, molecular, structural, and cognitive markers were abnormal for CDR > 0 compared to CDR = 0. Linear mixed models indicated rates of change in molecular biomarkers were similar for CDR = 0 and CDR > 0, suggesting that the separation in values between CDR = 0 and CDR > 0 must have occurred prior to the observation period. Rate of decline for structural and cognitive biomarkers was faster for CDR > 0 compared to CDR = 0 (P < 0.0001). Structural and cognitive biomarkers for CDR > 0 diverged from CDR 0 at 9 and 12 years before incident cognitive impairment, respectively. Within those who developed CDR > 0, a natural separation occurred for Pittsburgh compound B values. In particular, CDR > 0 who had at least one APOE ɛ4 allele had higher, and more rapid increase in Pittsburgh compound B, while APOE ɛ2 was observed to have slower increases in Pittsburgh compound B. Of molecular biomarker-positive participants followed for at least 10 years (n = 16-23), ∼70% remained CDR = 0 over the follow-up period. In conclusion, conversion from cognitively normal to CDR > 0 is characterized by not only the magnitude of molecular biomarkers but also rate of change in cognitive and structural biomarkers. Findings support theoretical models of biomarker changes seen during transition to cognitive impairment using longitudinal data and provide a potential time for changes seen during this transition. These findings support the use of molecular biomarkers for trial inclusion and cognitive/structural biomarkers for evaluating trial outcomes. Finally, results support a potential role for APOE ɛ in modulating amyloid accumulation in CDR > 0 with APOE ɛ4 being deleterious and APOE ɛ2 protective.

Perspectives on ethnic and racial disparities in Alzheimer's disease and related dementias: Update and areas of immediate need.

Alzheimer's disease and related dementias (ADRDs) are a global crisis facing the aging population and society as a whole. With the numbers of people with ADRDs predicted to rise dramatically across the world, the scientific community can no longer neglect the need for research focusing on ADRDs among underrepresented ethnoracial diverse groups. The Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment (ISTAART; alz.org/ISTAART) comprises a number of professional interest areas (PIAs), each focusing on a major scientific area associated with ADRDs. We leverage the expertise of the existing international cadre of ISTAART scientists and experts to synthesize a cross-PIA white paper that provides both a concise "state-of-the-science" report of ethnoracial factors across PIA foci and updated recommendations to address immediate needs to advance ADRD science across ethnoracial populations.

Older Adults' Expectations about Mortality, Driving Life and Years Left without Driving.

People are living and driving longer than ever before, with little preparation for transitioning to being non-drivers. We investigated driving expectations among drivers age 65 and older, including sociodemographic and driving context predictors. Cross-sectional data from 349 older drivers were explored to determine variation in how many years they expected to continue driving. General linear models examined predictors of both expectations. In this predominantly Black/African American sample, 76% of older drivers (mean age = 73 ± 5.7 years) expected a non-driving future, forecasting living an average of 5.75 ± 7.29 years after driving cessation. Regression models on years left of driving life and years left to live post-driving cessation predicted nearly half of the variance in older drivers' expectations with five significant predictors: income, current age, age expected to live to, self-limiting driving to nearby places and difficulty, visualizing being a non-driver. Many older drivers expect to stop driving before end of life.

Political Ideology, Confidence in Science, and Participation in Alzheimer Disease Research Studies.

BACKGROUND: Americans' confidence in science varies based on their political ideology. This ideological divide has potentially important effects on citizens' engagement with and participation in clinical studies of Alzheimer disease (AD). METHODS: A probability sample of 1583 Americans was surveyed about their willingness to participate in longitudinal AD research and about their political attitudes. These survey results were compared with a survey of 382 participants in a longitudinal AD study at the Knight Alzheimer Disease Research Center. RESULTS: Among Americans, more conservative ideology decreases willingness to participate in a hypothetical longitudinal cohort study of AD both directly and through its negative effect on confidence in science. The Knight Alzheimer Disease Research Center study participants expressed more liberal ideology and greater confidence in science than Americans in general. Of the survey respondents opposed to participation, over a quarter changed to neutral or positive if the study returned their research results to them. CONCLUSIONS AND RELEVANCE: Clinical studies of AD are likely biased toward participants who are more liberal and have higher confidence in science than the general population. This recruitment bias may be reduced by lowering the trust demanded of participants through measures such as returning research results to participants.

