Subthalamic stimulation in Parkinson disease: behavior and social adaptation.

Background: Bilateral subthalamic high-frequency stimulation significantly improves motor functions in patients with advanced forms of Parkinson disease (PD). This favorable effect contrasts with a growing number of reports that the treatment may result in psychiatric complications.

Objective: To analyze the presence of behavioral disorders and social maladjustment in PD patients successfully treated with continuous bilateral subthalamic stimulation.

Design: Prospective study.

Setting: University hospital.

Methods: Twenty PD patients underwent prospective evaluation for behavioral and personality changes, quality of life, and social functioning, 6 and 24 months after surgery to implant bilateral stimulating electrodes within the subthalamic nucleus.

Results: At 6 and 24 months after surgery, parkinsonian motor disability (on-stimulation/off-medication) was improved by 81% and 67%, respectively, and the severity of levodopa-related motor complications was improved by 84% and 70%, respectively. Levodopa-equivalent dosage was decreased by 79% and 66%, respectively; severity of depression was improved by 21% and 33%, respectively; and severity of anxiety was improved by 43% and 64%, respectively. The patients' personality traits were unmodified. Twenty-four months after surgery, the global score for quality of life was improved by 28%, whereas scores for social adjustment remained stable.

Conclusions: Provided that patients with PD are rigorously selected for neurosurgery, subthalamic stimulation (1) improves mood, anxiety, and quality of life; (2) does not result in severe permanent psychiatric disorders or modify patients' personality; and (3) does not ameliorate social adaptation.