Of human bondage: food craving, obsession, compulsion, and addiction

Is it more than a linguistic accident that the same term, craving, is used to describe intense desires for both foods and for a variety of drugs of abuse? There is strong evidence for common pathways that are affected by most addictive drugs. As the other contributors to this volume will indicate, a strong case can also be made for some shared substrates for food and drug rewards in animals. There has been less explicit work on this topic in humans but many lines of evidence support the common mechanism view: Opioid peptides seem to influence food palatability for humans. There is mounting evidence for comorbidity between drug/alcohol abuse and excessive craving or liking for sweets. Anecdotally, elderly individuals tend to 'age-out' of drug abuse, and the elderly also experience markedly fewer food cravings with age. If we focus on the compulsive aspects of food and drug cravings, there is also evidence for overlap: for example, activity in the orbitofrontal cortex is associated with cocaine and alcohol craving. This area is also implicated in the pathology of obsessive-compulsive disorder. Although there is no direct evidence of orbitofrontal involvement in food cravings, there is indirect evidence such as higher than expected co-occurrence of obsessive-compulsive behavior and eating disorders. As a result of bringing together evidence for common substrates for food and for drug rewards, we hope to be able to advance fundamental knowledge of motivational processes and to promote the development of better treatments for drug addiction and for eating disorders.