Cognitive decline and literacy among ethnically diverse elders

Prevalence of mild cognitive impairment and dementia in older non-western immigrants in the Netherlands: a cross-sectional study

OBJECTIVE

In the Netherlands, persons of Turkish, Moroccan and Surinamese descent form the largest groups of non-western immigrants. A high prevalence of mild cognitive impairment (MCI) and dementia has been described in immigrant populations in the United States of America and the United Kingdom. We determined the prevalence of MCI and dementia in older community-dwelling adults from the largest non-western immigrant groups in the Netherlands.

METHODS

Participants, aged 55 years and older, of Turkish, Moroccan (Arabic or Berber), Surinamese (Creole or Hindustani) or Dutch descent were recruited via their general practitioners. Cognitive deficits were assessed using the Cross-Cultural Dementia screening instrument, which was validated in poorly educated people from different cultures. Differences in prevalence rates of MCI and dementia between the immigrant groups and a native Dutch group were analysed using chi-square tests.

RESULTS

We included 2254 participants. Their mean age was 65.0 years (standard deviation, 7.5), and 44.4% were male. The prevalence of MCI was 13.0% in Turkish, 10.1% in Moroccan-Arabic, 9.4% in Moroccan-Berber and 11.9% in Surinamese-Hindustani participants, compared to 5.9% in Surinamese-Creoles and 3.3% in native Dutch. The prevalence of dementia was 14.8% in Turkish, 12.2% in Moroccan Arabic, 11.3% in Moroccan Berber and 12.6% in Surinamese-Hindustani participants, compared to 4.0% in Surinamese-Creoles and 3.5% in native Dutch.

CONCLUSIONS

MCI and dementia were three to four times more prevalent in the majority of non-western immigrant groups when compared to the native Dutch population. These differences are important for planning and improving healthcare facilities. Copyright © 2016 John Wiley & Sons, Ltd.

Association of psychological, cognitive, and functional variables with self-reported executive functioning in a sample of nondemented community-dwelling older adults

Subjective executive functioning (EF) measures provide valuable information about real-world difficulties, although it is unclear what variables actually associate with subjective EF scores. We investigated subjective EF in 245 nondemented, community-dwelling older adults (aged 70 and above) from the Einstein Aging Study. Partial correlational analyses controlling for age were performed between the nine Behavior Rating Inventory of Executive Function-Adult version (BRIEF-A) clinical scales and objective EF tests, self-reported mood and personality, and informant-reported activities of daily living. The significance level was set at p < .006 for all analyses (two-tailed). Most notably, higher worry/oversensitivity, physiological anxiety, and fear of aging were significantly associated with increased EF difficulties on all nine BRIEF-A scales. Additionally, increased EF difficulties on five or more BRIEF-A scales were significantly associated with lower conscientiousness, higher neuroticism, and higher depressive symptom scores. The only objective neuropsychological test that significantly correlated with increased EF difficulties (on four BRIEF-A scales) was a measure of practical judgment. Overall, results indicate that interpretation of subjective EF scores must account for self-report of mood and personality. Moreover, the BRIEF-A only minimally taps objective EF as measured by performance-based measures. We discuss the theoretical and practical implications of these findings.

Adult age differences in information foraging in an interactive reading environment

When learning about a single topic in natural reading environments, readers are confronted with multiple sources varying in the type and amount of information. In this situation, readers are free to adaptively respond to the constraints of the environment (e.g., through selection of resources and time allocation for study), but there may be costs of exploring and switching between sources (e.g., disruption of attention, opportunity costs for study). From an ecological perspective, such properties of the environment are expected to influence learning strategies. In the current study, we used a novel reading paradigm to investigate age differences in the effects of information richness (i.e., sentence elaboration) and costs of switching between texts (i.e., time delay) on selection of sources and study time allocation. Consistent with the ecological view, participants progressed from less informative to more informative texts. Furthermore, increased switch cost led to a tendency to allocate more effort to easier materials and to greater persistence in reading, which in turn, led to better memory in both immediate and delayed recall. Older adults showed larger effects of switch cost, such that the age difference in delayed recall was eliminated in the high switch cost condition. Based on an ecological paradigm of reading that affords choice and self-regulation, our study provided evidence for preservation with age in the ability to adapt to changing learning environments so as to improve performance. (PsycINFO Database Record

The Consistency Assumption for Causal Inference in Social Epidemiology: When a Rose is Not a Rose

The assumption that exposures as measured in observational settings have clear and specific definitions underpins epidemiologic research and allows us to use observational data to predict outcomes in interventions. This leap between exposures as measured and exposures as intervened upon is typically supported by the consistency assumption. The consistency assumption has received extensive attention in risk factor epidemiology but relatively little emphasis in social epidemiology. However, violations of the consistency assumption may be especially important to consider when understanding how social and economic exposures influence health. Efforts to clarify the definitions of our exposures, thus bolstering the consistency assumption, will help guide interventions to improve population health and reduce health disparities. This article focuses on the consistency assumption as considered within social epidemiology. We explain how this assumption is articulated in the causal inference literature and give examples of how it might be violated for three common exposure in social epidemiology research: income, education and neighborhood characteristics. We conclude that there is good reason to worry about consistency assumption violations in much of social epidemiology research. Theoretically motivated explorations of mechanisms along with empirical comparisons of research findings under alternative operationalizations of exposure can help identify consistency violations. We recommend that future social epidemiology studies be more explicit to name and discuss the consistency assumption when describing the exposure of interest, including reconciling disparate results in the literature.

Jump, Hop, or Skip: Modeling Practice Effects in Studies of Determinants of Cognitive Change in Older Adults

Improvements in cognitive test scores upon repeated assessment due to practice effects (PEs) are well documented, but there is no empirical evidence on whether alternative specifications of PEs result in different estimated associations between exposure and rate of cognitive change. If alternative PE specifications produce different estimates of association between an exposure and rate of cognitive change, this would be a challenge for nearly all longitudinal research on determinants of cognitive aging. Using data from 3 cohort studies-the Three-City Study-Dijon (Dijon, France, 1999-2010), the Normative Aging Study (Greater Boston, Massachusetts, 1993-2007), and the Washington Heights-Inwood Community Aging Project (New York, New York, 1999-2012)-for 2 exposures (diabetes and depression) and 3 cognitive outcomes, we compared results from longitudinal models using alternative PE specifications: no PEs; use of an indicator for the first cognitive visit; number of prior testing occasions; and square root of the number of prior testing occasions. Alternative specifications led to large differences in the estimated rates of cognitive change but minimal differences in estimated associations of exposure with cognitive level or change. Based on model fit, using an indicator for the first visit was often (but not always) the preferred model. PE specification can lead to substantial differences in estimated rates of cognitive change, but in these diverse examples and study samples it did not substantively affect estimated associations of risk factors with change.

Performance of low-educated elders with depression on Addenbrooke's Cognitive Examination-Revised (ace-r) test

Along with cognitive disorders, depression has been a concern for mental health services due to its highly debilitating effect on the functioning and quality of life of the elderly. However, there is still little understanding of the cognitive alterations resulting from depression or of the difficult differential diagnosis with mild cognitive impairment (MCI). It is known that performance on cognitive tests is strongly influenced by education but few studies have been conducted involving low-educated populations.

