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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. [ABSTRACT FROM AUTHOR]

Objective. Although studies have indicated that the human basal ganglia have a specific role in different memory systems, the functional significance of the striatal dopamine activities for the basal ganglia remains less clear. This study assessed the relationship between measures of striatal dopamine activities and indices of different memory systems in healthy individuals.Method. Single photon emission computed tomography and [[1][2][3]I]IBZM (iodobenzamide) were used to assess the striatal dopamine D[2]/D[3] receptor density in 62 healthy volunteers aged between 19 and 61 years. All subjects underwent a Wechsler Memory Scale-Revised test.Results. Dopamine D[2]/D[3] receptor densities in the striatum decline with age. Stepwise regression analysis showed that verbal delayed recall and working memory account for most of the variance in dopamine D[2]/D[3] measurements. These relationships remain significantly after controlling for age effects.Conclusions. Brain striatal dopamine activities are also significantly associated with various memory systems, in addition to motor functions. This may explain why patients with neuropsychiatric disorders may have both memory and motor impairments. [ABSTRACT FROM AUTHOR]