A study published this week in AIDS Research and Human Retroviruses suggests that frequent alcohol intake, alone or in combination with crack-cocaine, accelerates HIV disease progression through direct action on CD4 cells.

Alcohol also increased viral load in patients taking antiretroviral therapy (ART) by promoting poorer adherence to ART. No significant increase in viral load was observed in patients not on ART.

The study was conducted over 30 months and followed HIV-positive adults with histories of alcohol and illegal drug use.

Most of the participants (77 percent) were African-American, with the remainder mostly Hispanic (13 percent) or Caucasian (7 percent).

Researchers monitored ART adherence, CD4 cell count, and HIV viral load (the amount of virus in the blood) in study participants to determine level of disease progression over time.

“These results provide evidence that frequent alcohol use alone, or in combination with crack-cocaine, is a risk factor for accelerated HIV disease progression,” wrote the study authors, “specifically a faster decline of CD4+ cell count and increased HIV viral load.”

The study found that alcohol users who consumed more than two drinks daily were almost three times more likely to develop a significant drop in CD4 cells. The drop occurred regardless of initial CD4 cell count and viral load, antiretroviral use over time, time since diagnosis, age, or gender.

They also found that the decline in CD4 cells from alcohol or substance abuse was independent of ART adherence.

The authors suggest that alcohol may directly influence disease progression by affecting CD4 cells and the immune system. This is consistent with previous studies showing that alcohol is an immune suppressant.

However, they acknowledged that other unmeasured behaviors might have accelerated HIV disease progression.

The study did not find a link between moderate alcohol intake (one or fewer drinks daily) and reduced CD4 cell count or increased viral load.

However, an earlier study showed significantly lower CD4 cell count and increased viral load in moderate and at-risk drinkers compared to non-drinkers. Researchers noted that these disparities require further investigation.

The effects of alcohol on HIV disease progression have been unclear, with many studies giving conflicting results.

Earlier observational studies, where HIV-positive individuals were followed over time, failed to establish a link between alcohol consumption and HIV disease progression.

Animal and laboratory studies, in contrast, have shown a significant effect of alcohol on HIV disease progression, susceptibility to AIDS-associated infections, and viral load. Studies conducted after the introduction of ART have also confirmed that alcohol reduces viral load response, CD4 cell recovery, and adherence to ART.

Additionally, a large study following heavy alcohol users consuming four or more times per week while receiving HAART concluded that heavy drinkers were less likely than moderate or non-drinkers to reach undetectable viral loads and were more likely to have low CD4 cell counts.

Experts advise that people with HIV should avoid recreational drugs and excessive drinking to minimize damage to the immune system.

For more information on alcohol and HIV, please see the United States Department of Veteran Affairs website. For more information on the study, please see the AIDS Research and Human Retroviruses (pdf) website.