Objective

To evaluate the performance of elders with low education and no dementia on Addenbrooke's Cognitive Examination-Revised (ACE-R) test and its cognitive domains, and compare patients with Current Major Depressive Episode (CMDE) against those without depressive symptoms.

Methods

A retrospective, cross-sectional analytical study was conducted based on medical files of patients treated at the Cerebral Aging Clinic of the Hospital São Lucas of the PUCRS. The study included 116 individuals with low education (< 8 years of education) aged between 60 and 84 (69.6 ± 6.4) years, with MCDE (N = 41) and controls (N = 75).

Results

No significant difference was observed between control and MCDE groups in median scores on the ACE-R, Mini-Mental State Examination, and the five cognitive domains. There was also no difference between the groups on separate analyses of results on the clock drawing test, the categorical verbal and phonological fluency test, and the naming test.

Conclusion

The results of this study showed that depressive symptoms did not influence scores on the ACE-R tests conducted in elders with low education.

Age Differences and Educational Attainment Across the Life Span on Three Generations of Wechsler Adult Scales

Patterns of maintenance of ability across the life span have been documented on tests of knowledge ( Gc), as have patterns of steady decline on measures of reasoning ( Gf/Gv), working memory ( Gsm), and speed ( Gs). Whether these patterns occur at the same rate for adults from different educational backgrounds has been debated. In addition, age-related research is needed to study global IQs, especially in view of the increased reliance on IQ in capital punishment court cases. In this study, large representative samples of adults tested during the standardizations of three versions of the Wechsler Adult Intelligence Scale (WAIS) served as subjects: WAIS-R ( N = 1,480, ages 20-74), WAIS-III ( N = 2,093, ages 20-90), and WAIS-IV ( N = 1,800, ages 20-90). Based on regression analysis, patterns of aging on Full Scale IQ (FSIQ) and the four abilities (a) were essentially the same for males versus females and (b) characterized all levels of education across three generations of Wechsler’s adult scales.

Predictors of Retest Effects in a Longitudinal Study of Cognitive Aging in a Diverse Community-Based Sample

Better performance due to repeated testing can bias long-term trajectories of cognitive aging and correlates of change. We examined whether retest effects differ as a function of individual differences pertinent to cognitive aging: race/ethnicity, age, sex, language, years of education, literacy, and dementia risk factors including apolipoprotein E ε4 status, baseline cognitive performance, and cardiovascular risk. We used data from the Washington Heights-Inwood Columbia Aging Project, a community-based cohort of older adults (n=4073). We modeled cognitive change and retest effects in summary factors for general cognitive performance, memory, executive functioning, and language using multilevel models. Retest effects were parameterized in two ways, as improvement between the first and subsequent testings, and as the square root of the number of prior testings. We evaluated whether the retest effect differed by individual characteristics. The mean retest effect for general cognitive performance was 0.60 standard deviations (95% confidence interval [0.46, 0.74]), and was similar for memory, executive functioning, and language. Retest effects were greater for participants in the lowest quartile of cognitive performance (many of whom met criteria for dementia based on a study algorithm), consistent with regression to the mean. Retest did not differ by other characteristics. Retest effects are large in this community-based sample, but do not vary by demographic or dementia-related characteristics. Differential retest effects may not limit the generalizability of inferences across different groups in longitudinal research.

Alzheimer's disease and the elderly in Israel: are we paying enough attention to the topic in the Arab population?

With the continuing rise in the elderly population, Alzheimer’s disease (AD) and dementia represent an increasing public health concern worldwide. In recent years, research has focused on the relationship between AD and ethnicity. Israel, a multiethnic society, provides a natural laboratory for research on ethnicity and health. The largest ethnic group is that of Israeli Jews, followed by Arab citizens, mostly Arab Muslims, with smaller numbers of Arab Christians in addition to Druze, Circassians, and others. The aim of this review is to clarify ethnic differences in prevalence and risk factors for Alzheimer’s disease. We review available literature on ethnic differences in epidemiologic and risk factors for Alzheimer’s disease, including genetic differences as well as disparities in health access and quality of health services. We will conclude with research and policy implications.

Incidence of and risk factors for Alzheimer's disease and mild cognitive impairment in Korean elderly

BACKGROUND/AIMS

Knowledge of incidence rates and risk factors is essential for the development of strategies to treat patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI).

METHODS

A subpopulation of the Nationwide Survey on Dementia Epidemiology (460 Korean subjects aged ≥65 years from 2 rural and 2 urban districts) was followed up for 3.5 years. The age-specific incidence was estimated and risk factors were identified.

RESULTS

The age-standardized incidence of AD and MCI was 7.9 and 28.1 cases per 1,000 person-years, respectively. MCI was associated with a 6-fold increased risk of AD. Depression was a risk factor for AD with MCI. Age, lack of formal education, illiteracy, rural residence, and marital status were associated with the risk of AD.

CONCLUSION

Strategies to control modifiable risk factors should be implemented to decrease the incidence of AD.

The Predictive Impact of Biological and Sociocultural Factors on Executive Processing: The Role of Age, Education, and Frequency of Reading and Writing Habits

Although the impact of education and age on executive functions (EF) has been widely studied, the influence of daily cognitive stimulation on EF has not been sufficiently investigated. Therefore, the aim of the present study was to evaluate whether the age, education, and frequency of reading and writing habits (FRWH) of healthy adults could predict their performance on measures of inhibition and cognitive flexibility. Inhibition speed, inhibitory control, and set shifting were assessed using speed, accuracy, and discrepancy scores on the Trail-Making Test (TMT) and Hayling Test. Demographic characteristics and the FRWH were assessed using specialized questionnaires. Regression analyses showed that age and the FRWH predicted speed and accuracy on the TMT. The FRWH predicted both speed and accuracy on the Hayling Test, for which speed and accuracy scores were also partly explained by age and education, respectively. Surprisingly, only the FRWH was associated with Hayling Test discrepancy scores, considered one of the purest EF measures. This highlights the importance of regular cognitive stimulation over the number of years of formal education on EF tasks. Further studies are required to investigate the role of the FRWH so as to better comprehend its relationship with EF and general cognition.

RBANS Norms based on the Relationship of Age, Gender, Education, and WRAT-3 Reading to Performance within an Older African American Sample

OBJECTIVE

Due to factors including differences in educational opportunity, African Americans and Caucasians frequently differ on cognitive tests creating diagnostic error risks. Such differences have been found on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and preliminary norms based on a small sample of African Americans have been generated. In a larger sample of community-dwelling older African Americans, we explored sources of variance including age, gender, common medical conditions, years of education, and reading level to generate norms stratified on the most relevant bases.

METHOD

Three hundred and fifty-five African Americans aged 55+ and living independently completed the RBANS and health, education, and psychosocial interviews.

RESULTS

Hypertension and type 2 diabetes were unrelated to overall RBANS performance once age and education were accounted for. Age, education, and WRAT-3 Reading score (a proxy for scholastic attainment) were independent predictors of RBANS performance. Females performed better on List Learning, Story Memory, Fluency, Coding, List Recall, and List Recognition; males were superior on Line Orientation and Picture Naming.

