New research from the AIDS Institute at the University of California, Los Angeles (UCLA), reveals that stress enables the human immunodeficiency virus (HIV) to spread more quickly in infected persons and prevents antiretroviral drugs from restoring immune system function. The study, which was reported in the Proceedings of the National Academy of Sciences (98:12695-12700, 2001), is the first to pinpoint the molecular mechanisms linking stress and HIV infection. "Popular science has widely suspected that stress weakens the immune system," said Steve Cole, MD, lead author and UCLA assistant professor of hematology-oncology. "Now we’ve uncovered two reasons why."
Autonomic Nervous System Activity
The study enrolled 13 HIV-positive men, aged 25 to 54 years, who had never taken combination antiretroviral drugs. Researchers measured the baseline AIDS viral load and CD4 cell count in the blood of each subject. They then determined the level of autonomic nervous system (ANS) activity by calculating the blood pressure, skin moisture, and heart and pulse rate at rest for each patient.
"Persons with higher ANS activity tend to be more high-strung and easily stressed out," said coauthor Jerome Zack, MD, UCLA professor of medicine and associate director for basic sciences at the UCLA AIDS Institute. "We wanted to see what effect, if any, this had on our subjects’ ability to fight HIV infection." All 13 men in the study received a potent antiretroviral regimen to combat their HIV infection. Over the next 3 to 11 months, each man’s viral load and CD4 count was measured against his stress level ranking before he took the drugs.
The results showed that the higher the man’s stress level, the less he responded to the antiretroviral drugs. In fact, the average decline in viral load dropped more than 40 times for men with low ANS activity and less than 10 times for men with high ANS activity.
"After several months on retroviral drugs, the viral loads of five of the seven men with low ANS activity plummeted to undetectable levels in their blood," said Dr. Cole. "This happened to only one of the six men who exhibited high ANS activity."
CD4 Cell Count Recover