Depression doesn't just make people feel bad mentally; it also can leave them vulnerable to physical illness, according to a new study by researchers at the University of Wisconsin-Madison, published in the Proceedings of the National Academy of Sciences. The scientists were studying links between a person's psychological state and their immune response. They asked 52 volunteers, male and female, to write about the worst time of their lives and the best time. Researchers then measured their brain activity; increased activity in the right prefrontal area of the brain has been associated with stronger emotional response and depression. After the testing the individuals were given flu shots and were tested two weeks, four weeks, and six months later to determine their reaction to the shots. Individuals who had shown greater activity in the right prefrontal part of the brain later had lower amounts of flu antibodies in their blood, indicating a weaker response by their immune system.
Depression is a serious problem for many HIV-positive people who may struggle with how to cope with HIV infection, the stigma it carries, and its complex and sometimes toxic treatment. Although the researchers did not specifically study the effects of depression on the immune systems of HIV-positive people, it is possible that depression could further weaken immune responses to invading bacteria and viruses among HIV-positive people.