CONCLUSIONS

In addition to generating norms stratified by age, we provide descriptive statistics grouped by age and education, and by age and WRAT-3 Reading grade level, to provide clinicians with the opportunity to tailor their interpretation of scores based upon perceived best fit for their patient. Regression formulas are provided to address gender differences. To complement the standard index norms, we provide norms for alternative indexes representing additional an factor structure of cognitive domains.

Examining the association between late-life depressive symptoms, cognitive function, and brain volumes in the context of cognitive reserve

OBJECTIVE

The present study aimed to investigate whether cognitive reserve moderated the association between depressive symptoms and cognition, as well as brain volumes in a sample of older adults.

METHODS

Non-demented participants (n = 3484) were selected from the Washington Heights/Hamilton Heights Inwood Columbia Aging Project (Northern Manhattan). A subsample of these participants without dementia (n = 703), who had brain imaging data, was also selected for a separate analysis. Depressive symptomatology was assessed with the 10-item Center for Epidemiologic Studies Depression Scale. Reading level and years of education were used as measures of cognitive reserve. Four distinct cognitive composite scores were calculated: executive function, memory, visual-spatial, and language.

RESULTS

Multiple regression analysis revealed interaction effects between both measures of cognitive reserve and depressive symptoms on all the cognitive outcome measures except for visual-spatial ability. Those with greater reserve showed greater cognitive decrements than those with lower levels of reserve as depressive symptoms increased. A borderline interaction effect was revealed between reading level and depressive symptoms on total brain volumes. Those with lower reading scores showed greater volume loss as depressive symptoms increased than those with higher reading scores.

CONCLUSIONS

Our findings indicate that the association between late-life depressive symptoms and core aspects of cognition varies depending on one's level of cognitive reserve. Those that had greater levels of education and/or reading ability showed a greater decrease in memory, executive, and language performances as depressive symptoms increased than those with lower years of education and reading ability.

Cognitive reserve and cognitive function in healthy older people: a meta-analysis

The associations between proxy measures of cognitive reserve (CR) and cognition vary across studies and cognitive domains. This meta-analysis aimed to assess the relationship between CR and cognition in multiple domains (memory, executive function, visuospatial ability, and language). CR was considered in terms of three key proxy measures - educational level, occupational status, and engagement in cognitively stimulating activities - individually and in combination. One-hundred and thirty-five studies representing 128,328 participants were included. Of these, 109 used a measure of education, 19 used a measure of occupation, 31 used a measure of participation in cognitively stimulating activities, and 6 used a combination of these. All three proxy measures had a modest positive association with cognition; occupational status and cognitive activities showed the most variation across cognitive domains. This supports the view that the commonly used proxy measures of CR share an underlying process but that each additionally provides a unique contribution to CR.

Relationship of medial temporal lobe atrophy, APOE genotype, and cognitive reserve in preclinical Alzheimer's disease

This study evaluated the utility of baseline and longitudinal magnetic resonance imaging (MRI) measures of medial temporal lobe brain regions collected when participants were cognitively normal and largely in middle age (mean age 57 years) to predict the time to onset of clinical symptoms associated with mild cognitive impairment (MCI). Furthermore, we examined whether the relationship between MRI measures and clinical symptom onset was modified by apolipoprotein E (ApoE) genotype and level of cognitive reserve (CR). MRI scans and measures of CR were obtained at baseline from 245 participants who had been followed for up to 18 years (mean follow-up 11 years). A composite score based on reading, vocabulary, and years of education was used as an index of CR. Cox regression models showed that lower baseline volume of the right hippocampus and smaller baseline thickness of the right entorhinal cortex predicted the time to symptom onset independently of CR and ApoE-ɛ4 genotype, which also predicted the onset of symptoms. The atrophy rates of bilateral entorhinal cortex and amygdala volumes were also associated with time to symptom onset, independent of CR, ApoE genotype, and baseline volume. Only one measure, the left entorhinal cortex baseline volume, interacted with CR, such that smaller volumes predicted symptom onset only in individuals with lower CR. These results suggest that MRI measures of medial temporal atrophy, ApoE-ɛ4 genotype, and the protective effects of higher CR all predict the time to onset of symptoms associated with MCI in a largely independent, additive manner during the preclinical phase of Alzheimer's disease.

Independent effects of HIV infection and cocaine dependence on neurocognitive impairment in a community sample living in the southern United States

BACKGROUND

Prior studies have established that methamphetamine and HIV can have additive deleterious effects on neurocognitive functioning, but there has been relatively little research on other stimulants like cocaine. This study investigated the effects of cocaine and HIV on neurocognitive impairment in a large, well-characterized sample.

METHODS

The sample included 193 adults across four groups: HIV-positive cocaine users (n = 48), HIV-negative cocaine users (n = 53), HIV-positive non-drug users (n = 60), and HIV-negative non-drug users (n = 32). Cocaine users met criteria for lifetime dependence and had past-month cocaine use. A comprehensive battery assessed substance abuse and neurocognitive functioning.

RESULTS

Participants were mostly male (66%) and African-American (85%), with a mean age of 46.09 years. The rate of global impairment was 33%, with no significant main effects across groups on likelihood of impairment. There were main effects for cocaine on processing speed and executive functioning, with cocaine users having greater impairment (F = 9.33 and F = 4.22, respectively), and for HIV on attention, with HIV-infected persons having greater impairment (F = 5.55). There was an interaction effect for executive functioning, with the three patient groups having greater impairment than controls (F = 5.05). Nonparametric analyses revealed significant additive impairment in the presence of both HIV and cocaine for processing speed.

CONCLUSIONS

While cocaine does not appear to increase vulnerability to global HIV-associated neurocognitive impairment, it does have independent adverse effects on executive functioning and processing speed. Given prior evidence that domain-specific deficits predict real-world impairments, our results may help explain the poorer behavioral and functional outcomes observed in HIV-infected cocaine users.

Fund of Information is More Strongly Associated with Neuropsychological Functioning Than Education in Older Spanish Adults

Educational influence on cognitive performance has been extensively agreed in Neuropsychology. Nonetheless, recent studies highlighted the need of better measurements to assess benefit from the schooling experience in order to further understand schooling influence on cognition. The WAIS-III Information subtest is proposed here to measure this influence at old age. Ninety-five older adults were divided according to their educational attainment and their Information subtest score, and completed extensive neuropsychological assessment. Performance on the Information subtest had a significant effect on all same cognitive functions as educational attainment, but also on additional domains. Moreover, cognitive performance on several tasks can be classified in three levels as a function of Information score. The WAIS-III Information subtest could be of special interest as a measurement of the benefit from educational experience not only to study cognition in Spanish older populations but also heterogeneous samples in terms of educational experiences and environments.

Education mitigates age-related decline in N-Acetylaspartate levels

BACKGROUND

Greater educational attainment is associated with better neurocognitive health in older adults and is thought to reflect a measure of cognitive reserve. In vivo neuroimaging tools have begun to identify the brain systems and networks potentially responsible for reserve.

METHODS

We examined the relationship between education, a commonly used proxy for cognitive reserve, and N-acetylaspartate (NAA) in neurologically healthy older adults (N=135; mean age=66 years). Using single voxel MR spectroscopy, we predicted that higher levels of education would moderate an age-related decline in NAA in the frontal cortex.

