Hippocampal-subfield microstructures and their relation to plasma biomarkers in Alzheimer's disease.

Hippocampal subfields exhibit differential vulnerabilities to Alzheimer's disease-associated pathology including abnormal accumulation of amyloid-ß deposition and neurofibrillary tangles. These pathological processes extensively impact on the structural and functional interconnectivities of the subfields and may explain the association between hippocampal dysfunction and cognitive deficits. In this study, we investigated the degree of alterations in the microstructure of hippocampal subfields across the clinical continuum of Alzheimer's disease. We applied a grey matter-specific multi-compartment diffusion model (Cortical-Neurite orientation dispersion and density imaging) to understand the differential effects of Alzheimer's disease pathology on the hippocampal subfield microstructure. A total of 119 participants were included in this cross-sectional study. Participants were stratified into three categories, cognitively normal (n = 47), mild cognitive impairment (n = 52), and Alzheimer's disease (n = 19). Diffusion MRI, plasma biomarkers and neuropsychological test scores were used to determine the association between the microstructural integrity and Alzheimer's disease-associated molecular indicators and cognition. For Alzheimer's disease-related plasma biomarkers, we studied amyloid-ß, total tau and neurofilament light; for Alzheimer's disease-related neuropsychological tests, we included the Trail Making Test, Rey Auditory Verbal Learning Test, Digit Span and Montreal Cognitive Assessment. Comparisons between cognitively normal subjects and those with mild cognitive impairment showed significant microstructural alterations in the hippocampal cornu ammonis (CA) 4 and dentate gyrus region, whereas CA 1-3 was the most sensitive region for the later stages in the Alzheimer's disease clinical continuum. Among imaging metrics for microstructures, the volume fraction of isotropic diffusion for interstitial free water demonstrated the largest effect size in between-group comparisons. Regarding the plasma biomarkers, neurofilament light appeared to be the most sensitive biomarker for associations with microstructural imaging findings in CA4-dentate gyrus. CA 1-3 was the subfield which had stronger correlations between cognitive performance and microstructural metrics. Particularly, poor performance on the Rey Auditory Verbal Learning Test and Montreal Cognitive Assessment was associated with decreased intracellular volume fraction. Overall, our findings support the value of tissue-specific microstructural imaging for providing pathologically relevant information manifesting in the plasma biomarkers and neuropsychological outcomes across various stages of Alzheimer's disease.

Tau-related white-matter alterations along spatially selective pathways.

Progressive accumulation of tau neurofibrillary tangles in the brain is a defining pathologic feature of Alzheimer's disease (AD). Tau pathology exhibits a predictable spatiotemporal spreading pattern, but the underlying mechanisms of this spread are poorly understood. Although AD is conventionally considered a disease of the gray matter, it is also associated with pronounced and progressive deterioration of the white matter (WM). A link between abnormal tau and WM degeneration is suggested by findings from both animal and postmortem studies, but few studies demonstrated their interplay in vivo. Recent advances in diffusion magnetic resonance imaging and the availability of tau positron emission tomography (PET) have made it possible to evaluate the association of tau and WM degeneration (tau-WM) in vivo. In this study, we explored the spatial pattern of tau-WM associations across the whole brain to evaluate the hypothesis that tau deposition is associated with WM microstructural alterations not only in isolated tracts, but in continuous structural connections in a stereotypic pattern. Sixty-two participants, including 22 cognitively normal subjects, 22 individuals with subjective cognitive decline, and 18 with mild cognitive impairment were included in the study. WM characteristics were inferred by classic diffusion tensor imaging (DTI) and a complementary diffusion compartment model - neurite orientation dispersion and density imaging (NODDI) that provides a proxy for axonal density. A data-driven iterative searching (DDIS) approach, coupled with whole-brain graph theory analyses, was developed to continuously track tau-WM association patterns. Without applying prior knowledge of the tau spread, we observed a distinct spatial pattern that resembled the typical propagation of tau pathology in AD. Such association pattern was not observed between diffusion and amyloid-ß PET signal. Tau-related WM degeneration is characterized by an increase in the mean diffusivity (with a dominant change in the radial direction) and a decrease in the intra-axonal volume fraction. These findings suggest that cortical tau deposition (as measured in tau PET) is associated with a lower axonal packing density and greater diffusion freedom. In conclusion, our in vivo findings using a data-driven method on cross-sectional data underline the important role of WM alterations in the AD pathological cascade with an association pattern similar to the postmortem Braak staging of AD. Future studies will focus on longitudinal analyses to provide in vivo evidence of tau pathology spreads along neuroanatomically connected brain areas.

