CORVALLIS - An increasing number of American men are taking anabolic steroids -not for an advantage in competitive bodybuilding or weightlifting, but to increase their self-image and to look more impressive in a room full of people.

It's a kind of reverse Barbie Doll syndrome, where adolescent males and young men seek imposing size instead of slender proportions.

"These are not Olympic athletes, they do it for cosmetic reasons," said Ray Tricker, an associate professor of public health at Oregon State University. "They may feel sub-par and want to be respected. They want to be bigger and stronger, and have an imposing presence.

"They want to walk into a room," he added, "and see people's jaws drop."

A team of researchers from Oregon and California has been studying the effects of steroid use by American men. Results of two research projects in this field are detailed in the July issue of the New England Journal of Medicine and in the forthcoming October edition of the Journal of Clinical Endocrinology and Metabolism.

Not surprisingly, the research team found that ingesting large doses of testosterone does indeed increase muscle size and strength. Measurements of mood and aggression resulting from steroid use are more difficult to assess.

The researchers found no difference in aggression between a group of subjects taking 600 milligrams of testosterone a week with that of a placebo group. But within the two groups of individuals some results varied, though not sufficiently to demonstrate a statistical difference between the placebo and experimental groups.

And the researchers are convinced through personal observation that some people are more prone than others to aggressive behavior following steroid use.

But they don't know how or why.

"We observed some obvious changes in behavior among some people and our theory is that there is some physiological or psychological mechanism that predisposes some individuals to aggressive behavior," Tricker said.

A number of subjects, monitored primarily through their "significant others," were found to be angrier, more impatient, and more prone to vulgar language after steroid use. Interestingly, so were some of the placebo team - which Tricker attributes to the subjective nature of the testing model.

However, all of the trained observers - including physicians and clinical psychologists - said there was little doubt that aggressive behavior increased in some individuals following ingestion of anabolic steroids.

The researchers say their work is important because an estimated 300,000 to 1 million people in the United States are taking steroids. The team hopes to expand its efforts and learn more about how steroids work, then develop a model of prediction for at-risk behavior, Tricker said.

Team members include Shalender Bhasin, Carlos Callegari and Brenda Clevenger from the Charles R. Drew University of Medicine and Science in Los Angeles; Thomas W. Storer and Thomas J. Bunnell, El Camino College in Torrence, Calif.; Nancy Berman, Jeffrey Phillips and Richard Casaburi, UCLA; and Tricker and Aida Shirazi, OSU.

Not all steroid use, of course, is illegal. The average male naturally produces about seven milligrams of testosterone daily and production of the hormone occurs until about the age of 70, when there is a significant dropoff, Tricker said. But in some countries - Azerbaijan, for example - men produce testosterone at later ages and some can still procreate past the age of 100.

Some doses of steroids, especially testosterone, may be clinically prescribed for hypergonadal - or sexually dysfunctional - males, and infertile females. But in some cases steroid use by Americans is illegal, under-the-counter, and for the purposes of gaining size or strength.

Steroid users are able to break through naturally occurring plateaus in the development of muscle size and strength through an increase in nitrogen retention, Tricker said. However, prolonged steroid use can lead to an irregular heartbeat, atrophy of the testicles, massive outbreaks of acne, and in extreme cases, the development of feminine breasts.

Less is known about the psychological effects of steroids, though evidence is mounting that violence and aggression can be by-products of steroid use. Tricker cited one recent case of a steroid user fatally shooting a store attendant in a fit of anger over a trivial disagreement.

"These are not necessarily competitive athletes, but may be more like the guy next door," Tricker said. "If only, say, one in 10 steroid users is at-risk for aggressive or violent behavior, we may have as many as 100,000 of these walking time bombs. And they could do a lot of damage.

"Remember, these guys in general are pretty big and strong."