RESULTS

After controlling for the variance associated with cardiorespiratory fitness, sex, annual income, and creatine levels, there were no significant main effects of education (B=0.016, P=0.787) or age (B=-0.058, P=0.204) on NAA levels. However, consistent with our predictions, there was a significant education X age interaction such that more years of education offset an age-related decline in NAA (B=0.025, P=0.031). When examining working memory via the backwards digit span task, longer span length was associated with greater education (P<0.01) and showed a trend with greater NAA concentrations (P<0.06); however, there was no age X education interaction on digit span performance nor a significant moderated mediation effect between age, education, and NAA on digit span performance.

CONCLUSIONS

Taken together, these results suggest that higher levels of education may attenuate an age-related reduction in neuronal viability in the frontal cortex.

APOE and mild cognitive impairment: the Framingham Heart Study

BACKGROUND

The risk apolipoprotein E-4 (APOE4) poses for mild cognitive impairment (MCI) may vary based on the neuropsychological definition of MCI.

SETTING

A community-based cohort study.

METHODS

Using two psychometric neuropsychological impairment definitions, we examined APOE4 and prevalent MCI among older adults or pre-MCI among middle-aged adults. Neuropsychological, clinical and genetic data were collected on 2,239 Framingham Offspring Cohort participants free from clinical stroke or dementia (62±9 years; 54% women). Prevalent amnestic MCI was defined from neuropsychological performances≥1.5 SD below the mean based on (i) age and education or (ii) age and Wide Range Achievement Test-3 Reading (WRAT-3 Reading) performance adjustment.

RESULTS

In the entire sample, multivariable-adjusted logistic regressions found that APOE4 was associated with amnestic MCI when using the age and WRAT Reading definition (odds ratio [OR]=1.7, P=0.002) but not the age and education definition (OR=1.0, P=0.90). Results were modified by age, such that APOE4 was associated with amnestic MCI in participants≥65 years using both the age and WRAT Reading definition (OR=2.4, P<0.001) and the age and education definition (OR=1.7, P=0.04).

CONCLUSION

APOE4 risk for prevalent amnestic MCI varies depending on the definition of objective neuropsychological impairment for MCI. Our findings support existing literature emphasising the need to refine MCI neuropsychological profiling methods.

Life experience and demographic influences on cognitive function in older adults

OBJECTIVE

We examined the influence of a broad spectrum of life experiences on longitudinal cognitive trajectories in a demographically diverse sample of older adults.

METHOD

Participants were 333 educationally, ethnically, and cognitively diverse older adults enrolled in a longitudinal aging study. Mixed-effects regression was used to measure baseline status in episodic memory, executive functioning, and semantic memory and change in a global cognition factor defined by change in these 3 domain-specific measures. We examined effects of life experience variables (literacy, childhood socioeconomic status, morphometric measures of physical development, life course physical and recreational activity) on longitudinal cognitive trajectories, covarying for age, apolipoprotein E (APOE) genotype and demographics (education, ethnicity, language).

RESULTS

Non-Latino Whites had higher baseline cognition, but life experience variables attenuated ethnic differences in cognitive scores. Age, literacy, childhood socioeconomic status, and physical activity significantly influenced baseline cognition. Age, APOE ε4, and decline in intellectually and socially stimulating recreational activity from mid to late life were independently associated with increased late life cognitive decline. Higher literacy and late life recreational activity were associated with less decline. Literacy had similar effects for English and Spanish readers/speakers. Bilingual English and Spanish speakers did not differ from English Speakers in cognitive performance.

CONCLUSIONS

Life experience variables, especially literacy level, were strongly related to baseline cognition and substantially attenuated effects of race/ethnicity and education. Cognitive change was best explained by age, APOE ε4, literacy, and current recreational activities. Literacy had robust associations with baseline cognition and cognitive change in both English and Spanish speakers.

Deconstructing racial differences: the effects of quality of education and cerebrovascular risk factors

OBJECTIVES

To evaluate the effects of vascular conditions and education quality on cognition over time in White and African American (AA) older adults.

METHOD

We investigated cross-sectional and longitudinal racial differences in executive functioning (EF) and memory composites among Whites (n = 461) and AAs (n = 118) enrolled in a cohort study. We examined whether cerebrovascular risk factors and Shipley Vocabulary scores (a proxy for education quality) accounted for racial differences.

RESULTS

On average, AAs had lower quality of education and more cerebrovascular risk factors including hypertension, diabetes, and obesity. AAs had lower mean EF and memory at baseline, but there were no group differences in rates of decline. Cross-sectional racial differences in EF and memory persisted after controlling for vascular disease, but disappeared when controlling for Shipley Vocabulary.

DISCUSSION

Quality of education appears to be more important than cerebrovascular risk factors in explaining cross-sectional differences in memory and EF performance between White and AA older adults. Further investigation is needed regarding the relative contribution of education quality and cerebrovascular risk factors to cognitive decline among ethnically/racially diverse older adults.

Can individual conditions during childhood mediate or moderate the long-term cognitive effects of poor economic environments at birth?

Recent analyses revealed that the business cycle at the time of birth influences cognitive functioning at older ages, and that those individuals born during economic boom periods on average display better cognitive functioning later in life. The current study examines the impact of childhood conditions on late-life cognitive functioning and investigates whether they mediate or moderate the effects of the business cycle at the time of birth. The underlying purpose is to find potential starting points for societal interventions that may counterbalance the negative long-term outcomes of adverse living conditions early in life. We use data from 7935 respondents at ages 60+ in eleven European countries from the first three waves of the Survey of Health, Ageing and Retirement in Europe (SHARE). The survey data was collected in 2004, 2006/07, and 2008/09. Country fixed-effects models are used to examine the impact of macro-economic deviations in the year of birth and the indicators of childhood circumstances on late-life cognitive functioning. This study shows that the effects of boom and recession periods at birth are not simply mediated or moderated by living conditions during childhood. Conditions at birth have biological long-run effects on late-life cognitive functioning. Individuals born during boom periods display signs of having better cognitive functioning later in life, whereas recessions negatively influence cognition. Furthermore, a series of childhood conditions in and of themselves influence late-life cognition. Good childhood cognition, high education as well as a high social status, favourable living arrangements, and good health have a positive impact. Policy interventions should aim at a better access to school or measures to improve the economic and social situations of disadvantaged households.

Older adults with limited literacy are at increased risk for likely dementia

BACKGROUND

Low literacy is common among the elderly and possibly more reflective of educational attainment than years of school completed. We examined the association between literacy and risk of likely dementia in older adults.

METHODS

Participants were 2,458 black and white elders (aged 71-82) from the Health, Aging and Body Composition study, who completed the Rapid Estimate of Adult Literacy in Medicine and were followed for 8 years. Participants were free of dementia at baseline; incidence of likely dementia was defined by hospital records, prescription for dementia medication, or decline in Modified Mini-Mental State Examination score. We conducted Cox proportional hazard models to evaluate the association between literacy and incidence of likely dementia. Demographics, education, income, comorbidities, lifestyle variables, and apolipoprotein E (APOE) ε4 status were included in adjusted analyses.

