Binge drinking in adolescence, even if discontinued, may increase the risk for anxiety later in life, according to a study led by an Indian origin scientist.

"Binge drinking early in life modifies the brain and changes connectivity in the brain, especially in the amygdala, which is involved in emotional regulation and anxiety, in ways we don't totally understand yet," said Subhash Pandey, a professor at the University of Illinois at Chicago in the US, and lead author of the study.

"But what we do know is that epigenetic changes are lasting, and increase susceptibility to psychological issues later in life, even if drinking that took place early in life is stopped," Pandey said in a statement.

"Epigenetics" refers to chemical changes to DNA, RNA, or specific proteins associated with chromosomes that change the activity of genes without changing the genes themselves, according to the study published in the journal Biological Psychiatry.

Epigenetic alterations are required for the normal development of the brain, but they can be modified in response to environmental or even social factors, such as alcohol and stress.

These kinds of epigenetic alterations have been linked to changes in behaviour and disease, researchers said.

Adolescent rats were exposed to ethanol (a type of alcohol) for two days on and two days off or to the same protocol using saline for 14 days. All rats underwent an assessment for anxiety.

Pandey and his colleagues exposed adolescent rats to a regimen designed to mimic binge drinking.

Those rats exhibited anxious behaviour later in life, even if the binge drinking regimen stopped in late adolescence and the rats were allowed to mature to adulthood without any further exposure to alcohol.

These rats also had lower levels of a protein called Arc in the amygdala. Arc is important for the normal development of synaptic connections in the brain.

Rats with less Arc also had about 40 per cent fewer neuronal connections in the amygdala compared with rats that were not exposed to alcohol.

"We believe that the decrease in Arc levels is caused by epigenetic changes that alter the expression of Arc, and an enhancer RNA, which modifies the expression of Arc. These changes are caused by adolescent alcohol exposure," said Pandey.