Impulsivities and Parkinson's Disease: Delay Aversion Is Not Worsened by Deep Brain Stimulation of the Subthalamic Nucleus

Abstract

Deep Brain Stimulation (DBS) of the Subthalamic Nucleus (STN) improves motor symptoms in Parkinson's disease (PD), but can exert detrimental effects on impulsivity. These effects are especially related to the inability to slow down when high-conflict choices have to be made. However, the influence that DBS has on delay aversion is still under-investigated. Here, we tested a group of 21 PD patients on and off stimulation (off medication) by using the Cambridge Gamble Task (CGT), a computerized task that allows the investigation of risk-related behaviours and delay aversion, and psychological questionnaires such as the Barratt Impulsiveness Scale (BIS), the Sensitivity to Punishment and to Reward Questionnaire (SPSRQ), and the Quick Delay Questionnaire (QDQ). We found that delay aversion scores on the CGT were no higher when patients were on stimulation as compared to when they were off stimulation. In contrast, PD patients reported feeling more impulsive in the off stimulation state, as revealed by significantly higher scores on the BIS. Higher scores on the sensitivity to punishment subscale of the SPSRQ highlighted that possible punishments influence patients' behaviours more than possible rewards. Significant correlations between delay aversion scores on the CGT and QDQ delay aversion subscale suggest that these two instruments can be used in synergy to reach a convergent validity. In conclusion, our results show that not all impulsivities are detrimentally affected by DBS of the STN and that the joint use of experimental paradigms and psychological questionnaires can provide useful insights in the study of impulsivity.

Effects of deep brain stimulation of the subthalamic nucleus on inhibitory and executive control over prepotent responses in Parkinson's disease

“…Similarly, negative results were reported by Torta et al (2012) who examined risk taking behavior and delay aversion, both characteristics of impulsivity, on the Cambridge Gambling task. STN DBS in PD had no effect on delay aversion or risk taking on this task.…”

Impulsivity and Compulsivity After Subthalamic Deep Brain Stimulation for Parkinson’s Disease

“…Impulsive participants may impulsively discount future reward, i.e., show increased delay discounting. The Cambridge Gambling Task (Rogers et al, 1999), used by Torta et al (2012), measures delay aversion, identifying subjects who repeatedly pick the initial bet offered, and results are here presented alongside studies of delay discounting, the measure of impulsive tendencies it most closely resembled.…”

“…Impulsivity scores on the Barratt Impulsiveness Scale (BIS-11, Patton and Stanford, 1995) were measured in six studies (total of 165 patients) comparing scores either between DBS On and Off conditions (Torta et al, 2012;Seinstra et al, 2016), or between DBS On and PD-patients On medication or healthy controls (Hälbig et al, 2009;Evens et al, 2015;Hagelweide et al, 2018;Irmen et al, 2019). One study reported significantly worse impulsivity scores in a DBS-group compared to healthy controls (Hälbig et al, 2009).…”

“…Four studies measured DBS-related delay discounting in a total of 108 PD patients ( Table 2; Torta et al, 2012;Evens et al, 2015;Seinstra et al, 2016;Seymour et al, 2016). None of these studies found evidence that DBS activation interferes with subjects' ability to delay claiming a reward in order to maximize total reward, suggesting that DBS does not affect this aspect of impulsivity.…”

Parkinson's Disease, the Subthalamic Nucleus, Inhibition, and Impulsivity

“…Other than deficits in motor inhibition summarized in Table 3 and increased loss-chasing in a gambling task, 135 investigators have not found any detrimental effects of STN-DBS on other features of impulsivity and risk taking. 136,137 More direct and "causal" evidence of the role of the STN in inhibitory and executive control comes from a handful of studies of subthalamotomy in PD. Postsubthalamotomy deficits on the Stroop in 30% of the PD patients and deterioration in release from proactive inhibition on a memory test, with normal performance in 98% of the sample before and 50% of the sample after surgery, have been reported.…”