February 12, 2009
In an oral presentation at CROI 2009 in Montreal, Canada, information from three studies (FRAM, CARDIA and MESA) show that HIV infection increases the risk that someone will develop hardening of the arteries, or a progressive thickening and hardening of the walls of arteries from fat deposits (called atherosclerosis). The increased risk posed by HIV is similar to the increased risk for this condition posed by diabetes, smoking, high blood pressure and high cholesterol. The impact of HIV therapy on this story is not clear. In at least one study, people who used intermittent HIV therapy were at higher risk for heart disease compared to those who stayed on continuous therapy.
A total of 433 HIV-positive people from the FRAM (Fat Redistribution and Metabolic Change in HIV Infection) study were compared to 5,749 healthy HIV-negative people from CARDIA (Coronary Artery Risk Development in Young Adults) and MESA (Multi-Ethnic Study of Atherosclerosis). Comparing the HIV-positive group in FRAM to the HIV-negative group in FRAM:
In order to assess the impact of HIV on the circulatory system, researchers chose to measure two areas of that system that are prone to early changes associated with hardening of the arteries, sometimes called cardiovascular disease or CVD. Using an ultrasound, they measured the thickness (IMT, intimal medial thickness), of the artery walls. They measured both the common carotid artery, which provides blood to the head and the internal bulb region, which is believed to be more relevant though also more difficult to measure. (Seven other projects have studied this same question, with 2 showing HIV increasing artery thickness while the other 5 did not. However, the latter 5 only measured the common carotid, which is a less accurate predictor of disease than internal region.)
Results show that the HIV-positive people had more signs of hardening of the arteries (thicker artery walls) compared to the HIV-negative groups, when adjusting for other factors that may further increase risks of CVD such as age, race, gender, diabetes, smoking, blood fat levels and hypertension. The thickening of the artery was more significant in the more relevant internal region. This affect was seen at a higher rate in HIV-positive women than HIV-positive men.
These results compliment other study findings at the conference showing aging effects on the brain and how a person's normal aging can affect the course of HIV disease. In a 51-person study on the aging of brain cells, it was found that the brains of people with HIV can be up to 20 years older than their HIV-negative counterparts. This appeared to be due to an imbalanced blood flow to the brain, perhaps due to low level inflammation. The other study on the effects of normal aging shows that aging produces similar processes to HIV infection, namely increased levels of systemic inflammation as well as activation of certain immune cells.
It's becoming more accepted that constant inflammation in many areas of the body (even low level inflammation) contributes to the premature aging found in many people living with HIV. It's clearer now from this study that HIV infection has a significant affect on people with HIV to develop atherosclerosis at an earlier age, equal to that of other risk factors like smoking. However, the researchers also stated that a person developing hardening of the arteries likely comes from various factors, including the effect from using HIV drugs. This study further adds data to the general observation that people living with HIV "age" in many ways faster than HIV-negative individuals of a similar age.