Sex Differences in Neuroanatomical Changes with Aging

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Abstract
Structural changes in the brain associated with normal aging have not yet been delineated. For example, it is still controversial whether neurons are lost during normal aging.1 In an autopsy study, I found that the size of the corpus callosum decreased with age between 25 and 70 years of age in cognitively normal men but remained constant in women. Sixty-two consecutive brain specimens, which had no gross neuropathologic features, were obtained from autopsies initiated rapidly after death and were immersion-fixed in formalin. The mean age was 54 years (range, 26 to 69) for the men (n = 23) and 52 years (range, 35 to 68) for the women (n = 39) ( Table 1 ). The mean (±SD) brain weight (at three weeks of fixation) was 1435± 103 g for the men and 1245±87 g for the women; these weights were comparable to mean brain weights of 1410 g and 1280 g for large groups of 51-to-55-year-old men and women, respectively.2 All specimens were from cognitively normal men and women, as documented by the medical history and examinations and by neuropsychological testing (including the Wechsler Adult Intelligence Scale) done for research purposes. The mean (±SD) full-scale IQ for the men was 115± 10 and that for the women was 113±10.