Alzheimer Disease Biomarkers and Driving in Clinically Normal Older Adults: Role of Spatial Navigation Abilities.

PURPOSE: Older adults experience impaired driving performance, and modify their driving habits, including limiting amount and spatial extent of travel. Alzheimer disease (AD)-related pathology, as well as spatial navigation difficulties, may influence driving performance and driving behaviors in clinically normal older adults. We examined whether AD biomarkers [cerebrospinal fluid (CSF) concentrations of Aß42, tau, and ptau181] were associated with lower self-reported spatial navigation abilities, and whether navigation abilities mediated the relationship of AD biomarkers with driving performance and extent. METHODS: Clinically normal older adults (n=112; aged 65+) completed an on-road driving test, the Santa Barbara Sense of Direction scale (self-report measure of spatial navigation ability), and the Driving Habits Questionnaire for an estimate of driving extent (composite of driving exposure and driving space). All participants had a lumbar puncture to obtain CSF. RESULTS: CSF Aß42, but not tau or ptau181, was associated with self-reported navigation ability. Lower self-reported navigation was associated with reduced driving extent, but not driving errors. Self-reported navigation mediated the relationship between CSF Aß42 and driving extent. CONCLUSIONS: Findings suggest that cerebral amyloid deposition is associated with lower perceived ability to navigate the environment, which may lead older adults with AD pathology to limit their driving extent.

Driving cessation over a 24-year period: Dementia severity and cerebrospinal fluid biomarkers.

INTRODUCTION: With 36 million older adult U.S. drivers, safety is a critical concern, particularly among those with dementia. It is unclear at what stage of Alzheimer's disease (AD) older adults stop driving and whether preclinical AD affects driving cessation. METHODS: Time to driving cessation was examined based on Clinical Dementia Rating (CDR) and AD cerebrospinal fluid biomarkers. 1795 older adults followed up to 24 years received CDR ratings. A subset (591) had cerebrospinal fluid biomarker measurements and was followed up to 17 years. Differences in CDR and biomarker groups as predictors of time to driving cessation were analyzed using Kaplan-Meier curves and Cox proportional models. RESULTS: Higher CDR scores and more abnormal biomarker measurements predicted a shorter time to driving cessation. DISCUSSION: Higher levels of AD biomarkers, including among individuals with preclinical AD, lead to earlier driving cessation. Negative functional outcomes of preclinical AD show a nonbenign phase of the disease.

The interaction of sleep and amyloid deposition on cognitive performance.

Sleep difficulties are emerging as a risk factor for dementia. This study examined the effect of sleep and amyloid deposition on cognitive performance in cognitively normal adults. Sleep efficiency was determined by actigraphy. Cerebrospinal fluid Aß42 levels <500 pg mL-1 , indicating amyloid deposition, was present in 23 participants. Psychometric tests included the Free and Cued Selective Reminding Test, Trail Making Test A and B, Animal Fluency, Letter Number Sequencing, and the Mini Mental State Examination. The interaction term of sleep efficiency and amyloid deposition status was a significant predictor of memory performance as measured by total Selective Reminding Test scores. While Trail Making Test B performance was worse in those with amyloid deposition, sleep measures did not have an additive effect. In this study, amyloid deposition was associated with worse cognitive performance, and poor sleep efficiency specifically modified the effect of amyloid deposition on memory performance.

Genetic Comparison of Symptomatic and Asymptomatic Persons With Alzheimer Disease Neuropathology.

OBJECTIVE: The objective was to determine whether symptomatic and asymptomatic persons with Alzheimer disease (AD) neuropathology have different allele counts for single-nucleotide polymorphisms that have been associated with clinical late-onset AD. METHODS: Data came from the National Alzheimer's Coordinating Center Uniform Data Set and Neuropathology Data Set, and the Alzheimer's Disease Genetics Consortium (ADGC). Participants had low to high AD neuropathologic change. The 22 known/suspected genes associated with late-onset AD were considered. "Symptomatic" was defined as Clinical Dementia Rating global score >0. RESULTS: Sixty-eight asymptomatic and 521 symptomatic participants met inclusion criteria. Single-nucleotide polymorphisms associated with ABCA7 [odds ratio (OR)=1.66; 95% confidence interval (CI), 1.03-2.85] and MAPT (OR=2.18; CI, 1.26-3.77) were associated with symptomatic status. In stratified analyses, loci containing CD2AP (OR=0.35; 95% CI, 0.16-0.74), ZCWPW1 (OR=2.98; 95% CI, 1.34-6.86), and MAPT (OR=3.73, 95% CI, 1.30-11.76) were associated with symptomatic status in APOE e4 carriers. CONCLUSIONS: These findings potentially explain some of the variation in whether a person with AD neuropathology expresses symptoms. Understanding why some people remain cognitively normal despite having AD neuropathology could identify pathways to disease heterogeneity and guide treatment trials.

