Teen brains in jeopardy from alcohol
Teenagers face greater harm from alcohol, warn developmental neuroscience experts, because the immature wiring of their still-developing, vulnerable brain seems to allow them to drink more without falling over or falling asleep.
And while they could remain out partying with a blood alcohol concentration high enough to send an adult crawling to bed, the overly alcohol-sensitive and easily disrupted memory and learning parts of their teenage brain, including the hippocampus, could suddenly go off- line causing blackouts or at least greatly impairing decision-making.
It then left the teenagers to wake the next morning unsure of what they had been up to or full of regrets.
And having been still on their feet, while severely under the influence and with impaired judgment, they were more at risk of finding they had become the victim of a fight, traffic accident or sexual assault.
Research on rodent models and preliminary work with humans had revealed adolescents' brains reacted differently to alcohol and were less able to pick up the negative feedback and warning signs of damage being done to the body, said Associate Professor Dan Lubman of the Orygen Youth Health Research Centre at the University of Melbourne.
They could reach much higher blood-alcohol concentrations without feeling the ill effects of intoxication or experiencing sedation, unco-ordination or deteriorating balance and movement.
And without this feedback, they were at greater risk of binge-drinking.
All this occurred, Professor Lubman said, at a time that the teenage brain was highly vulnerable - busy growing into a leaner, more efficient machine and dramatically changing physically, emotionally, cognitively, intellectually and socially - and it was more susceptible to any damage or disruptions triggering mental health or substance-abuse problems or resulting in trauma.
Even before the addition of alcohol, the teenage brain was finding sound decision-making difficult because the limbic system emotion-controlling part had matured faster than the frontal regulating-behaviour part, fuelling a keen interest in pleasure and thrill-seeking.
"We do not yet really understand the mechanisms underpinning all this," said Professor Lubman. "But it seems to be that at the same blood alcohol concentration the adolescent brain does not seem to be as affected in that way. They do not get the same signals. They can drink a lot more and get a lot higher blood alcohol concentration without falling over or falling asleep.
"It is good if you want to show you can hold your liquor but it is bad in terms of its effect on the brain. They are able to drink much more without getting that negative feedback that it is actually doing them harm.
"That is why I think we are seeing all this binge- drinking occurring during adolescence. They feel like they can drink a lot more and stay up and stay alert, but the problem is that often they do not realise how intoxicated they are.
"Even though they might be up and around and partying, what might be happening is that the blood alcohol concentrations have reached a level where it is really impairing their ability to remember and learn.
"And what appears to happen, and we see this quite commonly clinically, is it seems that young people report much more blackouts associated with drinking."
Still more needed to be learnt, he said, about the severity of the resulting long-term damage to the teenage brain, with longitudinal studies on "before and after" alcohol yet to be set up.
To date most of the evidence collected over the past decade had come from animal models and human research based on cross-sectional studies, comparing the brains of adolescents who were heavy drinkers with adolescents who were not.
Such US work had found teenage drinkers had a smaller hippocampus, a change that was enough to result in subtle memory and learning problems that would see grades fall from a B to a C or a C to a D.
"We are now just starting to understand how alcohol affects the brain and that it affects the brain differently depending on your developmental stage," he said. "Certainly the evidence from animal models and the preliminary evidence from human studies suggests that it does cause significant harm.
"With the burden of disease for 15 to 24-year-old males, eight of the 10 leading causes of disability and burden of disease are drugs and alcohol and mental health disorders. Certainly six out of the top 10 are those for young women."
Now with increasing evidence that alcohol was one of the most problematic substances in society, Professor Lubman said it was time to question whether Australia had been too liberal in allowing it to be so readily available and accessible, used as a rite of passage to adulthood and tolerating the negative effects associated with it.
His advice is to tell teenagers that avoiding or limiting alcohol is the best way to ensure their brains remain healthy and grow in the right way so that the risk of mental health problems and associated stress and trauma are reduced.
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