Rat study suggests why teens get hooked on cocaine more easily t...( WASHINGTON New drug research sugges...),Health

WASHINGTON New drug research suggests that teens may get addicted and relapse more easily than adults because developing brains are more powerfully motivated by drug-related cues. This conclusion has been reached by researchers who found that adolescent rats given cocaine a powerfully addicting stimulant were more likely than adults to prefer the place where they got it. That learned association endured: Even after experimenters extinguished the drug-linked preference, a small reinstating dose of cocaine appeared to rekindle that preference but only in the adolescent rats.

The research, performed at McLean Hospital, Harvard Medical Schools largest psychiatric facility, was reported in the April issue of Behavioral Neuroscience, published by the American Psychological Association.

Evidence that younger brains get stuck on drug-related stimuli reinforces real-world data. Epidemiological studies confirm that of people in various age groups who experiment with drugs, teens are by far the most likely to become addicted. Thus, the new findings may be useful in developing new treatments for youthful addiction.

In the study, psychologists Heather Brenhouse, PhD, and Susan Andersen, PhD, who directs McLeans Developmental Psychopharmacology Laboratory, introduced rats that were 38 or 77 days old (equivalent to 13 or 20 human years) to an apparatus with one central and two larger side chambers that had different flooring, wall colors and lighting. For three days in a row, the researchers injected the rats with saline solution in the morning and placed them in one side chamber for an hour. Four hours later, they injected them with a preference-forming dose of cocaine (either 10 or 20 mg per kg of weight, to assess two doses known to be habit-forming) and placed them in the opposite-side chamber for an hour. Conditioning this way kept the rats from associating the symptoms of withdrawal with the non-drug chamber.

On Day 4, the
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