Enjoying a couple of drinks or three can be a great way to unwind, oil the conversation and unleash the inner merrymaker. But why do some of us push on despite swearing “never again” after the last hangover from hell? Researchers from Australia and the US say they’ve shown – in rats at least – how alcohol impacts brain regions associated with stress and pleasure, and, perhaps not surprisingly, dampens our impulse control.
“We show binge alcohol consumption over a long period of time changes the parts of the brain that manage our responses to stress,” says Selena Bartlett from the University of Queensland, senior author of a study published in the journal Neuroscience.
“In fact, although alcohol is pleasurable in the first few glasses, over time, it makes us more stressed in the long run.”
The study found that long-term alcohol use impacted neurons sensitive to emotional stimuli such as anxiety and stress in the brain’s basolateral amygdala and resulted in loss of inhibition. The main role of the basolateral amygdala, or complex, is around our response to fear.
“Too much alcohol makes it harder to say ‘no’ or ‘enough’,” says Bartlett.
“Over time, this can lead to compulsive alcohol-seeking, an inability to self-limit intake despite negative consequences and the emergence of physical and affective withdrawal symptoms, all of which are the basis of alcohol use disorders.”
For the study, Bartlett and team exposed healthy rats to 10 weeks of binge drinking and abstinence. The critters were given two drinking bottles, one with 20% ethanol and the other with water, that were weighed and refilled daily. On Mondays, Wednesdays and Fridays they were deprived of alcohol as the ethanol bottle was exchanged for water.
Six out of 10 rats became heavy drinkers, showing markedly increased preference for ethanol from their very first taste – but not all.
So, why do some people overindulge while others find it easy to drink moderately and stop after they’ve had an elegant sufficiency?
Decades of research has found that traumatic experiences in early life, inherited from many generations, lead to heavy drinking later in life. Bartlett says the current study, led by first author Paul Klenowski from the University of Massachusetts, adds to that.
“Taken altogether, this means people who have experienced a lot of stress or trauma in the early parts of their life, including the lives of their parents, drink alcohol to relieve the stress,” she explains. “However, the alcohol then creates more stress on the brain over time. This leads to a vicious cycle, hence why some people become heavier drinkers than others.”
Current challenges could also trigger moderate drinkers to hit the turps.
“Alcohol consumption is a great indicator of the amount of stress experienced in people’s lives,” says Barlettt. “Even a lower to moderate drinker, under enough life stress – such as the COVID-19 pandemic – can have the possibility of becoming dependent and addicted.”
On the positive side, she says progress has been made using neuroplasticity to retrain the brain. “Addiction is the outcomes of genetics and early life experience. To change addiction we have to change the underlying causes.”
Related reading: Even moderate drinking is bad
Natalie Parletta is a freelance science writer based in Adelaide and an adjunct senior research fellow with the University of South Australia.
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