Apolipoprotein E and intellectual achievement

OBJECTIVES: To determine whether apolipoprotein E (apo E) genotype influences intellectual achievement in cognitively normal individuals. DESIGN: Between 1994 and 1999 we performed apo E testing on 1,000 self-described cognitively normal residents of Maricopa County and detailed neuropsychological testing on a subset of 250. SETTING: Tertiary care academic medical center. PARTICIPANTS: Cognitively normal adults genotyped for apo E. MEASUREMENTS: Measures of intellectual background included years of education and a demographically based estimate of intellectual capacity (demographic intellectual quotient (DIQ)). Measures of intellectual achievement, which included Wechsler Adult Intelligence Scale revised (WAIS-R), information (WAISI), and vocabulary (WAISV) scores, occupational intellectual requirements (OIR), and census-derived estimates of household income, were compared between apo E genetic subgroups while adjusting for intellectual background and demographic variables. RESULTS: WAISI, WAISV, OIR, and income correlated with age, sex, education, and DIQ, but after controlling for these variables there were no clinically significant differences between apo E-e4 homozygotes and noncarriers on any measure. CONCLUSIONS: No clinically significant differences between genotypes were observed for the effects of education and DIQ on WAISI, WAISV, OIR, or income, although a larger sample Size would be required to exclude smaller, clinically insignificant differences.