Reliable diagnosis of nigrostriatal degeneration by dopamine transporter SPECT despite drug interaction with venlafaxine or bupropion

Purpose: This study examined the impact of venlafaxine and bupropion on the detection of nigrostriatal degeneration by dopamine transporter (DAT)-SPECT.

Methods: 43 patients (70.7 ± 8.6y, 44% female) with [¹²³I]FP-CIT-SPECT under venlafaxine (n = 26, 37.5-225 mg/d), bupropion (n = 16, 150 or 300 mg/d) or both (n = 1) were included retrospectively. The striatal specific [¹²³I]FP-CIT binding ratio (SBR), its left-right asymmetry and the putamen-to-caudate ratio were transformed to z-scores and submitted to a cluster analysis for data-driven categorization.

Results: Two clusters were identified. The first cluster (37% cases) showed a Parkinson's disease (PD)-like pattern: median striatal SBR/asymmetry/putamen-to-caudate z-score -4.5/4.9/-3.8. The second cluster (63%) showed symmetric reduction with normal intra-striatal gradient: median striatal SBR/asymmetry/putamen-to-caudate z-score -2.7/0.4/0.2. Patients with follow-up clinical reference diagnoses of neurodegenerative (n = 8) and non-neurodegenerative (n = 16) parkinsonism fell exclusively into the former or the latter cluster, respectively (p < 0.001).

Conclusion: Venlafaxine and bupropion cause uniform reduction of the striatal [¹²³I]FP-CIT SBR that can be distinguished from PD-like reductions.