How underage binge-drinking may lead to increased anxiety, alcoholism in adults

A new study has revealed that binge-drinking during adolescence may affect adult behavior through long-lasting changes in genes.

Lead author Subhash Pandey from University of Illinois at Chicago College of Medicine said that this may be the mechanism through which adolescent binge-drinking increases the risk for psychiatric disorders, including alcoholism, in adulthood.

On-and-off exposure to alcohol during adolescence altered the activity of genes needed for normal brain maturation, said Pandey, adding that the gene alterations increased anxiety-like behaviors and preference for alcohol in adulthood.

The behavioral effects, he said, were due to "epigenetic" changes, which previous research has shown can be influenced through environmental substances, including alcohol. Epigenetic changes, which can be long-lasting or permanent in an individual and can be heritable, regulate many processes, including brain development and maturation during adolescence.

To model adolescent binge-drinking in humans, the researchers gave 28-day-old rats alcohol for two days in a row, followed by two days off, and repeated this pattern for 13 days. Rats exposed to alcohol during adolescence exhibited changes in behavior that lasted into adulthood, long after exposure to alcohol ended. They showed increased anxiety-like behaviors and drank more alcohol in adulthood.

When researchers analyzed tissue from a part of the brain called the amygdala, they found in the exposed rats that the DNA and histones appeared to be tightly wrapped. They also found increased levels of a protein called HDAC2, which modifies histones in a way that causes DNA to be wound tighter around them.

These epigenetic changes in turn were linked to lowered expression of a gene that nerve cells need in order to form new synaptic connections. Pandey believes the lowered activity of this gene may be due to the tighter winding of its DNA.

Pandey added that the study provides a mechanism for how binge-drinking during adolescence may lead to lasting epigenetic changes that result in increased anxiety and alcoholism in adults. Intermittent alcohol exposure degrades the ability of the brain to form the connections it needs to during adolescence.

He noted that the brain doesn't develop as it should, and there are lasting behavioral changes associated with this.

The study appears in the journal Neurobiology of Disease.