40 Chapter 2 Figure 1. Scatterplot of BMI at baseline (x axis) and at last follow-up (y axis) for all patients. The vertical distance to the diagonal represents the change in BMI. Dashed lines indicate the various BMI categories, so that a change in category after surgery can be seen for each subject. Patients below the diagonal had a decrease in BMI and those above the diagonal had an increase in BMI. In both OCD and MDD, there were no significant differences in the changes in BMI between the diagnostic groups, or between responders and nonresponders to DBS. DISCUSSION There was no significant change in body weight on the group-level after vALIC DBS for either OCD or MDD. The potential of this therapy to change reward-related behavior did not result in significant weight loss in these patients, who were overweight on average at baseline. We did find a trend towards a decline in BMI in the subgroup of patients with (morbid) obesity, but we did not see a replication of the substantial weight loss previously described (1). The vALIC is currently being explored as a potential target for DBS in obesity for its assumed role in reward-related behavior (4-6). Evidence for the involvement of the NAc/vALIC in compulsive eating and obesity is limited to preclinical studies that show low D2-binding in the striatum in obese individuals after food-related sensory stimuli, and in animal studies that show reduced caloric intake and weight loss associated with an upregulation of the D2 receptor. There were increased DA levels in diet-induced obese rats treated with NAc shell DBS (7), whilst mice treated with NAc shell DBS were found to have a decrease in binge-eating and an increase in immediate D2 gene expression in the NAc shell. In diet-induced obese mice, chronic NAc shell DBS reduced caloric intake and led to weight loss (8).
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