Can deep brain stimulation be a therapeutic option for Parkinson's disease dementia?

Background Although dementia is regarded as a contraindication for deep brain stimulation in patients with Parkinson's disease, there exist patients with Parkinson's disease dementia who can benefit motorically from deep brain stimulation. Aim To review the clinical outcome of deep brain stimulation in patients with Parkinson's disease dementia and discuss whether deep brain stimulation can be a therapeutic option in those patients. Methods We report five patients who underwent bilateral subthalamic deep brain stimulation despite the presence of dementia at the preoperative evaluations because of the presence of medically intractable motor and non‐motor symptoms that could be relieved by deep brain stimulation. Results After surgery, motor symptoms improved greatly, and some non‐motor symptoms also improved in all patients. However, in four patients, the motor improvements lasted just 2 or 3 years, and then, the patients deteriorated with the emergence of end‐stage problems despite there being more continued benefit that could not have been achieved by medical treatment. The remaining one patient showed excellent response until the last follow‐up at 7 years after surgery. Conclusion Deep brain stimulation provides some benefit not provided by medical treatment alone to patients with Parkinson's disease dementia, although its benefits do not last as long as in non‐demented patients. However, this benefit does not necessarily mean that deep brain stimulation can be performed in patients with Parkinson's disease dementia. More discussion is required on whether deep brain stimulation in Parkinson's disease dementia can be justified and in which patients it should be carried out.