The Prevalence of Cognitive Impairment Among Adults With Incident Heart Failure: The "Reasons for Geographic and Racial Differences in Stroke" (REGARDS) Study.

BACKGROUND: Cognitive impairment (CI) is estimated to be present in 25%-80% of heart failure (HF) patients, but its prevalence at diagnosis is unclear. To improve our understanding of cognition in HF, we determined the prevalence of CI among adults with incident HF in the REGARDS study. METHODS AND RESULTS: REGARDS is a longitudinal cohort study of adults ≥45 years of age recruited in the years 2003-2007. Incident HF was expert adjudicated. Cognitive function was assessed with the Six-Item Screener. The prevalence of CI among those with incident HF was compared with the prevalence of CI among an age-, sex-, and race-matched cohort without HF. The 436 participants with incident HF had a mean age of 70.3 years (SD 8.9), 47% were female, and 39% were black. Old age, black race, female sex, less education, and anticoagulation use were associated with CI. The prevalence of CI among participants with incident HF (14.9% [95% CI 11.7%-18.6%]) was similar to the non-HF matched cohort (13.4% [11.6%-15.4%]; P < .43). CONCLUSIONS: A total of 14.9% of the adults with incident HF had CI, suggesting that the majority of cognitive decline occurs after HF diagnosis. Increased awareness of CI among newly diagnosed patients and ways to mitigate it in the context of HF management are warranted.

Verbal fluency in a national sample: Telephone administration methods.

OBJECTIVES: Describe novel methods for ascertaining verbal fluency in a large national sample of adults, examine demographic factors influencing performance, and compare scores to studies using in-person assessment. METHODS/DESIGN: Participants were from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a national, population-based, longitudinal study of stroke in adults aged 45 years and older. Letter and semantic fluency were gathered, using Letter "F" and Animal Naming, via a telephone-based assessment with computer-assisted scoring of digital recordings. RESULTS: Initial letter and semantic fluency scores were obtained on 18 505 and 18 072 participants, respectively. For both fluency tests, scores were normally distributed. Younger age and more years of education were associated with better performances (p < 0.0001). The mean and standard deviation for matched subgroups, based on age, gender, and education, were quite comparable with scores reported out of samples using an in-person administration format. Telephone-based assessment also allowed for a level of quality control not available via in-person measurement. CONCLUSIONS: Telephone-based assessment of verbal fluency and computer-assisted scoring programs designed for this study facilitated large-scale data acquisition, storage, and scoring of protocols. The resulting scores have similar characteristics to those obtained by traditional methods. These findings extend validation of cognitive assessment methods, using survey research staff and computer-assisted technology for test administration.

Arsenic Exposure in Relation to Ischemic Stroke: The Reasons for Geographic and Racial Differences in Stroke Study.

BACKGROUND AND PURPOSE: The purpose of this case-cohort study was to examine urinary arsenic levels in relation to incident ischemic stroke in the United States. METHODS: We performed a case-cohort study nested within the REGARDS (REasons for Geographic and Racial Differences in Stroke) cohort. A subcohort (n=2486) of controls was randomly sampled within region-race-sex strata while all incident ischemic stroke cases from the full REGARDS cohort (n=671) were included. Baseline urinary arsenic was measured by inductively coupled plasma-mass spectrometry. Arsenic species, including urinary inorganic arsenic and its metabolites monomethylarsonic acid and dimethylarsinic acid, were measured in a random subset (n=199). Weighted Cox's proportional hazards models were used to calculate hazard ratios and 95% confidence intervals of ischemic stroke by arsenic and its species. RESULTS: The average follow-up was 6.7 years. Although incident ischemic stroke showed no association with total arsenic or total inorganic arsenic, for each unit higher level of urinary monomethylarsonic acid on a log-scale, after adjustment for potential confounders, ischemic stroke risk increased ≈2-fold (hazard ratio=1.98; 95% confidence interval: 1.12-3.50). Effect modification by age, race, sex, or geographic region was not evident. CONCLUSIONS: A metabolite of arsenic was positively associated with incident ischemic stroke in this case-cohort study of the US general population, a low-to-moderate exposure area. Overall, these findings suggest a potential role for arsenic methylation in the pathogenesis of stroke, having important implications for future cerebrovascular research.

