Striatal dopamine transporters and cognitive functioning in healthy men and women

Objective: There is growing interest in distinguishing the biological bases of sex differences in behavior from environmental influences. Sex hormone levels seem to be related to some cognitive abilities, particularly memory, and the dopaminergic system participates in the mediation of memory. The d opamine transporter is the primary indicator of dopaminergic tone. This stu dy investigated the relationship between cognition and dopamine transporter availability in healthy men and women. Method: Dopamine transporter levels were measured with a technetium-99m rad iolabeled analog of cocaine, TRODAT-1, in 66 healthy volunteers (30 men and 36 women). A neuropsychological battery designed to target functions assoc iated with dopaminergic activity was administered during the uptake interva l between the radiopharmaceutical injection and image acquisition, Results: Women and younger participants had higher dopamine availability in the caudate nucleus, and these groups also performed better on verbal lear ning tasks. Furthermore, dopamine transporter availability was correlated w ith learning performance within groups. Relationships between dopamine avai lability in the caudate and putamen and executive and motor functioning wer e observed in women, but not in men. Conclusions: The results provide further evidence for age effects and sex d ifferences in the neuromodulatory influences of dopamine on behavior in hum ans.