The correlation between striatal dopamine D2/D3 receptor availability and verbal intelligence quotient in healthy volunteers.

BACKGROUND Although a correlation between the central dopaminergic system and intelligence may exist, the results from imaging studies remain inconclusive. The aim of this study was to explore the relationship between striatal dopamine D2/D3 receptor availability and verbal intelligence quotient (VIQ) using single photon emission computed tomography (SPECT). METHOD Striatal D2/D3 receptor availability of 64 healthy subjects was determined with the [123I]iodobenzamide ([123I]IBZM) ligand. Intelligence quotients (IQs) of the subjects were measured by the Wechsler Adult Intelligence Scale--Revised (WAIS-R). RESULTS In addition to age, left striatal D2/D3 receptor availability correlated positively with VIQ. In females, left striatal D2/D3 receptor availability was the only variable that correlated significantly with the similarities subtest of VIQ. CONCLUSIONS There is a relationship between left striatal D2/D3 receptor availability and verbal intelligence, which varies, predominantly in males.