Learned Associations May Heighten Teens' Risk of Cocaine Addiction
> 4/23/2008 12:40:47 PM

Adolescents who try cocaine are more likely than adults to become addicted to the substance, and a new study appearing in the April issue of Behavioral Neuroscience may help explain why. Using rats, researchers from Harvard Medical School's McLean Hospital found that learned associations related to the drug may be especially influential on the teenaged brain and provide motivation for continued drug use.

Over the course of three days, the researchers injected rats with cocaine (either 10 or 20 mg per kg of weight) and placed them within a special apparatus consisting of a main room and two side rooms that were designed to look different from each other. The rats were conditioned to associate cocaine with a specific room, and when they no longer had cocaine in their systems and were allowed to roam the apparatus freely, they displayed a clear preference for the room where they had received cocaine injections. Next, the researchers measured the amount of time necessary to undo this learned association. After stopping the cocaine injections, they continued to place the rats within the apparatus each day, and the results illustrated age-related differences. When compared to older rats (whose age corresponded to 20 human years), younger rats (equivalent to 13 human years) needed 75 percent more trials before they lost their preference for the cocaine-associated room.

To further examine the differences between younger and older rats, the researchers tested whether the cocaine-related preference could be reestablished after having been extinguished. This time, they injected the rats with a smaller dose of cocaine (5 mg per kg). Among rats who had initially received a 20 mg per kg dose, the likelihood of showing renewed preference for the cocaine-associated room was equal. But of those who had first received a 10 mg per kg dose, the younger rats were much more likely to experience renewed preference, an indication that, compared to adults, teens may be more vulnerable to cues associated with smaller doses of cocaine, and these cues may also prove more difficult to eradicate.

The teenaged brain is still developing, and this may help explain why the context of drug use could have a greater affect on teens' subsequent behaviors than on adults'. The frontal cortex may be especially important, as prior research conducted by the McLean Hospital researchers indicates. Recently, they demonstrated that adolescent rats have greater expression of dopamine, a neurotransmitter implicated in addiction, in the prefrontal cortex than younger and older rats. This may make teens more likely to develop strong preferences for stimuli associated with the release of dopamine, which, the researchers surmise, could include people, places, or events.

The factors involved in teenaged addiction may differ in important ways from those that affect adults, and by investigating these differences, researchers may be able to point toward effective treatment strategies for specific subgroups. This study indicates that teens may become addicted more easily than adults and have a higher risk of relapse, and the researchers suggest that longer treatment programs could help teens to avoid drug-related cues and overcome their addictions. More research on the ways in which context and associations influence drug use is called for, and as we learn more about factors that contribute to drug addiction in teenagers, we will be better able to address their specific needs.

No comments yet.

Post Your Comments

Post a comment
Email Address:
Verification Code:
Input the 8 characters you see above:


Drug Abuse
Sexual Addiction
Eating Disorders
Alzheimer's Disease

About TOL | Contact Us | Defining Behavioral Fitness | For Healthcare Professionals | Links | Privacy Policy