This cross-sectional study examined cognitive subtypes and influential factors in HIV-positive (HIV+) adults.
Two-step cluster analysis was conducted on a neurocognitive test battery in a sample (N = 78) of adults and older adults with HIV (Mage = 46.1). Next, cognitive, functional, and mental and physical health differences were compared between the HIV+ clusters and an HIV- reference group (N = 84; Mage = 47.9).
A two-cluster solution emerged, with a lower performing cluster exhibiting poorer performance across all domains except psychomotor speed, and a “normal” cluster displaying similar performance as the HIV- group. The most influential factors to classification in the lower performing cluster were older age and presence of stroke and hypertension. There were trends for longer duration of HIV-infection, higher unemployment rates, and greater prevalence of Hepatitis C co-infection in the lower performing cluster.
These findings suggest that there are not unique cognitive subtypes in HIV, but rather a subset of individuals who exhibit globally normal performance and those with below average performance. Older age and the related cardiovascular comorbidities of both aging and HIV medications may be key influential factors to variability in neurocognitive functioning in this population and thus should be considered in future studies. Implications for research and practice are provided.
Cluster analysis; HIV/AIDS; older adults; Neurocognitive impairment
Using a large, national sample, this study examined perceived caregiving strain and other caregiving factors in relation to all-cause mortality.
The REasons for Geographic and Racial Differences in Stroke (REGARDS) study is a population-based cohort of men and women aged 45 years and older. Approximately 12% (n = 3,710) reported that they were providing ongoing care to a family member with a chronic illness or disability. Proportional hazards models were used for this subsample to examine the effects of caregiving status measures on all-cause mortality over the subsequent 5-year period, both before and after covariate adjustment.
Caregivers who reported high caregiving strain had significantly higher adjusted mortality rates than both no strain (hazard ratio [HR] = 1.55, p = .02) and some strain (HR = 1.83, p = .001) caregivers. The mortality effects of caregiving strain were not found to differ by race, sex, or the type of caregiving relationship (i.e., spouse, parent, child, sibling, and other).
High perceived caregiving strain is associated with increased all-cause mortality after controlling for appropriate covariates. High caregiving strain constitutes a significant health concern and these caregivers should be targeted for appropriate interventions.
Caregiving; Mortality; Strain.
To assess whether there are differences in the strength of association with incident stroke for specific periods of life in the Stroke Belt (SB).
The risk of stroke was studied in 24,544 black and white stroke-free participants, aged 45+, in the Reasons for Geographic and Racial Differences in Stroke study, a national population-based cohort enrolled 2003–2007. Incident stroke was defined as first occurrence of stroke over an average 5.8 years of follow-up. Residential histories (city/state) were obtained by questionnaire. SB exposure was quantified by combinations of SB birthplace and current residence and proportion of years in SB during discrete age categories (0–12, 13–18, 19–30, 31–45, last 20 years) and entire life. Proportional hazards models were used to establish association of incident stroke with indices of exposure to SB, adjusted for demographic, socioeconomic (SES), and stroke risk factors.
In the demographic and SES models, risk of stroke was significantly associated with proportion of life in the SB and with all other exposure periods except birth, ages 31–45, and current residence. The strongest association was for the proportion of the entire life in SB. After adjustment for risk factors, the risk of stroke remained significantly associated only with proportion of residence in SB in adolescence (hazard ratio 1.17, 95% confidence interval 1.00–1.37).
Childhood emerged as the most important period of vulnerability to SB residence as a predictor of future stroke. Improvement in childhood health circumstances should be considered as part of long-term health improvement strategies in the SB.
The association between years of education and cognitive function in older adults has been studied extensively, but the role of quality of education is unknown. We examined indicators of childhood educational quality as predictors of cognitive performance and decline in later life.
Participants included 433 older adults (52% African American) who reported living in Alabama during childhood and completed in-home assessments of cognitive function at baseline and 4 years later. Reports of residence during school years were matched to county-level data from the 1935 Alabama Department of Education report for school funding (per student), student–teacher ratio, and school year length. A composite measure of global cognitive function was utilized in analyses. Multilevel mixed effects models accounted for clustering of educational data within counties in examining the association between cognitive function and the educational quality indices.
