AIM: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an established therapy for patients with Parkinson’s disease (PD) associated with motor complications of long term L-dopa treatment.

MATERIAL and METHODS: Here we report two cases with DBS- induced manic episode, focusing on the functional and anatomic correlates of psychiatric adverse effects of STN stimulation.

RESULTS: We present two cases of PD with motor complications due to long term L-dopa treatment that developed their first episodes of mania with psychotic symptoms after bilateral STN-DBS implantation. DBS-induced psychiatric adverse effects may be attributable either to limbic connections and STN-specific oscillations or stimulation of the medial forebrain bundle.