Gray matter volume effects. (A) and (B) Apolipoprotein (APOE)-dependent gray matter (GM) distribution. Carriers exhibited a tendency toward more hippocampal atrophy (A), whereas non-carriers showed a tendency toward more prefrontal volume loss (B). (C), (D) and (E) Correlations between GM volume and cognitive performance. In carriers of the APOE ε4 allele, performance on the Trail Making Test part A (TMT-A) correlated with GM volume in the right frontal region as well as the bilateral temporal and parietal regions (C). Correlations with TMT-A performance in non-carriers occurred in the bilateral temporal and parietal regions (D). Carriers exhibited a correlation between delayed verbal recall performance and hippocampal volume (E), whereas recall performance in non-carriers did not correlate with GM volume. The results are presented at P < 0.005 for whole brain, uncorrected.