(Medical Xpress) -- Researchers have found evidence that early drug and alcohol use is associated with lower levels of educational attainment.
Studying male twins who served in the military during the Vietnam era, they found that those who began drinking or using drugs as young teens or who became dependent on alcohol, nicotine or marijuana, were less likely to finish college than those who didnt use alcohol or drugs until later in life and never became dependent.
The study, by investigators at Washington University School of Medicine in St. Louis and the Palo Alto Veterans Affairs Health Care System, will be published in the August 2012 issue of Alcoholism: Clinical & Experimental Research but is now available online.
We cant say that substance dependence or early substance use causes lower educational achievement, but we do see a strong association, says lead author Julia D. Grant, PhD, research assistant professor of psychiatry. Even after we statistically controlled for the genes and the environmental factors that twins share, we found a relationship between substance use and educational achievement.
Past studies about the relationship between substance use and education have delivered mixed results. But this study of 6,242 twins shows a link between fewer years of schooling and the onset of drinking before age 14.
Studying identical and fraternal twin pairs is useful for examining things like substance use and education because we can asses the extent to which a given behavior is influenced by genetic factors and by factors related to family and environment, Grant says. Since identical twins share all of their genes and fraternal share about half, we can set up statistical comparisons to tease many of those factors apart.
In the analysis, Grants group found that when men in the study began to drink or use drugs early in their teen years or if they became a drug addict or alcoholic, they were less likely to complete 16 years of education.
In addition, she says the men in the study were surveyed when most were in their late 30s of early 40s, a point in their lives where it was less likely they would further their education.
Veterans, she says, were a particularly good group to follow because it is rare for anyone to serve in the military without finishing high school or earning a GED. In addition, because of the G.I. Bill, veterans are less likely to have financial constraints that would prevent them from attending college.
Grant says the findings provide more evidence that early drug and alcohol use is associated with a large number of problems later in life.
Drugs and alcohol affect many lifetime milestones such as marriage, parenthood and employment, which are closely linked to education, she says. These events in later life all are influenced by early substance use, and this study provides further evidence that as a society, we need to continue our public-health efforts to reduce underage drinking, smoking and use of drugs.
More information: Grant JD, et al. Associations of alcohol, nicotine, cannabis and drug use/dependence with educational attainment: evidence from cotwin-control analyses. Alcoholism: Clinical & Experimental Research, Early View vol. 36 (8), August 2012.