Genetic variation in apolipoprotein E alters regional gray matter volumes in remitted late-onset depression

The apolipoprotein E (ApoE) gene has been confirmed as the major genetic risk factor for late-onset Alzheimer's disease (AD). The effect of ApoE polymorphism on brain morphology still remains unclear in remitted late-onset depression (RLOD).

A total of 37 patients with remitted geriatric depression were investigated with optimized voxel-based morphometry. We tested for differences in gray matter volume between ApoE epsilon4 allele noncarriers (n=25) and ApoE epsilon4 allele carriers (n=12) in RLOD patients.

The volumes of right medial frontal gyrus, left middle frontal gyrus and left inferior occipital gyrus were significantly smaller in RLOD patients with ApoE epsilon4 allele carriers as compared to ApoE epsilon4 allele noncarriers. There was a significant positive correlation between gray matter volume of right medial frontal gyrus and Digit Span Test score in RLOD patients with ApoE epsilon4 allele carriers.

This study is cross-sectional, therefore it cannot determine whether abnormal gray matter volume is a state marker or trait marker of RLOD with ApoE epsilon4 allele carriers.

Our findings support the hypothesis that the ApoE genotype might be associated with structural changes in RLOD.