The goal of the present paper is to assess whether pallidotomy influences the degree of depression in Parkinson disease patients (PD). The prevalence of depression in PD patients has been reported to range from 45% to 50%. Deep depression is observed in 7% of patients. Previous data suggested that several factors can determine depression in PD patients. It is assumed that psychological factors, neurotransmitter dysfunctions (i.e. dopaminergic, serotoninergic and noradrenergic disease), and basal ganglia lesions may lead to depression.

The emotional state of 30 patients (16 women, 14 men) with PD was examined with depression tests: the Beck Depression Inventory and the Montgomery Asberg Depression Rating Scale twice - three days before and three days after pallidotomy. The age-matched control group was tested twice within a week.

The difference in the degree of depression before and after surgery was significant. Statistically significant difference in the degree of depression between healthy individuals and PD patients before pallidotomy was reported (p=0,07). Moreover, the results obtained after pallidotomy in the experimental group did not reveal any differences with the control group. It was noticed that sex has significantly influenced the degree of depression as measured before and after surgery with both tests.

The results obtained in the study showed that stereotactic pallidotomy reduced depression symptoms in PD patients. This finding is compatible with Lauerbach's model, according to which ablation or deep medial globus pallidus stimulation should inhibit thalamic and cortical activity, thus reducing depression symptoms.