Subthalamic stimulation and neuropsychiatric symptoms in Parkinson's disease: results from a long-term follow-up cohort study.

Background: Reports on behavioural outcomes after subthalamic nucleus deep brain stimulation in Parkinson's disease are controversial and limited to short-term data. Long-term observation in a large cohort allows a better counselling and management.

Methods: To determine whether a long-term treatment with subthalamic stimulation induces or reduces impulse control behaviours, neuropsychiatric fluctuations and apathy, 69 patients treated with subthalamic stimulation are prospectively and retrospectively assessed using Ardouin Scale of Behavior in Parkinson's Disease before and after 3-10 years of stimulation.

Results: At a mean follow-up of 6 years, all impulse control disorders and dopaminergic addiction were significantly decreased, apart from eating behaviour and hypersexuality. Neuropsychiatric fluctuations also significantly improved (ON euphoria: 38% of the patients before surgery and 1% after surgery, P<0.01; OFF dysphoria: 39% of the patients before surgery and 10% after surgery, P<0.01). However, apathy increased (25% of the patients after surgery and 3% before, P<0.01). With the retrospective analysis, several transient episodes of depression, apathy, anxiety and impulse control disorders occurred.

Conclusions: Bilateral subthalamic nucleus stimulation was overall very effective in improving impulse control disorders and neuropsychiatric fluctuations in parkinsonian patients in the long term despite a counteracting frequent apathy. Transient episodes of impulse control disorders still occurred within the follow-up. These findings recommend a close follow-up in parkinsonian patients presenting with neuropsychiatric symptoms before deep brain stimulation surgery.

Clinical Trial Registration: NCT01705418;Post-results.