Apolipoprotein E epsilon4 genotype and gender: effects on memory.

OBJECTIVE: Episodic recognition memory for odors and visual was assessed in apolipoprotein E (ApoE) epsilon4-positive and epsilon4-negative men and women diagnosed with Alzheimer disease (AD) and a healthy age- and gender-matched comparison group.
METHODS: A total of 38 AD patients and 38 age- and gender-matched healthy older adults completed a recognition memory task involving three categories of stimuli: odors, faces, and symbols.
RESULTS: In the healthy comparison group, men who were epsilon4 negative outperformed epsilon4-positive men in recognition memory for odors and committed fewer false-positive errors. However, there were no significant differences between epsilon4-negative and epsilon4-positive women in the comparison group. No significant gender or ApoE status differences were detected in recognition memory for faces or symbols in the comparison group. In patients with AD, epsilon4-negative women outperformed epsilon4-positive women in recognition memory for odors and committed significantly fewer false-positive errors. However, there were no significant differences between epsilon4-positive and epsilon4-negative men. There were no significant gender or ApoE status differences in recognition memory for faces or symbols in AD patients.
CONCLUSION: The results demonstrate that recognition memory for olfactory stimuli may be particularly impaired in healthy older men with the epsilon4 allele. In patients with AD, odor memory impairments may be less severe in women who are negative for the epsilon4 allele. The results offer new insight into how recognition memory is affected by gender, the epsilon4 allele, and the modality of the stimulus to be remembered in healthy older adults and patients with AD.