RESULTS

Twenty-three percent of participants had limited literacy (<9th-grade level). Limited literacy, as opposed to adequate literacy (≥9th-grade level), was associated with greater incidence of likely dementia (25.5% vs17.0%; unadjusted hazard ratio [HR] = 1.75, 95% confidence interval 1.44-2.13); this association remained significant after adjustment. There was a trend for an interaction between literacy and APOE ε4 status (p = .07); the association between limited literacy and greater incidence of likely dementia was strong among ε4 noncarriers (unadjusted HR = 1.85) but nonsignificant among ε4 carriers (unadjusted HR = 1.25).

CONCLUSIONS

Limited literacy is an important risk factor for likely dementia, especially among APOE ε4-negative older adults, and may prove fruitful to target in interventions aimed at reducing dementia risk.

The association between educational level and dementia in rural Tanzania

The majority of people with dementia worldwide live in developing countries. Studies from the developed world have reported an association between lower educational attainment and dementia, but there are few data from the developing world where literacy and educational levels are frequently much lower. In this study we assessed the association between education and dementia prevalence in a rural Tanzanian setting.

Methods

In phase I, 1198 individuals aged 70 and over were assessed using the Community Screening Instrument for Dementia (CSI-D). In phase Ii a stratified sample of those seen in phase I were fully assessed and a clinical diagnosis based on DSM-IV criteria was made where appropriate. Information regarding literacy, highest attained educational level and occupation were also collected.

Results

The median subject cognitive score on the CSI-D was 25.7 (IQR 22.7 to 28.0) for females and 27.7 (IQR 25.7 to 29.4) for males. This difference was significant (U=117770.0, z= -9.880, p<0.001). In both males and females a lower CSI-D subject cognitive score was significantly associated with having had no formal education (U=34866.5, z= -6.688, p<0.001, for females; U=20757.0, z= -6.278, p<0.001, for males). After adjusting for the effect of age, having no formal education was significantly associated with greater odds of having 'probable dementia' by CSI-D, as was illiteracy. Amongst those interviewed in phase II, there was no significant difference in literacy or education between those with diagnosed DSM-IV dementia and those without.

Conclusion

In this rural Tanzanian population, we found a significant association between low levels of education and dementia by CSI-D. This relationship was not significant in cases meeting DSM-IV criteria for dementia.

Association of vascular risk factors with cognition in a multiethnic sample

OBJECTIVES

To examine the relationship between cardiovascular risk factors (CVRFs) and cognitive performance in a multiethnic sample of older adults.

METHOD

We used longitudinal data from the Washington Heights-Inwood Columbia Aging Project. A composite score including smoking, stroke, heart disease, diabetes, hypertension, and central obesity represented CVRFs. Multiple group parallel process multivariate random effects regression models were used to model cognitive functioning and examine the contribution of CVRFs to baseline performance and change in general cognitive processing, memory, and executive functioning.

RESULTS

Presence of each CVRF was associated with a 0.1 SD lower score in general cognitive processing, memory, and executive functioning in black and Hispanic participants relative to whites. Baseline CVRFs were associated with poorer baseline cognitive performances among black women and Hispanic men. CVRF increase was related to baseline cognitive performance only among Hispanics. CVRFs were not related to cognitive decline. After adjustment for medications, CVRFs were not associated with cognition in Hispanic participants.

DISCUSSION

CVRFs are associated with poorer cognitive functioning, but not cognitive decline, among minority older adults. These relationships vary by gender and medication use. Consideration of unique racial, ethnic, and cultural factors is needed when examining relationships between CVRFs and cognition.

Amyloid burden, neuronal function, and cognitive decline in middle-aged adults at risk for Alzheimer's disease

The relative influence of amyloid burden, neuronal structure and function, and prior cognitive performance on prospective memory decline among asymptomatic late middle-aged individuals at risk for Alzheimer's disease (AD) is currently unknown. We investigated this using longitudinal cognitive data from 122 middle-aged adults (21 "Decliners" and 101 "Stables") enrolled in the Wisconsin Registry for Alzheimer's Prevention who underwent multimodality neuroimaging [11C-Pittsburgh Compound B (PiB), 18F-fluorodeoxyglucose (FDG), and structural/functional magnetic resonance imaging (fMRI)] 5.7 ± 1.4 years (range = 2.9-8.9) after their baseline cognitive assessment. Covariate-adjusted regression analyses revealed that the only imaging measure that significantly distinguished Decliners from Stables (p = .027) was a Neuronal Function composite derived from FDG and fMRI. In contrast, several cognitive measures, especially those that tap episodic memory, significantly distinguished the groups (p's<.05). Complementary receiver operating characteristic curve analyses identified the Brief Visuospatial Memory Test-Revised (BVMT-R) Total (.82 ± .05, p < .001), the BVMT-R Delayed Recall (.73 ± .06, p = .001), and the Reading subtest from the Wide-Range Achievement Test-III (.72 ± .06, p = .002) as the top three measures that best discriminated the groups. These findings suggest that early memory test performance might serve a more clinically pivotal role in forecasting future cognitive course than is currently presumed.

Changes in memory before and after stroke differ by age and sex, but not by race

BACKGROUND

Post-stroke memory impairment is more common among older adults, women and blacks. It is unclear whether post-stroke differences reflect differential effects of stroke per se or differences in prestroke functioning. We compare memory trajectories before and after stroke by age, sex and race.

METHODS

Health and Retirement Study participants aged ≥50 years (n = 17,341), with no stroke history at baseline, were interviewed biennially up to 10 years for first self- or proxy-reported stroke (n = 1,574). Segmented linear regression models were used to compare annual rates of memory change before and after stroke among 1,169 stroke survivors, 405 stroke decedents and 15,767 stroke-free participants. Effect modification was evaluated with analyses stratified by baseline age (≤70 vs. >70), sex and race (white vs. nonwhite), and using interaction terms between age/sex/race indicators and annual memory change.

RESULTS

Older (>70 years) adults experienced a faster memory decline before stroke (-0.19 vs. -0.10 points/year for survivors, -0.24 vs. -0.13 points/year for decedents, p < 0.001 for both interactions), and among stroke survivors, larger memory decrements (-0.64 vs. -0.26 points, p < 0.001) at stroke and faster memory decline (-0.15 vs. -0.07 points/year, p = 0.003) after stroke onset, compared to younger adults. Female stroke survivors experienced a faster prestroke memory decline than male stroke survivors (-0.14 vs. -0.10 points/year, p < 0.001). However, no sex differences were seen for other contrasts. Although whites had higher post-stroke memory scores than nonwhites, race was not associated with rate of memory decline during any period of time; i.e. race did not significantly modify the rate of decline before or after stroke or the immediate effect of stroke on memory.

CONCLUSIONS

Older age predicted worse memory change before, at and after stroke onset. Sex and race differences in post-stroke memory outcomes might be attributable to prestroke disparities, which may be unrelated to cerebrovascular disease.

Cognitive reserve moderates relation between global cognition and functional status in older adults

The ability to perform instrumental activities of daily living (IADLs) is necessary for independent living. Research suggests that community-dwelling older adults are at risk for experiencing subtle decrements in the performance of IADLs. Neuropsychological tests have been used to account for differences in IADL status. Studies of the relationship between cognitive ability and functional status have produced variable results, however, and cognitive ability appears to be only a moderate predictor. Several studies of normal aging have revealed cognitive and functional benefits of higher cognitive reserve (CR) in healthy, nondemented older adults. The purposes of the present study were to: (a) examine the relationship between global cognitive ability and IADL performance among 53 community-dwelling older adults, and (b) determine whether formal education, as a proxy of CR, significantly moderates this relationship. Consistent with previous findings, global cognitive ability accounted for a considerable portion of variance in IADL performance [ΔR(2) = .54; ΔF(2, 53) = 67.96; p < .001]. Additionally, CR modestly but significantly attenuated this relationship [ΔR(2) = .044; ΔF(4, 53) = 5.98; p = .018; total R(2) = .65]. This finding suggests that community-dwelling older adults with lower levels of formal education may be at greater risk for functional decrements associated with age-related cognitive decline.

