Personality and Deep Brain Stimulation of the Subthalamic Nucleus in Parkinson’s Disease

Aims: Certain personality features and psychiatric symptoms are often observed in Parkinson’s Disease (PD) but the effects of deep brain stimulation (DBS) of the subthalamic nucleus (STN) on psychiatric aspects of PD remain largely unclear. We aimed to evaluate changes in personality and psychiatric symptoms before and after STN-DBS in patients affected by PD. Moreover, motor symptoms and L-dopa equivalent daily dose (LEDD) were also investigated.

Methodology: Eighteen PD patients consecutively admitted at the San Giovanni Battista Hospital of the University of Turin to undergo STN-DBS were recruited. Participants were neurologically assessed using the Unified Parkinson’s Disease Rating Scale (UPDRS), and the Hoehn and Yahr scale. They were also psychiatrically evaluated with both self-report and clinician-rated instruments: Temperament and Character Inventory (TCI), Beck Depression Inventory (BDI), State-Trait Anxiety Inventory – Y form (STAI-Y), Hamilton Depression Rating Scale (HAM-D), and Hamilton Anxiety Rating Scale (HAM-A).

Results: After STN-DBS, temperament dimensions of the TCI significantly changed whilst character did not. Moreover, both HAM-D and HAM-A improved but BDI and STAI-Y resulted unmodified. We found significant improvements as regards the UPDRS part II and part III scales and L-dopa equivalent daily dose.

Conclusions: The change we found on biological dimensions of temperament after STN-DBS raises the intriguing hypothesis that surgery may entail subtle modifications of personality in PD patients. Further studies are needed to confirm these findings.