Hi, dear I have gone through your question. I can understand your concern. Your brother has parkinson s disease. DBS( deep brain stimulation) is approved in treatment of parkinson and essential tremor. There is also the potential for neuropsychiatric side-effects, including apathy, hallucinations, compulsive gambling, hypersexuality, cognitive dysfunction, and depression. However, these may be temporary and related to correct placement and calibration of the stimulator and so are potentially reversible. However incresing of essential tremor is not known side effects. He should check the eletrode placement also. Consult your doctor and take treatment accordingly. Hope I have answered your question. If you have any doubts then feel free to ask me. I will be happy to answer. Thanks for using health care magic. Wish you a very good health.