Higher student–teacher ratio was associated with worse cognitive function and greater school year length was associated with better cognitive function. These associations remained statistically significant in models adjusted for education level, age, race, gender, income, reading ability, vascular risk factors, and health behaviors. The observed associations were stronger in those with lower levels of education (≤12 years), but none of the education quality measures were related to 4-year change in cognitive function.
Educational factors other than years of schooling may influence cognitive performance in later life. Understanding the role of education in cognitive aging has substantial implications for prevention efforts as well as accurate identification of older adults with cognitive impairment.
Cognitive aging; Education; Health disparities
Systematic cognitive training produces long-term improvement in cognitive function and less difficulty in performing activities of daily living. We examined whether cognitive training was associated with reduced rate of incident dementia. Participants were from the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study (n=2,802). Incident dementia was defined using a combination of interview- and performance-based methods. Survival analysis was used to determine if ACTIVE treatment affected the rate of incident dementia during 5 years of follow-up. A total of 189 participants met criteria for incident dementia. Baseline factors predictive of incident dementia were older age, male gender, African American race, fewer years of education, relationship other than married, no alcohol use, worse MMSE< worse SF-36 physical functioning, higher depressive symptomatology, diabetes, and stroke (all p<.05). A multivariable model with significant predictors of incident dementia and training group revealed that cognitive training was not associated with a lower rate of incident dementia. Cognitive training did not affect rates of incident dementia after 5 years of follow-up. Longer follow-up or enhanced training may be needed to fully explore the preventive capacity of cognitive training in forestalling onset of dementia.
Cognitive training; Intervention; Aging; Dementia; Prevention; Cognition
Rates of mild cognitive impairment (MCI) have varied substantially, depending on the criteria used and the samples surveyed. The present investigation used a psychometric algorithm for identifying MCI and its’ stability to determine if low cognitive functioning was related to poorer longitudinal outcomes. The Advanced Cognitive Training of Independent and Vital Elders (ACTIVE) study is a multi-site longitudinal investigation of long-term effects of cognitive training with older adults. ACTIVE exclusion criteria eliminated participants at highest risk for dementia (i.e., MMSE<23). Using composite normative for sample- and training- corrected psychometric data, 8.07% of the sample had amnestic impairment, while 25.09% had a non-amnestic impairment at baseline. Poorer baseline functional scores were observed in those with impairment at the first visit, including a higher rate of attrition, depressive symptoms, and self-reported physical functioning. Participants were then classified based upon the stability of their classification. Those who were stably impaired over the five-year interval had the worst functional outcomes (e.g., IADL performance), and inconsistency in classification over time also appeared to be associated increased risk. These findings suggest that there is prognostic value in assessing and tracking cognition to assist in identifying the critical baseline features associated with poorer outcomes.
cognitive impairment; research classification; cognitive aging; longitudinal follow-up
We examined job control, job demands, social support at work, and job strain (ratio of demands to control) in relation to risk of any dementia, Alzheimer’s disease (AD), and vascular dementia (VaD).
A cohort study.
The population-based Study of Dementia in Swedish Twins.
A total of 257 dementia cases (167 AD, 46 VaD) and 9,849 non-demented individuals.
Dementia diagnoses were based on telephone screening for cognitive impairment followed by in-person clinical work-up. An established job exposure matrix was matched to main occupation categories to measure work characteristics.
In generalized estimating equations (adjusted for the inclusion of complete twin pairs), lower job control was associated with greater risk of any dementia (odds ratio [OR]=1.17, 95% confidence interval [95%CI] 1.04-1.31) and VaD specifically (OR=1.39, 95% CI 1.07-1.81). Lower social support at work was associated with increased risk of dementia (OR=1.15, 95% CI 1.03-1.28), AD (OR=1.14, 95% CI 1.00-1.31), and VaD (OR=1.28, 95% CI=1.02-1.60). Greater job strain was associated with increased risk of VaD only (OR=1.28, 95% CI 1.02-1.60), especially in combination with low social support (OR=1.35, 95% CI 1.11-1.64). Age, gender, education, and cardiovascular disease were controlled. Results were not explained by work complexity or manual work. No differences in work-related stress scores were observed in the 54 twin pairs discordant for dementia, although only two pairs included a twin with VaD.
