Age-related differences in episodic memory: a synergistic contribution of genetic and physiological vascular risk factors.

OBJECTIVE: Vascular risk is associated with impairments in age-sensitive cognitive functions. However, age-associated differences in vascular risk and cognitive functioning can be explained in part by genetic factors, such as the presence of ε4 allele of the Apolipoprotein E (APOE) gene. Although the links between these factors and cognitive deficits are frequently reported, their joint impact on healthy adults is rarely investigated. We hypothesized that phenotypic indicators of vascular risk (increased pulse pressure and high blood cholesterol levels) and genetic (APOE ε4 allele) risk factors would exert a synergistic negative influence on episodic memory in healthy rather than typical adults.
METHOD: We measured blood pressure, blood cholesterol levels, recognition memory, and free recall in a life span sample of normotensive adults 18-77 years of age. APOE genotype was determined from buccal cultures.
RESULTS: A general linear model analysis showed that elevated pulse pressure was associated with poorer memory but only in the carriers of ε4 allele--APOE Status × PP interaction, F(1, 110) = 4.82, η²(p) = .042, p = .03-whereas advanced age was associated with lower memory scores only in ε3 homozygotes: APOE Status × Age, F(1, 110) = 4.92, η²(p) = .043, p = .029.
CONCLUSIONS: A joint influence of relatively mild risk factors is associated with reduced memory performance, even in healthy adults.