There are two reasons to investigate connections between alcohol, HIV infection and AIDS: alcohol adversely affects the immune system, and alcohol influences high-risk sexual behaviour.
Background
Human immunodeficiency virus (HIV) is widely accepted as the agent that causes acquired immunodeficiency syndrome (AIDS). However, a growing number of researchers in the scientific community theorise that lifestyles featuring systematic and heavy drug and alcohol abuse damage the immune system, leading to the syndrome known as AIDS. These researchers point out that there is no scientific proof that a virus is involved at all or any proof that such a virus even exists – no one has ever actually isolated and seen the so-called HIV virus. Meanwhile, the accepted theory is that HIV, a virus, is transmitted through sexual contact with an infected individual, through exchange of infected blood or blood products, or to a newborn from an infected mother.
HIV-infected persons may harbour the virus for many years with no clinical signs of disease. Eventually, the theory goes, HIV destroys the body’s immune system, mainly by impairing a class of white blood cells whose regulatory activities are essential for immune protection. As a result, people who have AIDS are prone to lung infections, brain abscesses, and a variety of other infections caused by microorganisms that usually do not produce disease in healthy people. Those who have AIDS also are prone to cancers such as Kaposi’s sarcoma, a skin cancer rarely seen in non-HIV-infected populations. The diagnosis of AIDS depends in part on the presence of one or a number of these infections and cancers.
Alcohol and the immune system
Alcohol can impair normal immune responses that protect the body from disease. Chronic alcohol consumption has been shown to reduce the number of infection-fighting white blood cells in laboratory animals and in humans. Chronic alcohol ingestion or alcohol dependence can depress antibody production and other immune responses in animals and in humans. Alcohol can suppress activities of certain immune system cells, called macrophages, that help keep the lungs free from infection. In addition, alcoholics appear to be more susceptible to bacterial infections and cancer than are non-alcoholics. Studies in animals and humans indicate that consuming alcohol during pregnancy can decrease immune resistance in the offspring. Alcohol’s generally immunosuppressive effects could mean that:
• Drinking may increase vulnerability to HIV infection among people exposed to the virus
• Among people who are already HIV infected, alcohol-induced immunosuppression might add to HIV-induced immunosuppression, and speed the onset or exacerbate the pathology of AIDS-related illness
These are complex ideas and areas of intense investigation, but so far only a few studies have been published. Researchers have learned that alcohol can impair white blood cell responses to HIV. A provocative study that warrants replication found that a single drinking episode depressed certain immune responses of white blood cells taken from healthy volunteers. In addition, white blood cells isolated after this drinking episode were more susceptible to HIV infection than were cells isolated from subjects who did not drink, hinting that even occasional alcohol consumption may increase the likelihood of infection upon exposure to HIV.
Whether alcohol use influences the progression of AIDS in persons already infected with HIV has been explored in a recent study of homosexual men. While these researchers found that neither alcohol nor other drugs seem to influence the progression of HIV infection or the development of AIDS, their results await confirmation. Clearly, more research is needed to understand alcohol’s role in HIV infection and the course of ensuing disease.
Alcohol and sexual behaviour
Sexual practices considered to be high risk for acquiring HIV from an infected individual include vaginal or anal intercourse without a condom; other sexual practices that facilitate exchange of blood, semen, or other body secretions; and unprotected sexual activities with multiple partners. The frequency with which sexual partners engage in such practices also influences the risk for exposure to HIV.
Alcohol’s relationship to high-risk sexual behaviour may be explained in two ways. First, alcohol use may be a marker for a risk-taking temperament: those who drink alcohol may also engage in a variety of high-risk activities, including unsafe sexual practices, as a part of a ‘problem behaviour syndrome’. Second, alcohol may influence high-risk behaviours at specific sexual encounters by affecting judgment and disinhibiting socially learned restraints. These are not mutually exclusive interpretations.
In addition, these two explanations have different implications for the prevention of high-risk sexual behaviour. Among people who have a risk-taking temperament, reducing alcohol consumption may not reduce high-risk sexual behaviour. However, among those who are more likely to take sexual risks when they are drinking than when they are not, reducing alcohol consumption should also reduce high-risk sexual behaviour.
There are two approaches to studying alcohol’s relationship to sexual behaviour that may result in HIV infection. One approach examines whether alcohol use, in general, is correlated with sexual risk-taking behaviour in general. In this approach, an observed association between drinking and high-risk sexual activity could imply that these two behaviours are part of a larger risk-taking tendency, or that alcohol itself influences sexual risk-taking or both. Another approach examines the consequences of alcohol use during specific sexual encounters. An observed connection between alcohol use and sexual risk-taking during specific encounters suggests a direct influence of alcohol on such behaviour.
A number of studies have identified associations between drinking and high-risk sexual activity. These studies also have found that an absence of or a reduction in alcohol use is associated with a decrease in high-risk sexual behaviour. A study of heterosexual drinking habits and sexual behaviour found that women and men who frequently combined alcohol use with sexual encounters were generally less likely to use condoms during intercourse. Similarly, a study of homosexual men found alcohol or other drug use combined with sexual activity to be strongly associated with high-risk sexual behaviour: even those who drank only occasionally at the time of sexual encounters were twice as likely to be categorised as ‘high risk,’ based on the frequency of involvement in a range of sexual practices within non-monogamous relationships, than were those who did not drink. Further, those men who did not drink during sexual encounters were three times more likely to be classified in a ‘no risk’ category than were men who combined drinking with sexual activity. Recently, a reduction in alcohol use among homosexual men has been associated with a reduction in high-risk sexual behaviour.
Other studies that examine the consequences of alcohol use at specific sexual encounters also have demonstrated a connection between alcohol use and high-risk sexual behaviour. Scottish adolescents who drank at the time of first intercourse were less likely to have used a condom than those who did not drink. A survey of adolescents in Massachusetts revealed that teens were less likely to use condoms if sexual activity followed drinking or other drug use. Similarly, adult homosexual men and heterosexual women (but not heterosexual men) reported that they were less likely to use a condom during those sexual encounters in which they felt intoxicated. These reports of simultaneous alcohol use and high-risk sexual behaviour suggest that alcohol can directly influence sexual risk-taking. However, these combined behaviours may still reflect a risk-taking tendency in some individuals.
Further research is needed to define conditions under which alcohol use is linked to high-risk sexual activity. Information generated from such studies will be vital for developing and improving programs to prevent HIV transmission.