Risk Factors for Poststroke Cognitive Decline: The REGARDS Study (Reasons for Geographic and Racial Differences in Stroke).

BACKGROUND AND PURPOSE: Poststroke cognitive decline causes disability. Risk factors for poststroke cognitive decline independent of survivors' prestroke cognitive trajectories are uncertain. METHODS: Among 22 875 participants aged ≥45 years without baseline cognitive impairment from the REGARDS cohort (Reasons for Geographic and Racial Differences in Stroke), enrolled from 2003 to 2007 and followed through September 2015, we measured the effect of incident stroke (n=694) on changes in cognitive functions and cognitive impairment (Six-Item Screener score <5) and tested whether patient factors modified the effect. Median follow-up was 8.2 years. RESULTS: Incident stroke was associated with acute declines in global cognition, new learning, verbal memory, and executive function. Acute declines in global cognition after stroke were greater in survivors who were black (P=0.04), men (P=0.04), and had cardioembolic (P=0.001) or large artery stroke (P=0.001). Acute declines in executive function after stroke were greater in survivors who had

Antihypertensive Medication and Dementia Risk in Older Adult African Americans with Hypertension: A Prospective Cohort Study.

BACKGROUND: African Americans are especially at risk of hypertension and dementia. Antihypertensive medications reduce the risk of cardiovascular events, but may also reduce the risk of dementia. OBJECTIVE: To assess the longitudinal effects of antihypertensive medications and blood pressure on the onset of incident dementia in a cohort of African Americans. DESIGN: Prospective cohort. PARTICIPANTS: 1236 community-dwelling patients from an inner-city public health care system, aged 65 years and older, with a history of hypertension but no history of dementia, and who had at least three primary care visits and a prescription filled for any medication. MAIN MEASURES: Blood pressure was the average of three seated measurements. Dementia was diagnosed using a two-stage design, with a screening evaluation every 2 to 3 years followed by a comprehensive in-home clinical evaluation for those with a positive screen. Laboratory, inpatient and outpatient encounter data, coded diagnoses and procedures, and medication records were derived from a health information exchange. KEY RESULTS: Of the 1236 hypertensive participants without dementia at baseline, 114 (9%) developed incident dementia during follow-up. Individuals prescribed any antihypertensive medication (n = 816) were found to have a significantly reduced risk of dementia (HR = 0.57, 95% CI 0.37-0.88, p = 0.0114) compared to untreated hypertensive participants (n = 420). When this analysis was repeated including a variable indicating suboptimally treated blood pressure (> 140 mmHg systolic or >90 mmHg diastolic), the effect of antihypertensive medication was no longer statistically significant (HR = 0.65, 95% CI 0.32-1.30, p = 0.2217). CONCLUSIONS: Control of blood pressure in older adult African American patients with hypertension is a key intervention for preventing dementia, with similar benefits from most of the commonly available antihypertensive medications.

Changes of glucose levels precede dementia in African-Americans with diabetes but not in Caucasians.

INTRODUCTION: Changes in glucose levels may represent a powerful metabolic indicator of dementia in African-Americans with diabetes. It is unclear whether these changes also occur in Caucasians. METHODS: A secondary data analysis using electronic medical records from 5228 African-Americans and Caucasians aged ≥65 years was carried out. Mixed effects models with repeated serum glucose measurements were used to compare changes in glucose levels between African-Americans and Caucasian patients with and without incident dementia. RESULTS: African-Americans and Caucasians with diabetes had significantly different changes in glucose levels by dementia status (P < .0001). African-Americans experienced a significant decline in glucose levels before the dementia diagnosis (estimated glucose decline 1.3421 mg/dL per year, P < .0001) than those who did not develop dementia. Caucasians with and without dementia showed stable glucose levels over time (P = .3071). DISCUSSION: Significant changes in glucose levels precede dementia in African-American patients with diabetes but not in Caucasians.

Glucose level decline precedes dementia in elderly African Americans with diabetes.

