Deepening the decisional processes under value-based conditions in patients affected by Parkinson's disease: A comparative study

Abstract

Patients affected by Parkinson's disease (PD) display a tendency toward making risky choices in value-based conditions. Possible causes may encompass the pathophysiologic characteristics of PD that affect neural structures pivotal for decision making (DM) and the dopaminergic medications that may bias choices. Nevertheless, excluding patients with concurrent impulse control disorders, results are few and mixed. Conversely, other factors, such as individual differences (e.g., emotional state, impulsivity, consideration for future consequences) and cognitive functioning, in particular executive functions (EFs), are involved, even though few studies investigated their possible role. The present study investigated (1) the differences in value-based DM between 33 patients with PD without impulse control disorders and 33 matched healthy controls, and (2) the relationships among decisional performances, EFs, and individual differences in a group of 42 patients with PD who regularly undertake dopaminergic medications. All participants underwent an individual assessment to investigate value-based DM, cognitive abilities, and individual differences associated with DM. Nonparametric analyses showed the presence of riskier decisions in patients compared with healthy controls, depending on the characteristics of the decisional situation. Moreover, parameters of the decisional tasks involving the number of risky choices were significantly related to the posology of dopaminergic medications, EFs, and individual differences. Findings were discussed, highlighting possible clinical implications.

Keywords: Decision making; Dopamine; Executive functions; Game of Dice Task; Iowa Gambling Task; Parkinson’s disease.

Fig. 1

Individual data points for the severity of disease assessed through the UPDRS III (N = 42)

Fig. 2

Correlations between decisional tasks (i.e., IGT and GDT), dopaminergic medications, neuropsychological tests, and emotional and behavioral differences. Note: CFC_fut = Consideration of Future Consequences Scale – future; DA_LEDD = levodopa equivalent daily dose of dopamine agonists; DASS_anxiety = Depression Anxiety Stress Scale – anxiety; DASS_depression = Depression Anxiety Stress Scale – depression; DB = digit span backward; DII_DI = Dickman Impulsivity Inventory – dysfunctional impulsivity; DII_FI = Dickman Impulsivity Inventory – functional impulsivity; FA = alternate fluencies; FP = phonemic fluencies; LCB_tot = locus of control of behavior; Ldopa_LEDD = levodopa equivalent daily dose of levodopa; SI = shifting index; Stroop_E = Stroop test errors; Stroop_T = Stroop test time; TAS_F1 = Toronto alexithymia scale – difficulty in identifying feelings; TAS_tot = Toronto alexithymia scale – total score