["The protective effect of the apolipoprotein E (APOE) ε2 allele against Alzheimer's disease (AD) is controversial.", 'Our purpose was to clarify if the ε2 allele affects regional cortical thicknesses and volumes.', '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.', '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.'] Is aPOE ε2 allele associated with larger regional cortical thicknesses and volumes?