US scientists, who investigated the influence of anabolic steroids on hamsters, claim that the drugs may cause lasting aggression.
The effects of steroid may continue for minimum of two years and trigger permanent changes in brain, the Behavioral Neuroscience study reveals.
But, according to a UK expert, it is impossible to set the length of effect in a body of a human, based on a study in animals such as hamsters.
People who have used steroids for a long time may suffer from hallucinations, mood swings, and paranoia as well as high blood pressure, liver damage, stroke, increased risk of heart disease and finally - some types of cancer.
Quit using steroids may lead to depression.
Playfulness
A team of researchers at Northeastern University in Boston investigated the reaction of adolescent hamsters when another hamster was placed in their cage.
The scientists found that hamsters obviously defend their territory by wrestling, play-fighting and nibbling, even if they are normally tame.
But hamsters injected with popular steroids that were hidden in oil, started to behave in extremely aggressive way.
Even after the steroids were withdrawn, the newly aggressive hamsters assaulted, chased and bit their ‘guests’.
The level of their aggressiveness was 10 times higher than in case of hamsters injected only with oil.
The effects continued for nearly two weeks, which is the half of their adolescence.
After this period, the hamsters reverted to their usual playful behaviour.
Post-mortems on the animals proved there had also been changes in the activity of their brains.
While the hamsters were injected with steroids, so called ‘anterior hypothalamus’ — a part of their brains that is responsible for aggression and social behaviour, pumped out more of a neurotransmitter known as vasopressin.
Three weeks after steroids withdrawal, levels of vasopressin had subsided, together with the aggressive behaviour.
Long-term risks
Dr Richard Melloni, a head of the research, stated that the part of the brain which they investigated is similar in humans and rodents. This is why the experts say their findings may be applicable to humans.
Dr Melloni said: "Because the developing brain is more adaptable and pliable, steroids could change the trajectory if administered during development."
"If you hit the right areas of the brain at the right time, you make permanent changes."
And he added: "It’s our hope that people considering the use of these drugs weigh the long-term health risks and the serious potential for aggression and violence."
According to the researchers, the findings can be a helpful tool in development of treatments for aggressive behaviour, whether or not it is the effect of steroid abuse.
However, Professor Jonathan Seckl of the University of Edinburgh, noted: "Steroids are linked to aggressive behaviour and that can persist afterwards. But this study showed effects for a few days, and you can’t say that will translate into years for humans."
Professor Seckl said the effects observed in the animals could simply have been down to drugs’ slow-release mechanism — which means their effects could still be noticed in the body for a few days after stopping taking the steroids.
But he emphasized: "This study does show you get really significant behavioural effects from steroids - in animals and humans. "I see plenty of people who abuse steroids, usually young men into athletics or weight-lifting, and the effects do go on for a long time after they have stopped."
