NEW YORK (Reuters Health) – Many patients who undergo deep brain stimulation of the subthalamic nucleus for Parkinson’s disease become overweight or obese, according to the results of the first-ever prospective study with long-term follow-up to investigate this topic. By 16 months after treatment, over 80% of subjects were overweight or obese.

“This finding highlights the necessity to understand the underlying mechanisms and to provide a diet management with a physical training schedule appropriate for patients with Parkinson’s disease,” Dr. Stephanie Bannier, from Gabriel Montpied Hospital, Clermont-Ferrand, France, and colleagues state.

The results, reported in the Journal of Neurology, Neurosurgery, and Psychiatry for May, are based on a study of weight changes in 22 patients treated with deep brain stimulation. Dual x-ray absorptiometry was used to assess weight and body composition before surgery and at 3 months and 16 months, on average, after surgery.

Prior to surgery, none of the patients were underweight and half were overweight. By 3 and 16 months, the proportion of overweight or obese subjects had climbed to 68% and 82%, respectively (p < 0.001). Rapid weight gain was noted in the first 3 months after treatment with men gaining 3.5 kg, on average, and women gaining 2.6 kg, the report indicates. In men, the body mass index increased by 1.14 and 2.02, on average, by 3 and 16 months, and in women the corresponding increases were 1.04 and 2.11. In both genders, the weight gain was mostly due to an increase in fat mass. Deep brain stimulation was effective in combatting Parkinson’s symptoms. At 3 months, a 60.7% improvement was noted in the “off” dopa condition. Likewise, motor complications improved significantly with a 82.8% reduction in dyskinesia duration and a 92.7% reduction in off period duration (p < 0.0001 for both). The authors conclude that all patients undergoing deep brain stimulation should be counseled about weight gain and receive appropriate nutritional advice. They note that even patients who were normal weight at baseline or who gained little weight during the first 3 months after treatment may still gain significant amounts of weight later on. J Neurol Neurosurg Psychiatry 2009;80:484-488.