Work-related stress including low job control and low social support at work may increase the risk of dementia, particularly VaD. Modification to work environment that includes attention to social context and provision of meaningful roles for the workers may contribute to the efforts to promote cognitive health.
Work-related stress; job strain; dementia; vascular dementia
Within the context of the ACTIVE study, the current investigation explored the relationships between objective memory and two components of subjective memory (frequency of forgetting and use of external aids) over a five-year period. Relationships were assessed using parallel process latent growth curve models. Results indicated that changes in objective memory were associated with changes in perceived frequency of forgetting, but not with use of external aids (calendars, reminder notes) over time. Findings suggest that memory complaints may accurately reflect decline in objective memory performance, but that these memory changes are not necessarily related to compensatory behaviors.
objective memory; subjective memory; latent growth curves; later adulthood
To determine whether incidence of impaired cognitive screening status is higher in the southern Stroke Belt region of the United States than in the remaining U.S.
A national cohort of adults ≥ age 45 was recruited by the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study from 2003–2007. Participants’ global cognitive status was assessed annually by telephone with the Six-item Screener (SIS) and every two years with fluency and recall tasks. Participants who reported no stroke history and who were cognitively intact at enrollment (SIS > 4 of 6) were included (N = 23,913, including 56% women, 38% African Americans and 62% European Americans, 56% Stroke Belt residents and 44% from the remaining contiguous United States and the District of Columbia). Regional differences in incident cognitive impairment (SIS score ≤ 4) were adjusted for age, sex, race, education, and time between first and last assessments.
1,937 participants (8.1%) declined to an SIS score ≤ 4 at their most recent assessment, over a mean of 4.1 (± 1.6) years. Residents of the Stroke Belt had greater adjusted odds of incident cognitive impairment than non-Belt residents (OR = 1.18; 95% CI 1.07 – 1.30). All demographic factors and time independently predicted impairment.
Regional disparities in cognitive decline mirror regional disparities in stroke mortality, suggesting shared risk factors for these adverse outcomes. Efforts to promote cerebrovascular and cognitive health should be directed to the Stroke Belt.
We examined the relationship of cognitive and functional measures with life space (a measure of spatial mobility examining extent of movement within a person’s environment) in older adults, and investigated the potential moderating role of personal control beliefs. Internal control beliefs reflect feelings of competence and personal agency, while attributions of external control imply a more dependent or passive point of view. Participants were 2,737 adults from the ACTIVE study, with a mean age of 74 years. Females comprised 76% of the sample, with good minority representation (27% African American). In multiple regression models controlling for demographic factors, cognitive domains of memory, reasoning, and processing speed were significantly associated with life space (p<.001 for each), and reasoning ability appeared most predictive (B=.117). Measures of everyday function also showed significant associations with life space, independent from the traditional cognitive measures. Interactions between cognitive function and control beliefs were tested, and external control beliefs moderated the relationship between memory and life space, with the combination of high objective memory and low external control beliefs yielding the highest life space (t=−2.07; p=.039). In conclusion, older adults with better cognitive function have a larger overall life space. Performance-based measures of everyday function may also be useful in assessing the functional outcome of life space. Additionally, subjective external control beliefs may moderate the relationship between objective cognitive function and life space. Future studies examining the relationships between these factors longitudinally appear worthwhile to further elucidate the interrelationships of cognitive function, control beliefs, and life space.
aging; cognition; control beliefs; life space
In 129 community-dwelling older adults, feedback regarding qualification for an insurance discount (based on a visual speed of processing test; Useful Field of View) was examined as a prospective predictor of change in self-reported driving ability, driving avoidance, and driving exposure over 3 months, along with physical, visual, health, and cognitive variables. Multiple regression models indicated that after controlling for baseline scores on the outcome measures, failure to qualify was a significant predictor of increased avoidance over 3 months (p = .02) but not change in self-rated driving ability or exposure. Female gender (p = .03) was a significant predictor of subsequent lower self-rated driving ability. Overall, the findings of this study provide support for the role of feedback in the self-monitoring of older adults’ driving behavior through avoidance of challenging driving situations but not through driving exposure or self-rated driving ability.
