The result of a French study showed that deep brain stimulation for Parkinson's disease could trigger obesity in some patients.

Although weight gain is a recognized side effect of neurostimulation of the subthalamic nucleus, it has not been studied, according to Dr. Fran ois Tison and researchers from the CHU of Bordeaux. The results of their research were presented this week at a neurology conference in Tours.

The study evaluated 22 Parkinson's disease patients before and after subthalamic nucleus deep brain stimulation and then at intervals of 3 months, 12 months and 18 months.

Compared to baseline, 20 patients had a weight increased of 7.9% after 3 months. After 18 months, their weight had increased by 12.6%. Three patients had weight gains of 15%, classing them as obese.

The same team, with colleagues from the nutritional-diabetes service, also tried to characterize the modification of energy balance in the patients after the therapy. They studied 6 patients before stimulation, 6 patients after stimulation and 8 controls.

Again, they observed a 13.5% weight increase in patients after stimulation and a significantly higher body mass index than the control group (27.9 compared to 23.1).

They also reported a reduction of energy expenditure at rest in patients who had undergone treatment. It remained lower than that of the controls (20.3 cal/kg of lean mass/minute versus 25.6 cal/kg of lean mass/minute).

"The weight increase in people with Parkinson's disease who have had (subthalamic nuclear deep brain stimulation) could be explained by a decrease of energy expenditure at rest without simultaneous reduction in the calorific intakes, " said the authors.