Background Imaging and postmortem studies provide converging evidence that, beginning
in adolescence, gray matter volume declines linearly until old age, while cerebrospinal fluid
volumes are stable in adulthood (age 20-50 years). Given the fixed volume of the cranium in
adulthood, it is surprising that most studies observe no white matter volume expansion after
approximately age 20 years. We examined the effects of the aging process on the frontal
and temporal lobes. Methods Seventy healthy adult men aged 19 to 76 years underwent …