Use of recreational drugs, like marijuana and cocaine, appeared to have little impact on CD4 or CD8 cells, say the authors of a study published in the journal Drug and Alcohol Dependence.

Chun Chao, PhD, of the department of epidemiology at Jonsson Comprehensive Cancer Center at the University of California at Los Angeles, and her colleagues examined survey data and medical records from men who have sex with men (MSM) enrolled in the national Multicenter AIDS Cohort Study (MACS), which began enrolling in 1984.

All of the men in the study, both those who were HIV positive and HIV negative, filled out surveys reporting their use of alcohol and recreational drugs and had their CD4 and CD8 cell counts measured at regular intervals over the course of time. Because triple combination antiretroviral therapy could have masked any effects of the recreational drugs on CD4 and CD8 counts in people who are HIV positive, Chao’s team focused on the years prior to 1996, when triple combination therapy was introduced.

The team found no statistically significant associations between use of marijuana, cocaine, poppers or amphetamines and CD4 and CD8 cell counts, percentages or rates of change in either HIV-positive or -negative men. This held true even in men who reported frequent (at least weekly) or continuous substance use in the previous year.

Though Chao’s team state that their study indicates that recreational drugs do not appear to have an impact on a person’s immune status, other studies have found a connection between heavy use of alcohol or drugs and poorer medication adherence and overall health and survival in people living with HIV.