Dissociation Of Decision Making Under Ambiguity And Decision Making Under Risk In Obsessive-Compulsive Disorder

Objective Obsessive-compulsive disorder (OCD) is a chronically debilitating disorder.Neurophysiological studies have found a series of impairments of cognition function inpatients with OCD, and deficit in domain of decision making is a prominent clinicalmanifestation. Some researchers even regard decision making impairments as the underlyingproblem of obsessive and compulsive symptoms. Neuroimaging and neurophysiologicalstudies also indicate the dysfunction of the orbitofrontal cortex (OFC) is associated with OCD,whereas results concerning changes in dorsolateral prefrontal cortex (DLPFC) activity areinconsistent. The aim of the current study was to investigate decision making under ambiguityassessed by the Iowa Gambling Task (IGT) and decision making under risk assessed by theGame of Dice Task (GDT) in OCD patients. Previous studies have shown performance on theIGT is related to the function of the OFC, and superior performance on the GDT is linked tointact functioning of the DLPFC. So another goal of our study was to discuss theneurobiological abnormalities in OCD.Methods Forty-five patients who met a DSM-IV diagnosis for OCD (recruited frominpatient and outpatient of Mental Health Center of Anhui Province) and forty-eight healthycontrol group (CG) subjects matched for age, gender, education were assessed by the IGT, theGDT and a neuropsychological test battery related to executive functions, including TrailMaking Test (TMT), Stroop Colour Word Test (SCWT) and Wisconsin Card Sorting Test(WCST). The Digit Span Test (DS) and Verbal Fluency Test (VF) were also assessed.Additionally, the OCD patients were measured by Yale-Brown Obsessive-Compulsive Scale(Y-BOCS), Hamilton Anxiety Scale (HAMA) and Beck Depression Inventory (BDI). The IGTincludes advantageous choices and disadvantageous choices, and the GDT includes riskyalternatives and non-risky alternatives. We investigated the total netscore on the IGT of thetwo groups by subtracting the number of disadvantageous choices from the number ofadvantageous choices, and the total netscore on the GDT by subtracting the number of risky alternatives from the number of non-risky alternatives. In this study, an attempt has beenmade to study the influence of the severity of symptoms on the IGT and the GDT within theOCD patients. Moreover, we investigated whether medicated and unmedicated OCD patientsperform differently on the IGT and the GDT.Results The OCD patients (4.80±16.55) performed inferior compared with the CG (3.12±16.39) on the IGT (t=2.32, p=0.023), however, performances of the two groups had nodifferences on the GDT (OCD:4.76±10.08; CG:2.67±11.95, t=0.91, p=0.366). Andperformances of the two groups had no differences on TMT, SCWT, WCST, DS and VF (allP>0.05). Additionally, performances of the OCD patients on the IGT and GDT were notrelated to age of onset (r=-0.05,-0.20), duration of illness (r=0.02,-0.14), Y-BOCS (r=0.01,0.12), HAMA (r=-0.03,-0.06) and BDI (r=0.09,0.08)(all P>0.10), and medicatedvs. unmedicated patients with OCD performed on the IGT [(-4.34±16.20) vs.(-5.62±16.43),t=1.54, p=0.131)] and the GDT [(3.92±10.48) vs.(5.89±9.65), t=0.64, p=0.523]at a comparable level.Conclusion While OCD patients are impaired on decision making under ambiguity, theyare unimpaired on decision making under risk. There is a clear dissociation of decisionmaking under ambiguity and decision making under risk in OCD patients. Our results alsoindicate decision making under ambiguity and decision making under risk are differentcognition process, and emphasize dysfunctions of the OFC and intact functioning of DLPFCin patients with OCD.