Some People May Be Predisposed to Substance Abuse

According to scientists, drug addicts may be born, not made. A new study has found that some people are predisposed to drug addiction because of the way their brains operate.

The researchers studied rats dependent on cocaine to help come to their conclusions. The findings pinpoint a hidden vulnerability that made the rats more impulsive and more likely to become dependent on a drug.

Specifically, the rats that compulsively self-administered cocaine intravenously were more likely to have fewer brain cell surface receptors for the neurotransmitter dopamine in an area of the brain called the nucleus accumbens. This is in comparison to rats that were less prone to addiction.

"The study is the first to conclusively demonstrate that changes in dopamine receptors in the nucleus accumbens pre-date cocaine use," said lead researcher Dr. Jeffrey Dalley of Cambridge University's Behavioral and Clinical Neuroscience Institute in the U.K.

The findings are published in the March 2 issue of the journal Science.

"We have known for a long time that some behaviors are associated with drug addiction - such as impulsivity and risk taking in general," said Gerome Breen, an addiction researcher at the Institute of Psychiatry, King's College London. "What this study does is identify a biological basis for the behavior and the mechanism by which it leads to addiction."

Although Dr. Breen was not involved with the research, he said that even though the brain defect makes rats more vulnerable to drug addiction, the findings could not be used to specifically identify people as born addicts.

Along with helping scientists to understand and treat addiction, the findings could lead to a simple blood test to alert doctors and parents as to whether a child has the predisposition to become an addict.

Researchers agree that drug addiction and impulsivity are linked but it has been unclear until now which comes first.

Understanding the neurological changes that help trigger and sustain addiction is a key to developing effective prevention and treatment of addiction. Studies have noted a large number of differences in the brain of a drug addict and a healthy person, but "it's been basically impossible to know which ones were there before they started to take the drug and which were a consequence of the exposure to the drug," said Dr. Nora Volkow, director of the U.S National Institute on Drug Abuse.

The next step in the research will involve investigating which genes lead to the deficit.

Sources:
http://society.guardian.co.uk/drugsandalcohol/story/0,,2024916,00.html
http://www.lex18.com/Global/story.asp?S=6164452&nav=EQls
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/03/02/nscience02.xml