Age-related cognitive deficits mediated by changes in the striatal dopamine system

Objective: The study examined the influence of losses in dopaminergic funct ion on age-related cognitive deficits. Method: Eleven healthy subjects (21- 68 years of age) completed a set of cognitive tasks used to assess perceptu al speed and episodic memory. D-2 receptor binding was measured in the caud ate and the putamen by using positron emission tomography. Results: A gradu al age-related deterioration was found for all cognitive tasks and for D-2 binding in both striatal structures. Statistical control of D-2 binding eli minated the age-related cognitive variation, whereas residual effects of D- 2 binding were seen after the analysis controlled for age. Conclusions: D-2 receptor binding is a more important factor than chronological age in acco unting for variation in cognitive performance across the adult lifespan. Ch anges in dopaminergic neurotransmission play an important role in aging-rel ated cognitive decline.