Apomorphine effects on episodic memory in young healthy volunteers

RationaleDopamine (DA) modulates working memory. However, the relation between DA systems and episodic (declarative) memory is less established. Frontal lobe DA function may be involved. We were interested in assessing whether apomorphine (Apo), a drug used extensively in clinical research as a probe of DA function, has an effect on episodic memory test performance in healthy volunteers.ObjectiveTo investigate the effect of a presynaptic dose of Apo on episodic memory tests and on other tests thought to be sensitive to frontal lobe functions.MethodsTwenty healthy subjects were treated with Apo HCl (5 μg/kg sc) or placebo (10 subjects/group) in a randomized, double blind parallel group design and performance on a battery of cognitive tests was assessed.ResultsApomorphine significantly impaired performance on tests of source recognition (d.f. = 19, p = 0.05) and item recognition memory (d.f. = 19, p < 0.05), and memory interference (d.f. = 19, p < 0.010). No significant change was found on other tests (Go/no-Go Test, Categorized Words, Stroop, Trail Making Test, and verbal fluency).ConclusionFindings in this small sample of subjects suggest that dopaminergic transmission affects episodic memory functions.