Pharmacopsychiatry 2003; 36 - 216
DOI: 10.1055/s-2003-825459

Neurobiological effects of TMS: Functional neuroimaging of dopaminergic neurotransmission using SPECT and [123I] IBZM

O Pogarell 1, R Ella 1, F Jakob 1, TC Baghai 1, C Mulert 1, W Koch 2, G Pöpperl 2, K Tatsch 2, R Rupprecht 1, HJ Möller 1, U Hegerl 1, F Padberg 1
  • 1Department of Psychiatry, Ludwig-Maximilians-University, Munich, Germany
  • 2Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich, Germany

Transcranial magnetic stimulation (TMS) is effective in the treatment of moderate to severe depression. To elucidate acute TMS effects on dopaminergic neurotrans-mission, we investigated depressed patients under TMS using a dynamic nuclear medicine technique (1–3).

Patients underwent a SPECT study using a [123I]IBZM bolus followed by a continuous infusion. In equilibrium two SPECT scans were performed, before and after TMS challenge. The change in striatal IBZM binding between pre- and post-TMS scans was used as a measure of endogenous dopamine release triggered by TMS.

Five complete data sets are available. Four studies showed a mean 2% (range: 1.2 to 4.2) reduction in IBZM binding to striatal D2 receptors, in one patient binding was unchanged (p<0.05, one-sided Wilcoxon).

The reduction of IBZM binding is suggestive of an increase in endogenous dopaminergic stimulation. Our preliminary data provide in vivo evidence of a dopaminergic mechanism of the acute TMS effects in depressed patients.

1. Padberg, F. et al. Neuropsychopharmacology 27 (2002):638–645.

2. Keck, M. et al. Neuropharmacology 43 (2002):101–109.

3. Laruelle, M. et al. J Nucl Med 36 (1995):1182–1190.