Associations between CAMCOG-R subscale performance and formal education attainment in South African older adults.

ABSTRACT Background: The Cambridge Cognitive Examination-Revised (CAMCOG-R) is a sensitive screening tool for the early diagnosis of dementia in older adults. Overall performance on the CAMCOG-R is influenced by educational attainment. Few studies have, however, examined the association between educational attainment and performance on the individual CAMCOG subscales. We aimed to address this question in a sample from a low-and middle-income country (LAMIC), where resource constraints may have compromised access to, and quality of, education for many older adults. Methods: Participants, all over 60 years of age, were 51 cognitively healthy community-dwelling volunteers and 47 individuals diagnosed with mild-moderate stage Alzheimer's disease (AD). Most participants had some high school education. They were administered the CAMCOG-R under standardized conditions. Results: Within both the control and AD patient groups, there were significant associations between years of completed education and CAMCOG-R total score, MMSE score, and CAMCOG-R Language subscale score. In both groups, level of education was not associated with scores on these subscales: in controls, recent memory, R 2 = .21, p = .055, learning memory, R 2 = .16, p = .398, attention/calculation, R 2 = .19, p = .467, and perception, R 2 = .18, p = .984; in AD patients, recent memory, R 2 = .14, p = .340, learning memory, R 2 = .03, p = .680, perception, R 2 = .09, p = .723, and attention/calculation, R 2 = .19, p = .097. Conclusions: Some CAMCOG-R subscale scores were more strongly associated with educational attainment than others. Importantly, however, performance on the recent memory and learning memory subscales was not affected by education. These subscales are sensitive indicators of amnestic mild cognitive impairment (MCI) and early AD. These subscales may therefore remain valid for use as an AD screening tool in resource-poor healthcare settings.

Psychosocial stress associated with memory performance in older South African adults.

Older adults with past or current chronic stress exposure perform poorly on memory assessments and are at higher risk for Alzheimer's disease (AD). In low- or middle-income countries, many older adults are, or have been, exposed to stress-provoking events. Few published studies examine such populations, however, and few take multiple measures of stress. In a sample of South African older adults with mild-to-moderate AD (n = 65) and healthy controls (n = 69), we assessed relations between stress (psychosocial and physiological), memory performance, and patient status. Participants, all aged > 60, were administered the Perceived Stress Scale (a questionnaire assessing subjective psychosocial stress) and the Cambridge Cognitive Examination-Revised (CAMCOG-R; a test battery measuring performance across several cognitive domains). We measured their salivary cortisol concentrations as a proxy for physiological stress. Patients reported significantly higher levels of psychosocial stress than controls, p = .008. Logistic regression showed that psychosocial stress, but not cortisol, predicted AD patient status. CAMCOG-R Memory subscale scores were significantly associated with psychosocial stress, r = -.18, p = .040, but not with cortisol levels. These findings are the first on the topic to emerge from a low-or middle-income country. We replicated findings from previous studies conducted in high-income countries, with data supporting predictions derived from the glucocorticoid cascade/neurotoxicity hypothesis. The results suggest that clinical interventions focused on increasing resilience of older adults to effects of chronic stress may help protect against declining memory performance and reduce the risk for AD.

Prevalence of HIV-1 Infection in an elderly rural population and associations with neurocognitive impairment.

OBJECTIVE: We explored the prevalence of HIV infection in older rural South Africans and its associations, as well as the point prevalence of dementia and its associations with HIV and aging. DESIGN: We utilized a cross-sectional analytic design. METHODS: Using the brief Community Screening Instrument for Dementia together with a rapid HIV test, we conducted a home-based screening survey among 1150 older South Africans. We explored the prevalence of HIV and dementia, and their associations using descriptive statistics and logistic regression analysis. RESULTS: The HIV prevalence was 4.78%. Overall, participants were on average 71.3 years old, with nearly 70% having no primary school education. HIV+ participants were significantly younger, more likely to be single and had lower BMI. The overall dementia prevalence was 11.04%. HIV+ participants had higher rates of dementia compared with HIV- participants (18.18 vs. 10.68%) but the difference was NS. In adjusted analysis, screened dementia was associated with older age, the presence of self-reported depression and HIV+ status. Participants were also more likely to self-report cognitive impairment if they were older, depressed and had objective evidence of dementia. CONCLUSION: Infection with HIV in rural older South Africans is a prevalent problem, and together with older age, is a significant contributor to cognitive impairment. It is possible that HIV infection contributes to dementia on the basis of an acceleration of degeneration - because our HIV-infected participants were younger - AND an accentuation of aging - because of the higher rates of impairment for similar age groups.

Both Reaction Time and Accuracy Measures of Intraindividual Variability Predict Cognitive Performance in Alzheimer's Disease.