Older drivers; Driving ability; Self-regulation; Self-rated driving; Driving exposure; Driving avoidance
The purpose of this study was to: (1) examine cognitive performance differences in older and younger adults with and without HIV, and (2) determine if such differences were related to a laboratory measure of instrumental activities of daily living (IADLs). Ninety-eight HIV-positive (69 younger, 29 older) and 103 HIV-negative (84 younger, 19 older) adults were evaluated on a number of cognitive measures. Controlling for a number of confounders, age by HIV status interactions were found on two cognitive measures, indicating poorer cognitive performance for those aging with HIV. Poorer performance on these cognitive measures corresponded with poorer performance on the Timed Instrumental Activities of Daily Living (TIADL) test. These findings suggest that as adults age with HIV, they may be at risk for cognitive declines that would impair their ability to engage in activities important for maintaining independent living.
HIV; AIDS; Aging; Neuropsychology; Cognition; IADLs
We examined the association between extremely low-frequency magnetic fields (EMF) and the risk of dementia and Alzheimer’s disease using all 9,508 individuals from the Study of Dementia in Swedish Twins (HARMONY) with valid occupational and diagnostic data.
Dementia diagnoses were based on telephone screening followed by in-person clinical workup. Main lifetime occupation was coded according to an established EMF exposure matrix. Covariates were age, gender, education, vascular risk factors, and complexity of work. Based on previous research, data were also analyzed separately for cases with disease onset by age 75 years versus later, men versus women, and those with manual versus nonmanual main occupation. We used generalized estimating equations with the entire sample (to adjust for the inclusion of complete twin pairs) and conditional logistic regression with complete twin pairs only.
Level of EMF exposure was not significantly associated with dementia or Alzheimer’s disease. However, in stratified analyses, medium and high levels of EMF exposure were associated with increased dementia risk compared with low level in cases with onset by age 75 years (odds ratio: 1.94, 95% confidence interval: 1.07–3.65 for medium, odds ratio: 2.01, 95% confidence interval: 1.10–3.65 for high) and in participants with manual occupations (odds ratio: 1.81, 95% confidence interval: 1.06–3.09 for medium, odds ratio: 1.75, 95% confidence interval: 1.00–3.05 for high). Results with 42 twin pairs discordant for dementia did not reach statistical significance.
Occupational EMF exposure appears relevant primarily to dementia with an earlier onset and among former manual workers.
Dementia; Magnetic fields; Occupation; Alzheimer’s disease
The CLOX is a clock drawing test used to screen for cognitive impairment in older adults, but there is limited normative data for this measure. This study presents normative data for the CLOX derived from a diverse sample of 585 community-dwelling older adults with complete cognitive data at baseline and 4-year follow-up. Participants with evidence of baseline impairment or substantial 4-year decline on the Mini-Mental State Examination were excluded from the normative sample. Spontaneous clock drawing (CLOX1) and copy (CLOX2) performances were stratified by age group and reading ability from the Wide Range Achievement Test, 3rd edition (WRAT-3). Lowest mean CLOX scores were observed for the oldest age group (75+ years old) with the lowest WRAT-3 reading scores. For all groups, average scores were higher for CLOX2 than CLOX1. These normative data may be helpful to clinicians and researchers for interpreting CLOX performance in older adults with diverse levels of reading ability.
