The Study Of Intertemporal Decision-making Of Schizophrenia And Their Unaffected Siblings

Background Intertemporal choices are decisions with consequences in multiple time periods and constitute a significant part of social cognition.The shared neuropathological characteristics of patients with schizophrenia and their siblings might express intermediate phenotypes in behavior that could be used to further characterize the illness.Objective We recruited schizophrenic patients,their unaffected siblings and age-,sex-and education-matched healthy controls and to explore whether the ability of intertemporal choice have impairment in schizophrenic patients,as well as the impairment of intertemporal choice still exists in their unaffected siblings to a certain degree.Method Schizophrenic patients(N = 25),their unaffected siblings(N = 25)and healthy controls(N =30)underwent a computerized version of the “Intertemporal choice” task,meanwhile carried out the “Delay-discounting” task and “Valuation” task.Participants chose between sooner-smaller(SS)and later-larger(LL)options in now-trials and in not-now-trials,and the proportion of LL(%)options was estimated from the participants’ responses.All the subjects received a battery of cognitive neuropsychological test assessment besides.Results In “Intertemporal choice” task,the schizophrenic patients showed a significantly preference to choose LL options across the three reward difference levels(small,intermediate,large)either in now-trials or not-now-trials compared with their unaffected siblings and healthy controls.Compared to healthy controls,schizophrenic patients and their unaffected siblings both had a tendency to choose larger-later reward(more patient choice)either in now-trials or not-now-trials,especially in small difference level.No significant difference between the schizophrenic patients and their unaffected siblings groups.In “Delay-discounting” task: the value of k:(schizophrenia(0.005±0.009),unaffected siblings(0.011±0.014),healthy controls(0.024±0.029))respectively.At the same time,the k between three groups had remarkable difference,especially three groups existed gradient effect and the differences were statistically significant(F=9.487,P<0.001).Compared with patients group and healthy controls,the k of schizophrenia and unaffected siblings both were significantly lower than that in the healthy controls,the differences were statistically significant(P<0.05);There were no significant differences between schizophrenia and their unaffected siblings(P<0.05).In valuation task,there were no significant differences between three groups.Moreover,the schizophrenic patients group demonstrated significantly lower scores in several cognitive tasks,including attention,executive functions and cognitive processing,when compared with the other two groups.Pearson correlation analysis not showed any relationship between neuropsychological test and the value of k.Conclusions The present study shows that schizophrenic patients and their unaffected siblings all have impairments in their intertemporal decision-making function,which prompt the intertemporal decision-making may be the trait-oriented impairment of the illness of schizophrenia.In addition,the finding may support that the patients and their unaffected siblings all have frontal-striatal network dysfunction in intertemporal choice task processing.Their intertemporal decision-making performance was associated with executive function performance.