Addiction is a brain disease, and it matters
Leshner, A. I (1997)
Science, 278

Abstract

Drug addiction is a chronic, relapsing disease that results from the prolonged effects of drugs on the brain. Addiction has embedded behavioural and social-context aspects that are important parts of the disorder itself. Therefore, the most effective treatment approaches will include biological, behavioural, and social-context components.

Introduction

Scientists have identified neural circuits that subsume the actions of every known drug of abuse, and they have specified common pathways that are affected by almost all drugs. They have also identified and cloned the major receptors for virtually every abusable drug, as well as the natural ligands for most of those receptors. Research has begun to reveal major differences between the brains of addicted and non-addicted individuals and to indicate some common elements of addiction.

Drug abuse and addiction as public health problems

Drug abuse is a dual-edged health issue, as well as a social issue. It affects both the health of the individual and the health of the public. Drug use, directly or indirectly, is a major vector for the transmission of many serious infectious diseases. Because of this, we must include in our overall strategies a committed public health approach, including extensive education and prevention efforts, treatment, and research.

What matters in addiction

It doesn’t matter what physical withdrawal symptoms, if any, occur. Many of the most addicting and dangerous drugs do not produce severe physical symptoms upon withdrawal.

What matters is whether or not a drug causes the essence of addiction, compulsive drug seeking and use, even in the face of negative health and social consequences. These behaviours are the elements responsible for the massive health and social problems that drug addiction brings in its wake. The treatment should be directed to this.

Addiction is a brain disease

Virtually all drugs of abuse have common effects, either directly or indirectly, on a single pathway deep within the brain. This is the mesolimbic reward system.

Acute drug use modify brain function in critical ways. Prolonged drug use causes pervasive changes in brain function that persist long after the individual stops taking the drug. Significant effects of chronic use have been identified for many drugs at all levels.

Initially, drug use is a voluntary behaviour, but when the changes in the brain are made, the individual moves into a state of addiction.

A major goal of treatment must be either to reverse or to compensate for those brain changes. This can be accomplished through either medications or behavioural treatments.

Not just a brain disease

Addiction is not just a brain disease. It is a brain disease for which the social contexts in which it has both developed and is expressed are critically important. Exposure to conditioned cues can be a major factor in causing persistent or recurrent drug cravings and drug use relapses even after successful treatment.

The behavioural and social cue components must also be addressed when treating addiction.

A chronic, relapsing disorder

For most people, addiction is a chronic, relapsing disorder.