SEX-DIFFERENCES IN AGING OF THE HUMAN FRONTAL AND TEMPORAL LOBES

This study investigated effects of age and sex on regional brain struc ture in humans, focusing on the frontal and temporal lobes. Hemispheri c volumes were obtained from magnetic resonance images (MRIs) of 96 yo ung (53 men, 43 women; aged 18-40 years) and 34 older (17 men, 17 wome n; aged 41-80) healthy volunteers. Images (5 mm axial spin-echo, repet ition time of 3000 msec and echo times of 30 and 80 msec) were reslice d along the anterior commissure-posterior commissure (AC-PC) axis to s tandardize for differences in head tilt, and imported into a computer program where borders of the frontal and temporal robes were delineate d. The program calculated regional brain volumes based on slice data f rom which CSF was segmented out. An age x sex x hemisphere x region in teraction indicated that age-related reductions in brain volume were s exually dimorphic, lateralized, and region specific. Greater decrement s in brain volume occurred with age in the frontal lobe than in the te mporal robe. Age-related reductions in both regions were greater in me n than in women, demonstrating that sexual dimorphisms in human neuroa natomy are not fixed, but continue to change throughout adulthood. The possibility that gonadal hormones play a role in the promotion and/or prevention of neural atrophy with aging is discussed.