Dementia researchers around the world prioritize the urgent need for sensitive measurement tools that can detect cognitive and functional change at the earliest stages of Alzheimer's disease (AD). Sensitive indicators of underlying neural pathology assist in the early detection of cognitive change and are thus important for the evaluation of early-intervention clinical trials. One method that may be particularly well-suited to help achieve this goal involves the quantification of intraindividual variability (IIV) in cognitive performance. The current study aimed to directly compare two methods of estimating IIV (fluctuations in accuracy-based scores vs. those in latency-based scores) to predict cognitive performance in AD. Specifically, we directly compared the relative sensitivity of reaction time (RT)-and accuracy-based estimates of IIV to cognitive compromise. The novelty of the present study, however, centered on the patients we tested [a group of patients with Alzheimer's disease (AD)] and the outcome measures we used (a measure of general cognitive function and a measure of episodic memory function). Hence, we compared intraindividual standard deviations (iSDs) from two RT tasks and three accuracy-based memory tasks in patients with possible or probable Alzheimer's dementia (n = 23) and matched healthy controls (n = 25). The main analyses modeled the relative contributions of RT vs. accuracy-based measures of IIV toward the prediction of performance on measures of (a) overall cognitive functioning, and (b) episodic memory functioning. Results indicated that RT-based IIV measures are superior predictors of neurocognitive impairment (as indexed by overall cognitive and memory performance) than accuracy-based IIV measures, even after adjusting for the timescale of measurement. However, one accuracy-based IIV measure (derived from a recognition memory test) also differentiated patients with AD from controls, and significantly predicted episodic memory performance. The findings suggest that both RT- and accuracy-based IIV measures may be useful indicators of underlying neuropathology. The present study therefore contributes toward an understanding of the relative utility of RT- and accuracy-based IIV measures in detecting neurocognitive impairment in older adults, and also advances the empirical evaluation of sensitive markers of cognitive change in patients with AD.

Dementia Prevalence in a Rural Region of South Africa: A Cross-Sectional Community Study.

BACKGROUND: Dementia is a growing concern for low- and middle-income countries where longevity is increasing and service provision is poor. Global prevalence estimates vary from 2% to 8.5% for those aged 60 years and older. There have been few dementia studies in sub-Saharan Africa, and prevalence data are lacking for South Africa. OBJECTIVE: To conduct a large dementia prevalence study in a low income rural population in South Africa. METHODS: 1,394 Xhosa-speaking community dwellers, aged ≥60 y (mean age±sd 71.3±8.3 y), in three clinic catchment areas, were screened at home. Trained community health workers administered the brief Community Screening Instrument for Dementia (CSID) to participants and informants to assess cognitive and functional capacity. Depressive symptoms were assessed with three questions from the EURO-D. RESULTS: The prevalence estimate using published CSID sensitivity/specificity values was 0.8 (95% CI: 0.06-0.09). Using CSID cut-off scores the estimated prevalence was 0.12 (95% CI: 0.10-0.13), with 161 screen-positives. Both methods gave a rate of 0.11 (95% CI: 0.09-0.13) for those over 65 years (n = 1051). 68.6% of participants were female and 69.8% had less than 7 years of education. Dementia risk was associated with older age and symptoms of depression, but not with sex. The association with education was not significant when controlled for by age. CONCLUSIONS: Dementia prevalence estimates were higher than expected for this low-income rural community. There is a need for increased dementia awareness and feasible support interventions. We also need further studies of regional prevalences, dementia subtypes, and modifiable risk factors in South Africa.

High levels of von Willebrand factor and low levels of its cleaving protease, ADAMTS13, are associated with stroke in young HIV-infected patients.

BACKGROUND: Stroke associated with human immunodeficiency virus infection may occur through a variety of mechanisms. Von Willebrand factor is a marker of endothelial dysfunction, and is elevated in human immunodeficiency virus infection. High levels of von Willebrand factor, a protein involved in platelet adhesion and aggregation, and low levels of ADAMTS13, a metalloproteinase that cleaves von Willebrand factor, have been associated with an increased risk of thrombosis. AIM: To investigate the role of von Willebrand factor and ADAMTS13 in the pathogenesis of human immunodeficiency virus-related stroke in young patients. METHODS: A case-control study (n = 100) comprising three participant groups: human immunodeficiency virus-positive antiretroviral therapy-naïve young strokes (n = 20), human immunodeficiency virus-negative young strokes (n = 40), and human immunodeficiency virus-positive antiretroviral therapy-naïve nonstroke controls (n = 40). von Willebrand factor and ADAMTS13 levels were measured in plasma samples collected five- to seven-days poststroke. RESULTS: Human immunodeficiency virus-positive stroke participants had higher von Willebrand factor levels than human immunodeficiency virus-negative strokes (173·5% vs. 135%, P = 0·032). They tended to have higher levels of von Willebrand factor than human immunodeficiency virus-positive nonstroke controls (173·5% vs. 129%, P = 0·061). Human immunodeficiency virus-positive stroke participants had lower levels of ADAMTS13 than human immunodeficiency virus-positive nonstroke controls (0% vs. 23·5% P = 0·018) most likely due to the effect of the acute stroke. However, in the nonstroke group, these levels were significantly reduced compared with population norms. von Willebrand factor levels in all human immunodeficiency virus-positive participants were negatively correlated with CD4 counts. CONCLUSIONS: Stroke in human immunodeficiency virus infection is associated with a prothrombotic state, characterized by elevated von Willebrand factor and low ADAMTS13 levels.