Amyloid Imaging, Cerebrospinal Fluid Biomarkers Predict Driving Performance Among Cognitively Normal Individuals.

Postmortem brain studies of older drivers killed in car accidents indicate that many had Alzheimer disease (AD) neuropathologic changes. We examined whether AD biomarkers are related to driving performance among cognitively normal older adults. Individuals with normal cognition, aged 65+ years, and driving at least once per week, were recruited. Participants (N=129) took part in clinical assessments, a driving test, and positron emission tomography imaging with Pittsburgh compound B (PIB) and/or cerebrospinal fluid (CSF) collection. General linear models tested whether the number of driving errors differed as a function of each of the biomarker variables (mean cortical binding potential for PIB, and CSF Aß42, tau, ptau181, tau/Aß42, ptau181/Aß42). Higher ratios of CSF tau/Aß42, ptau181/Aß42, and PIB mean cortical binding potential, were associated with more driving errors (P<0.05). Preclinical AD may have subtle cognitive and functional effects, which alone may go unnoticed. However, when combined, these changes may impact complex behaviors such as driving.

Mood Changes in Cognitively Normal Older Adults are Linked to Alzheimer Disease Biomarker Levels.

OBJECTIVES: To evaluate whether cerebrospinal fluid (CSF) and PET Pittsburgh Compound B (PiB) biomarkers of underlying Alzheimer disease (AD) pathology (ß-amyloid42 [Aß42], tau, phosphorylated tau181 [ptau181], tau/Aß42, ptau181/Aß42 and mean cortical binding potential [MCBP] for PET-PiB) predict changes in mood in cognitively normal older adults. SETTING: Knight Alzheimer's Disease Research Center (ADRC) at Washington University (WU). PARTICIPANTS: Participants, 65 years of age or older, were enrolled from longitudinal studies at the WU Knight ADRC. MEASUREMENTS: CSF, PET-PiB biomarkers, Clinical Dementia Rating (CDR), Mini-Mental State Examination (MMSE), Profile of Mood States-Short Form (POMS-SF), the Geriatric Depression Scale (GDS), and Neuropsychiatric Inventory Questionnaire (NPI-Q). RESULTS: Data from 118 participants at baseline and 66 participants at one-year follow-up were analyzed. CSF and PET biomarkers were not associated cross-sectionally with any mood disturbances at baseline (p > 0.05). Changes in mood as indicated by the total mood disturbance score on the POMS-SF, selected POMS-SF subscales, GDS, and NPI-Q scores from baseline to one-year follow-up were associated with (p < 0.05) CSF and PET-PiB biomarkers. There was no statistically significant decline in cognitive functioning. CONCLUSIONS: Generally, higher values of CSF and PET-PiB biomarkers are associated with more changes in mood in cognitively normal older adults. Further work is needed to understand the temporal development of mood changes over several years during the phase of preclinical AD. Evaluating mood as a noncognitive outcome may provide further insight into the development of preclinical AD in cognitively normal older adults.

Pathological correlates of white matter hyperintensities on magnetic resonance imaging.

BACKGROUND/AIMS: We investigated the histopathological correlates of white matter hyperintensities (WMHs) in participants with Alzheimer's disease (AD) or cerebrovascular disease, and in aged controls. METHODS: We reviewed 57 participants who had neuropathology and in whom neuroimaging was done. In addition to AD pathology, cortical microinfarcts, lacunes, and cerebral hemorrhages were assessed. Small-vessel disease included arteriolosclerosis and cerebral amyloid angiopathy. Postmortem brain tissue corresponding to regions of WMHs was investigated in 14 participants. The variables included: demyelination of the deep and periventricular white matter (WM), atrophy of the ventricular ependyma, and thickness of blood vessels. Partial Spearman's rank test and linear regression analysis, adjusted for age at the clinical evaluation and the duration to death, were performed. RESULTS: The severity of arteriosclerosis was correlated with the volume of periventricular hyperintensity (PVH) estimated by magnetic resonance imaging. Deep white matter hyperintensity (DWMH) volume was correlated with the presence of cortical microinfarcts and cerebral hemorrhages. The severity of the breakdown of the ventricular lining was correlated with PVHs, and DWMHs correlated with the severity of deep WM demyelination. The diameter of small blood vessels was not associated with WMHs. CONCLUSION: WMHs are consistent with small-vessel disease and increase the tissue water content. We found no association between WMHs and the thickness of small blood vessels.

