What are people with Parkinson's disease really impaired on when it comes to making decisions? A meta-analysis of the evidence

Abstract

Parkinson's disease (PD) is associated with motor and cognitive impairment caused by dopamine dysregulation in the basal ganglia. Amongst a host of cognitive deficits, evidence suggests that decision-making is impaired in patients with PD, but the exact scope of this impairment is still unclear. The aim of this review was to establish which experimental manipulations commonly associated with studies involving decision-making tasks were most likely to generate impairments in performance in PD patients. This allowed us to address the question of the exact scope of the decision-making deficits in PD and to hypothesize about the role of the basal ganglia in decision-making processes. We conducted a meta-analysis of available literature, which revealed that the two key predictors of impairment in PD were the feedback structure of the decision-making task and the medication status of patients while performing the tasks. Rather than a global impairment in decision-making ability, these findings suggest that deficiencies in choice-behaviour in patients with PD stem from dysfunctions at the outcome evaluation stage of the decision-making process.

Event-related potentials and cognition in Parkinson’s disease: An integrative review

“…While PD patients have been repeatedly demonstrated to be impaired on tasks that require adaptive decisions among a set of options, this deficit does not seem to be a general one (Ryterska et al, 2013). First, decision-making in PD typically improves when patients are tested off their dopaminergic medication (e.g., Cools et al, 2003).…”

“…Then, the outcomes of the chosen action need to be evaluated in order to update value representations for future decisions (Rangel et al, 2008). A recent meta-analysis suggests that PD-related decision-making deficits can largely be attributed to alterations in this latter process of feedback evaluation (Ryterska et al, 2013).…”

Decisions, Decisions: The Neurobiology of the effects of Dopamine Replacement Therapy on Decision-Making in Parkinson’s Disease

“…These findings might be related to earlier discussion of disrupted feedback processing. A meta-analysis by Ryterska et al (2013) concurred with this hypothesis, concluding that when feedback is explicit, decision-making is more likely to be affected by DRT in PD. Likewise, as mentioned, risky behaviour in PD disappeared when explicit feedback was removed in a gambling task (Labudda et al, 2010).…”

“…Researchers have found some mixed results on this task; in some studies, patients perform equally as well as healthy controls and, in others, they perform worse (Ryterska et al, 2013). Additionally, different studies have implicated different brain regions in the IGT.…”

“…Thus, it may be puzzling why Mrs. A, and many others with PD, show poor decision-making, high impulsivity, and impaired reward-processing (Weintraub et al, 2010). Dopamine replacement therapy (DRT) in the form of levodopa and dopamine agonists are largely successful in reducing the motor symptoms seen in PD, by targeting the dramatic degradation of dopamine-producing neurons in the substantia nigra pars compacta (Clark & Dagher, 2014;Ryterska, Jahanshahi, & Osman, 2013). However, any manipulation of dopamine levels in the substantia nigra has knock-on effects for interconnected frontostriatal regions involved in decision-making (Zgaljardic, Borod, Foldi, & Mattis, 2003).…”