MONDAY, Dec. 12 (HealthDay News) -- Drinking too much alcohol can lead to unsafe sex, a new study confirms.

Unsafe sex is the most common cause of HIV infection and finding ways to prevent unsafe sex is a major goal of public health efforts to prevent HIV/AIDS.

Alcohol use has long been associated with HIV incidence. However, it hasn't been clear whether unsafe sex associated with alcohol use actually led to HIV infection, or whether certain personality traits, such as sensation-seeking or risky behavior, led to both alcohol use and unsafe sex.

In this study, researchers led by Jurgen Rehm, director of social and epidemiological research at the Centre for Addiction and Mental Health in Ontario, Canada, conducted 12 experiments that tested this cause-and-effect relationship. They concluded that alcohol affects decision-making and that this effect increases with the amount of alcohol consumed.

The more alcohol the participants drank, the more willing they were to engage in unsafe sex, the study authors said. For each 0.1 milligrams per milliliter increase in blood alcohol level, there was a 5 percent increase in a participant's likelihood of having unsafe sex.

The study is published in the January issue of the journal Addiction.

"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," Rehm commented in a journal news release. "This result also helps explain why people at risk often show this behavior despite better knowledge: Alcohol is influencing their decision processes."

More information

The U.S. Department of Health and Human Services has more about practicing safer sex at womenshealth.gov.