Cognitive impairments and mood disruptions negatively impact instrumental activities of daily living performance in the first three months after a first stroke.

BACKGROUND: Cognition and mood play crucial roles in post-stroke recovery; however, the stroke literature is unclear as to how impairments in both domains influence performance of instrumental activities of daily living (IADL). OBJECTIVE: (1) Evaluate the extent to which mood and cognition at two weeks post-stroke predict performance three months post-stroke. (2) Assess performance differences in patients with impairments in both cognition and mood to patients with impairments in either cognition or mood. METHODS: Inpatients with a first-ever ischemic or hemorrhagic stroke were assessed at 2 weeks (n = 52) and at 3 months (n = 41) post-stroke. Patients completed a battery of neuropsychological tests, self-report measures and performance-based tests. Cognitive impairments and mood disruptions were assessed at 2 weeks and three months and IADL performance, as assessed by the Executive Function Performance Test, was evaluated at three months. RESULTS: Complete data from the 41 patients assessed at both time points were analyzed. Regression analysis showed that composite cognition and composite mood variables at two weeks post-stroke predicted 48% of the variance in IADL performance at three months (F3,37 = 12.04; adjusted R(2) = 0.48, P < 0.001). Statistically significant differences were found in performance scores for patients with a single impairment (M = 7.86, SD = 7.81) and for those with impairments in both mood and cognition (M = 19.2, SD = 13.2) (t(39) = - 3.41, P = 0.008). CONCLUSION: The results of this study suggest that cognitive and mood impairments at two weeks post-stroke are important predictors of performance in complex activities required for full independence at home and should be routinely assessed in stroke rehabilitation.

Prevalence of amyloid PET positivity in dementia syndromes: a meta-analysis.

IMPORTANCE: Amyloid-ß positron emission tomography (PET) imaging allows in vivo detection of fibrillar plaques, a core neuropathological feature of Alzheimer disease (AD). Its diagnostic utility is still unclear because amyloid plaques also occur in patients with non-AD dementia. OBJECTIVE: To use individual participant data meta-analysis to estimate the prevalence of amyloid positivity on PET in a wide variety of dementia syndromes. DATA SOURCES: The MEDLINE and Web of Science databases were searched from January 2004 to April 2015 for amyloid PET studies. STUDY SELECTION: Case reports and studies on neurological or psychiatric diseases other than dementia were excluded. Corresponding authors of eligible cohorts were invited to provide individual participant data. DATA EXTRACTION AND SYNTHESIS: Data were provided for 1359 participants with clinically diagnosed AD and 538 participants with non-AD dementia. The reference groups were 1849 healthy control participants (based on amyloid PET) and an independent sample of 1369 AD participants (based on autopsy). MAIN OUTCOMES AND MEASURES: Estimated prevalence of positive amyloid PET scans according to diagnosis, age, and apolipoprotein E (APOE) ε4 status, using the generalized estimating equations method. RESULTS: The likelihood of amyloid positivity was associated with age and APOE ε4 status. In AD dementia, the prevalence of amyloid positivity decreased from age 50 to 90 years in APOE ε4 noncarriers (86% [95% CI, 73%-94%] at 50 years to 68% [95% CI, 57%-77%] at 90 years; n = 377) and to a lesser degree in APOE ε4 carriers (97% [95% CI, 92%-99%] at 50 years to 90% [95% CI, 83%-94%] at 90 years; n = 593; P < .01). Similar associations of age and APOE ε4 with amyloid positivity were observed in participants with AD dementia at autopsy. In most non-AD dementias, amyloid positivity increased with both age (from 60 to 80 years) and APOE ε4 carriership (dementia with Lewy bodies: carriers [n = 16], 63% [95% CI, 48%-80%] at 60 years to 83% [95% CI, 67%-92%] at 80 years; noncarriers [n = 18], 29% [95% CI, 15%-50%] at 60 years to 54% [95% CI, 30%-77%] at 80 years; frontotemporal dementia: carriers [n = 48], 19% [95% CI, 12%-28%] at 60 years to 43% [95% CI, 35%-50%] at 80 years; noncarriers [n = 160], 5% [95% CI, 3%-8%] at 60 years to 14% [95% CI, 11%-18%] at 80 years; vascular dementia: carriers [n = 30], 25% [95% CI, 9%-52%] at 60 years to 64% [95% CI, 49%-77%] at 80 years; noncarriers [n = 77], 7% [95% CI, 3%-18%] at 60 years to 29% [95% CI, 17%-43%] at 80 years. CONCLUSIONS AND RELEVANCE: Among participants with dementia, the prevalence of amyloid positivity was associated with clinical diagnosis, age, and APOE genotype. These findings indicate the potential clinical utility of amyloid imaging for differential diagnosis in early-onset dementia and to support the clinical diagnosis of participants with AD dementia and noncarrier APOE ε4 status who are older than 70 years.

