Drug Addiction and Stress Have Similar Effects on the Brain

A study has found that addictive drugs and stress act on the ventral tegmental area of the brain to increase both production of dopamine and sensitivity of the neurons in the region. The study was published in the February 20, 2003, issue of Neuron.

Working with mice, investigators from the Stanford University Medical Center (Stanford, CA, USA; www.stanford.edu) observed that cocaine, morphine, amphetamines, nicotine, and alcohol all caused dopamine-producing neurons to become more sensitive to glutamate. Stress triggered an identical set of changes in the brain. On the other hand, drugs that affected the brain but were not addictive did not cause dopamine-producing neurons to become more sensitive. Treating mice with the glucocorticoid receptor antagonist RU486 protected the animals from the effects of stress but did not block the addictive activity of cocaine.

"What we have identified is a single change caused by drugs of abuse with different molecular mechanisms,” explained senior author Dr. Robert Malenka, professor of psychiatry and behavioral sciences at the Stanford University School of Medicine. Furthermore, while stress itself may not be addictive, it can cause a reformed addict to relapse. "When drug addicts who are in remission and are doing fine are subject to stress, they very often relapse,” Dr. Malenka said.




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Stanford University Medical Center