Shy Men Have Lower Resistance to AIDS, Poorer Response to Antiretroviral Drugs, Study Says
Men who are introverted exhibit lower resistance to AIDS than extroverted men and benefit "far less" from antiretroviral drug treatment, according to a study published in the December issue of the journal Biological Psychiatry, the Washington Post reports (Vedantam, Washington Post, 12/22). Steve Cole of the University of California-Los Angeles and colleagues measured social inhibition and autonomic nervous system activity on multiple occasions in 54 HIV-positive men who have sex with men. The researchers then monitored for 12 to 18 months the patients' viral loads and CD4+ T cell counts (Cole et al., Biological Psychiatry, December 2003). The study, which is the first to demonstrate through lab tests the connection between being introverted and the progression of AIDS, found that introverted HIV-positive men had nearly eight times the number of HIV viral particles in their blood as extroverted men. In addition, the viral load among extroverted men fell 162-fold after antiretroviral drug treatment initiation, compared with only 20-fold among introverted men, Cole said (Washington Post, 12/22). The effects on viral load and antiretroviral drug therapy were independent of the mens' length of infection, type of therapy, demographic characteristics and health-relevant behavior, the researchers found (Biological Psychiatry, December 2003).
Nervous System Response
"People who have the shy, sensitive temperament seem to be more prone to having sympathetic nervous system responses. They are more stressed by lots of things, including contact with unfamiliar people," Cole said. Because shy people's nervous systems are more likely to produce stress reactions to social situations, they maintain their internal stress balance by limiting social contact, according to the Post. Cole said that norepinephrine, a neurotransmitter involved in stress reactions, could be the link between such social inhibition and the progression of AIDS. When norepinephrine is transmitted from one neuron to another, some spills into the blood stream and changes how the heart works, Cole said, adding that if a cell is infected with the neurotransmitter, the virus grows 10 times faster. Researchers must now study whether blocking norepinephrine by using beta-blockers has an affect on the progression of AIDS, Cole said. Anthony Fauci, director of the NIH National Institute of Allergy and Infectious Diseases, said that the research is "promising" but that the connections between the neurological and immune systems are complex and it is "unlikely" that there is only one mechanism to explain the connection between shyness and the progression of AIDS, according to the Post (Washington Post, 12/22).