TUESDAY, Dec. 13, 2005 (HealthDay News) -- The use of anabolic steroids to improve performance has rocked the world of amateur professional sports, and a new animal study suggests these performance-enhancing drugs may also be addictive.
When given the choice, hamsters voluntarily infused themselves with powerful anabolic steroids, researchers report.
This may mean that "what makes animals feel good when they take steroids is their effect directly on the brain," said lead researcher Ruth Wood, a professor of cell and neurobiology at the University of Southern California. "It's not because it makes them bigger and stronger. Steroids are not just acting below the neck."
Androgenic-anabolic steroids are commonly abused by athletes and bodybuilders. Steroids were banned from Olympic competition in 1975, and were labeled controlled substances by U.S. officials in 1991.
One 2002 study by researchers at the University of Michigan found that the lifetime incidence of steroid use among high school seniors was 4 percent -- comparable to that of crack cocaine (3.8 percent) or heroin (1.7 percent).
There are a lot of complicated reasons why people take steroids, Wood said. "They take steroids to improve their athletic performance or change their body shape," she added. "But an animal has none of these motivations. They will voluntarily take steroids, which indicate to us that perhaps steroids are addictive."
Her team's findings were presented Tuesday at the American College of Neuropsychopharmacology's annual conference in Waikoloa, Hawaii.
In their experiments, Wood's team implanted hamsters with small portals for the self-administration, via a simple device, of commonly abused steroids directly into their brains.
When the hamster activated the portal it received either a microgram of testosterone, or one of several commonly abused steroids: nandrolone, drostanolone, stanozolol or oxymetholone.
Wood's team found the animals had a preference for testosterone and the two most powerful steroids, nandrolone or drostanolone. The hamsters did not voluntarily inject the weak steroids stanozolol or oxymetholone.
The findings suggest that steroids may be addictive, Wood said.
"Steroids may cause dependence, which may make it difficult for people to quit. For people who are chronic users, we may need better strategies to stop them [from] taking steroids," she said.
One expert isn't convinced that steroids themselves are addictive, or whether humans seek secondary benefits, such as muscle enhancement.
"There is not enough data showing primary reinforcing effects of androgenic-anabolic steroids," said Bruce Svare, a professor of psychology and neuroscience at the State University of New York and director of the National Institute for Sports Reform. "Just how much of the effects of androgenic-anabolic steroids in humans are primary reinforcing and how much are secondary reinforcing is unknown."
"Some [humans] report euphoria and a sense of invincibility, but it does not approach the positive hedonic effects of classic drugs of abuse like heroin and cocaine," he noted.
"My presumption is that androgenic-anabolic steroids use in humans is still largely driven by secondary reinforcing effects, but there also may be some primary reinforcing effects as demonstrated by the author of this paper," Svare said.
Another expert thinks that even the hint that steroids might be addictive is another reason to clamp down on their use.
"This finding gives us one more reason to address steroid use by professional athletes as a matter of societal urgency," said Dr. David L. Katz, director of the Prevention Research Center at Yale University School of Medicine.
"Steroid use is not a minor matter of private choices by grown-ups willing to accept certain consequences for certain gain," Katz said. "Steroid use is a bona fide medical hazard, and a potentially addictive one at that. A nation of responsible adults, with the well-being of their children in mind, should do everything required to banish the practice."
More information
For more on the dangers of steroid abuse, head to the American Academy of Pediatrics.
