Cause, effect & underage drinking

Two interesting findings about underage drinking. The first on the relationship between early alcohol use and chronic alcohol problems later in life. The second looks at the relationship between early alcohol use and poor judgment later in life.

We've known for some time that there is a relationship between early drinking and alcohol problems later in life. What's been unclear is the nature of that relationship. Does early exposure to alcohol cause changes in the adolescent brain that lead to problems later in life? Does early exposure facilitate the expression of genes that are related to alcoholism? These two theories would suggest that early exposure to alcohol has the potential to cause alcohol problems later in life. Or, is early exposure an indicator of risk factors such as the environment the young person is in or risk taking behavior? These would suggest that there is no causal relationship.

A new study supports the gene expression theory:

Background: Research suggests that individuals who start drinking at an early age are more likely to subsequently develop alcohol dependence. Twin studies have demonstrated that the liability to age at first drink and to alcohol dependence are influenced by common genetic and environmental factors, however, age at first drink may also environmentally mediate increased risk for alcohol dependence. In this study, we examine whether age at first drink moderates genetic and environmental influences, via gene × environment interactions, on DSM-IV alcohol dependence symptoms.

Methods: Using data on 6,257 adult monozygotic and dizygotic male and female twins from Australia, we examined the extent to which age at first drink (i) increased mean alcohol dependence symptoms and (ii) whether the magnitude of additive genetic, shared, and nonshared environmental influences on alcohol dependence symptoms varied as a function of decreasing age. Twin models were fitted in Mx.

Results: Risk for alcohol dependence symptoms increased with decreasing age at first drink. Heritable influences on alcohol dependence symptoms were considerably larger in those who reported an age at first drink prior to 13 years of age. In those with later onset of alcohol use, variance in alcohol dependence was largely attributable to nonshared environmental variance (and measurement error). This evidence for unmeasured gene × measured environment interaction persisted even when controlling for the genetic influences that overlapped between age at first drink and alcohol dependence symptoms.

Conclusions: Early age at first drink may facilitate the expression of genes associated with vulnerability to alcohol dependence symptoms. This is important to consider, not only from a public health standpoint, but also in future genomic studies of alcohol dependence.

On the second matter, Scientific American [via 3 Quarks Daily] suggests that there is a causal relationship between early exposure to alcohol and poor judgement long after the effects of the alcohol wear off:

It's no secret that binge drinking and faulty decision-making go hand in hand, but what if poor judgment lingered long after putting the bottle down and sobering up? A new study with rats suggests that heavy alcohol consumption in adolescence could put people on the road to risky behavior.

Several studies have associated heavy drinking in youth with impaired judgment in adulthood, but these studies didn't resolve whether alcohol abuse actually predisposes people to develop bad decision-making skills, or if the people who indulged in excessive inebriation were risk-taking types to begin with. As Selena Bartlett, a director in the Ernest Gallo Clinic and Research Center at the University of California, San Francisco, explains, you cannot put adolescents in a room and ask them to consume alcohol to see what happens. But scientists can conduct these kinds of experiments with rats, an animal that Bartlett, who was not part of the study, says is "excellent for modeling changes in behavior" as a result of alcoholism.

In the new study published this week in Proceedings of the National Academy of Sciences, scientists at the University of Washington

(U.W.) in Seattle fed alcohol to a group of rats and found that their ability to make good decisions was impaired even long after they stopped consuming booze.