A higher than expected frequency of suicide has been reported among patients undergoing subthalamic nucleus deep brain stimulation (STN DBS) for advanced Parkinson's disease (PD). We conducted a retrospective survey of 200 patients with PD who underwent STN DBS. Two patients (1%) committed suicide and four (2%) attempted suicide, despite clear motor improvements. Suicidal patients did not differ from non-suicidal patients with respect to age, disease duration or preoperative depressive and cognitive status. Suicidal behaviour was associated with postoperative depression and/or altered impulse regulation. Suicidal behaviour is a potential hazard of STN DBS, calling for careful preoperative assessment and close postoperative psychiatric and behavioural follow-up.Despite a high frequency of depression, the incidence of suicide among patients with Parkinson's disease (PD) is similar to 1 or 10 times lower than that recorded in the general population.2 Recently, concerns have been raised about a higher than expected frequency of suicide among patients undergoing subthalamic nucleus deep brain stimulation (STN DBS) for advanced PD. We therefore examined the prevalence and characteristics of completed and attempted suicides in a large cohort of patients who underwent STN DBS in our centre. METHODSWe reviewed the files of all 200 patients with PD (127 men and 73 women; mean age 61.8 (8.6) years; disease duration 14.8 (4.8) years) who underwent bilateral STN DBS in our centre between 1997 and 2006. During the study period, 24 patients died. There were two suicides, two deaths in undetermined circumstances and one death by defenestration 3 days after surgery. This latter patient was in a postoperative confusional state and the stimulator had not yet been switched on; we considered that death was more likely accidental than intentional and did not include this case among the suicides. Six patients were monitored in other centres, for geographic reasons, and 12 patients were lost to follow-up (possibly following unreported death). At the end of the study period, all of the remaining 158 patients were followed-up in our centre by the same neurologist (J-MG). STN DBS was performed under local or general anaesthesia. STN coordinates were calculated from preoperative MRI and intraoperative ventriculographic data and were confirmed by intraoperative recording of neuronal activity with semi-microelectrodes and turn amplitude analysis. Scores on the Mattis Dementia Rating Scale (MDRS, maximum score 144) and the Montgomery-Asberg Depression Scale (MADRS, maximum score 60) were compared with a t test between suicidal patients and the last 75 consecutive non-suicidal patients who had undergone the same preoperative assessment of depression. All patients who attempted suicide were interviewed by a psychologist (TS). RESULTSTwo patients (1%) committed suicide and four patients (2%) attempted suicide, a mean 12.0 (7.2) months after surgery, despite fair to excellent motor improvement. Attempted and completed suicides occurred b...