Iowa gambling task in schizophrenia : an examination of the effect of tobacco-smoking in risk/reward decision making

Abstract

Background: Cognitive deficit is prominent in schizophrenia patients. We investigated the decision-making ability among schizophrenia patients and healthy controls based on their performance in the Iowa Gambling Task (IGT), a laboratory task developed for measuring individuals’ decision-making ability. We hypothesized that deficits in IGT performance in schizophrenia patients could be specifically ameliorated by smoking tobacco. In order to test this hypothesis, we compared smoking and non-smoking schizophrenia patients with healthy subjects, on their IGT performance.

Method: Ten smokers with schizophrenia, 9 non-smokers with schizophrenia, 16 non-psychiatric non-smokers and 7 non-psychiatric smokers were administered the computerized version of IGT. The Fagerstrom Test for Nicotine Dependence (FTND) was used to assess the degree of smoking dependence of subjects and to group the smokers and non-smokers.

Results: Subjects with schizophrenia performed significantly worse than non-psychiatric controls on IGT. Moreover, smokers with schizophrenia performed significantly better than non-smokers in the task. Furthermore, when comparing IGT performance of all the 4 groups, non-psychiatric non-smokers performed significantly better than psychiatric smokers in the IGT.

Conclusions: Similar to the results of previous research, schizophrenia patients performed worse than controls in the IGT, suggesting impairments in risk/ reward decision-making. Cigarette smoking may partially ameliorate schizophrenia patients’ performance deficits on neurological tasks, including the IGT. These findings on schizophrenia patients are clinically important since it is believed that the ability to make timely and correct decisions can result in good treatment compliance and coping strategies thus facilitates recovery. Last but not least, further research is needed to explain how smoking tobacco facilitates cognitive functioning in schizophrenia patients.