Academic journal article Alcohol Research

Co-Occurring Risk Factors for Alcohol Dependence and Habitual Smoking

Academic journal article Alcohol Research

Co-Occurring Risk Factors for Alcohol Dependence and Habitual Smoking

Article excerpt

Update on Findings From the Collaborative Study on the Genetics of Alcoholism

Habitual smoking and alcohol dependence frequently co-occur, and the genetic factors that influence both conditions appear to overlap. The Collaborative Study on the Genetics of Alcoholism (COGA) has investigated genetic factors that contribute to both alcohol dependence and habitual smoking. Using a sample of families densely affected with alcohol dependence, COGA investigators have identified regions of the genome likely to contain genes that specifically contribute to alcohol dependence and habitual smoking, as well as regions likely to contain genes that contribute to the development of both conditions. Further genetic analyses (i.e., candidate gene studies) have helped identify specific genes that may contribute to the development of alcohol dependence and habitual smoking. These analyses have implicated several genes that encode parts of receptors for the neurotransmitter gammaaminobutyric acid (GABA) in the development of alcohol or nicotine dependence, respectively. Other studies have identified additional candidate genes for alcohol or nicotine dependence. The results to date suggest that both common and drug-specific genetic influences play a role in the development of alcohol and nicotine dependence. KEY WORDS: Alcohol and tobacco; alcohol; nicotine; co-use; co-abuse; biological basis; animal studies; animal models; genetics; selected strains; mesolimbic dopamine system; cross-tolerance

Excessive alcohol use and smoking are among the top contributors to preventable early mortality in the United States today (Mokdad et al. 2004). Alcohol-related deaths stem from a variety of chronic diseases, including liver disease, cancers, and cardiovascular disease, as well as from acute consequences of alcohol con-sumption, such as alcohol-related car crashes, other accidents, suicides, and acute alcohol toxicity. Moreover, the public health impact of heavy drinking and alcohol dependence is not limited to effects on the individual drinker. Factors such as alcohol-related car crashes and violence as well as harm to the unborn children of pregnant women who drink (e.g., fetal alcohol syndrome) also contribute to the soci-etal cost of alcohol problems (Harwood 2000). Smoking similarly is associated with significant mortality and morbid-ity caused by multiple cancers, lung disease, and heart disease.

More people are addicted to nico-tine (the active ingredient in tobacco) and alcohol than to any other drugs of abuse (Grant et al. 2004). Moreover, alcohol and nicotine dependence often occur together in the same person, suggesting that the two disorders are not independent. Thus, the prevalence of nicotine dependence among people with alcohol dependence is more than three times higher (45.4 percent) than in the general population (12.8 percent). Likewise, the prevalence of alcohol dependence is about four times higher among people with nicotine dependence (13.5 percent) than in the general population (3.8 percent) (Grant et al. 2004).

Although environmental factors (e.g., availability of the drugs) have a substantial impact on the development of alcohol and nicotine dependence, it is well established that genetic factors also play a large role. Studies of identical and fraternal twins have consistently determined that the heritability of alcohol dependence-the estimated degree of variability in the risk of alcohol dependence that is accounted for by genetic factors-is between 50 and 60 percent; the heritability of nicotine dependence is comparable (for a review, see Tyndale 2003). Furthermore, twin-based research has indicated that the genetic factors that contribute to alcohol and nicotine dependence may overlap. In those studies, the genetic correlation between the two disorders-which estimates the degree of overlap in genetic factors and can range between 0 (no overlap) and 1 (complete overlap)-was found to be 0.68, indicating substantial overlap (True et al. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.