Long-term effects of STN DBS on mood: psychosocial profiles remain stable in a 3-year follow-up

Iris Kaiser 1 2 Ilse Kryspin-Exner 1 Thomas Brcke 0 Dieter Volc 3 Franois Alesch 2 0 Department of Neurology , Wilhelminenspital, Vienna , Austria 1 Department of Clinical and Health Psychology, Institute of Psychology, University of Vienna , Austria 2 Department of Neurosurgery, Medical University of Vienna , Austria 3 Department of Neurology , Confraternitat, Vienna , Austria Background: Deep brain stimulation of the subthalamic nucleus significantly improves motor function in patients with severe Parkinson's disease. However, the effects on nonmotor aspects remain uncertain. The present study investigated the effects of subthalamic nucleus deep brain stimulation on mood and psychosocial functions in 33 patients with advanced Parkinson's disease in a three year follow-up. Methods: Self-rating questionnaires were administered to 33 patients prior to surgery as well as three, six, twelve and 36 months after surgery. Results: In the long run, motor function significantly improved after surgery. Mood and psychosocial functions transiently improved at one year but returned to baseline at 36 months after surgery. In addition, we performed cluster and discriminant function analyses and revealed four distinct psychosocial profiles, which remained relatively stable in the course of time. Two profiles featured impaired psychosocial functioning while the other two of them were characterized by greater psychosocial stability. Conclusion: Compared to baseline no worsening in mood and psychosocial functions was found three years after electrode implantation. Moreover, patients can be assigned to four distinct psychosocial profiles that are relatively stable in the time course. Since these subtypes already exist preoperatively the extent of psychosocial support can be anticipatory adjusted to the patients' needs in order to enhance coping strategies and compliance. This would allow early detection and even prevention of potential psychiatric adverse events after surgery. Given adequate psychosocial support, these findings imply that patients with mild psychiatric disturbances should not be excluded from surgery. - Background Parkinson's disease (PD) is a progressive movement disorder ensuing from dopaminergic depletion of the basal ganglia, substantia nigra pars compacta. The resulting disruption of the motor circuit that connects the basal ganglia to the motor cortex leads to the clinical manifestations of tremor, rigidity, bradykinesia and postural instability. Since limbic and associative loops are also affected by dopaminergic loss, cognitive and behavioural abnormalities are frequently encountered in PD patients [1-4]. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment to improve motor function in patients with advanced Parkinson's disease. Studies with respect to short- and long-term efficacy of STN-DBS have shown marked improvements in motor function as well as a reduction of antiparkinsonian drug treatment [57]. However, the effects of STN DBS on psychosocial functions are not well understood. Some studies reported positive changes in mood, depression and anxiety after surgery [8-10]. Several investigations showed adverse effects of STN DBS on mood. Although many of them were single case reports, documented mood changes include depression [11-13](hypo)mania [14-17],visual hallucinations [18] and behavioural changes, like apathy, irritability, emotional lability, hypersexuality and aggressiveness [5,12,17,19]. Some behavioural abnormalities were related to electrode displacement [15,20,21] or to stimulation parameters [18,22-24]. Changes may also be related to activity modification within the basal ganglia-thalamo-cortical circuits by chronic stimulation of the STN. Since there are hardly any long-term studies, the effects of STN DBS on mood are incompletely understood. The aim of the current study was to investigate both short- and long-term effects of STN-DBS on mood and psychosocial functions in a consecutive series of 33 patients with idiopathic PD. We analyzed patient data of the short-term follow-up that have been gathered in the study of Kalteis et al (2006) and additionally collected long-term data of the same patients [25]. Methods Patients Patients were selected for STN DBS according to the CAPSIT-PD protocol [26]. Subjects had to meet following inclusion criteria: diagnosis of idiopathic PD determined by the presence of at least two of the four cardinal motor symptoms; intractable motor fluctuations, disabling dyskinesias or freezing episodes; clear responsiveness to dopaminergic substitution therapy, demonstrated by an apomorphine test before surgery [27]; inconspicuous brain magnetic resonance imaging (MRI) scan. Exclusion criteria were previous neurosurgical history, native language other than German, substance abuse, a mini-mental state examination score (MMSE) below 24, presence of a severe psychiatric disease based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) and withheld informed consent. 35 consecutive patients obtained bilateral STN DBS during the assessment period. Two subjects generally refused to participate in the study. Hence, in the present investigation data of 33 PD patients (22 men, 11 women) were evaluated at baseline (see Table 1). One year after surgery patient number declined to 31 due to two deaths that were unrelated to STN DBS. During the long-term followup two patients withdrew informed consent, one patient died and one patient was excluded due to severe cognitive deterioration. In summary 27 subjects completed the entire investigation. The present study was approved by the Ethics-Committee of the Medical University of Vienna (trial registration number: 353/96). Surgical procedure 35 patients were treated with bilateral implantation surgery in a single operative session (Lead 3389, Medtronic Inc.). Due to a lack of cooperation one patient received the brain electrodes in two procedures. Implantation of pulse generators was performed in a second procedure one week later. We used the same surgical procedure which was described elsewhere (25). Assessments To investigate short- and long-term effects of STN DBS all patients administered clinical and self-rating questionnaires prior to surgery and four times postoperatively (three, six, twelve and 36 months). To establish a baseline score, patients were assessed three times prior to electrode implantation, in fact eight to six weeks, four weeks and two weeks. Patients (n = 33) Before surgery motor symptoms were evaluated on and off medication, however psychological assessments were exclusively conducted in the on state. After surgery patients were assessed while receiving medication with stimulators turned on. Psychological assessment Prior to surgery all patients underwent a comprehensive psychological evaluation. The psychological assessment included well-established self-rating scales commonly used in the assessm (...truncated)