Influence of deep brain stimulation on the psychiatric status in patients with Parkinson´s disease

Deep brain stimulation (DBS) of the subthalamic nucleus (Stn) is an effective treatment to improve motor function in advanced Parkinson`s disease. Short- and long-term outcome of Stn-DBS have evaluated marked improvement in motor function and a reduction of antiparkinsonian drug treatment. Adverse effects on mood, cognitive function, and speech have been observed. The influence of this treatment on mood and behaviour is not clear. Reported adverse mood changes are depression, mania, anxiety, hallucinations, aggression, irritability, disinhibition, mirthful laughter and suicidal tendency. These changes may be related to a modification of the activity of the basal ganglia- thalamo-cortical circuits by chronic stimulation of the subthalamic nucleus or to microsurgical lesions. There is a lack of prospective studies. The aim of this prospective study was to examine the effects of Stn-DBS on mood and quality of life in a consecutive series of 35 patients with idiopathic Parkinson`s disease, who underwent surgery for bilateral Stn-DBS. The assessment methods were well-established clinical and self rating scales. All patients were examined at eight assessment times. We assessed the patients three times before surgery: six to eight, four weeks and two weeks. To investigate short- and long-term effects of bilateral subthalamic deep brain stimulation the patients were evaluated five times: three, nine weeks, three, six, and twelve months after surgery. The motor function improved significantly after surgery. The patients as a group reported a significant improvement in mood, depression, anxiety, psychological and non-specific somatic symptoms, distress, and quality of sleep. Physical and psychosocial dimensions of quality of life ameliorated significant after surgery. In most cases the improvement appeared after surgery and was stable over the time course until one year. Our results suggest that the Stn-stimulation has a positive impact on mood psychological function and quality of life.