Genetic variation in memory functioning.
On the basis of a review of the literature the contribution of genetic factors for individual differences in memory performance is discussed. Explorations of such influences on memory have just begun. Most of those studies that have been conducted in order to find a quantitative trait locus for memory have focused on ApolipoproteinE (ApoE). One form of this gene is strongly associated with cardiovascular disease in middle age and to late-onset Alzheimer's disease. Some studies have demonstrated an association between ApoE and memory even in non-demented individuals. Other studies have failed to demonstrate this association. Based on data from a prospective cohort study (Betula) in our own laboratory, we have assessed and examined associations between three different forms of ApoE and performance on episodic memory tests. Cross-sectional comparisons revealed non-significant differences in episodic memory performance between carriers of the three alleles. Analyses of change scores in longitudinal data revealed that allele epsilon 4 was related to a lower level of memory performance than alleles epsilon 2 and epsilon 3. This effect was most pronounced in tasks providing cognitive support at both encoding and retrieval, suggesting a deficit in utilizing such support in carriers of the epsilon 4 allele.