WASHINGTON — Too much testosterone can kill brain cells, researchers said Tuesday in a finding that may help explain why steroid abuse can cause behavior changes like 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 such brain illnesses as Alzheimer's.
"Too little testosterone is bad, too much is bad, but the right amount is perfect," said Barbara Ehrlich of Yale University in Connecticut, who led the study.
Testosterone is key to the development, differentiation and growth of cells and is produced by both men and women, although men produce about 20 times more of the hormone.
It can also be abused, and recent scandals have involved athletes who use the hormone, or steroids that turn into testosterone in the body, for an unfair advantage.
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"Other people have shown that high levels of steroid can cause behavioral changes," Ehrlich said in a telephone interview.
"We can show that when you have high levels of steroids, you have high testosterone and that can destroy the nerve cells. We know that when you lose brain cells you lose function."
Ehrlich's team tried the same thing with the "female" hormone estrogen, just to be fair.
"We were surprised, but it actually looks like estrogen is neuroprotective. If anything, there is less cell death in the presence of estrogen," she said.
Writing in the Journal of Biological Chemistry, Ehrlich and colleagues said their findings meant people should think twice about supplementing with testosterone.
