This month, a carefully done study showed that shy men have much less resistance to the AIDS virus than extroverted men and benefit far less from treatment with anti-retroviral drugs. It is the first study to demonstrate through laboratory tests a connection between being introverted and the course of AIDS in individuals, researchers said.

Previous work had shown that AIDS progresses more rapidly in gay men who were in the closet, compared with those who were "out." Initially, [Steve Cole] said, scientists speculated that the hiding and secrecy raised the stress level and made them vulnerable. But increasingly, he said, scientists think of being in the closet as a marker - rather than a cause - of poor outcomes. Because shy people are more sensitive to humiliation, rejection and the opinions of others, shyness could be the reason some gay men with HIV stay in the closet as well as have worse outcomes with AIDS.

"It's squirted out of one neuron and is received by another neuron," Cole said. "This happens with such intensity that norepinephrine spills into the blood. That changes how your heart works. If we infect a cell with this, the virus grows 10-fold faster." The next step would be to examine whether blocking norepinephrine affects the AIDS outcome, Cole said. Common heart medications called beta-blockers can keep the body from responding to the neurotransmitter.