Correlation between different memory systems and striatal dopamine D2/D3 receptor density: a single photon emission computed tomography study

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 [123I]IBZM (iodobenzamide) were used to assess the striatal dopamine D2/D3 receptor density in 62 healthy volunteers aged between 19 and 61 years. All subjects underwent a Wechsler Memory Scale-Revised test. RESULTS: Dopamine D2/D3 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 D2/D3 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.