The S-TOFHLA as a measure of functional literacy in patients with mild Alzheimer's disease or mild cognitive impairment

In developing countries, education levels vary dramatically, and the number of years of schooling does not always correlate with the true level of educational competency. This study was designed to verify the accuracy of the Short-Test of Functional Health Literacy in Adults (S-TOFHLA) in individuals with mild cognitive impairment (MCI) and mild Alzheimer's disease (AD), when compared with healthy controls (HCs), in order to assess its utility as a measure of functional literacy. One hundred forty-eight subjects were divided into three groups: HC (n = 61), MCI patients (n = 42), and AD patients (n = 45). The S-TOFHLA does not seem to be suitable as an instrument to measure functional literacy for patients with advanced cognitive impairment, but proved to be appropriate in both the HC group and MCI patients in numeracy and prove to be useful as an adjuvant to estimate IQ, reading ability, and premorbid IQ, as an indicator of cognitive reserve.

Modelling longitudinal changes in older adults' memory for spoken discourse: findings from the ACTIVE cohort

Episodic memory shows substantial declines with advancing age, but research on longitudinal trajectories of spoken discourse memory (SDM) in older adulthood is limited. Using parallel process latent growth curve models, we examined 10 years of longitudinal data from the no-contact control group (N = 698) of the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) randomised controlled trial in order to test (1) the degree to which SDM declines with advancing age, (2) the predictors of these age-related declines and (3) the within-person relationship between longitudinal changes in SDM and longitudinal changes in fluid reasoning and verbal ability over 10 years, independent of age. Individuals who were younger, were White, had more years of formal education, were male and had better global cognitive function and episodic memory performance at baseline demonstrated greater levels of SDM on average. However, only age at baseline uniquely predicted longitudinal changes in SDM, such that declines accelerated with greater age. Independent of age, within-person decline in reasoning ability over the 10-year study period was substantially correlated with decline in SDM (r = .87). An analogous association with SDM did not hold for verbal ability. The findings suggest that longitudinal declines in fluid cognition are associated with reduced spoken language comprehension. Unlike findings from memory for written prose, preserved verbal ability may not protect against developmental declines in memory for speech.

The impact of mild traumatic brain injury on cognitive functioning following co-occurring spinal cord injury

Meta-analytic studies have shown that mild traumatic brain injury (MTBI) has relatively negligible effects on cognitive functioning at 90 or more days post-injury. Few studies have prospectively examined the effects of MTBI in acute physical trauma populations. This prospective, cohort study compared the cognitive performance of persons who sustained a spinal cord injury (SCI) and a co-occurring MTBI (N = 53) to persons who sustained an SCI alone (N = 64) between 26 and 76 days (mean = 46) post-injury. The presence of MTBI was determined based on acute medical record review using a standardized algorithm. Primary outcome measures were seven neuropsychological tests that evaluated visual, verbal, and working memory, perceptual reasoning, and processing speed that controlled for potential upper extremity impairment. Persons who sustained SCI with or without MTBI had lower than expected performance across all neuropsychological tests, on average about 1 SD below the mean. Analysis of covariance indicated that persons with MTBI did not evidence greater impairment on any neuropsychological test. The aggregated effect size (Cohen's d) was -0.16. The strongest predictors of neuropsychological test scores were education, race, history of learning problems, and days from injury to rehabilitation admission. MTBI did not predict performance on any neuropsychological test. These findings are consistent with other controlled studies that indicate a single MTBI has negligible long-term impacts on cognition.

Quality of education and memory test performance in older men: the New York University Paragraph Recall Test normative data

OBJECTIVES

Memory evaluation is a key component in the accurate diagnosis of cognitive disorders.One memory procedure that has shown promise in discriminating disease-related cognitive decline from normal cognitive aging is the New York University Paragraph Recall Test; however, the effects of education have been unexamined as they pertain to one's literacy level. The current study provides normative data stratified by estimated quality of education as indexed by irregular word reading skill.

METHOD

Conventional norms were derived from a sample (N = 385) of cognitively intact elderly men who were initially recruited for participation in the PREADViSE clinical trial. A series of multiple linear regression models were constructed to assess the influence of demographic variables on mean NYU Paragraph Immediate and Delayed Recall scores.

RESULTS

Test version, assessment site, and estimated quality of education were significant predictors of performance on the NYU Paragraph Recall Test. Findings indicate that estimated quality of education is a better predictor of memory performance than ethnicity and years of total education. Normative data stratified according to estimated quality of education are presented.

DISCUSSION

The current study provides evidence and support for normativedata stratified by quality of education as opposed to years of education.

Specific early vulnerability of high-order executive function to focal brain lesions and long-term impact on educational persistence: Sparing of incidental episodic memory

OBJECTIVE

We investigated mental functions expected to remain impaired or not ain adulthood following childhood-onset brain lesions.

METHODS

Thirty unilaterally lesioned young adults were tested a decade after lesion onset with an effort-demanding complex executive function (EF) task as well as a task of incidental declarative retrospective episodic recognition memory (IRM). Thirty neurotypical participants were also tested.

RESULTS

The EF task was significantly impaired in the lesion group and significantly more so than the IRM task. Regarding the lesioned cases, performance on EF, but not IRM, was significantly positively correlated with long-term educational persistence (EP). Both EF and EP but not IRM were significantly positively correlated with the age of onset of the lesion. Severity of neurological impairment was unrelated to any variable.

CONCLUSION

Mental abilities acquired through early schooling remain impaired into adulthood when early schooling is disturbed, not everyday memory which does not depend on schooling.

Relationship of cognitive reserve and APOE status to the emergence of clinical symptoms in preclinical Alzheimer's disease

The APOE ε4 allele increases the risk of developing Alzheimer's disease, whereas the APOE ε2 allele reduces risk. We examined whether cognitive reserve (CR), as measured by an index consisting of education, reading, and vocabulary, modifies these associations. CR was measured at baseline in 257 cognitively normal individuals (mean age 57.2 years) who have been followed for up to 17 years (mean follow-up = 9.2 years). Cox regression models showed that CR and APOE ε4 independently affected the risk of progressing from normal cognition to onset of clinical symptoms: CR reduced risk by about 50% in both ε4 carriers and non-carriers, while ε4 increased risk by about 150%. In contrast, APOE ε2 interacted with CR, such that CR was more protective in ε2 carriers than non-carriers. This suggests that individuals with an ε2 genotype may disproportionately benefit from lifetime experiences that enhance cognition.

Cognitive function is a risk for health literacy in older adults with diabetes

AIMS

Cognitive impairment is common in older adults with diabetes, yet it is unclear to what extent cognitive function is associated with health literacy. We hypothesized that cognitive function, independent of education, is associated with health literacy.