Normative data; Clock drawing test; Reading ability; Older adults; Aging
Studies have found that adults with possible mild cognitive impairment (MCI) exhibit decrements in everyday functioning (e.g., Wadley, V. G., Crowe, M., Marsiske, M., Cook, S. E., Unverzagt, F. W., Rosenberg, A. L., et al. (2007). Changes in everyday function among individuals with psychometrically defined mild cognitive impairment. Journal of the American Geriatrics Society, 55, 1192–1198). However, it is not known whether driving mobility and life space mobility are reduced in such individuals. The current study examined 5-year trajectories of mobility change in older adults (N = 2,355) with psychometrically defined MCI from the Advanced Cognitive Training for Independent and Vital Elderly trial. Mixed effect models evaluated group differences for the following mobility outcomes: driving space, life space, driving frequency, and driving difficulty. Relative to cognitively normal participants, participants with possible MCI showed reduced baseline mobility for all outcomes as well as faster rates of decline for driving frequency and difficulty. These results suggest that mobility declines could be features of MCI, and changes in mobility may be particularly important for researchers and clinicians to monitor in this population.
Driving; Life space; Mild cognitive impairment; Mobility; Older adults
We investigated whether factors related to health disparities – race, rural residence, education, perceived racial discrimination, vascular disease, and health care access and utilization – may moderate the association between diabetes and cognitive decline.
Participants were 624 community-dwelling older adults (49% African American, 49% rural) who completed in-home Mini-Mental State Examination at baseline and four-year follow-up.
Diabetes at baseline predicted cognitive decline over four years in regression models adjusted for a number of possible confounds. Only perceived discrimination and health utilization showed significant interaction effects with diabetes. Among African Americans who reported experiencing racial discrimination, there was a stronger relationship between diabetes and cognitive decline. Among participants who reported absence of visiting a physician within the past six months, the association between diabetes and cognitive decline was substantially larger.
Findings suggest that factors related to health disparities may influence cognitive outcomes among older adults with diabetes.
diabetes; cognitive decline; older adults; health disparities
To examine the relationship between subjective cognitive function and subsequent cognitive decline among individuals with psychometrically defined amnestic mild cognitive impairment (MCI), and to determine whether the presence of depressive symptoms modifies this relationship.
Fifty-five individuals met psychometric criteria for amnestic mild cognitive impairment (MCI). Cognitive decline was measured using the Mini-Mental State Examination (MMSE), which was administered at baseline and at follow-up two years later. Subjective cognitive function was examined using two different one-item memory complaints, as well as a scale focused on current level of cognitive function relative to past function and a scale focused on forgetting in specific everyday situations.
In multiple regression analyses, the one-item complaint of change in memory at baseline predicted future cognitive decline. There was a significant interaction effect whereby this association was stronger in participants who endorsed fewer symptoms of depression.
Individuals showing memory deficits consistent with amnestic MCI have at least some insight regarding cognitive decline and the extent to which subjective cognitive function is useful in predicting future decline may depend on what particular questions are asked as well as presence of depressive symptoms.
subjective cognitive function; mild cognitive impairment; depression; cognitive decline
Mild Cognitive Impairment (MCI) involves subtle functional losses that may include decrements in driving skills. We compared 46 participants with MCI to 59 cognitively normal controls on a driving evaluation conducted by a driving rehabilitation specialist who was blinded to participants’ MCI classification. Participants with MCI demonstrated significantly lower performance than controls on ratings of global and discrete driving maneuvers, but these differences were not at the level of frank impairments. Rather, performance was simply less than optimal, which to a lesser degree was also characteristic of a subset of the cognitively normal control group. The finding of significantly lower global driving ratings, coupled with the increased incidence of dementia among people with MCI and the known impact of dementia on driving safety, suggests the need for increased vigilance among clinicians, family members, and individuals with MCI for initially benign changes in driving that may become increasingly problematic over time.
Mild Cognitive Impairment; Functional Ability; Instrumental Activities of Daily Living; Driving
Older adults are at higher risk of falling and of suffering greater devastating effects from such falls. The objective of this study was to longitudinally examine predictors for risk of falling such as cognitive composites (reasoning, memory, speed of processing) along with traditional predictors. Data on falls, cognition, objective functional tests, visual acuity, and demographics were collected on older adults at baseline (N = 698) and at a two-year annual follow-up (n = 550). By using hierarchical multiple regression, we found that older age, being an older Caucasian woman, poorer performance on Turn 360 at baseline, and having a better memory at baseline predicted higher reports of falling in the past two months at the two-year annual follow-up. These results confirm prior findings except for memory; however, better memory as a predictor of falls may indicate that there is a recall bias dependent on memory function.
