Why Are Drugs Abused By Humans?

Psychiatric Times February 2005 Vol. XXII Issue 2

At the New York Academy of Medicine's 71st annual Thomas William Salmon Lecture, Nora D. Volkow, M.D., director of the National Institute on Drug Abuse (NIDA) told attendees that she has been obsessed with trying to understand what neurobiological changes explain aberrant behavior in addictive people. "We don't know to what extent changes in people who are addicted are effects of chronic drug exposure, effects of genes that predispose them to become addicted or effects of the environment that facilitate the translation of addiction," she explained. "I'm going to start to try to dissect those elements."

Delivered last December, Volkow's talk, "Addiction: The Neurobiology of Behavior Gone Awry," focused on imaging studies exploring what role--if any--the brain's dopamine(Drug information on dopamine)rgic system has on addiction (Volkow et al., 2004). In introducing Volkow, John M. Kane, M.D., called her a "national treasure" with more than 300 peer-reviewed publications as well as a key role in setting national drug policy and NIDA's research agenda. She formerly held three concurrent positions at Brookhaven National Laboratory and was the first to use imaging to investigate neurochemical changes occurring in the human brain during drug addiction.

Volkow said her group began studying dopamine two decades ago because it was known that drugs of abuse, whether legal or illegal, increase that neurotransmitter in specific brain areas--increases that appear crucial for reinforcing effects.

"This property has been recognized as indispensable in the characteristic a drug has to have to induce repeated administration, but what's not understood is whether dopamine is involved in the loss of controls toward drug administration that occurs with addiction," she said. "I'm going to concentrate only on dopamine D2 receptors … because it's one of the [areas] where we've seen consistent abnormalities across drug addictions."

Volkow first described an imaging study of inpatients who abused cocaine and whose brains were scanned about a month after the last use of cocaine and again three months later (Volkow et al., 1990). Results documented that decreases in D2 receptors shown in people addicted to cocaine as compared to controls persisted at least four months after last drug use.