Decisional impulsivity in obesity

Introduction: Elevations in impulsivity have been clearly shown in various psychiatric conditions, especially in those of addiction. Evidence does suggest some overlap between the pathological use of food and drugs but no clear evidence to date has been made available with regards to obesity. In this study we hypothesize that obese subjects would have relatively more impulsive profiles when compared to healthy volunteers. Method: Delayed discounting is also studied by means of the Monetary Choice Questionnaire, also hypothesizing impairments in this subtype of impulsivity. Results: Obese subjects sought less evidence prior to making a decision when compared to healthy controls. Greater delayed discounting was also evident in this cohort of subjects as compared to healthy ones. Premature responding was not shown to occur in the obese subjects. Conclusion: Obesity is therefore characterized by impaired reflection impulsivity and greater delayed discounting. Both suggest a deficit in deciding on the basis of future outcomes that are more difficult to represent. This evidence could suggest possible therapeutic domains which need targeted interventions on the aspects of decision making deficits.peer-reviewe

Reward sensitivity and waiting impulsivity: shift towards reward valuation away from action control

Background Impulsivity and reward expectancy are commonly inter-related. Waiting impulsivity, measured using the rodent 5-Choice Serial Reaction Time (5-CSRT) task, predicts compulsive cocaine seeking and sign (or cue) tracking. Here we assess human waiting impulsivity using a novel translational task, the 4-CSRT, and the relationship with reward cues. Methods Healthy volunteers (n=29) performed the monetary incentive delay task as a functional MRI study where subjects observe a cue predicting reward (cue) and wait to respond for high (£5), low (£1) or no reward. Waiting impulsivity was tested with the 4-CSRT. Results For high reward prospects (£5 – no reward), greater waiting impulsivity on the 4-CSRT correlated with greater medial orbitofrontal cortex (OFC) and lower supplementary motor area (SMA) activity to cues. In response to high reward cues, greater waiting impulsivity was associated with greater subthalamic nucleus connectivity with OFC and greater subgenual cingulate connectivity with anterior insula but decreased connectivity with regions implicated in action selection and preparation. Conclusion These findings highlight a shift towards regions implicated in reward valuation and a shift towards compulsivity away from higher level motor preparation and action selection and response. We highlight the role of reward sensitivity and impulsivity, mechanisms potentially linking human waiting impulsivity with incentive approach and compulsivity, theories highly relevant to disorders of addiction.status: publishe