Objective: This retrospective longitudinal cohort study examined body weight trajectories surrounding unilateral and staged bilateral deep brain stimulation (DBS) across surgical targets in individuals with Parkinson’s disease (PD) and essential tremor (ET).

Background: DBS is an established therapy for PD and ET. While postoperative weight gain has been described in PD, weight trajectories before and after staged bilateral DBS remain incompletely characterized across diagnoses and targets.

Method: We conducted a retrospective longitudinal cohort study of patients with PD or ET undergoing unilateral and staged bilateral DBS targeting the subthalamic nucleus (STN), globus pallidus internus (GPi), or ventral intermediate nucleus (VIM). Percent change in body weight relative to surgery-specific baseline was analyzed using linear mixed-effects models with random participant intercepts. Time from unilateral to contralateral implantation was assessed with Kaplan-Meier methods.

Results: The first-side cohort included 828 patients (603 PD, 225 ET). Patients with PD demonstrated progressive preoperative weight decline followed by significant postoperative weight gain after unilateral DBS, peaking at 2.06% (p<0.001) within the first 12–18 months before gradually returning toward baseline. After staged bilateral implantation (n=248), patients with PD exhibited more sustained postoperative weight gain, remaining significantly above baseline through 3 years (1.51%, p<0.01). In contrast, patients with ET demonstrated minimal and inconsistent weight change across unilateral and staged bilateral procedures. Time-to-escalation analysis (n=1,058 unilateral cases) differed significantly across three targets (log-rank p<.001); although pairwise comparison of PD-STN and PD-GPi cohorts showed no significant difference in time to escalation (p=0.28).

Conclusion: DBS is associated with diagnosis-dependent weight changes. Patients with PD demonstrate reproducible perioperative weight loss followed by postoperative gain, particularly after staged bilateral implantation, whereas patients with ET show minimal deviation from baseline. These findings suggest DBS-related weight change reflects interaction between stimulation and disease-specific clinical trajectories rather than target-specific effects within PD. This work informs patient counseling and highlights the need for prospective metabolic characterization in DBS cohorts.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/body-weight-increases-after-dbs-in-parkinsons-disease-but-not-essential-tremor/