Interrater Reliability of the Record of Driving Errors (RODE).

The Record of Driving Errors (RODE) is a novel standardized tool designed to quantitatively document the specific types of driving errors that occur during a standardized performance-based road test. The purpose of this study was to determine interrater reliability between two occupational therapy driver rehabilitation specialists who quantitatively scored specific driving errors using the RODE in a sample of older adults diagnosed with dementia (n=24). Intraclass correlation coefficients of major driving error and intervention categories indicated almost perfect agreement between raters. Using raters with adequate training and similar professional backgrounds, it is possible to have good interrater reliability using the RODE on a standardized road test.

Physical activity and cognitive trajectories in cognitively normal adults: the adult children study.

Increased physical activity may protect against cognitive decline, the primary symptom of Alzheimer disease. In this study, we examined the relationship between physical activity and trajectories of cognitive functioning over serial assessments. Cognitively normal (Clinical Dementia Rating 0) middle-aged and older adults (N=173; mean age, 60.7 ± 7.8 y) completed a self-report measure of physical activity and a battery of standard neuropsychological tests assessing processing speed, attention, executive functioning, and verbal memory. At baseline, individuals with higher physical activity levels performed better on tests of episodic memory and visuospatial functioning. Over subsequent follow-up visits, higher physical activity was associated with small performance gains on executive functioning and working memory tasks in participants with one or more copies of the apolipoprotein ε4 allele (APOE4). In APOE4 noncarriers, slopes of cognitive performance over time were not related to baseline physical activity. Our results suggest that cognitively normal older adults who report higher levels of physical activity may have slightly better cognitive performance, but the potential cognitive benefits of higher levels of physical activity over time may be most evident in individuals at genetic risk for Alzheimer disease.

The effect of APOE ε4 allele on cholinesterase inhibitors in patients with Alzheimer disease: evaluation of the feasibility of resting state functional connectivity magnetic resonance imaging.

This work is to determine whether apolipoprotein E (APOE) genotype modulates the effect of cholinesterase inhibitor (ChEI) treatment on resting state functional connectivity magnetic resonance imaging (rs-fcMRI) in patients with Alzheimer disease (AD). We retrospectively studied very mild and mild AD participants who were treated (N=25) or untreated (N=19) with ChEIs with respect to rs-fcMRI measure of 5 resting state networks (RSNs): default mode, dorsal attention (DAN), control (CON), salience (SAL), and sensory motor. For each network, a composite score was computed as the mean of Pearson correlations between pairwise time courses extracted from areas comprising this network. The composite scores were analyzed as a function of ChEI treatment and APOE ε4 allele. Across all participants, significant interactions between ChEI treatment and APOE ε4 allele were observed for all 5 RSNs. Within APOE ε4 carriers, significantly greater composite scores were observed in the DAN, CON, and SAL for treated compared with untreated participants. Within APOE ε4 noncarriers, treated and untreated participants did not have significantly different composite scores for all RSNs. These data suggest that APOE genotype affects the response to ChEI using rs-fcMRI. Rs-fcMRI may be useful for assessing the therapeutic effect of medications in AD clinical trials.