Falling; Memory; Speed of Processing; Executive Functioning
Life-space, a measure of movement through one’s environment, may be viewed as one aspect of environmental complexity for older adults. We examined the relationship between life-space and subsequent change in cognitive function.
Participants were 624 community-dwelling Medicare beneficiaries (49% African American) who completed in-home assessments at baseline and follow-up 4 years later. The Life-Space Assessment was used at baseline to measure extent, frequency, and independence of participants’ movement within and outside the home. Cognitive decline was measured with the Mini-Mental State Examination (MMSE).
In a regression model adjusted for baseline MMSE, age, gender, race, residence (rural/urban), and education, greater life-space at baseline predicted reduced cognitive decline (β = −.177, p < .001). This association remained statistically significant in subsequent models that examined what proportion of the observed association was explained by baseline physical activity, physical function, vascular risk factors, comorbidity, and psychosocial factors. Physical function accounted for the largest proportion (37.3%) of the association between life-space and cognitive decline. There was no significant interaction between life-space and race, gender, or age in predicting cognitive decline. In a logistic regression analysis, participants in the highest quartile of life-space had 53% reduced odds of substantial cognitive decline (≥4 points on MMSE) compared to those in the lowest quartile.
These preliminary findings suggest that life-space may be a useful identifier of older adults at risk for cognitive decline. Future research should investigate the potential reciprocal relationship between life-space and cognitive function as well as the interrelationship between these factors and physical function.
Life-space; Cognition; Older adults; Cognitive decline
We evaluated whether the association between low education and greater risk of dementia is explained by genetic influences, using three different types of analyses. The HARMONY study (Swedish for “health” (Hälsa), “genes” (ARv), “environment” (Miljö), “and” (Och), and “new” (NY)) includes members of the Swedish Twin Registry who were aged 65 and older and alive in 1998, and who were screened and clinically assessed for dementia. There were 394 cases with dementia and 7786 unrelated controls. Analyses included co-twin control, tests for association between education and a measured genotype, and bivariate twin modeling. Low education was a significant risk factor for dementia both in case-control analyses (odds ratio=1.77, 95% confidence interval 1.38 to 2.28) and co-twin control analyses with monozygotic twin pairs (odds ratio=3.17, 95% confidence interval 1.26 to 7.93). Apolipoprotein E genotype was not associated with education and did not account for the relationship between education and dementia. Bivariate twin modeling showed that the association between education and dementia was not mediated by genetic influences in common between education and dementia. The association was mediated by shared environmental influences that were related to both dementia and to education. Low education is confirmed as a risk factor for dementia. Findings from three different analytic approaches showed that genetic influences did not explain this association.
Dementia; Education; Risk factors; Twin studies
Because many individuals with Mild Cognitive Impairment (MCI) will progress to a dementia diagnosis, this population is at high risk for losing functional independence. We examine trajectories of change in everyday function for individuals with cognitive deficits suggestive of MCI.
We utilized data from the longitudinal, multi-site Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study, which allowed for post-hoc classification of MCI status at baseline using psycho metric definitions for amnestic MCI, non-amnestic MCI, multi-domain MCI, and no MCI.
Six U.S. cities.
2832 volunteers (mean age 74 years; 26% African American) living independently, recruited from senior housing, community centers, and hospitals and clinics.
Mixed effect models examined changes in self-reported instrumental and basic activities of daily living (IADLs and ADLs) from the MDS Home Care Interview in 2,358 participants over a three-year period.
In models for IADL performance, IADL difficulty, and a Daily Functioning Composite, there was a significant time by MCI classification interaction for each MCI subtype, indicating that all MCI groups showed faster rates of decline in everyday function relative to cognitively normal participants with no MCI.
Results demonstrate the importance of MCI as a clinical entity that not only predicts progression to dementia but also predicts functional declines in activities that are key to autonomy and quality of life. MCI classification guidelines should allow for functional changes in MCI, and clinicians should monitor for such changes. Preservation of function may serve as a meaningful outcome for intervention efforts.
Mild Cognitive Impairment; functional change; ADL; IADL