A Preliminary Study of Dopamine Transporter Binding in Bipolar and Unipolar Depressed Patients and Healthy Controls

Abstract

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 [^99mTc]TRODAT-1 and single photon emission computed tomography imaging. We hypothesized that DAT levels might be higher in bipolar versus unipolar patients. Methods: [^99mTc]TRODAT-1 scans were acquired from 5 bipolar and 10 unipolar patients and from 46 healthy controls. Distribution volume ratio (DVR) of [^99mTc]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.