BRAIN-WEIGHT DOES NOT DECREASE WITH AGE IN ADULT RHESUS-MONKEYS

Cross-sectional studies on adult human autopsy material have shown tha t younger cohorts have heavier brains than older groups. We sought to determine whether a similar pattern is present in the rhesus monkey, a species that serves as a useful model of human brain and cognitive ag ing. Data were obtained from necropsies of 399 rhesus monkeys (180 fem ales; 219 males), of ages covering the entire adult lifespan of this s pecies. In addition to fresh brain weight, variables considered were a ge, sex, body weight, heart weight, identify of the prosector, and cir cumstance of death. Initial bivariate analyses revealed a significant sex difference in brain weight (mean for males: 96.1g; for females: 86 .1g; p < 0.001), as well as significant correlations of brain weight w ith body weight (r = 0.20, p < 0.01 for females; r = 0.27, p < 0.001 f or males), and heart weight (r = 0.27, p < 0.001 for females; r = 0.38 , p < 0.001 for males). Identity of prosector, circumstance of death, and age were not significantly related to brain weight in bivariate an alyses. Multiple linear regression, controlling for possible confoundi ng effects of body weight and sex, also suggested that brain weight is stable throughout adulthood in the rhesus monkey. (C) 1998 Elsevier S cience Inc.