Executive function and MRI prefrontal volumes among healthy older adults

Brain atrophy and decline in executive functioning have been reported during late life, but the relationship between the 2 phenomena is not clear. To examine associations between executive tasks and morphometry, MRIs of the prefrontal cortex from 23 healthy elders were manually masked and automatically segmented. Total brain matter of the bilateral orbitofrontal, anterior cingulate, gyrus rectus, precentral gyrus, and middle frontal gyrus were computed as ratios of intracranial volume. A neuropsychological battery of five clinical tests of executive function was administered. Better performance on a response inhibition task was associated with larger volume in anterior cingulate, and performance on a nonverbal inductive reasoning task was associated with larger gyrus rectus volumes. In contrast, larger orbitofrontal volumes were associated with lower verbal and nonverbal generative output. An aggregated error index from 4 executive tests correlated negatively with a regional composite brain index. In conclusion, some executive abilities correlate with volumes of specific prefrontal subregions despite a robust neural interconnectedness between the subregions.