Alcohol consumption can directly influence a person’s intention to have unsafe sex, according to a new study.

Researchers from the Centre for Addiction and Mental Health in Canada say that this finding could provide valuable insight in preventing the spread of HIV/AIDS because unsafe sex is the leading cause of HIV infection.

Researchers explain the importance of the results by stating that the occurrence of HIV, in countries like United States and the United Kingdom, has not decreased and in some cases has actually increased, despite general knowledge and significant campaigns to prevent unsafe sex.

Researchers conducted a meta-analysis of 12 experiments that tested the cause-and-effect relationship of alcohol consumption and participants’ willingness to engage in unsafe sex. Researchers randomly assigned participants to a drinking group or a sober group, and measured their intention to have sex without a condom.

After combining the results, researchers found that alcohol consumption significantly affects decision-making, and that the willingness to engage in unsafe sex rises with the amount of alcohol consumed. The more participants drank, the more likely they were to have unsafe sex.

The results show that an increase in blood alcohol level of 0.1mg/mL resulted in a five percent increase of probability of engaging in unprotected sex, and remained stable in sensitivity analyses that corrected potential bias such as certain individual personality traits, such as sensation-seeking or a disposition for risky behavior.

"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", said Dr. J. Rehm, the Principal Investigator of the study in a statement. "This result also helps explain why people at risk often show this behavior despite better knowledge: alcohol is influencing their decision processes."

The study will be published in the January issue of the journal Addiction.