Correlation between fine motor activity and striatal dopamine D₂ receptor density in patients with schizophrenia and healthy controls

Striatal dopamine D₂ receptor density is an important indicator of many neuropsychiatric disorders and also of motor activity. This study examined the relationship between a fine motor task (finger tapping test, FTT) and striatal D₂ dopamine receptor density by examining 20 healthy volunteers and 20 schizophrenic patients. Striatal D₂ receptor density was determined with single photon emission computed tomography using [¹²³I]IBZM (iodo-benzamide). The correlation between the FTT score and striatal D₂ receptor density was statistically significant not only in the patient group but also in healthy controls. The FTT scores and striatal D₂ receptor density were lower in medicated patients than that in healthy controls. Compared with the Simpson-Angus Scale scores, the FTT scores were more strongly associated with striatal D₂ receptor density. The use of neuroleptic medication seemed to influence the associations between FTT scores and striatal D₂ receptor density in the patient group. The FTT scores and striatal D₂ receptor density were age-sensitive in healthy controls. FTT may be a more sensitive tool for detecting neuroleptic-induced motor impairment in patients with schizophrenia. The sensitivity of the FTT to age and neuroleptic effects may be explained in part by a decline in dopamine D₂ density.