A research conducted by Roh-Yu Shen, a researcher at the University at Buffalo’s Research Institute on Addictions (RIA), has discovered that a change in the brain that occurs after drug use, may further add to drug addiction.
The latest finding has been reported in the January 2007 issue of the journal Biological Psychiatry. The research showcases that that repeated exposure to different types of drugs of abuse such as cocaine, nicotine, amphetamine, and alcohol lead to a constant or long-term reduction in the electrical activity of dopamine neurons in the brain.
Dopamine neurons are the origin of the reward pathway responsible for the “feel good” experience that is such a strong component of drug use and abuse.
Roh-Yu Shen, Ph.D., a neuroscientist and the lead investigator on the study, states, “A persistent reduction in dopamine neuron electrical activity after repeated exposure to different types of drugs appears to be the result of excessive excitation of dopamine neurons. This represents a new and potentially critical neural mechanism for addiction and provides a working model that suggests how the reward pathway function is altered and how these changes can be responsible for triggering intense craving and compulsive drug-seeking.”
Initial exposure to drugs of abuse causes dopamine neurons to release dopamine in target areas of the brain that provide the reward effect of using drugs. Repeated abuse of drugs results in long-lasting changes in the function of the reward pathway that leads to craving for drugs and the compulsion for more drugs.
Shen is a senior research scientist at RIA and holds adjunct appointments in the Department of Pathology and Anatomical Sciences in the UB School of Medicine and Biomedical Sciences and Department of Psychology in the UB College of Arts and Sciences. Her colleagues on this study include Kar-Chan Choong, RIA research assistant, who performed the experiments, and Alexis C. Thompson, Ph.D., RIA research scientist and research associate professor in UB’s Department of Psychology.
According to the Shen, the constant or long-lasting nature (3-6 weeks in animal models equivalent to approximately two years in humans) of this effect helps to explain why it is so difficult to abstain from using cocaine, nicotine, amphetamine and alcohol. In addition, she added, it is a time-dependent effect that is not seen immediately after drug use, but rather is evident over a period of time following drug use and intensifies over time.
Shen and colleagues have concluded that the persistent reduction in dopamine activity parallels the long-lasting nature of addictive behaviors, including intensified craving and compulsive drug-seeking behavior. The next step is for treatment researchers to develop treatment protocols that develop on this biological finding.