METHODS

The sample included 537 African American, American Indian, and White men and women 60 years or older. Measures of cognitive function included the Mini-Mental State Examination (MMSE), Verbal Fluency, Brief Attention, and Digit Span Backward tests. Health literacy was assessed using the S-TOFHLA.

RESULTS

Cognitive function was associated with health literacy, independent of education and other important confounders. Every unit increase in the MMSE, Digit Span Backward, Verbal Fluency or Brief Attention was associated with a 20% (p<.001), 34% (p<.001), 5% (p<.01), and 16% (p<.01) increase in the odds of having adequate health literacy, respectively.

CONCLUSIONS

These results suggest that cognitive function is associated with health literacy in older adults with diabetes. Because poor cognitive function may undermine health literacy, efforts to target older adults on improving health literacy should consider cognitive function as a risk factor.

Relationship of cognitive reserve and cerebrospinal fluid biomarkers to the emergence of clinical symptoms in preclinical Alzheimer's disease

The levels of β-amyloid (Aβ) and phosphorylated tau (p-tau), as measured in cerebrospinal fluid, have been associated with the risk of progressing from normal cognition to onset of clinical symptoms during preclinical Alzheimer's disease. We examined whether cognitive reserve (CR) modifies this association. Cerebrospinal fluid was obtained at baseline from 239 participants (mean age, 57.2 years) who had been followed for up to 17 years with clinical and cognitive assessments (mean follow-up, 8 years). A composite score based on the National Adult Reading Test, vocabulary, and years of education at baseline was used as an index of CR. Cox regression models showed that the increased risk of progressing from normal cognition to symptom onset was associated with lower CR, lower baseline Aβ, and higher baseline p-tau. There was no interaction between CR and Aβ, suggesting that the protective effects of higher CR are equivalent across the observed range of amyloid levels. In contrast, both tau and p-tau interacted with CR, indicating that CR was more protective at lower levels of tau and p-tau.

Cognitive reserve components as expressed in traumatic brain injury

Traumatic brain injury (TBI) is the most common cause of brain damage, resulting in long-term disability. The "reserve" construct has been proposed to account for the reported mismatch between brain damage and its clinical expression. Although numerous studies have used various measures thought to reflect this construct, few studies have examined its underlying structure in clinical populations, and no studies have systematically studied this construct in TBI. In the present study, structural equation modeling technique was used to evaluate several models hypothesized to represent cognitive reserve (CR) in TBI. A broad range of data typically reported in the literature as representing CR was collected from 89 individuals who sustained moderate-to-severe TBI. Analyses revealed a best fitting model that consisted of three separate factors representing premorbid intelligence, socioeconomic status and leisure activity, with distinct pattern of associations among the three factors. Findings provide empirical support for the notion of a multi-factorial CR and suggest a coherent framework for further investigation.

Risk factors for mild cognitive impairment among Mexican Americans

BACKGROUND

Although a great deal of literature has focused on risk factors for mild cognitive impairment (MCI), little published work examines risk for MCI among Mexican Americans.

METHODS

Data from 1628 participants (non-Hispanic n = 1002; Mexican American n = 626) were analyzed from two ongoing studies of cognitive aging and Alzheimer's disease, Project FRONTIER (Facing Rural Obstacles to health Now Through Intervention, Education & Research) and TARCC (Texas Alzheimer's Research & Care Consortium).

RESULTS

When looking at the full cohorts (non-Hispanic and Mexican American), age, education, Apolipoprotein E (APOE) ε4 status and gender were consistently related to MCI diagnosis across the two cohorts. However, when split by ethnicity, advancing age was the only significant risk factor for MCI among Mexican Americans across both cohorts.

CONCLUSIONS

The current data suggest that many of the previously established risk factors for MCI among non-Hispanic cohorts may not be predictive of MCI among Mexican Americans and point to the need for additional work aimed at understanding factors related to cognitive aging among this underserved segment of the population.

Effects of education on the progression of early- versus late-stage mild cognitive impairment

BACKGROUND

Highly educated participants with normal cognition show lower incidence of Alzheimer's disease (AD) than poorly educated participants, whereas longitudinal studies involving AD have reported that higher education is associated with more rapid cognitive decline. We aimed to evaluate whether highly educated amnestic mild cognitive impairment (aMCI) participants show more rapid cognitive decline than those with lower levels of education.

METHODS

A total of 249 aMCI patients enrolled from 31 memory clinics using the standard assessment and diagnostic processes were followed with neuropsychological evaluation (duration 17.2 ± 8.8 months). According to baseline performances on memory tests, participants were divided into early-stage aMCI (-1.5 to -1.0 standard deviation (SD)) and late-stage aMCI (below -1.5 SD) groups. Risk of AD conversion and changes in neuropsychological performances according to the level of education were evaluated.

RESULTS

Sixty-two patients converted to AD over a mean follow-up of 1.43 years. The risk of AD conversion was higher in late-stage aMCI than early-stage aMCI. Cox proportional hazard models showed that aMCI participants, and late-stage aMCI participants in particular, with higher levels of education had a higher risk of AD conversion than those with lower levels of education. Late-stage aMCI participants with higher education showed faster cognitive decline in language, memory, and Clinical Dementia Rating Sum of Boxes (CDR-SOB) scores. On the contrary, early-stage aMCI participants with higher education showed slower cognitive decline in MMSE and CDR-SOB scores.

CONCLUSIONS

Our findings suggest that the protective effects of education against cognitive decline remain in early-stage aMCI and disappear in late-stage aMCI.

Language Disorders in Multilingual and Multicultural Populations

We review the characteristics of developmental language disorders (primary language impairment, reading disorders, autism, Down syndrome) and acquired language disorders (aphasia, dementia, traumatic brain injury) among multilingual and multicultural individuals. We highlight the unique assessment and treatment considerations pertinent to this population, including, for example, concerns of language choice and availability of measures and of normative data in multiple languages. A summary of relevant, recent research studies is provided for each of the language disorders selected.

Limited health literacy and decline in executive function in older adults

Limited health literacy is associated with worse executive function, but the association between limited health literacy and decline in executive function has not been established because of a lack of longitudinal studies. The authors aimed to examine this association by studying a prospective cohort in the setting of a randomized controlled trial to promote walking in older adults. Participants were community-dwelling older adults (65 years of age or older) who scored 2 or more on the Mini-Cog, without depression (score of less than 15 on the 9-item Patient Health Questionnaire), and who completed baseline and 12-month evaluations (n = 226). Health literacy was measured using the Short Test of Functional Health Literacy in Adults. Executive function measured at baseline and 12 months using the Trail Making Test (TMT), Controlled Oral Word Association Test, and Category Fluency. The associations between health literacy and 12-month decline in each test of executive function were modeled using multivariate linear regression. Health literacy was found to be limited in 37% of participants. Limited health literacy was associated with reduced performance on all 3 executive function tests. In fully adjusted models, limited health literacy was associated with greater 12-month decline in performance on the TMT than higher health literacy (p = .01). In conclusion, older adults with limited health literacy are at risk for more rapid decline in scores on the TMT, a measure of executive function.

