P3-134: apoe genotype and cognitive performance in tsimane and moseten of bolivia

The ε4 allele of the apolipoprotein gene (APOE) is an established risk factor for Alzheimer's disease (AD), with evidence predominantly from Caucasian populations. Results are mixed whether non-demented older adult ε4 carriers perform more poorly on cognitive tests. Some evidence indicates that APOE influences AD risk through episodic memory. We therefore hypothesized ε4 carriers would show lower episodic memory scores. Participants were indigenous lowland Bolivians practicing subsistence level horticulture (469 Tsimane; 86 Moseten) aged ≥55 (mean 66, range 55-96), with data from both cognitive testing and APOE genotyping from PCR. Culturally/linguistically adapted cognitive tests included episodic memory, digit span forward, semantic fluency, visual scan, and visuoconstructional ability. Episodic memory included immediate memory (average of 3 learning trials for an 8-word list), and delayed recall assessed after 10 minutes. General linear modelling evaluated whether memory scores were associated with carrying the ε4 allele. Distribution of APOE genotypes was not significantly different between Tsimane and Moseten populations: unadjusted 21% ε3/ε4 heterozygotes; 1% ε4/ε4 homozygotes. Controlling for population, age, gender, and education, there was a significant effect for delayed recall: those carrying an ε4 allele scored significantly lower, b = −0.705, SE = 0.203, p = .0006, ηP2 = 0.024. Neither immediate memory nor any other cognitive test showed a significant ε4 effect. There were no significant interactions between APOE and population, age, gender, or education. Within each population, controlling for age, gender, and education, the ε4 main effect was significant on delayed recall for both Tsimane, b = −0.527, SE = 0.212, p = .0131, ηP2 = 0.0132, and Moseten, b = −0.935, SE = 0.427, p = .0316, ηP2 = 0.0558, with a trend for Moseten on immediate memory, b = −0.589, SE = 0.240, p = .0163, ηP2 = 0.0692.