Hooked on Fitness Keeping fit may actually be addictive. Take away a mouse's running wheel and its brain registers a jump in neurologic activity in circuits of craving much like that seen during withdrawal from addiction.
Angry for Life Adolescents who take anabolic steroids to bulk up may get more than they bargained for—a long-term inclination to aggression, even after they stop using the drugs. Steroids diminish the brain's ability to make serotonin, a neurotransmitter that keeps hostility in check.
The Wages of Shyness The shy are more susceptible than the rest of us to viral infection, including AIDS, according to UCLA researchers. Their highly sensitive nervous systems render them extremely susceptible to stress, and the constant exposure to stress has the effect of wearing down the immune system.
