This special Focus issue of Nature Reviews Neuroscience explores our current understanding of addiction. The issue opens with a Review on page 623 by Robison and Nestler that examines how drugs of abuse can alter the transcriptional potential of genes. This phenomenon may partly underlie the long-term changes in the brain that are seen with chronic drug abuse. The prefrontal cortex is one brain region that has recently been implicated in addiction. On page 652, Goldstein and Volkow review functional imaging studies that have shown that compulsive drug taking and other aspects of addiction can result from disruption to this region. In a Review on page 638, Paul J. Kenny explores the neural circuits that regulate the hedonic properties of food and addictive drugs. He highlights that both obesity and drug addiction may share underlying mechanisms. By contrast, Badiani and colleagues explore the behavioural, cognitive and neurobiological differences between opiate addiction and psychostimulant addiction in a Perspective on page 685. They stress that these differences have implications for addiction theories and treatment strategies. Lastly, on page 670 Heilig and colleagues review the influence of genetic heterogeneity on treatment responses in alcohol addiction, and suggest that genotype-based personalized therapies may improve the treatment of this condition.

Thanks to support from the National Institute on Alcohol Abuse and Alcoholism (NIAAA) and the National Institute on Drug Abuse (NIDA), National Institutes of Health, US Department of Health and Human Services, the articles in this issue are freely available online for 3 months at We hope that you enjoy this Focus issue, and to those of you heading to the Society for Neuroscience's annual conference, we look forward to meeting you in Washington, DC.