Alcohol can lead to unsafe sex: It's official

A new study has found that alcohol consumption directly impacts a person's intention to have unsafe sex. In other words, the more you drink, the stronger becomes your intention to engage in unsafe sex.

Unsafe sex is the most important pathway to HIV infection, and it is a main risk factor for the global burden of disease. Despite this knowledge, and substantial efforts to prevent unsafe sex, HIV incidence in most high income countries (such as the US or the UK) has not changed over the past decade. In some cases, it has even increased. Finding better ways to prevent unsafe sex is thus a major goal of public health efforts for HIV/AIDS prevention.

Alcohol consumption, especially heavy drinking, has long been associated with HIV incidence. However, there have been doubts about the cause-and-effect relationship. Researchers weren't sure if alcohol consumption caused HIV via unsafe sex, or whether certain personality traits in individuals, such as sensation-seeking or a disposition to risky behaviour in general, would lead to both alcohol use and unsafe sex.

The study, published in the January issue of the journal Addiction, summarizes the results of 12 experiments that tested this cause-and-effect relationship in a systematic way. After pooling the results, the researchers found that alcohol consumption affects decision-making, and that this impact rises with the amount of alcohol consumed. The more alcohol that participants consumed, the higher their willingness to engage in unsafe sex.

In these experiments, study participants were randomly allocated to one of two groups in which they either consumed alcohol or did not. Then their intention to engage in unsafe sex was measured. An increase in blood alcohol level of 0.1 mg/mL resulted in an increase of 5.0% (95% CI: 2.8% - 7.1%) in the indicated likelihood of engaging in unprotected sex. This result remained stable in sensitivity analyses aimed to correct for a potential publication bias.

"Drinking has a causal effect on the likelihood to engage in unsafe sex, and thus should be included as a major factor in preventive efforts for HIV", commented Dr. J. Rehm, the Principal Investigator of the study. "This result also helps explain why people at risk often show this behaviour despite better knowledge: alcohol is influencing their decision processes."

Future HIV/AIDS prevention programs should include the results of this study. For instance, efforts to reduce drinking, and especially to reduce heavy drinking occasions, will not only avoid compromising the immune system but will also lower the chance of engaging in unsafe sex, thereby reducing the number of new HIV infections.