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, reports The Washington Post. Steve Cole of the University of California, Los Angeles, and several 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 the patients' viral loads and T-cell counts over a period of 12 to 18 months. 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 a 20-fold decrease among introverted men. 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.