Betting on DBS: Effects of subthalamic nucleus deep brain stimulation on risk taking and decision making in patients with Parkinson’s disease.

Abstract

Objective Concerns persist that deep brain stimulation (DBS) for Parkinson’s disease (PD) increases impulsivity and/or induces excessive reward-seeking. We report here the performance of PD patients with implanted subthalamic nucleus electrodes, with stimulation on and off, on three laboratory tasks of risk-taking and decision-making. They are compared to PD patients maintained on medication and normal control subjects. Methods and Results In the Game of Dice Task, a test of “risky” decision-making, PD patients with or without DBS made highest-risk bets more often, and ended up with less money, than normal controls. There was a trend for DBS stimulation to ameliorate this effect. Deal or No-Deal is an “ambiguous” decision-making task that assessed preference for risk (holding on to one’s briefcase) over a “sure thing” (accepting the banker’s offer). Here, DBS patients were more conservative with stimulation on than off. They accepted smaller offers from the banker and won less money in the DBS-on condition. Overall, the two PD groups won less money than healthy participants. The Framing Paradigm assessed willingness to gamble on a fixed (unambiguous) prize depending on whether the reward was “framed” as a loss or a gain. Nonsurgical PD patients tended to be more risk-averse than normal subjects, whereas DBS patients were more willing to gamble for gains as well as losses both on and off stimulation. Conclusions On “risky” decision-making tasks, DBS patients were more risk-taking than normal, but stimulation may temper this tendency. In contrast, in an “ambiguous risk” situation, DBS patients were more risk-averse (conservative) than normal, and this tendency was greatest with stimulation.

The Subthalamic Nucleus, Limbic Function, and Impulse Control

“…Moreover, this effect was more pronounced in the DBS ON condition versus OFF (Brandt et al ., 2015). A study by Boller and colleagues corroborated these findings, demonstrating higher risk behavior in the DBS off condition versus DBS on.…”

A systematic review of decision-making impairments in Parkinson’s Disease: Dopaminergic medication and methodological variability

“…2 most studies found PD patients, both on and off medication, to be significantly impaired compared to HCs. Few studies focused specifically on the role of dopaminergic medication, but the possible impact hereof on decision-making was emphasized by several authors [23,28,29].…”

“…Some studies used a repeated measures approach when testing patients on/off medication [22,24,30], while others tested different subjects for the on and off medication condition [31,32]. Moreover, in some studies patients were tested several times, while HCs were only tested once [23,24]. This could potentially be problematic and result in test-retest effects confounding the results.…”

“…Decision-making is typically divided into two categories: 1) decision making under risk, which involves situations where probabilities are known or can be known [5]; 2) decision making under uncertainty, also called ambiguous decision-making, wherein probabilities in the situation are not known and cannot be deduced [5]. This distinction is not clearly defined, and although most studies define the Iowa Gambling Task (IGT) as a task of decision-making under uncertainty [5,22,23] other studies label the task as risky decision-making [24], or a combination of both [25]. Evidence has associated decision-making under risk with greater activation of the ventral striatum, while decisionmaking under uncertainty to a greater extent involved the orbitofrontal cortex [26,27].…”

Challenges in PD Patient Management After DBS: A Pragmatic Review

“…The relationship between DBS and ICD is controversial . Bilateral STN‐DBS was found to negatively affect decision‐making during acute postoperative stages, to improve decision‐making under risk, or to be unaffected . STN‐DBS has been identified as an independent risk factor for binge eating, to induce “punding,” and worsen ICD .…”