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Steroids May Alter Aggression Area of Brain

Anabolic Steroids in Adolescence Can Affect Behavior Later
WebMD Health News

Nov. 26, 2003 -- You've read the news: High-profile athletes are caught using illegal anabolic steroids. Now, a study shows that players pay a lengthy price -- their aggressive tendencies may be ramped-up long after they quit using steroids.

The report appears in the current issue of the journal Hormones and Behavior.

In the past 10 years, illegal use of anabolic steroids has risen among adolescents -- reaching near-epidemic proportions, writes lead researcher Jill M. Grimes, a behavioral psychologist with Northeastern University in Boston.

An estimated 500,000 or more eighth to 10th graders across the country use anabolic steroids every year -- and that number steadily increases every year. In fact, the numbers have doubled in four years: 2% of 10th grade boys used steroids in 1996; by 2000, that number jumped to 4%, Grimes reports.

This pattern of abuse is of particular interest because steroid use during adolescence is linked with more frequent and heavier use later in life -- despite the physical and psychological problems that anabolic steroids cause, including aggressive behavior, she writes.

Her studies have shown that hamsters given daily, high doses of anabolic steroids throughout adolescent development were more overtly aggressive in their interactions with other hamsters -- especially if they were not used to dealing with other hamsters.

This suggests that anabolic steroids used during adolescence stimulate aggression, possibly by affecting the activity of brain circuits that regulate this behavior, writes Grimes.

Embattled Hamsters

In this current study, she gave six preadolescent male hamsters daily injections of steroids for 30 days. The doses mimicked a "heavy use" regimen that an adolescent athlete might follow.

She picked six hamsters with low-aggression tendencies to be "intruder" hamsters; they got no steroid injections.

After the 30 days were up, she then put one "intruder" hamster in the "steroid-hamsters" cage -- then watched their behavior. She also noted number of attacks and bites, including wild pursuits, lunges, and "cornering" with intent to bite. Each test lasted 10 minutes.

As her previous tests have shown, animals treated with anabolic steroids were significantly more aggressive -- making more attacks and bites than their littermates.

  • One-half of the steroid-treated hamsters scored more than 20 total attacks. They were also quicker to attack, and stayed at it longer.
  • One-half of the untreated hamsters scored less than five attacks on their opponents.
  • A test of their brain chemistry showed significant changes in some -- but not all -- brain centers involved with aggressive behavior.

Daily steroid use may trigger aggression by altering brain activity, she explains. But with drug therapy, it's possible to decrease that aggression, as has been shown in studies of rats and squirrel monkeys.

Also, her study suggests that anabolic steroids affect each child's brain differently, she adds.

Together with her previous studies, there is important evidence here linking adolescent use of anabolic steroids and aggression -- at least in hamsters, writes Grimes. More studies are needed to ferret out the effects on adolescent humans.

SOURCE: Grimes, J. Hormones and Behavior, Nov. 2003; vol 44: pp 271-280.

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