Cognitive function in aged ovariectomized female rhesus monkeys.

To determine whether ovariectomy exacerbates age-related cognitive decline, the performance of 6 aged monkeys that had been ovariectomized early in life (OVX-Aged) was compared to that of 8 age-matched controls with intact ovaries (INT-Aged) and that of 5 young controls with intact ovaries (INT-Young) in tasks of visual recognition memory, object and spatial memory, and executive function. The OVX-Aged monkeys were marginally more impaired than the INT-Aged monkeys on the delayed nonmatching-to-sample with a 600-s delay. In contrast, they performed significantly better than the INT-Aged controls on the spatial condition of the delayed recognition span test. The hypothesis that prolonged estrogenic deprivation may exaggerate the age-related decline in visual recognition memory will require additional support. However, the findings suggest that long-term ovariectomy may protect against the development with aging of spatial memory deficits.