Impaired decision making among morbidly obese adults

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.

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.

Obese participants performed significantly 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.

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.