Consequences of teenage drug abuse
November 30th 2010 20:59
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Teenage drug abusers may experience more severe consequences later in life than adults who abuse drugs.
Studies conducted by Joshua Gulley, assistant professor of psychology, assessed the effects of high doses of amphetamine, a psychostimulant present in drugs that treat ADHD, on rats at different stages of life. When rats were exposed to large amounts of amphetamines during adolescence, they exhibited impaired working memory as adults.
“This is a long-lasting change we are talking about,” Gulley said, explaining that the studies were designed to be comparable to assessing how amphetamine abuse in humans that occurs during teen years would affect working memory at around age 30.
Lee Cox, associate professor of molecular and integrative physiology, collaborated with Gulley to study the effects of drug abuse on neuron function and physiology in the prefrontal cortex, an area of the brain that is believed to be important for working memory and decision-making.
“We know that in adolescence the prefrontal cortex is very underdeveloped,” Gulley said.
He added that it’s one of the last brain regions to develop into its adult-like state, a process that continues into a person’s mid-twenties. Additionally, the prefrontal cortex is an area of the brain that is particularly vulnerable to experiences during adolescence.
In other words, a teenager’s brain is different from an adult’s brain, and likewise, one would expect drugs to affect them differently. These differences are precisely what Gulley and co-workers have set out to discover.
“Much of the animal research has not been done on young animals because for a long time the assumption was the adult brain was basically the same as the adolescent brain,” Gulley said. “What we’ve realized over the past ten or so years is that’s completely not true.”
Studies on the effects of drugs on adolescents are especially important because most drug abusers have their first exposure to drugs while in their teens, Gulley said.
Gulley emphasized that the studies performed thus far look at the effects of high drug doses, comparable to levels that would be used if someone was abusing the drug.
Additional studies would be needed to determine the long-term effects of amphetamine doses comparable to those prescribed in drugs such as Adderall, which is used to treat ADHD.
The first round of studies on the effects of amphetamines on rats involved testing some animals for behavioral changes, and others for changes in neuronal physiology.
In the next round of studies, Gulley says they hope to discover how individual differences in animals affect the way they respond to drugs. To do so, they will simultaneously study the changes in behavior and physiology after adolescent drug exposure.
They expect to see rats with more disordered brain physiology having greater behavioral disorders, Gulley said. This observation would support the idea that neuronal changes are associated with, and perhaps causative of, the adverse effects on memory that have been observed in rats after adolescent drug exposure.
Luke Sherrill, a psychology graduate student who works with Gulley, studies the effects of alcohol abuse on rats with the goal of understanding its long-term ramifications.
Performed in collaboration with Janice Juraska, professor of psychology, studies thus far support the idea that “adolescent alcohol exposure can produce unique changes on the way neurons communicate and the way the brain develops in general,” Sherrill said.
Being on a college campus and observing how many students get into alcohol and other drugs, Sherrill says he became interested in understanding what happens in the brain as a result of these activities.
“There are so many people who use alcohol or other drugs,” Sherrill said. “It’s such a prevalent thing in society, and alcohol is so ingrained in our culture, but there’s still a lot that we don’t know about [its effects].”
Gulley said he would also like to better understand why many people try drugs at some point in their life, but only a small percentage become addicted.
Researchers are interested in being able to predict “who’s going to develop an addiction and who’s not, and [understand] what might be different about people who are more susceptible versus others,” Gulley said.
Once the differences are discovered, “the next step would be to target those differences and discover pharmacological interventions or behavioral interventions to prevent drug addiction before it happens,” said Benjamin Marcus, a senior in LAS who works in Gulley’s lab.
Given the complexity of a problem such as drug addiction, it is challenging to identify what causes it. A multitude of factors, both genetic and environmental, may contribute to whether or not a drug user develops an addiction.
“It’s a pretty multi-faceted disorder, so you have to think about how you’re going to dissect it down to all its individual components that you can then systematically address,” Sherrill said.
By studying the different effects of drug abuse on behavior and physiology one at a time, Sherrill said that researchers can work toward a more complete understanding of an extremely complex phenomenon.
Future studies in the Gulley lab will include investigating the effects of amphetamines on other behaviors, as well as continuing studies on alcoholism.
Emily Venheim, another psychology graduate student in Gulley’s lab, has already performed studies looking at the effects of amphetamine abuse on impulsive behaviors and said that next she will test its effects on different aspects of attention.
Venheim said that she is motivated by the possibility that the knowledge gleaned from these studies could one day be transferred to a clinical setting to help drug abusers overcome addiction.
Gulley said he ultimately hopes this research will lead to a clearer understanding of what factors contribute to drug addiction, as well as what specific physiological changes are caused by drug abuse that may be responsible for adverse behavioral effects.
“If we have the ability to understand this at a very basic level what specifically the drugs are changing, then we have a very strong potential to either reverse or prevent those changes,” Gulley said.
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