Idea density measured in late life predicts subsequent cognitive trajectories: implications for the measurement of cognitive reserve

OBJECTIVE

The Nun Study showed that lower linguistic ability in young adulthood, measured by idea density (ID), increased the risk of dementia in late life. The present study examined whether ID measured in late life continues to predict the trajectory of cognitive change.

METHOD

ID was measured in 81 older adults who were followed longitudinally for an average of 4.3 years. Changes in global cognition and 4 specific neuropsychological domains (episodic memory, semantic memory, spatial abilities, and executive function) were examined as outcomes. Separate random effects models tested the effect of ID on longitudinal change in outcomes, adjusted for age and education.

RESULTS

Lower ID was associated with greater subsequent decline in global cognition, semantic memory, episodic memory, and spatial abilities. When analysis was restricted to only participants without dementia at the time ID was collected, results were similar.

DISCUSSION

Linguistic ability in young adulthood, as measured by ID, has been previously proposed as an index of neurocognitive development and/or cognitive reserve. The present study provides evidence that even when ID is measured in old age, it continues to be associated with subsequent cognitive decline and as such may continue to provide a marker of cognitive reserve.

Non-native language use and risk of incident dementia in the elderly

Cognitive reserve is invoked to explain the protective effects of education and cognitively-stimulating activities against all-cause dementia and Alzheimer's disease (AD). For non-native English speakers (n-NES), speaking English may be a cognitive activity associated with lower dementia risk. We hypothesized that n-NES have lower risk of incident dementia/AD and that educational level might modify this relationship. Participants took part in the Einstein Aging Study (Bronx, NY), a longitudinal study of aging and dementia. All (n = 1779) spoke fluent English and self-reported birthplace and whether English was their first language. n-NES additionally reported mother tongue, age of English acquisition, and current percentile-use of a non-English language. Nested Cox proportional hazards models progressively adjusted for gender, race, education, and immigrant and marital status estimated hazard ratios (HR) for incident dementia/AD as a function of n-NES status. 390 (22%) participants were n-NES. 126 incident dementia cases occurred during 4174 person-years of follow-up (median 1.44; range 0-16); 101 individuals met criteria for probable/possible AD. There was no statistically-significant association between n-NES status and incident dementia in the fully-adjusted model (HR 1.26; 95% CI 0.76-2.09; p = 0.36). Results were similar for AD. Stratification of education into three groups revealed increased risk of dementia for n-NES with ≥ 16 years of education (HR 3.97; 95% CI 1.62-9.75; p = 0.003). We conclude that n-NES status does not appear to have an independent protective effect against incident dementia/AD, and that n-NES status may contribute to risk of dementia in an education-dependent manner.

Diagnostic accuracy of the MMSE in detecting probable and possible Alzheimer's disease in ethnically diverse highly educated individuals: an analysis of the NACC database

BACKGROUND

To validate and extend the findings of a raised cut score of O'Bryant and colleagues (O'Bryant SE, Humphreys JD, Smith GE, et al. Detecting dementia with the mini-mental state examination in highly educated individuals. Arch Neurol. 2008;65(7):963-967.) for the Mini-Mental State Examination in detecting cognitive dysfunction in a bilingual sample of highly educated ethnically diverse individuals.

METHODS

Archival data were reviewed from participants enrolled in the National Alzheimer's Coordinating Center minimum data set. Data on 7,093 individuals with 16 or more years of education were analyzed, including 2,337 cases with probable and possible Alzheimer's disease, 1,418 mild cognitive impairment patients, and 3,088 nondemented controls. Ethnic composition was characterized as follows: 6,296 Caucasians, 581 African Americans, 4 American Indians or Alaska natives, 2 native Hawaiians or Pacific Islanders, 149 Asians, 43 "Other," and 18 of unknown origin.

RESULTS

Diagnostic accuracy estimates (sensitivity, specificity, and likelihood ratio) of Mini-Mental State Examination cut scores in detecting probable and possible Alzheimer's disease were examined. A standard Mini-Mental State Examination cut score of 24 (≤23) yielded a sensitivity of 0.58 and a specificity of 0.98 in detecting probable and possible Alzheimer's disease across ethnicities. A cut score of 27 (≤26) resulted in an improved balance of sensitivity and specificity (0.79 and 0.90, respectively). In the cognitively impaired group (mild cognitive impairment and probable and possible Alzheimer's disease), the standard cut score yielded a sensitivity of 0.38 and a specificity of 1.00 while raising the cut score to 27 resulted in an improved balance of 0.59 and 0.96 of sensitivity and specificity, respectively.

CONCLUSIONS

These findings cross-validate our previous work and extend them to an ethnically diverse cohort. A higher cut score is needed to maximize diagnostic accuracy of the Mini-Mental State Examination in individuals with college degrees.

Epidemiology of Alzheimer disease

The global prevalence of dementia has been estimated to be as high as 24 million, and is predicted to double every 20 years until at least 2040. As the population worldwide continues to age, the number of individuals at risk will also increase, particularly among the very old. Alzheimer disease is the leading cause of dementia beginning with impaired memory. The neuropathological hallmarks of Alzheimer disease include diffuse and neuritic extracellular amyloid plaques in brain that are frequently surrounded by dystrophic neurites and intraneuronal neurofibrillary tangles. The etiology of Alzheimer disease remains unclear, but it is likely to be the result of both genetic and environmental factors. In this review we discuss the prevalence and incidence rates, the established environmental risk factors, and the protective factors, and briefly review genetic variants predisposing to disease.

Education and dementia in the context of the cognitive reserve hypothesis: a systematic review with meta-analyses and qualitative analyses

Background

Cognitive reserve (CR) or brain reserve capacity explains why individuals with higher IQ, education, or occupational attainment have lower risks of developing dementia, Alzheimer’s disease (AD) or vascular dementia (VaD). The CR hypothesis postulates that CR reduces the prevalence and incidence of AD or VaD. It also hypothesizes that among those who have greater initial cognitive reserve (in contrast to those with less reserve) greater brain pathology occurs before the clinical symptoms of disease becomes manifest. Thus clinical disease onset triggers a faster decline in cognition and function, and increased mortality among those with initial greater cognitive reserve. Disease progression follows distinctly separate pathological and clinical paths. With education as a proxy we use meta-analyses and qualitative analyses to review the evidence for the CR hypothesis.

Methodology/Principal Findings

We searched PubMed, PsycoINFO, EMBASE, HealthStar, and Scopus databases from January 1980 to June 2011 for observational studies with clear criteria for dementia, AD or VaD and education. One hundred and thirty-three articles with a variety of study designs met the inclusion criteria. Prevalence and incidence studies with odds ratios (ORs), relative risks or original data were included in the meta-analyses. Other studies were reviewed qualitatively. The studies covered 437,477 subjects. Prevalence and incidence studies with pooled ORs of 2.61 (95%CI 2.21–3.07) and 1.88 (95%CI 1.51–2.34) respectively, showed low education increased the risk of dementia. Heterogeneity and sensitivity tests confirmed the evidence. Generally, study characteristics had no effect on conclusions. Qualitative analyses also showed the protective effects of higher education on developing dementia and with clinical disease onset hastening a decline in cognition and function, and greater brain pathology.

Conclusion/Significance

This systematic review and meta-analyses covering a wide range of observational studies and diverse settings provides robust support for the CR hypothesis. The CR hypothesis suggests several avenues for dementia prevention.