Reexamining Decision-making Behaviors of Schizophrenia on Iowa Gambling Task: Insights from Expected Value and Gain-loss Frequency

Autor:	Mei Xu, 徐梅
Rok vydání:	2018
Druh dokumentu:	學位論文 ; thesis
Popis:	106 Many studies have shown that patients with schizophrenia (Sz) have gradual degeneration of executive function revealed by the Wisconsin Card Sorting Test (WCST). Recent studies have pointed out that schizophrenia may also exist decision-making dysfunction. And most studies apply the Iowa Gambling Task (IGT) to assess decision-making function under dynamic and uncertain conditions. Our study reviewed 38 relevent studies focusing on comparing IGT performance bewtween Sz and control(Ctrl). Based on the analysis of net score defined by the original IGT, there is a significant difference between Sz and Ctrl in 24 articles (63%) represented by Beninger et al. (2003), While 14 articles (37%) represented by Wilder et al. (1998) indicated no significant difference between two groups. Obviously, this revealed inconsisitent results among the literature of IGT performanc on schizophrenia. In order to elucidate the contradictory phenomenon, our research will carry out two studies: (1) Study one organized and analysed the IGT indicators of 38 articles, and observed the influence of different variables such as expected value and gain-loss frequency, and explored the relationship between these two views (expected value indicator and gain-loss frequent indicator (prominent deck B phenomenon)), so as to clarify the inconsistency of the literature. (2) Study two reexamined the validity of IGT indices between Sz and Ctrl in empirical experiments, and explored the correlations among decision-making behaviors, executive function and clinical symptoms. Study one included 38 articles and selected 18 articles which demostrated the tables or charts of four-deck choices in IGT. Study two recruited 61 schizophrenia patients (schizophrenia or schizoaffective disorder) diagnosed by psychiaists and 62 Ctrl participants. Each participant received computerized IGT and WCST, and Sz group additionally complete the Positive and Negative Syndrome Scale (PANSS) and the Personal and Social Performance Scale (PSP) evaluated by researchers. Study one indicated that expected value index and others can distinguish the difference between two groups. The IGT selection pattern of Sz in 18 literatures is relatively consistent and illustrated a robust prominent deck B phenomenon. However, the Ctrl’s selection pattern in 18 literatures is unstable, but still demonstrated prominent deck B phenomenon. Apparently, dependently obsevering the effect of expected value index might conceal the prominent deck B phenomenon. Study two reveals that no significant difference between two groups in terms of expectancy and the gain-loss frequency indicators. Therefore, most IGT indicators can’t distinguish the IGT performance between two groups. IGT performance of Sz and Ctrl both highlight with prominent deck B phenomenon. Additionally, it is notable that deck B and D of IGT and expected value index are correlated with partial indicators of WCST. Conversely, it is no significant correlation between IGT and PANSS and PSP, which is consistent with most of the literatures reviewed before. Study one finds gain-loss frequency impose a strong effect on selection pattern of Sz and Ctrl, and the inconsistency of IGT performance in the literature may results from the variation of the Ctrl rather than the Sz. Study two implies each index can’t distinguish the IGT patterns in two groups, but also shows IGT patterns largely influented by gain-loss frequency. Partial correlation exists between the IGT (decision-making) and WCST (executive function). According to the results of the two studies, gain-loss frequency exerts a dominant impact on IGT performance in two populations. Most behavioral indicators of IGT are not valid enough to discriminate the decision-making function between Sz and Ctrl. Yet, it is worth noting that the clinical version of IGT (Bechara, 2007 and 2016) still declares its reliable and valid to evaluate Sz, the clinical application of this assessment need to be revised urgently.
Databáze:	Networked Digital Library of Theses & Dissertations
Externí odkaz:	http://ndltd.ncl.edu.tw/handle/dx2twp Zobrazit plný text záznamu