STN-DBS does not change emotion recognition in advanced Parkinson's disease

Deep brain stimulation of the subthalamic nuclei (STN-DBS) for the treatment of levodopa-induced motor complications in advanced Parkinson's disease (APD) has been associated with neuropsychiatric disorders. It has been suggested that a postoperative decline in visual emotion recognition is responsible for those adverse events, although there is also evidence that emotional processing deficits can be present before surgery. The aim of the present study is to compare the ability to recognize emotions before and one year after surgery in APD.

Consecutively operated APD patients were tested pre-operatively and one year after STN-DBS by the Comprehensive Affect Testing System (CATS), which evaluates visual recognition of 7 basic emotions (happiness, sadness, anger, fear, surprise, disgust and neutral) on facial expressions and 4 emotions on prosody (happiness, sadness, anger and fear).

In a sample of 30 patients 6 had depression or apathy at baseline that significantly increased to 14 post-surgery. There were no significant changes in the tests of identity discrimination, discrimination of emotional faces, naming of emotional faces, recognition of emotional prosody, and naming of emotional prosody after STN-DBS. The results of emotion tests could not predict the development of the neuropsychiatric symptoms.

This study does not support the hypothesis of an acquired change in emotion recognition, either in faces or in prosody, after STN-DBS in APD patients. Neuropsychiatric symptoms appearing after STN-DBS should not be attributed to new deficits in emotional recognition.