INTRODUCTION: High blood glucose levels may be responsible for the increased risk for dementia in diabetic patients. METHODS: A secondary data analysis merging electronic medical records (EMRs) with data collected from the Indianapolis-Ibadan Dementia project (IIDP). Of the enrolled 4105 African Americans, 3778 were identified in the EMR. Study endpoints were dementia, mild cognitive impairment (MCI), or normal cognition. Repeated serum glucose measurements were used as the outcome variables. RESULTS: Diabetic participants who developed incident dementia had a significant decrease in serum glucose levels in the years preceding the diagnosis compared to the participants with normal cognition (P = .0002). They also had significantly higher glucose levels up to 9 years before the dementia diagnosis (P = .0367). DISCUSSION: High glucose levels followed by a decline occurring years before diagnosis in African American participants with diabetes may represent a powerful presymptomatic metabolic indicator of dementia.

Does targeted cognitive training reduce educational disparities in cognitive function among cognitively normal older adults?

OBJECTIVE: The aim of this study was to investigate educational differences in treatment responses to memory, reasoning, and speed of processing cognitive training relative to no-contact control. METHODS: Secondary analyses of the Advanced Cognitive Training for Independent and Vital Elderly trial were conducted. Two thousand eight hundred older adults were randomized to memory, reasoning, or speed of processing training or no-contact control. A repeated-measures mixed-effects model was used to investigate immediate post-training and 1-year outcomes with sensitivity analyses out to 10 years. Outcomes were as follows: (1) memory composite of Hopkins Verbal Learning Test, Rey Auditory Verbal Learning Test, and Rivermead Behavioral Memory Test; (2) reasoning composite of letter series, letter sets, and word series; and (3) speed of processing measured using three trials of useful field of view and the digit symbol substitution test. RESULTS: The effects of reasoning and memory training did not differ by educational attainment. The effect of speed of processing training did. Those with fewer than 12 years of education experienced a 50% greater effect on the useful field of view test compared with those with 16 or more years of education. The training advantage for those with fewer than 12 years of education was maintained to 3 years post-training. CONCLUSION: Older adults with less than a secondary education are at elevated risk of dementia, including Alzheimer's disease. The analyses here indicate that speed of processing training is effective in older adults with low educational attainment.

Nail Selenium Level and Diabetes in Older People in Rural China.

This cross-sectional study aimed to examine the association between selenium levels and diabetes in an older population with life-long natural exposure to selenium in rural China. A total of 1856 subjects aged 65 years or older from four Chinese rural counties with different environmental selenium levels were evaluated. Analysis of covariance models and logistic regression models were used to examine the relationship between nail selenium levels and serum glucose, serum insulin, insulin resistance [using the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR)], and the risk of diabetes. The mean nail selenium level was 0.461 µg/g and the prevalence rate of diabetes was 8.3% in this population. The mean nail selenium level was significantly higher in the group with diabetes than in the group without diabetes (P<0.0001). The adjusted odds ratios for diabetes were 2.65 (95% CI: 1.48 to 4.73), 2.47 (95% CI: 1.37 to 4.45), and 3.30 (95% CI: 1.85 to 5.88) from the second selenium quartile to the fourth quartile, respectively, compared with the first quartile group. The mean serum glucose and HOMA-IR in the higher selenium quartile groups were significantly higher than those of the lowest quartile group. However, no significant differences in insulin were observed among the four quartile groups. A long-term, higher level of exposure to selenium may be associated with a higher risk of diabetes. Future studies are needed to elucidate the association between selenium and insulin resistance.

Dementia incidence declined in African-Americans but not in Yoruba.

INTRODUCTION: To compare dementia incidence of African-American and Yoruba cohorts aged ≥70 years enrolled in 1992 and 2001. METHODS: African-Americans residing in Indianapolis and Yoruba in Ibadan, Nigeria without dementia were enrolled in 1992 and 2001 and evaluated every 2-3 years until 2009. The cohorts consist of 1440 African-Americans, 1774 Yoruba in 1992 and 1835 African-Americans and 1895 Yoruba in the 2001 cohorts aged ≥70 years. RESULTS: In African-Americans, dementia and Alzheimer's disease (AD) incidence rates were significantly lower in 2001 than 1992 for all age groups except the oldest group. The overall standardized annual dementia incidence rates were 3.6% (95% confidence interval [CI], 3.2%-4.1%) in the 1992 cohort and 1.4% (95% CI, 1.2%-1.7%) in the 2001 cohort. There was no significant difference in dementia or AD incidence between the Yoruba cohorts. DISCUSSION: Future research is needed to explore the reasons for the differential changes in incidence rates in these two populations.

