Both Cultural Factors and Genes Influence Drinking

The two genes that have the strongest associations with alcohol use and alcohol dependence (AD) are mitochondrial aldehyde dehydrogenase 2 (ALDH2) and alcohol dehydrogenase IB (ADH1B). Mutations of these genes are considered protective against the risk of developing AD. New research findings show that both Korean ethnicity and ALDH2 genotype may predict drinking behavior among Asian young adults.

Results will be published in the May issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.

“This study was part of a larger prospective study of genetic influences on cognitive and behavioral aspects of alcohol use in Asian-American college students,” said Christian S. Hendershot, a doctoral candidate in clinical psychology at the University of Washington and corresponding author for the study.

The researchers chose to examine Asian young adults because the mutated ALDH2*2 allele is found exclusively among individuals of northeast Asian heritage, while the ADH1B*2 allele is highly prevalent among northeast Asians, although it is also found in some Caucasians.

“In addition, much of the research on the alcohol metabolizing genes has focused on alcoholic treatment samples, as well as older adult samples,” said Hendershot. “This is a limitation because genetic influences on alcohol use appear to vary depending on the recruitment strategy used in the study, and over the course of development. In this study, we examined a range of alcohol-related behaviors that might emerge before the onset of AD. We also examined alcohol sensitivity, which is an established endophenotype for alcohol dependence.”

Researchers performed DNA analysis on 182 participants (58 Chinese males, 57 Chinese females; 28 Korean males, 39 Korean females), university undergraduates with a mean age of 20.2 years. Study participants also responded to a web-based survey on alcohol use and related behaviors, with a focus on alcohol sensitivity, heavy episodic and hazardous drinking, and drinking consequences.

“We found consistent additive effects of ethnicity and ALDH2 genotype on a range of drinking behaviours,” said Hendershot. More specifically, Korean ethnicity – vs. Chinese – and ALDH2 status – but not ADH1B status – consistently explained significant variance in alcohol consumption among the Asian young adults examined.

“The findings suggest that ADH1B may not influence drinking at this age,” he added. “Given that ALDH2*2 has stronger protective effects than ADH1B*2, the effects of ALDH2 might emerge earlier than those of ADH1B. We also found that ALDH2*2 was associated with a lower likelihood of alcohol-related problems, which suggests that ALDH2 status might predict social or interpersonal consequences of alcohol use in addition to actual drinking.”

Hendershot noted that prior epidemiological research has shown significant differences in drinking behavior across Asian ethnic groups.

“For instance, rates of alcohol use and alcohol dependence are higher in Korea compared to China,” he said. “Because Chinese and Koreans each show a high prevalence of ALDH2*2 and ADH1B*2, the differences in drinking between these groups can be attributed in part to cultural influences. In our study, these ethnic group differences were consistent and significant while controlling for genetic influences. If ethnicity can be a rough proxy for cultural differences, the findings suggest that cultural factors and ALDH2 are both important predictors of drinking in this sample. We need more research to identify specific cultural factors that explain these ethnic group differences.”