The objective of the study was to examine whether deep brain stimulation (DBS) of the subthalamic nucleus (STN), the globus pallidus internus (GPi), and/or the ventralis intermedius thalamic nucleus (Vim) was associated with making patients angrier pre to post-surgical intervention.

Secondary outcome analysis of the NIH COMPARE Parkinson's Disease DBS trial revealed that participants were angrier and had more mood and cognitive side effects following DBS. Additionally blinded on/off analysis did not change anger scores. The sample size was small but suggested that STN DBS may have been worse than GPi in provoking anger. We endeavored to examine this question utilizing a larger dataset (the UF INFORM database), and also we included a third surgical target (Vim), which has been utilized for a different disease, essential tremor.

Consecutive patients from the University of Florida Movement Disorders Center who were implanted with unilateral DBS for Parkinson's disease (STN or GPi) or essential tremor (Vim) were included. Patients originally implanted at outside institutions were excluded. Pre-operative and 4- to 6-month post-operative Visual Analog Mood Scale (VAMS) scores for all three groups were compared; additionally, pre-operative and 1- to 3-month scores were compared for STN and GPi patients. A linear regression model was utilized to analyze the relationship between the VAMS anger score and the independent variables of age, years with symptoms, Mini-Mental Status Examination (MMSE) score, handedness, ethnicity, gender, side of surgery, target of surgery, baseline Dementia Rating Scale (DRS) total score, baseline Beck Depression Index (BDI) score, micro- and macroelectrode passes, and years of education. Levodopa equivalent dosages and dopamine agonist use were analyzed for a potential impact on anger scores.

A total of 322 unilateral DBS procedures were analyzed, with STN (n=195), Vim (n=71), and GPi (n=56) making up the cohort. An ANOVA was used to detect significant differences among the three targets in the changes pre- to post-operatively. Similar to the COMPARE dataset, at 4months, the only subscore of VAMS to reveal a significant difference between the three targets was the angry subscore, with GPi revealing a mean (standard) change of 2.38 (9.53); STN, 4.82 (14.52); and Vim, −1.17 (11.51) (p=0.012). At 1–3months post-operation, both STN and GPi groups were significantly angrier (p=0.004), but there was no significant difference between the two groups. However, GPi patients were significantly more confused as compared to STN patients (p=0.016). The linear regression model which sought independent explanatory variables revealed a relationship between the VAMS anger score and the surgical target and the disease duration. The mean changes for STN and GPi DBS pre- to post-operation were 11.67 (p=0.001) and 8.21 (p=0.022) units more than those with Vim, respectively. For every year added of disease duration, the VAMS anger score increased by 0.24 (p=0.022). For the GPi and STN groups, number of microelectrode passes was significantly associated with angry score changes (p=0.014), with the anger score increasing 2.29 units per microelectrode pass. Independent variables not associated with the VAMS anger score included the surgery side, handedness, gender, ethnicity, education, age at surgery, MMSE, DRS, and BDI scores. Although the STN group significantly decreased in LED when compared to GPi, there was no relationship to anger scores. Similarly, dopamine agonist use was not different between STN and …