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

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

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.

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).

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