Biomedical subjects

K E Whitfield

Publications and source records attributed to K E Whitfield.

12 recordsLinked to original sources

PubMed2006

Genetic and environmental influences on body fat and blood pressure in African-American adult twins.

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.

Adult↗

PubMed2000

The effect of race and health-related factors on naming and memory. The MacArthur Studies of Successful Aging.

OBJECTIVES: The purpose of the analyses was to examine the impact of health-related variables on race differences in neuropsychological functioning (Boston Naming Task). METHODS: Using cross-sectional data from the MacArthur Successful Aging Study, the authors examined the relationship of demographic characteristics, health status, health habits, physical functioning, and speed of performance to naming and incidental recall of items from the Boston Naming Task. Participants were 1,175 healthy African American and European American older persons 70 to 79 years old. RESULTS: Regression analyses indicated that although race differences persisted for confrontational naming after controlling for demographic and health factors, there was no effect due to race for incidental recall scores or for savings scores for recall. DISCUSSION: The racial differences found in test performance may reflect differences in cultural appropriateness of the material rather than differences in ability.

Black or African American↗

PubMed1999

Individual differences in aging minorities.

To fully understand the differences present between various ethnic and racial groups, there must be an understanding of the heterogeneity that is represented within a given ethnic/racial group. The purpose of this article is to discuss the importance of an individual differences approach in studying the ethnic diversity of an aging population. Conceptual, methodological, and design issues are discussed with the goal of better understanding the developmental processes of aging minority elderly populations.

Aged↗

PubMed1995

Sex differences in ethanol-related behaviors in genetically defined murine stocks.

Over the past 30 years, there have been a number of important developments in our understanding of the etiology and consequences of excessive drinking among humans. Probably one of the most important findings to date is that there are large individual differences among humans in appetite for alcohol and age of onset of problem drinking. We recognize this finding in at least two different alcoholic types, each with its own estimate of genetic influence. We have also come to realize that there are important differences between men and women, both in etiology of problem drinking and in the consequences of chronic alcohol use. In this chapter, the advantages and limitations of applying genetically defined animal models, primarily, selected lines and inbred strains of mice, are evaluated with examples from the literature.

Alcohol Drinking↗

PubMed1994

Effect of visual complexity in identification of tachistoscopic images.

The present study of gender differences in hemispheric processing involved identification of tachistoscopically presented images of varying complexity. A computerized tachistoscopic program was administered to 24 men and 34 women. Time to identify contour and detailed pictures presented to the left or right cerebral hemisphere was recorded. Mean reaction time for contour pictures was significantly faster than for detailed pictures, and mean reaction time to the right hemisphere was significantly faster than that to the left hemisphere. The mean reaction time for men to identify pictures exposed to the left hemisphere was significantly slower than that for exposure to the right hemisphere for women. The mean reaction time for both men and women to identify contour pictures exposed to the right hemisphere was significantly faster than the mean time to identify detailed pictures presented to the left hemisphere. The interaction of gender, hemisphere, and complexity was also significant in that mean reaction times for men to identify detailed pictures presented to the left hemisphere were slower than the times for women to identify contour pictures presented to the right hemisphere. The results are discussed in relation to theories about hemispheres, gender, and differences in picture features.

Adolescent↗

PubMed1991

An analysis of task difficulty using the visually degraded stimulus task.

This article discusses the utility of the Visually Degraded Stimulus Task developed in 1986 by Vokey, Baker, Hayman, and Jacoby. The program provides 30 line drawings than can be presented in complete form prior to receiving incomplete forms of the same or similar drawings. In the incomplete form, a small percentage of a drawing can be added with each touch of the computer space bar. By this means the percentage of drawing required for identification can be obtained. In this article, difficulty levels of incomplete picture identification are provided for each drawing under conditions of no previous viewing (no prime), previous viewing in an alternate form (conceptual prime), and previous viewing of the same drawings (exact prime). Modifications to the microprocessor computer program are provided to increase its usefulness as a means of testing priming effects in visual memory. Program applications are provided for the study of memory and neuropsychology.

Adolescent↗

PubMedDate not supplied

Age cohort differences in the ability to perform closure on degraded figures.

Young (17-26) and old (60-80) men and women performed a perceptual closure task for degraded line drawings under three conditions of prior picture knowledge (exact, similar, no prior knowledge) and two conditions of perceptual noise (contour or detail drawings) resulting in six levels of task difficulty. Young and old subjects took equal advantage prior knowledge conditions, however, old subjects required a greater percentage of picture and more time to make closure under all conditions when compared to young subjects. To test the perceptual slowing hypothesis, old subject performance was regressed on that of young across three levels of task difficulty. The slope of these regression equations supported the notion of a perceptual slowing hypothesis to explain age cohort differences.

