Focus on the Lung

Article excerpt

Despite considerable experimental and clinical evidence that both human immunodeficiency virus (HIV)-1 infection and chronic alcohol abuse render people susceptible to serious lung infections (i.e., pneumonia), surprisingly little information is available regarding the interactions between these two conditions on lung health. The same is true for lung diseases such as asthma, emphysema, (1) chronic bronchitis, lung cancer, and pulmonary hypertension, which are not caused by infections but result from other disease processes. Thus, in most cases, little or no specific evidence suggests that the effects of concurrent HIV-1 infection and alcohol abuse are as great as or even greater than the sum of the effects of both individual conditions (i.e., are additive or synergistic) on these common noninfectious lung diseases in humans. However, findings from experimental animal models provide compelling reasons to infer that alcohol abuse has serious consequences on lung health in HIV-1--infected people. Moreover, recent discoveries in experimental models that complement researchers' understanding of the pathophysiology of HIV-1 infection and alcohol abuse in humans have provided clues to potential new therapies for patients with infectious and noninfectious lung disease. This article summarizes some of the experimental and clinical evidence that implicate alcohol abuse as a potential exacerbating factor on lung health in HIV-1--infected people.

ALCOHOL, HIV-I INFECTION, AND PNEUMONIA

Alcohol is the most frequently abused drug in the world (Lieber 1995). In the United States, 50 percent of the population regularly consumes alcohol, and in 2002 nearly 18 million American adults met the clinical diagnostic criteria for alcohol abuse or alcohol dependence (Grant et al. 2004). According to the most recent definition established by the American Psychiatric Association (2000) in the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR), substance use disorders, which have been separated into substance abuse and substance dependence, are characterized by repeated use despite adverse social and/or physical consequences. Dependence has been considered a more advanced stage of a substance use disorder with specific tolerance and withdrawal phenomena. In other words, abuse is characterized by the use of a substance with psychoactive properties either in socially inappropriate ways or in spite of serious medical, legal, or social consequences, such as disruption of one's personal or professional life. In contrast, dependence implies a state in which, in addition to the signs and symptoms of abuse, sudden withdrawal of the substance produces significant biological consequences. Thus, considerable overlap exists between alcohol abuse and alcohol dependence, and it is important to realize in this context that a drinker may suffer significant biological consequences of alcohol abuse (e.g., alcohol-related lung disease) even if he or she does not exhibit features of dependence, such as delirium tremens or other manifestations of a withdrawal syndrome. Further, it is important to note that alcohol abuse is not defined by the quantity of alcohol consumed but rather by the harmful consequences of its consumption. As a result, there is no consensus in clinical studies or experimental animal models on how to define alcohol abuse or even (harmful) chronic alcohol ingestion. Although this lack of standardization can complicate the interpretation of such studies, broad consensus exists among researchers and clinicians that chronic alcohol ingestion in excess of some safe threshold (which may vary among individuals) clearly is linked to multiple health problems. Unless otherwise specified, in this article, the term "alcohol abuse" refers to any type of alcohol use that results in adverse medical, legal, or social effects, regardless of whether it also meets the criteria for alcohol dependence.

HIV-1--infected populations in the United States, and throughout the world, show disproportionately high rates of alcohol abuse compared with the general population, which complicates all aspects of medical care for these patients (Fisher et al. …