Leiden psychologists have discovered that while testosterone has a large influence on the drinking habits of teenage boys, matters seem to be more complicated for girls and the "female" hormone oestradiol.
Small children grow into bigger ones and then adolescents. "Adults often think that teenagers are nothing but trouble, but adolescence is a wonderful time, offering many opportunities", remarks psychologist Barbara Braams. "For instance, teenagers are much better at coming up with creative solutions than people who are a bit older."
Nevertheless, there are plenty of things that teenagers are not so good at: life’s lessons still to be learnt. And that’s why teenagers experiment: with make-up, with sex, the Internet and stimulants. The whole essence of the word "experiment" is that the results could be anything, and when teenagers experiment with alcohol or hard drugs, the results are not always good.
In 2008, a paediatrician in Delft, Nico van der Lely, raised the alarm: more and more, and younger and younger, children were being admitted to his outpatients surgery with alcohol poisoning, some of whom had so much brain damage caused by their drinking that their intelligence dropped permanently. Accordingly, society needs to know why children drink.
The topic is also relevant to Braams’ doctoral research, as she wanted to find out more about the brain as we grow up. "The part of our brain that deals with rewards – good feelings after a certain experience – matures faster than the area of our brain that is in charge of controlling impulses, which causes an imbalance and that can lead to risky behaviour."
Master’s-degree student Erik de Water – who has by now graduated and is a PhD student himself – worked with Braams and her Leiden colleagues Jiska Peper and Eveline Crone to find out more about adolescent alcohol consumption. The psychologists visited secondary schools in Leiden, gave guest lessons about their research and recruited hundreds of test persons for their experiment.
Humans are not the only creatures to have this desire for experimenting, and adventuresome and thrill-seeking teenage years. The young adults of all sorts of animals push back the boundaries, take risks and get lost. Sometimes, they achieve something - new territory, perhaps, and sometimes they get into trouble. But the point here is that they don’t do it because they’ve been watching the wrong kinds of television programmes. There is evidently something in young animals that makes them adventurous.
It would seem that this "something" is the same sex hormones that are responsible for turning children into adults. These sex hormones also affect people and our consumption of alcohol. In boys, a relationship has been established between that and testoterone levels, and there is evidence from previous studies that the hormone oestradiol has something to do with how much girls drink.
In the scientific journal Hormones and Behavior, you can read how these hormones affect Leiden teenagers. The psychologists studied their alcohol consumption and their degree of sexual maturity by means of a questionnaire, and determined the amount of sex hormones with a saliva test.
The older someone is, the greater the chance that he or she has tried an alcoholic beverage. However, it emerged that physical maturity is slightly more important than age, which applies to both boys and girls. In addition, in boys, there was a relationship between the levels of testosterone and the chances that they had already tried strong drink. A similar relationship, but weaker, was found between alcohol consumption and oestradiol, although this hormone in girls did not appear to have any bearing on alcohol consumption.
Everyone already assumes that testosterone leads to drinking, that much has proved to be true, but what about oestradiol? And if affects boys, why not girls? The researchers put forward different explanations in their article: maybe the difference lies in the different concentrations; maybe the same hormone affects boys and girls differently. Girls’ monthly cycles have something to do with it, and although the researchers collected the hormones on the same day of the girls’ cycles, a relationship might have been discovered if the samples had been taken at another time.
"It’s always difficult to measure hormones," Braams explains, "and we actually expected to find an effect on girls too. We’re still investigating exactly how it all relates."
Perhaps the answer is even more straightforward: the relationship between oestradiol and alcohol consumption in boys could be indirect. In women, the ovaries produce that particular hormone but in boys, it’s made from testosterone. Consequently, boys with more testosterone also have higher levels of oestradiol and the relationship between the concentration of oestradiol and alcohol consumption could be caused by the fact that the level of testosterone has an effect on both. It could also be that the substance that is responsible for the conversion, aromatase, affects our alcohol consumption.
"We simply don’t know how much effect that conversion has", adds her fellow researcher Jiska Peper. "Those two hormones affect both boys and girls, but to a different degree. It is really very interesting to study the role of oestradiol because that hormone also influences how our brains develop."
The legal age for drinking in the Netherlands is currently sixteen. In 2006, the Health Council of the Netherlands recommended that children under the age of eighteen should not drink any alcoholic beverages. On strictly medical grounds, that age should be raised to 21 because your brain is not yet fully developed at eighteen, and the parts that are last to mature are the ones that are vulnerable to alcohol.
The number of children with alcohol poisoning – the tip of the iceberg – is growing year by year while their average age is dropping and the permillage with which they are admitted to hospital rises each year. Gradually, you can see that society is realising that it is doing itself no good by allowing teenagers to drink too much. Supermarkets are much stricter about selling booze, and the Rutte II administration wants to raise the minimum age for drinking to eighteen. If a drunken teenager is admitted to hospital, we are not only dealing with the costs of treatment – there is also a serious risk that the teenager will have permanently harmed him or herself by drinking.
To start with, young brains are more sensitive to addiction and that it noticeable in the excesses: twenty years ago, the average Korsakov patient was in his sixties; now, the average age is just over forty. The youngest patient in the Netherlands is 32.
An adolescent who drinks too much and too often obstructs the development of the prefrontal cortex, the area of the brain that regulates our cognitive and emotional control. Social behaviour, making schedules and keeping emotions under control are all tasks in which our frontal lobes play an essential part and precisely those task are the sort that are extremely important in our modern society. "By drinking in your teenage years, you might miss the chance to evolve into who you really are", as paediatrician Nico van der Lely sums it up in his book Onze kinderen en alcohol [Our children and alcohol].
Even more realistically: boozing knocks points off your IQ – the academic performance of more than forty per cent of teenagers admitted to hospital with alcohol poisoning is worse afterwards than you might expect on the grounds of their CITO test [exams held in the final year of primary school].
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