Adolescent↗

PubMedDate not supplied

The use of quantitative genetic methodology to gain insights into the origins of individual differences in later life.

There is great interest in the interindividual variability in aged populations. Knowledge of the etiology of these individual differences may lead to a more comprehensive understanding of aging. The purpose of this article is to discuss the use of quantitative genetic (or behavioral genetic) methodology to identify sources of individual variation in later life. These methods can provide insights into the proportion of environmental and genetic influences on behavior. Some of the basic procedures used in quantitative genetic analyses and their rationales are provided. In addition, the use of structural equation modeling to model genetic and environmental effects is discussed. Lastly, some of the special issues involved in quantitative genetic research on aged populations are discussed.

Aged↗

PubMedDate not supplied

Assessment of intellectual functioning of patients with Parkinson's disease using the Satz-Mogel (1962) short form of the Wechsler Adult Intelligence Scale.

The purpose of the present study was to compare the Satz-Mogel (S-M) short form of the Wechsler Adult Intelligence Scale--Revised (WAIS-R) with the full-scale WAIS-R to establish its utility in the assessment of intellectual functioning in patients with Parkinson's disease (PD). PD patients and elderly control subjects were administered a neuropsychological test battery that included the complete WAIS-R or the S-M. Results indicated that the S-M was a reliable measure of IQ. The PD subjects' Verbal, Performance, and Full-Scale IQ scores were inferior to that of controls, regardless of test form. Adjustments for depression and age did not alter these results. PD patients with more severe disease scored lower on some visual-spatial measures. Verbal decrements among PD patients may relate to problems in verbal fluency, categorical thinking, and impaired retrieval of verbal material. PD patients may experience patterns of subtle cognitive changes that include deterioration of some specific abilities as the disease progresses.

Aged↗

PubMedDate not supplied

Evaluating a measure of everyday problem solving for use in African Americans.

Results from previous research on everyday problem solving involving Caucasians suggests that it may be a useful concept in studying cognitive aging in African Americans. The purpose of this investigation was to examine: (1) the factor structure of an everyday problem solving in a sample of African Americans, (2) the internal consistency of everyday-problem solving in a sample of African Americans, and (3) the relationship of problem solving to demographic factors, physical functioning, and measures of fluid ability. The sample included subjects recruited from Baltimore, MD. The sample consisted of 249 community dwelling African-American adults with a mean age of 67.8 years (SD = 8.47). Variables included the Everyday Problem Solving Test (EPT), gender, age, education, physical functioning, and inductive reasoning. Everyday problem solving as a latent construct was confirmed and the split half reliability was high (.89). As in previous research, inductive reasoning and physical functioning were related to everyday problem solving abilities. We also found that certain domains of the EPT are more influenced by demographic factors than others. Our finding suggest that the Everyday Problems Test is appropriate for use with African American samples.

Adult↗

PubMedDate not supplied

Genetic and environmental influences on forced expiratory volume in midlife: a cross-cultural replication.

Previous research has shown that forced expiratory volume (FEV) is a useful predictor of remaining life in older adults. The present analyses are an attempt to replicate results from a study of Swedish twins which demonstrated substantial heritability of FEV with a sample of middle-aged Russian adult twins. Data were collected from 116 pairs of Russian twins (monozygote = 71, dizygotic = 45, mean age = 40.9 years). Phenotypic correlations between FEV, age, gender, height, and cigarette consumption (in pack years) were all significant, ranging from -.72 to .31. After the effects of age, gender, height, and smoking were partialled out of FEV, quantitative genetic analyses were conducted. Shared environmental effects were significant, accounting for 47% of the variance in FEV. Genetic effects, which accounted for about 28% of the variance, could be dropped from the model without a significant decrease in the fit. These results are discussed in relation to previous research conducted in other countries.

Adult↗

PubMedDate not supplied

Health indices as predictors of cognition among older African Americans: MacArthur studies of successful aging.

Using cross-sectional and longitudinal data from the MacArthur Successful Aging Study, this paper examines associations between cognition and indices of health in 224 elderly African Americans 70 to 79 years of age at initial interview. The results indicated that greater average peak expiratory flow was predictive of better cognitive performance at the first interview. One longitudinal analysis showed that gender was the only significant predictor of change (change as a continuous variable) with women tending to slightly improve their cognitive performance over time. When change was treated as a dichotomous variable (e.g., a decline of 6 or more points), lower levels of average peak expiratory flow and education were predictive of decline, and positive self-ratings of current health and changes in health in the past year were important factors in the improvement of cognitive performance. The results indicate that, in addition to education, health is an important predictor of the status and course of cognitive functioning in older African Americans.

Black or African American↗