The relationship of APOE genotype to cognitive functioning in older African-American and Caucasian community...

To determine whether cognitive decline associated with the apolipoprotein E (APOE) epsilon4 allele is different in older African Americans than it is in Caucasians.

Performance on a brief screen of cognitive functioning was examined at baseline (N = 1,891) and 4 years later (N = 1,389) to determine the extent to which the presence of APOE epsilon4 affected level of and change in performance, and whether this differed as a function of race, age, initial score, and change in score.

Five adjacent counties in the Piedmont area of North Carolina.

In 1986, a stratified random household sample of community residents age 65 and older (n = 4,162; 54% African-American, 45% Caucasian, 1% other race) formed the Duke Established Populations for Epidemiologic Studies of the Elderly. Of those available at the sixth annual wave, 76% were genotyped, with 1,891 providing baseline data on this wave, and the available survivors (n = 1,389) providing longitudinal data 4 years later.

The Short Portable Mental Status Questionnaire (SPMSQ), a brief screen of cognitive functioning, was administered to all subjects on both occasions. We examined score at baseline and cognitive decline (i.e., increase of 2+ errors) at follow-up. Control measures included demographic characteristics, health behaviors, health and functional status, and medication use. APOE status was coded as epsilon4 present versus absent.

APOE epsilon4 was significantly and uniquely related to lower score at baseline and significantly increased the odds of cognitive decline by 59%. There was no statistically significant interaction between APOE epsilon4 and age, race, initial SPMSQ score, or SPMSQ score at follow-up.

APOE epsilon4 is modestly, if significantly, related to poorer cognitive functioning and to decline in cognitive functioning. No differences were found by age or race in this community representative sample.