Adherence to a Mediterranean diet and prediction of incident stroke.

BACKGROUND AND PURPOSE: There are limited data on the potential association of adherence to Mediterranean diet (MeD) with incident stroke. We sought to assess the longitudinal association between greater adherence to MeD and risk of incident stroke. METHODS: We prospectively evaluated a population-based cohort of 30 239 individuals enrolled in REasons for Geographic and Racial Differences in Stroke (REGARDS) study, after excluding participants with stroke history, missing demographic data or food frequency questionnaires, and unavailable follow-up information. Adherence to MeD was categorized using MeD score. Incident stroke was adjudicated by expert panel review of medical records during a mean follow-up period of 6.5 years. RESULTS: Incident stroke was identified in 565 participants (2.8%; 497 and 68 cases of ischemic stroke [IS] and hemorrhagic stroke, respectively) of 20 197 individuals fulfilling the inclusion criteria. High adherence to MeD (MeD score, 5-9) was associated with lower risk of incident IS in unadjusted analyses (hazard ratio, 0.83; 95% confidence interval, 0.70-1.00; P=0.046). The former association retained its significance (hazard ratio, 0.79; 95% confidence interval, 0.65-0.96; P=0.016) after adjustment for demographics, vascular risk factors, blood pressure levels, and antihypertensive medications. When MeD was evaluated as a continuous variable, a 1-point increase in MeD score was independently associated with a 5% reduction in the risk of incident IS (95% confidence interval, 0-11%). We documented no association of adherence to MeD with incident hemorrhagic stroke. There was no interaction of race (P=0.37) on the association of adherence to MeD with incident IS. CONCLUSIONS: High adherence to MeD seems to be associated with a lower risk of incident IS independent of potential confounders. Adherence to MeD is not related to the risk of incident hemorrhagic stroke.

Trajectory of Cognitive Decline After Incident Stroke.

IMPORTANCE: Cognitive decline is a major cause of disability in stroke survivors. The magnitude of survivors' cognitive changes after stroke is uncertain. OBJECTIVE: To measure changes in cognitive function among survivors of incident stroke, controlling for their prestroke cognitive trajectories. DESIGN, SETTING, AND PARTICIPANTS: Prospective study of 23,572 participants 45 years or older without baseline cognitive impairment from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort, residing in the continental United States, enrolled 2003-2007 and followed up through March 31, 2013. Over a median follow-up of 6.1 years (interquartile range, 5.0-7.1 years), 515 participants survived expert-adjudicated incident stroke and 23,057 remained stroke free. EXPOSURE: Time-dependent incident stroke. MAIN OUTCOMES AND MEASURES: The primary outcome was change in global cognition (Six-Item Screener [SIS], range, 0-6). Secondary outcomes were change in new learning (Consortium to Establish a Registry for Alzheimer Disease Word-List Learning; range, 0-30), verbal memory (Word-List Delayed Recall; range, 0-10), and executive function (Animal Fluency Test; range, ≥0), and cognitive impairment (SIS score <5 [impaired] vs ≥5 [unimpaired]). For all tests, higher scores indicate better performance. RESULTS: Stroke was associated with acute decline in global cognition (0.10 points [95% CI, 0.04 to 0.17]), new learning (1.80 points [95% CI, 0.73 to 2.86]), and verbal memory (0.60 points [95% CI, 0.13 to 1.07]). Participants with stroke, compared with those without stroke, demonstrated faster declines in global cognition (0.06 points per year faster [95% CI, 0.03 to 0.08]) and executive function (0.63 points per year faster [95% CI, 0.12 to 1.15]), but not in new learning and verbal memory, compared with prestroke slopes. Among survivors, the difference in risk of cognitive impairment acutely after stroke, compared with immediately before stroke, was not statistically significant (odds ratio, 1.32 [95% CI, 0.95 to 1.83]; P = .10); however, there was a significantly faster poststroke rate of incident cognitive impairment compared with the prestroke rate (odds ratio, 1.23 per year [95% CI, 1.10 to 1.38]; P < .001). For a 70-year-old black woman with average values for all covariates at baseline, stroke at year 3 was associated with greater incident cognitive impairment: absolute difference of 4.0% (95% CI, -1.2% to 9.2%) at year 3 and 12.4% (95% CI, 7.7% to 17.1%) at year 6. CONCLUSIONS AND RELEVANCE: Incident stroke was associated with an acute decline in cognitive function and also accelerated and persistent cognitive decline over 6 years.

