Deep brain stimulation surgery for Parkinson's disease: the role of neuropsychological assessment.

Neuropsychological assessment has two primary roles in the DBS process. First, assessment of cognitive and emotional functioning ensures that only appropriate candidates undergo this surgical procedure. Patients with dementia, cognitive performance suggestive of an additional neuropathological process, or significant psychiatric impairments should not undergo DBS. Second, neuropsychological assessment is essential to determine the cognitive and emotional outcomes following surgery. At the present time, a disruption in verbal fluency is the only consistent cognitive decline associated with DBS. While worsening of depression and the development of symptoms of mania are potential side effects from DBS, more studies find that DBS is associated with improvements in emotional functioning. Based on the growing understanding of the risk factors and potential side effects to DBS, neuropsychological assessment is necessary to ensure that patients selected to undergo this surgical intervention will likely have positive cognitive and emotional outcomes, in addition to the expected benefits in motor functioning.