Impaired decision making among morbidly obese adults ☆ Amy Brogan a, ⁎ , David Hevey a , Georgia O'Callaghan a , Ruth Yoder b , Donal O'Shea b a School of Psychology, Trinity College Dublin, Dublin, Ireland b St. Columcille's Hospital, Loughlinstown, Co. Dublin, Ireland Received 23 October 2009; received in revised form 18 May 2010; accepted 29 July 2010 Abstract Objective: The Iowa Gambling Task (IGT) measures affective decision making and has revealed decision making impairments across a wide range of eating disorders. This study aimed to investigate affective decision making in severely obese individuals. Methods: Forty-two (12 male, 30 female) morbidly obese participants (mean BMI=41.45) and 50 comparison participants (17 male, 33 female) matched for age, gender and education, completed the IGT. Results: Obese participants performed sig- nificantly worse on the IGT compared to the comparison group, with 69% of the obese group demonstrating clinically impaired decision making. There was no evidence of learning across the five trial blocks in obese participants, with significant differences between the groups emerging in blocks 3, 4, and 5. IGT impairment was unrelated to BMI or eating pathology. Conclusion: Obese participants were significantly impaired on the IGT. The pattern of performance suggested a potential inability to maximise an immediate reward or program a delayed reward. The findings support the view that common decision making impairments exist across disordered eating populations. Future research is required to specify the source and mechanisms of these decision making deficits. The logical progression of this research is the development of interventions which improve decision making capacity and measure subsequent impact on psychological and physical outcomes. © 2011 Elsevier Inc. All rights reserved. Keywords: Choice behavior; Cognition; Decision making; Iowa Gambling Task (IGT); Obesity Introduction The obesity epidemic Increases in the prevalence of overweight and obesity among both adults and children have been observed worldwide, with such increases closely associated with increasing energy supply per capita in Western countries. In the United States, between 1980 and 2002, obesity prevalence doubled in adults 20 years or older [1], with the most rapid increase seen in those considered extremely obese [i.e., body mass index (BMI) ≥40] [2]. Addressing the neuropsychological basis of decision making in an obese population may help explain the rise in obesity. Decision making and the Iowa Gambling Task (IGT) Patients with ventromedial prefrontal cortex (VmPFC) lesions show severe impairments in personal and social decision making, despite otherwise normal intellectual function. These patients are described as having “myopia” for the future, oblivious to the consequences of their actions, with behavior guided largely by immediate rewards [3]. Damasio's [4] work with VmPFC patients formed the basis of his Somatic Marker Hypothesis (SMH), which regards decision making as a dual combination of “high reason” or logic, and emotion-based biasing signals or “somatic markers” that help regulate decision making in situations of complexity or uncertainty [5]. The IGT is a card game that tests the ability to postpone immediate Journal of Psychosomatic Research 70 (2011) 189 – 196 ☆ This research was funded by the Irish Research Council for the Humanities and Social Sciences (IRCHSS). ⁎ Corresponding author. School of Psychology, Trinity College Dublin, Dublin, Ireland. Tel.: +353 1 896 2970; fax: +353 1 671 2006. E-mail address: broganam@tcd.ie (A. Brogan). 0022-3999/10/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2010.07.012