Comparison of younger and older breast cancer survivors and age-matched controls on specific and overall quality of life domains.

BACKGROUND: Younger survivors (YS) of breast cancer often report more survivorship symptoms such as fatigue, depression, sexual difficulty, and cognitive problems than older survivors (OS). This study sought to determine the effect of breast cancer and age at diagnosis on quality of life (QoL) by comparing 3 groups: 1) YS diagnosed at age 45 years or before, 2) OS diagnosed between 55 and 70, and 3) for the YSs, age-matched controls (AC) of women not diagnosed with breast cancer. METHODS: Using a large Eastern Cooperative Oncology Group (ECOG) database, 505 YS were recruited who were aged 45 years or younger when diagnosed and 622 OS diagnosed at 55 to 70 years of age. YS, OS, and AC were compared on physical, psychological, social, spiritual, and overall QoL variables. RESULTS: Compared to both AC and to OS, YS reported more depressive symptoms (P = .005) and fatigue (P < .001), poorer self-reported attention function (P < .001), and poorer sexual function (P < .001) than either comparison group. However, YS also reported a greater sense of personal growth (P < .001) and perceived less social constraint (P < .001) from their partner than AC. CONCLUSIONS: YS reported worse functioning than AC relative to depression, fatigue, attention, sexual function, and spirituality. Perhaps even more important, YS fared worse than both AC and OS on body image, anxiety, sleep, marital satisfaction, and fear of recurrence, indicating that YS are at greater risk for long-term QoL problems than survivors diagnosed at a later age.

Age differences in the association of obstructive sleep apnea risk with cognition and quality of life.

Using a sample of 2925 stroke-free participants drawn from a national population-based study, we examined cross-sectional associations of obstructive sleep apnea (OSA) risk with cognition and quality of life and whether these vary with age, while controlling for demographics and comorbidities. Included participants from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study were aged 47-93 years. OSA risk was categorized as high or low based on responses to the Berlin Sleep Questionnaire. Cognitive function was assessed with standardized fluency and recall measures. Depressive symptoms were assessed with the four-item Center for Epidemiologic Studies Depression Scale. Health-related quality of life (HRQoL) was assessed with the Medical Outcomes Study Short Form-12 (SF-12). Multivariate analyses of covariance (mancova) statistics were applied separately to the cognitive and quality of life dependent variables while accounting for potential confounders (demographics, comorbidities). In fully adjusted models, those at high risk for OSA had significantly lower cognitive scores (Wilks' lambda = 0.996, F3,2786  = 3.31, P < 0.05) and lower quality of life [depressive symptoms and HRQoL] (Wilks' lambda = 0.989, F3,2786  = 10.02, P < 0.0001). However, some of the associations were age-dependent. Differences in cognition and quality of life between those at high and low obstructive sleep apnea risk were most pronounced during middle age, with attenuated effects after age 70 years.

Mild cognitive impairment, incidence, progression, and reversion: findings from a community-based cohort of elderly African Americans.

OBJECTIVE: To examine the long-term outcomes of community-based elderly African Americans by following their transitions from normal cognition to mild cognitive impairment (MCI) to dementia. METHODS: Participants were from the community-based Indianapolis Dementia Project. A total of 4,104 African Americans were enrolled in 1992 or 2001 and followed until 2009 with regularly scheduled evaluation of cognitive assessment. A two-stage sampling was used at each evaluation to select individuals for extensive clinical assessment following the results of Stage 1 cognitive testing. Age- and gender-specific incidence, progression, and reversion rates for MCI were derived using the person-year method in a dynamic cohort and predicted probabilities from weighted multinomial logistic models of transitional probabilities among normal cognition, MCI, and dementia. RESULTS: Annual overall incidence rate for MCI was 5.6% (95% confidence interval [CI]: 4.6%-6.6%). Annual progression rate from MCI to dementia was 5.9% (95% CI: 5.3%-6.5%), and annual reversion rate from MCI to normal was 18.6% (95% CI: 16.7%-20.4%). Both MCI incidence rates and MCI to dementia progression rates increased with age, whereas reversion rates from MCI to normal decreased with age. CONCLUSION: MCI progression to dementia was much more frequent in the older age groups than in younger participants where reversion to normal cognition is more common. Future research is needed to determine factors related to the heterogeneous outcomes in MCI individuals.

