Tuesday 6 December 2016

Alcohol has a much greater effect on adolescent brains

Published 21/04/2015 | 02:30

A World Health Organization survey in 2014 found that 39pc of Irish 15-year-olds had engaged in a session of binge-drinking, putting us just behind Austria, which topped the list in the 194 countries studied.

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It is timely to remind ourselves then that: "Research indicates that the human brain continues to develop into a person's early 20s and that exposure of the developing brain to alcohol may have long-lasting effects on intellectual capabilities," according to the Centre for Substance Abuse Prevention in the US.

Alcohol has a noticeable effect on brain cells and on the transmitters that pass signals along the nerves in various parts of the brain. And like a river, it has tributaries and distributaries that flow deep into several areas of the brain, causing damage and destruction like a deluge. And a binge is like a torrent of alcohol.

Three broad aspects of brain function are altered - the first is memory, the second is planning/decision making/judgement and the third is reward-seeking. Everybody knows that alcohol affects memory in certain ways and we now understand that the effects of alcohol on adolescent memory are much greater than its impact.

While immediate memory is not affected by alcohol consumption, the ability to lay down memories is, and so recall of information even 20 minutes later or of facts (known as explicit memory) such as telephone numbers or what you did last night, are impaired.

This is because of the impact it has on part of the brain known as the hippocampus. This is the unit for memory storage, particularly an area called CA1. The cells here are particularly sensitive to the effects of alcohol. Studies have found that heavy, extended drinking is associated with a 10pc reduction in hippocampal volume.

The second brain area that is smaller in adolescents who drink to excess compared to those who do not drink, is the pre-frontal cortex.

This is located behind the eyes and is regarded as the executive control centre. It allows us to weigh risks and rewards and it helps us to decide when to defer a particular action rather than pursuing immediate gratification.

This undergoes huge change during adolescence, more than any other area of the brain. It is responsible for the poor decision-making of many young people. It, too, is particularly sensitive to the effects of alcohol and under its influence, judgement and decision-making is even more impaired than it otherwise would be in that age group.

This is one of the reasons for suicidal behaviour being so closely associated with alcohol - judgement, delaying actions and weighing risks and benefits is compromised.

Alcohol has significant effects on a neurochemical called dopamine and this is present in plenty in the brain area called the nucleus accumbens, also called the reward centre.

During adolescence, dopamine cells are shed and so teenagers engage in risky behaviours to stimulate its production and generate feelings of excitement and pleasure. Alcohol itself also stimulates the production of dopamine and this explains why many alcoholics began drinking in their teenage years.

Thus, the young person will gain the thrills they are seeking by drinking while having less ability to put brakes on their behaviour since the restraining influence of the pre-frontal cortex is dampened, also by alcohol.

It seems that the adolescent brain is fighting a losing battle.

Surprisingly, adolescents are less sensitive to the sedating effects of alcohol than adults. Neither do they slur their words or lose their balance as early in the course of a drinking spree.

Their resilience against these effects is a problem, since tiredness and social impairment are cues to limit intake.

Instead, teenagers see themselves as being able "to hold my drink" since they are able to imbibe far more than adults before they get sleepy enough to stop. They are also less sensitive to certain post-intoxication "hangover" effects and this also reduces any motivation they might have to curtail their consumption. So, they are silently and invisibly damaging themselves.

The effect of maximal memory impairment combined with minimal evidence of intoxication explains why blackouts, previously thought to be a feature of the older long-established drinker, are now commonly seen in teenage and young adult drinkers also.

Irish teenagers and their parents should be warned of the grave effect alcohol has on the developing brain.

For those wanting more information they should read From Binge to Blackout: A Mother and Son Struggle with Drinking, by Toren and Chris Volkmann (2006 New American Library).

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