APOE ε2 allele is associated with larger regional cortical thicknesses and volumes.

BACKGROUND: The protective effect of the apolipoprotein E (APOE) ε2 allele against Alzheimer's disease (AD) is controversial. OBJECTIVE: Our purpose was to clarify if the ε2 allele affects regional cortical thicknesses and volumes. METHODS: Regional cortical thicknesses and volumes were measured with an automated pipeline in 109 subjects with mild cognitive impairment, 114 AD patients and 105 age-matched healthy controls. RESULTS: In the mild cognitive impairment group, the ε2 carriers had thicker regional cortices at the transverse temporal cortex and parahippocampal gyrus than the subjects with ε3/ε3, and a larger cerebral gray matter and smaller lateral ventricles than the ε3/ε3 and ε4 carriers. In the AD group, the ε2 carriers had significantly thicker entorhinal and transverse temporal cortices, a larger whole cerebral gray matter, and smaller lateral ventricles than the subjects with the ε3/ε3 genotype, and a significantly thicker entorhinal cortex and larger cerebral gray matter than ε4 carriers. No APOE2 effect was found in the control group. CONCLUSION: The APOE ε2 allele is associated with larger regional cortical thicknesses and volumes in mild cognitive impairment and AD.