Decision-making impairments in patients with pathological gambling

Abstract

Pathological gambling (PG) is most likely associated with functional brain changes as well as neuropsychological and personality alterations. Recent research with the Iowa Gambling Task suggests decision-making impairments in PG. These deficits are usually attributed to disturbances in feedback processing and associated functional alterations of the orbitofrontal cortex. However, previous studies with other clinical populations found relations between executive (dorsolateral prefrontal) functions and decision-making using a task with explicit rules for gains and losses, the Game of Dice Task. In the present study, we assessed 25 male PG patients and 25 male healthy controls with the Game of Dice Task. PG patients showed pronounced deficits in the Game of Dice Task, and the frequency of risky decisions was correlated with executive functions and feedback processing. Therefore, risky decisions of PG patients might be influenced by both dorsolateral prefrontal and orbitofrontal cortex dysfunctions.

Introduction

One of the most common problems of everyday life of patients with pathological gambling (PG) is uncontrolled and excessive financial risk-taking behavior leading to financial and social troubles. However, the underlying processes of risky decisions in PG are still unresolved. So far, only a few investigations have directly addressed neuropsychological correlates of decision-making and associated functions in PG. In this context, some studies suggest attentional and executive dysfunctions in PG patients (e.g. Rugle and Melamed, 1993, Specker et al., 1995). Cavedini et al. (2002b) administered a laboratory test assessing decision-making under ambiguous conditions (the Iowa Gambling Task; Bechara et al., 1994) in PG and found deficits in their sample. This task requires participants to choose between four different alternatives, each of which is associated with different gains and losses. Subjects have to learn to make advantageous decisions without having explicit knowledge about the rules of the game from the beginning of the task. Several studies employing this task revealed decision-making deficits in a wide range of neurological or psychiatric patients, such as patients with orbitofrontal/ventromedial prefrontal cortex lesions (Bechara et al., 1998, Bechara et al., 2000, Manes et al., 2002, Fellows and Farah, 2005), patients with frontal lobe dysfunctions due to substance addiction (Bechara et al., 2001, Bechara and Damasio, 2002, Bechara et al., 2002, Bechara and Martin, 2004), patients with Parkinson's and Huntington's disease (Stout et al., 2001, Thiel et al., 2003), schizophrenia (e.g. Whitney et al., 2004), obsessive-compulsive disorder (Cavedini et al., 2002a) or anorexia nervosa (Cavedini et al., 2004). The PG sample of Cavedini et al. (2002b) showed highly similar decision-making impairments compared with those of frontal lobe damaged patients. They further described a dissociation of poor Iowa Gambling Task performance from intact executive functions as assessed with the Wisconsin Card Sorting Test (WCST).

However, executive functions might have a substantial impact on decision-making processes if rules for reinforcement and punishment were explicitly told to the subjects and the outcome was defined by probabilities. Previously, we have shown that in a gambling task with explicit rules, the Game of Dice Task, decision-making is strongly related to executive functions measured with the WCST, i.e., in patients with Korsakoff's syndrome (Brand et al., 2005a) or with Parkinson's disease (Brand et al., 2005b). In the present study, we examined decision-making abilities of PG patients in a gambling task with explicit rules and predicted that deficits in this task would be correlated with performance in executive tasks.