An interesting read from Reuters:
WASHINGTON (Reuters) — Too much testosterone can kill brain cells, researchers say, in a finding that may help explain why steroid abuse can cause behavior changes such as aggressiveness and suicidal tendencies.
Tests on brain cells in lab dishes showed that while a little of the male hormone is good, too much of it causes cells to self-destruct in a process similar to that seen in brain illnesses such as Alzheimer's.
"Too little testosterone is bad, too much is bad but the rightamount is perfect," said Barbara Ehrlich of Yale University inConnecticut, who led the study.
Testosterone is key to thedevelopment, differentiation and growth of cells and is produced byboth men and women, although men produce about 20 times more of thehormone.
It can also be abused, and recent scandals haveinvolved athletes who use the hormone, or steroids that turn intotestosterone in the body, for an unfair advantage.
"Other people have shown that high levels of steroid can cause behavioral changes," Ehrlich said in a telephone interview.
"Wecan show that when you have high levels of steroids, you have hightestosterone and that can destroy the nerve cells. We know that whenyou lose brain cells you lose function."
Ehrlich's team tried the same thing with the "female" hormone estrogen, just to be fair.
"Wewere surprised, but it actually looks like estrogen is neuroprotective.If anything, there is less cell death in the presence of estrogen," shesaid.
Writing in the Journal of Biological Chemistry, Ehrlichand colleagues said their findings meant people should think twiceabout supplementing with testosterone, even if it does build musclemass and aid recovery after exercise.
"These effects of testosterone on neurons will have long-term effects on brain function," they wrote.
"Nexttime a muscle-bound guy in a sports car cuts you off on the highway,don't get mad — just take a deep breath and realize that it might notbe his fault," Ehrlich said in a statement.
The cells die via a process called apoptosis, also known as cell suicide or programmed cell death.
"Apoptosisis an important thing for the brain — the brain needs to weed out someof the cells. But when it happens too frequently, you lose too manycells and causes problems."
A similar process is seen inAlzheimer's disease, the most common cause of dementia in the UnitedStates, affecting an estimated 4.5 million Americans, and Huntington'sdisease, another fatal brain illness.
"Our results suggest thatthe responses to elevated testosterone can be compared with thesepathophysiological conditions," the researcherswrote.