Performance of the NINDS-CSN 5-minute protocol in a national population-based sample.

In 2006, the National Institute of Neurological Disorders and Stroke-Canadian Stroke Network (NINDS-CSN) Vascular Cognitive Impairment Harmonization Standards recommended a 5-Minute Protocol as a brief screening instrument for vascular cognitive impairment (VCI). We report demographically adjusted norms for the 5-Minute Protocol and its relation to other measures of cognitive function and cerebrovascular risk factors. We performed a cross-sectional analysis of 7199 stroke-free adults in the REasons for Geographic And Racial Differences in Stroke (REGARDS) study on the NINDS-CSN 5-Minute Protocol score. Total scores on the 5-Minute Protocol were inversely correlated with age and positively correlated with years of education, and performance on the Six-Item Screener, Word List Learning, and Animal Fluency (all p-values <.001). Higher cerebrovascular risk on the Framingham Stroke Risk Profile (FSRP) was associated with lower total 5-Minute Protocol scores (p <.001). The 5-Minute Protocol also differentiated between participants with and without confirmed stroke and with and without stroke symptom histories (p <.001). The NINDS-CSN 5-Minute Protocol is a brief, easily administered screening measure that is sensitive to cerebrovascular risk and offers a valid method of screening for cognitive impairment in populations at risk for VCI.

Vascular risk factors and cognitive decline in a population sample.

We examined several vascular factors in relation to the rates of decline in 5 cognitive domains in a population-based cohort. In an age-stratified random sample (N=1982) aged 65+ years, we assessed at baseline the cognitive domains of attention, executive function, memory, language, and visuospatial function, and also vascular, inflammatory, and metabolic indices. Random effects models generated slopes of cognitive decline over the next 4 years; linear models identified vascular factors associated with these slopes, adjusting for demographics, baseline cognition, and potential interactions. Several vascular risk factors (history of stroke, diabetes, central obesity, C-reactive protein), although associated with lower baseline cognitive performance, did not predict rate of subsequent decline. APOE*4 genotype was associated with accelerated decline in language, memory, and executive functions. Homocysteine elevation was associated with faster decline in executive function. Hypertension (history or systolic blood pressure >140 mm Hg) was associated with slower decline in memory. Baseline alcohol consumption was associated with slower decline in attention, language, and memory. Different indices of vascular risk are associated with low performance and with rates of decline in different cognitive domains. Cardiovascular mechanisms explain at least some of the variance in cognitive decline. Selective survival may also play a role.

APOE ε4 and the risk for Alzheimer disease and cognitive decline in African Americans and Yoruba.

BACKGROUND: There is little information on the association of the APOEe4 allele and AD risk in African populations. In previous analyses from the Indianapolis-Ibadan dementia project, we have reported that APOE ε4 increased the risk for Alzheimer's disease (AD) in African Americans but not in Yoruba. This study represents a replication of this earlier work using enriched cohorts and extending the analysis to include cognitive decline. METHODS: In this longitudinal study of two community dwelling cohorts of elderly Yoruba and African Americans, APOE genotyping was conducted from blood samples taken on or before 2001 (1,871 African Americans & 2,200 Yoruba). Mean follow up time was 8.5 years for African Americans and 8.8 years for Yoruba. The effects of heterozygosity or homozygosity of ε4 and of the possession of e4 on time to incident AD and on cognitive decline were determined using Cox's proportional hazards regression and mixed effects models. RESULTS: After adjusting for covariates, one or two copies of the APOE ε4 allele were significant risk factors for incident AD (p < 0.0001) and cognitive decline in the African-American population (p < 0001). In the Yoruba, only homozygosity for APOE ε4 was a significant risk factor for AD (p = 0.0002) but not for cognitive decline (p = 0.2346), however, possession of an e4 allele was significant for both incident AD (p = 0.0489) and cognitive decline (p = 0.0425). CONCLUSIONS: In this large longitudinal comparative study, APOE ε4 had a significant, but weaker, effect on incident AD and on cognitive decline in Yoruba than in African Americans. The reasons for these differences remain unclear.