A new study helps explain why people with HIV age faster than their HIV-negative counterparts, despite similar lifestyles. Additionally, the findings might offer poz people the ability to calculate how many years certain factors are adding to their biological age.
The study, published in the journal AIDS, suggests that those living with HIV who have had CD4 T-cell counts drop below 200 (and those who have specific co-infections) are especially at risk of experiencing advanced aging.
Researchers have long known that being HIV-positive is linked with an increased risk of disability, illness, and death — and have speculated that those living with the virus are aging faster than HIV-negative peers. But in order to evaluate this, Davide De Francesco, a research statistician at University College London, and his colleagues compared 134 HIV-positive participants with 79 HIV-negative people with similar sociodemographic and lifestyle factors.
Participants were all 45 years old or older. The HIV-positive participants were on treatment and had undetectable HIV viral loads (< 50 copies/ml) for at least 12 months. Thirty-one percent of those with HIV had had a prior clinical AIDS diagnosis.
The scientists looked at associations between a set of 10 biomarkers tied to aging with sociodemographic factors (age, sex, ethnicity, sexual orientation, education), lifestyle risk factors (smoking, alcohol consumption, and drug use), use of specific antiretroviral drugs, chronic viral co-infections (hepatitis B, hepatitis C, and cytomegalovirus), and specific HIV-related factors (CD4 and CD8 cell-counts; CD4/CD8 ratio; whether one’s CD4 count has ever dipped below 200, the number of years since HIV diagnosis, and whether they’d had a prior AIDS diagnosis).
Incorporating the biomarkers into calculations, the researchers found that those with HIV had significantly greater biological age than chronological age by a mean of 13.2 years in HIV-positive participants compared to a mean of 5.5 years in their HIV-negative counterparts.
No connection was found between age advancement and ethnicity, sexual orientation, or lifestyle factors — including smoking. The latter was so out of step with other studies showing that smoking ages people, that the study authors suggest that the low incidence of smoking among participants may have skewed the results.
But there were correlations between age advancement and hepatits B or cytomegalovirus (CMV) diagnoses, low CD4 and CD8 cell counts, and the CD4/CD8 ratio. Other parameters found to increase the biological age advancement were the time since their HIV diagnosis, the duration of treatment with antiretroviral medications (in particular the protease inhibitor saquinavir), and having had a CD4 cell count drop below 200/mm.
Researchers also calculated specific years increased by particular factors, finding for example an biological age increase of:
+ .28 years for every year since one received their HIV-positive diagnosis
+ .25 years for every year on antiretroviral therapy
+ 3.48 years for having a CD4 count drop below 200/mm
+ 1.70 years for having a prior AIDS diagnosis
+ 1.2 years for each year on saquinavir
+ 7.4 years if also living with hepatitis B
+ 1.9 years per each log increase of CMV IgG antibodies
Researchers admitted they were stumped about the issues with saquinavir, stating that “the reason why we only observed an association between age advancement and exposure to saquinavir, but not other HIV protease inhibitors, remains unclear, and suggests this observation should be interpreted with caution.”
As NAM’s AIDSmap notes, protease inhibitors, are “all known to promote vascular aging,” so only finding correlations between this one PI and increased aging was odd.
However, the impact of comorbities hep B and CMV were far less confusing. Both viruses cause chronic antigenic stimulation, which causes systemic immune activation. “In particular,” AIDSmap reports, “CMV reactivation and concurrent immune responses to control infection have been known to be associated with aging and increased morbidity and mortality in both the general population and people living with HIV.”