Early environmental stress and biological vulnerability to drug abuse.

It has long been believed that stress and drug abuse are related. Studies using animal models have repeatedly demonstrated that stressed animals more readily self-administer alcohol or other drugs. Similarly, human patients consistently report in clinical interviews that stress is one reason for taking drugs. There are also studies that document neurophysiological, neuroanatomical, neurochemical, and physiological changes to animals and humans who are stressed. Many of these changes occur within biological systems that are also affected by psychoactive drugs. Early response to stress also modifies neurodevelopment in permanent ways, and these neuroadaptations occur within the same neuronal systems which comprise the drug-reward circuit. But absent are studies in humans that link early stress and modifications of neurodevelopment with increased vulnerability to drug abuse. This article provides a glimpse of research relating stress to alteration of brain functions and to drug abuse, and points to the work of others in this volume for more details. We hope this attempt to understand how early stress affects the developing brain and increases vulnerability to drug abuse will lead to a new program of research in this emerging area.