Memory scores in middle-aged rats predict later deficits in memory, paradoxical sleep, and blood glucose regulation in old age.

Age-related deficits in memory are correlated with deficits in paradoxical sleep and poor glucose tolerance in rats. The present experiment used a longitudinal design to determine whether memory or glucose tolerance in middle-aged rats could predict deficits in memory, sleep, and glucose tolerance in old age. Correlations were obtained between spontaneous alternation scores and glucose tolerance levels in middle age (14 months) and inhibitory avoidance, daytime sleep, and glucose tolerance levels in old age (24 months). Spontaneous alternation scores, but not glucose tolerance levels, predicted performance on all 3 behavioral and biological measures in old age. Measures of functional integrity, such as memory, may be sensitive predictors of subsequent age-related change in specific cognitive and neurobiological systems.