The drink is linked to 40 percent fewer neuronal connections in the emotional centre of the brain.
Binge drinking alcohol early in life is linked to developing anxiety later on.
The effects may be permanent, even if alcohol is given up after adolescence.
A previous study has also shown that very shy people can become highly anxious the day after drinking alcohol.
Dubbed ‘hangxiety’, the condition combines a hangover with heightened anxiety.
This rat study, however, found that alcohol reduced the number of neuronal connections in the amygdala, a brain region important for emotion.
Professor Subhash Pandey, study co-author, explained:
“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.
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.”
The conclusions come from a study of adolescent rats who were fed alcohol in a simulation of human binge drinking.
The results showed that the rats became more anxious later in life, even when they stopped binge drinking after adolescence.
They also had lower levels of an important protein in their amygdala.
The protein, called ‘Arc’, is critical to the formation of neuronal connections in the brain.
Rats with lower levels of Arc had 40 percent fewer neuronal connections in the amygdala.
Professor Pandey explained that alcohol has epigenetic effects; these are changes to gene expression, rather than the genetic code itself:
“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.”
Professor Pandey continued:
“Exposure to alcohol causes epigenetic reprogramming to occur, leading to molecular changes in the amygdala, which are long-lasting, even in the absence of more alcohol.
If the amygdala has deficits in its wiring or connectivity, and these modifications are long-lasting, the individual is at risk for psychological issues based on difficulties in regulating emotions, such as anxiety or depression and the development of alcohol use disorder later in life.”
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The study was published in the journal Biological Psychiatry (Kyzar et al., 2019).
