One of the single most influential factors on current and future cognitive functioning is educational attainment. We examined the influence of educational desegregation on cognitive performance using Horn's Gf-Gc theory among older African Americans. The data on 197 African Americans included school attendance (desegregated [DS] or segregated [SS]) and the number of years they attended desegregated schools. Using measures of fluid (inductive reasoning and spatial ability) and crystallized (number concept and vocabulary) ability to assess cognition, the results showed that the DS group had significantly higher mean cognitive scores compared to the SS group. After controlling for age, gender, years of education, and years in desegregated schools, however, we found no difference between the DS and SS groups on measures of number concept, inductive reasoning, and general fluid and crystallized abilities but found differences for measures of vocabulary and spatial ability. The results were discussed in relation to differences in schooling and other potential influences over the life course.

In twin research, typically both members of a pair must participate. Survivorship of members of intact pairs compared to surviving members of nonintact twin pairs may reflect differences in psychosocial and health factors, and represent a potential selection bias relative to the general population. The purpose of the present study is to examine health, cognition, and well-being among members of African American intact twin pairs compared to individuals from nonintact twin pairs. Data from the Carolina African American Twin Study of Aging (CAATSA) were used for analyses. Subjects ranged in age from 25 to 89 years of age (mean = 59.78 years, SD = 12.84 years). CAATSA implements a 3-h protocol to collect data on demographics, health, cognition, and well-being. Data from one randomly selected member of each twin pair (N = 78) was compared to data from surviving members of nonintact twin pairs (N = 52). The results indicated significant differences on 11 of the 39 measures (i.e., age, education, forced expiratory volume, mean standing and sitting systolic and diastolic blood pressures, cognitive impairment score, alpha span, digit symbol, and logical memory). In each case, members of intact twin pairs performed better than surviving members of nonintact twin pairs. After controlling demographic variables, only blood pressures differed between the groups. It appears that using only pairs in research on older African American twins may represent a selection bias in estimating origins of individual variability in cognitive functioning and health but not psychological well-being.

This study examined whether measures of health status enhance the prediction of performance on everyday problem solving in adult African Americans. The sample consisted of 209 community-dwelling African American adults with a mean age of 66.82 years (SD=7.95). The following variables were included in the analysis: Everyday Problems Test (EPT), summary index of chronic illnesses (cardiovascular disease, hypertension, arthritis, stroke, and diabetes), self-rated health (current health, health in the past month, health compared with others, health compared with 5 years ago), and demographic information. Using hierarchical regression and follow-up communality analysis, the authors found that the number of chronic illnesses and self-rated health as compared with 5 years prior were significant and unique predictors of performance on the EPT but did not account for all of the demographic-related variance. The results indicate that health indices contribute to the variability in everyday cognition in this understudied population.

Results: In men, additive genetic effects accounted for 77% of the variance in WC, 59% in WHR, and 89% in BMI. In women, additive genetic effects accounted for 76% of the variance in WC, 56% in WHR, and 73% in BMI. The remaining variance in both men and women was attributed to unique environmental effects (WC, 21%; WHR, 36%; BMI, 11% in men and WC, 22%; WHR, 38%; BMI, 27% in women) and age (WC, 2%; WHR, 5% in men and WC, 2%; WHR, 6% in women). When BMI was controlled in the analysis of WC and WHR, it accounted for a portion of the genetic and environmental variance in WHR and over onehalf of the genetic and environmental variance in WC. Discussion: There are both genetic and environmental influences on WC, WHR, and BMI, and independent of BMI, there are genetic and environmental effects on WC and WHR among both genders. The results from this AfricanAmerican twin sample are similar to findings among white twin samples.

The purpose of this study was to examine the relationship between social support, health status, and everyday problem solving in African Americans. The sample included subjects recruited from Baltimore, Maryland. The sample consisted of 249 community-dwelling African American adults, 32% of whom were male, with a sample mean age of 67.8 years (SD = 8.47 years). Variables included: Everyday Problem Solving Test (EPT), social support given and received, physical limitations, counts of chronic illness, smoking, and demographic information. Using stepwise regression, age, education, physical limitations, and social support given were found to be significant predictors of performance on the EPT. Further analysis found support for a partial mediating effect of physical limitations on the relationship between social support and everyday problem solving. The results indicate that there may be differences in the cognitive abilities of those actively involved in social activities.

Objective: African Americans have a particularly high prevalence of excessive body fat and high blood pressure. Genetic and environmental influences may be implicated for both of these risk factors. We investigated the potential for common genetic and environmental influences on body fat (waist circumference (WC), body mass index (BMI)) and blood pressure measures (systolic and diastolic pressure (SBP, DBP)) among African-American male and female subjects. Research methods and procedures: Measurements were taken as part of the Carolina African-American Twin Study of Aging (CAATSA). The CAATSA sample contains 217 same-sex African-American male and female twins with average age of 47 years. This analysis included 39 monozygotic male pairs (MZ), 43 dizygotic male pairs (DZ); 63 MZ female pairs, and 72 DZ female pairs. Maximum likelihood quantitative genetic analyses were used. Results: The total genetic variance for SBP was 22% in male subjects and 40.1% in female subjects. Of this total variance, 3.1% was in common with BMI in male subjects and 6% was in common with BMI in female subjects. After controlling for the effects of BMI, WC had less than 1% of its variance in common with SBP in male and female subjects. For DBP, the total genetic variance was 16.9% in male and 38.7% in female subjects. Of this total variance 6.1% was in common with BMI in male subjects and 3.7% was in common in female subjects. Again, WC had less than 1% of its genetic variance in common with DBP in both male and female subjects. The environmental variance common among these measures was also very small. The remaining variance was primarily accounted for by genetic and environmental effects unique to each measure as well as age. Discussion: Based on the very small common genetic variance for BMI, SBP, and DBP as well as WC and the blood pressure measures, our results suggest that searching for common genes among these measures may be inconclusive.

As the aging population continues to become more diverse, there is growing interest in understanding the similar and unique aspects of aging within and across people of different ethnic groups. The impact of culture on the sources of variation identified in quantitative genetic approaches has not been well discussed in the literature. The purpose of this paper is to review previous research pertinent to the cultural aspects of quantitative genetic approaches and methodologies, and provide conceptual and statistical approaches for advancing the science. To meet this objective, results from previously published studies as well as preliminary data analyses from the Carolina African American Twin Study of Aging will be presented. There are three themes to draw from the issues discussed in this paper: (1) avoiding genetic reductionism, (2) interpreting differential heritabilities, and (3) modeling cultural influences.