The overarching goal of this project is to test the hypothesis that impulsivity underlies pathological eating inobese participants with Binge Eating Disorder (BED). Our model proposes that binge eating is analogous todrug addiction, and impulsivity is an underlying factor in these addictive behaviors. Studies on patients withbulimia nervosa have reported greater impulsivity compared to normal controls, and there is an associationbetween poor treatment response and high impulsivity in bulimics. There has been less work with BED andobese individuals; however, impulsivity might be expected to play a prominent role in excessive eating. Thishypothesis is supported in a recent study indicating that women with BED show greater motor impulsivity onthe Barratt Impulsivity Scale compared to those without BED (Nasser et al. 2004). In the proposed study, thecognitive and motor forms of impulsivity will be tested in participants with and without BED, using delaydiscounting (DD) and Go/No-go tasks, neurocognitive and personality tests, sweet-preference testing andmagnetic resonance imaging (MRI) to test whether the impulsivity is associated with underlyingneurobiological abnormalities in BED patients and controls. Magnetic resonance spectroscopy (MRS) will beused to measure brain GABA levels with BED, and diffusion tensor imaging (DTI) will be used to observewhite matter abnormalities that have been found in cocaine abusing individuals. Imaging results will berelated to personality, impulsivity, and neuropsychological data, thus investigating the neurobiological roots ofimpulsivity in BED. BED and control groups will also be tested for sweet-taste preference, as preference forsweets is predictive of impulsive behavior and various forms of drug abuse.
The specific aims for this projectare: 1) To assess impulsivity in participants with BED compared to weight-matched controls by theirperformance on DD and Go/No-go tasks and to relate the results to personality instruments, neurocognitivemeasures, sweet preference, and imaging results. Comparisons will also be made to cocaine-usingparticipants and controls in Project 2, 2) To assess white matter microstructure in participants with BED andcontrols using DTI measures, 3) to assess brain GABA in participants with BED and controls by employingMRS and correlating results with duration of illness as well as measures of impulsivity, personality andneurocognitive tests. Most of the proposed techniques have never been used in BED patients, and thefindings will prove useful in understanding the relationship between BED, cocaine addiction, and impulsivity.These findings may aid in early screening of BED, prevention of obesity, and development of behavioral andpharmacological treatments for obese individuals.
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