For those out there who dream of being a little more manly, be careful what you wish for. A new Yale study reports that excessive testosterone kills brain cells. Neurons in lab dishes treated with large doses of the hormone for just a few hours began committing the cellular suicide known as apoptosis. The study used concentrations higher than those normally found in the body, but steroid abuse is known to increase testosterone to dangerous levels. Neuronal death may explain the behavioral changes seen in some steroid users. As one author puts it:
Next time 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 not be his fault.
(Honestly, I always suspected that certain drivers’ noggins were full of kamikaze brain cells.)
Just in case women weren’t feeling smug enough reading this, the researchers ran a similar trial with estrogen and discovered that it may be “neuroprotective,” resulting in less cell death. And another recent study found that treatment with progesterone—a hormone involved in the menstrual cycle—improves survival among brain injury victims. So for gals who have bemoaned our wildly fluctuating female hormones since puberty, take heart: they may wreak havoc with our bodies, but they do a brain good.
Late-breaking addition: Check out these Data articles on the relationship between testicle size and brain size in bats and the toxicity of testosterone.