NIDA Director: Research Shows Substance Disorder a Chronic Disease

Nora Volkow, MD, receives the John P. McGovern, MD, Award from Louis E. Baxter, Sr., MD, FASAM, ASAM Acting Immediate Past President.

Nora Volkow, MD, receives the John P. McGovern, MD, Award from Louis E. Baxter, Sr., MD, FASAM, ASAM Acting Immediate Past President.

Nora Volkow, MD, has had a respected career as a leading researcher in how addiction affects the brain, and as Director of the National Institute on Drug Abuse she has focused her efforts on how some brains react to drugs of abuse. Saturday, she shared some of her scientific findings when she delivered the John P. McGovern, MD, Award and Lecture on Addiction and Society.

“My main mission is to change the culture and the view of substance use disorder so it is accepted as a medical disease,” Dr. Volkow said when she delivered her address during the ASAM Annual Awards Luncheon. Public perception that addiction is a social, moral, or criminal problem is shifting largely thanks to Dr. Volkow’s landmark work in defining addiction as a disease of the brain. She said she has used her studies to “come to understand the abnormalities of the brain” of people when they use drugs of abuse.

Drugs of abuse increase DA (dopamine) in the nucleus accumbens, which is believed to trigger the neuroadaptions that result in addiction, reported Dr. Volkow, who has used brain imaging to investigate the effects of drugs of abuse. Her studies have documented changes in dopamine production that affect functions in the frontal brain regions associated with motivation, drive and pleasure in addiction.

“How are different brain circuits regulated by DA involved in addiction?” she asked.

She answered that question by showing that cocaine abusers had lower dopamine increases and reduced reinforcing responses to methylphenidate. Brain scans of alcoholics also showed a decreased dopamine release and decreased reinforcing responses to methylphenidate.

Memory/conditioning studies in rats have shown that when they received a neutral stimuli with a drug, it elicited dopamine increases and reinstated drug self-administration. This demonstrates the relationship between increased dopamine production and drug craving when there is an underlying addiction.

In human subjects, cocaine abusers who were shown a video of cocaine scenes had decreased binding of [11C]raclopride, presumably a result of dopamine increases. This showed that cue-induced increases in dopamine are associated with craving.

This is “fundamental” in the understanding of how addiction affects the brain , Dr. Volkow said.

“This means a person addicted to a drug will have an automatic release of dopamine in response to environmental cues or what we understand as craving,” she said, and this craving “activates the urge to get a drug.”

In a study of addiction and the motivation and executive control circuits of the brain, changes in dopamine function were linked with disruption of frontal lobe activity. This was assessed by multiple tracer studies that evaluated the dopamine D2 receptors and brain glucose metabolism in subjects with addiction. Researchers found that the overexpression of dopamine D2 receptors reduces alcohol-self-administration.

“This makes us realize that these are not diseases where you have abnormality in one brain region,” Dr. Volkow said. “Addiction is a disease that disrupts multiple functional networks that are crucial … in making a decision.”

With this knowledge, researchers now can look for ways to counter what is happening to the brains of individuals with addictions, she said.

“It identifies the need for multiple approaches that will enable us to strengthen those circuits that are weakened by addiction,” Dr. Volkow said. “We may ultimately be able to use more medications to strengthen them.

“Substance disorder is a chronic disease. And it needs to be treated that way.”