SPECT imaging of D2 receptors in depression

Abstract

The basal ganglia have received increasing attention with regard to their role in time pacing, motor function and other components of cognition. The aim of this study was to test whether the finer the motor activity and/or time perception performance were, the higher the striatal dopamine D2 binding would be. Single photon emission computed tomography (SPECT) with [123I]iodobenzamide (IBZM) was performed to measure striatal D2 receptor densities. A battery of neuropsychological tests, including the Wisconsin Card Sorting Test (WCST), the finger tapping test (FTT), and an attention test, was performed by patients with schizophrenia. Results indicated a strong correlation between the FTT score and striatal D2 receptor binding. Neuroleptic dosage plays an important role in the relationship between cognitive tasks and striatal dopamine receptor densities. In addition, the striatal D2 receptor density is more significantly correlated with attentional tests that consider the time effect than those that do not. Among the three tests performed, the WCST was least significantly correlated with striatal D2 receptor densities. A decrease in striatal dopamine D2 receptor density seems to be associated with impaired performance on optimal timing tasks and motor processing in patients with schizophrenia.