The influence of apoe status on episodic and semantic memory: Data from a population-based study.

In a prospective cohort study, the authors demonstrated a more pronounced ε4-related deficit for participants 70 years of age and older in tasks assessing episodic recall. Apolipoprotein E (APOE) and age interacted for episodic memory tasks, whereas the interaction for semantic memory tasks was between APOE and test wave. Heterozygotes of ε4 between middle-age and young-old participants performed at a higher level than noncarriers of this allele in recall tasks. A dose effect was found such that carriers of 2 ε4 alleles failed more profoundly in acquiring and recollecting episodic information than carriers of 1 ε4 allele, who in turn failed more than carriers of non-ε4 alleles. The pattern of findings observed for older ε4 carriers suggests that these individuals have particular difficulty when the executive task demands are high. Several factors (e.g., smaller hippocampal volumes, less effective neural repair mechanisms) may account for these findings. On the basis of the data obtained, the authors argue that analyses of the effect of specific genes in cognition should be accompanied by assessment of performance at a specific level, with due attention to the individual's age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)