Environmental Factor, April 2006, National Institute of Environmental Health Sciences
NIDA Director Delivers Spirit Lecture
By Colleen Chandler
Drug addiction is a disease of the brain, according to Nora Volkow, director of the National Institute of Drug Abuse. Volkow delivered the fifth annual Spirit Lecture on March 20 at NIEHS. The annual event honors "Women Sustaining the American Spirit." Volkow's talk was aimed at changing to way people think about drug abuse to ensure they understand the concept that they are dealing with a medical disease, not a lack of will.
Chronic exposure to drugs creates changes in the brain that causes addiction, which by definition, the person has no control over, she said. While vulnerability to drug addiction is partially genetically determined, exposure at certain stages, such as adolescence, is much more harmful than exposure at other stages. Drug abuse, Volkow said, is a developmental disease that often begins in adolescence, and sometimes in late childhood. In adolescents' developing brains, the target areas for drugs of abuse are significantly larger than in adults, while the areas that allow a person to inhibit emotion or suppress impulses is not fully developed in adolescence, she said.
It is extraordinarily important to recognize that the earlier someone begins taking drugs, the more severe the resulting addiction will be. Volkow also said environmental factors such as the availability of drugs, family support, poverty and crime, all play a role in either protecting or putting people at risk for drug abuse.
Animal studies have shown that if you stress an animal, it is more likely to take drugs, therefore, applying stressors is akin to stimulating drug abuse, she said. A primate study conducted by Wake Forest University researchers showed that dominant animals within the social structure had more dopamine receptors, are less likely to experience stress and less susceptible to drug addiction. By contrast, subordinate animals had fewer receptors and were more vulnerable to addiction. While human social structures are more complex, allowing an individual to be dominant in some areas of his or her life while being subordinate it others, the social environment and related stress clearly emerges as an important factor in addiction, Volkow said.
She said addressing the problem of addiction requires an approach that considers social factors, behavioral factors, neuronal circuits, protein expression and the genome. Only then can targeted interventions be created to protect people at greater risks for drug addiction, she said.
A physician and psychiatrist, Volkow was appointed director of NIDA in 2003. She pioneered the use of brain imaging to investigate toxic effects of drugs and the effects of drugs responsible for their addictive properties in the human brain.
Before joining NIDA, Volkow was a professor in the Department of Psychiatry and was associate dean of the medical school at the State University of New York - Stony Brook. She is a member of the National Academy of Sciences' Institute of Medicine.