Research reportApolipoprotein E ϵ4 is positively related to spatial performance but unrelated to hippocampal volume in healthy young adults

- Effects of APOE ϵ4 on spatial and episodic memory were assessed in young adults.
- APOE ϵ4 carriers were superior on spatial memory tasks compared to non-carriers.
- APOE ϵ4 had positive effects on episodic memory with spatial components.
- Effects of APOE ϵ4 on cognition were comparable in men and women.
- Sex but not APOE ϵ4 status had an effect on hippocampal volume.

The apolipoprotein E (APOE) ϵ4 allele is known to be a major genetic risk factor for Alzheimer's disease (AD). It has been linked to especially episodic memory decline and hippocampal atrophy in both healthy and demented elderly populations. In young adults, ϵ4 carriers have shown better performance in episodic memory compared to non-carriers. Spatial memory, however, has not been thoroughly assessed in relation to APOE in spite of its dependence on the hippocampus. In this study, we assessed the effect of APOE genotype on a variety of spatial and episodic memory tasks as well as hippocampal volume assessed through manual tracing in a sample of young adults (N = 123). We also assessed whether potential effects were modulated by sex. The presence of one or more ϵ4 alleles had positive effects on spatial function and memory and object location memory, but no effect on word recognition. Men were superior to women in spatial function and memory but there were no sex differences in the other tasks. In spite of APOE ϵ4 carriers having superior performance in several memory tasks, no difference was found as a function of APOE genotype in hippocampal volume. To our knowledge, this study is the first to show that APOE ϵ4 has a positive effect on spatial ability in young adults.