A preliminary study of dopamine transporter binding in bipolar and unipolar depressed patients and healthy controls

Objective: We examined striatal dopamine transporter (DAT) binding in bipolar and unipolar depressed patients and compared these values to those obtained from healthy control subjects using the selective DAT radioligand [Tc-99m]TRODAT-1 and single photon emission computed tomography imaging. We hypothesized that DAT levels might be higher in bipolar versus unipolar patients. Methods: [Tc-99m]TRODAT-1 scans were acquired from 5 bipolar and 10 unipolar patients and from 46 healthy controls. Distribution volume ratio (DVR) of [Tc-99m]TRODAT-1 binding affinity was calculated for regions of interest in the striatum. Results: Bipolar patients had greater DVR values compared to controls in the right posterior putamen (p = 0.001) and in the left caudate region (p = 0.007). Bipolar patients had modestly lower DAT binding in all brain regions examined, and a significantly lower DVR in the right caudate region compared to unipolar patients (p = 0.05). Conclusion: These data suggest that striatal DAT density may be increased in bipolar and unipolar depressed patients compared to controls, and that bipolar and unipolar depressed patients may have a different pattern of striatal DAT binding. Copyright (c) 2007 S. Karger AG, Basel.