Hard Evidence: Is the teenage brain wired for addiction?

The younger you are when you have your first alcoholic drink, the more likely you are to develop problems later on in life.

As a nation, we are drinking much more than we used to, which is partly attributable to alcohol being cheaper and more available than ever. Many British teenagers get into the habit early, although recent trends suggest this situation is improving (alcohol consumption among teenagers is slightly lower than it was ten years ago).

Nonetheless, drinking alcohol during adolescence is not a good idea, because the younger you are when you have your first alcoholic drink, the more likely you are to develop problems later on in life. The same is true for cigarette smoking and the use of illicit drugs such as cannabis and cocaine.

Rates of teenage drinking are dropping. NatCen

 

Arrested development

Why are adolescents particularly vulnerable to addiction? A large part of the answer comes from our understanding of the neurobiology of brain development during adolescence. The brain does not reach maturity until fairly late in life, with new connections between brain cells being formed right up until people are in their mid-20s.

Importantly, the brain does not mature at a uniform rate. The more primitive regions of the brain, including the reward system and other areas of the subcortex such as those parts that process emotions, reach maturity relatively early (when people are in their early teens).

The prefrontal cortex is a late bloomer. National Institute of Health

The more “advanced” parts of the brain, such as the prefrontal cortex, are not fully developed until much later. In behavioural terms this means adolescents are particularly sensitive to their emotions and to things that are novel and motivationally appealing, but they are relatively unable to control their behaviour and plan for the future.

Taking risks

My research suggests this can explain why some adolescents drink more than others: teenagers who were relatively poor at exerting self-control, or who took more risks on a computer test of risk-taking, were more likely to drink heavily in the future.

This creates perfect conditions for vulnerability to addiction during adolescence, because the motivational “pull” of alcohol and other drugs is very strong, whereas the ability to control behaviour is relatively weak. Many scientists think if adolescents do drink a lot, and if they do it frequently, then this might cause long-lasting changes in the way that the brain is organised, which can make it very difficult to stop drinking.

We certainly see changes in the brains of people with alcohol problems (compared to people without problems), but it can be difficult to work out if alcohol caused those brain changes, or if those people had slightly different brains before they started drinking, and these subtle differences may have led them to start drinking in the first place.

Starting early carries greater risk. NatCen

 

Addiction and behaviour

In principle, adolescent brains could be vulnerable to “behavioural” addictions as well as alcohol and drug addiction, for exactly the same reason. Very few behavioural addictions are officially recognised by psychiatrists and psychologists at the moment (gambling addiction is the only exception).

The Channel 4 documentary Porn on the Brain shown this week asked whether pornography is addictive, and if adolescents could be getting hooked. As shown in the programme, it certainly seems to be the case that a minority of adolescents who use pornography exhibit some of the characteristic features of addiction, such as feeling unable to control their use of porn, and loss of interest in other activities.

Their patterns of brain activity when viewing porn seem to be similar to those seen in people with alcohol and drug addictions when they look at pictures of alcohol and other drugs. It remains to be seen whether addiction to porn will eventually be recognised as a psychological disorder, but it is clear that it can create problems for some adolescents and young adults who use it.

What can be done? Although it’s obvious, parents should do what they can to prevent their children from experimenting with alcohol, smoking and other drugs for as long as possible. The same applies to other things that might eventually be considered “addictive”. School-based prevention programmes can also be successful, including a recent program that is tailored to different personality types and has shown some promise at reducing alcohol consumption in teenagers.

Hard Evidence is a series of articles in which academics use research evidence to tackle the trickiest public policy questions.

Matt Field receives funding from the Medical Research Council, Economic and Social Research Council, Wellcome Trust, British Academy and Alcohol Research UK. He is affiliated with the UK Centre for Tobacco and Alcohol Studies.

This article was originally published at The Conversation. Read the original article.

Teenages making a toast in a pub. Photo: Getty

Matt Field is Professor of Experimental Addiction Research at the University of Liverpool.

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Not just a one-quack mind: ducks are capable of abstract thought

Newborn ducklings can differentiate between objects that are the same and objects that are different, causing scientists to rethink the place of abstract thinking.

There’s a particular loftiness to abstract thought. British philosopher and leading Enlightenment thinker John Locke asserted that “brutes abstract not” – by which he meant anything which doesn’t fall under the supreme-all-mighty-greater-than-everything category of Homo sapiens was most probably unequipped to deal with the headiness and complexities of abstract thinking.

Intelligence parameters tail-ended by “bird-brained” or “Einstein” tend to place the ability to think in abstract ways at the Einstein end of the spectrum. However, in light of some recent research coming out of the University of Oxford, it seems that the cognitive abilities of our feathery counterparts have been underestimated.

In a study published in Science, led by Alex Kacelnik – a professor of behavioural psychology – a group of ducklings demonstrated the ability to think abstractly within hours of being hatched, distinguishing the concepts of “same” and “different” with success.

Young ducklings generally become accustomed to their mother’s features via a process called imprinting – a learning mechanism that helps them identify the individual traits of their mothers. Kacelnik said: “Adult female ducks look very similar to each other, so recognising one’s mother is very difficult. Ducklings see their mothers from different angles, distances, light conditions, etc, so their brains use every possible source of information to avoid errors, and abstracting some properties helps in this job.”

It’s this hypothesised abstracting of some properties that led Kacelnik to believe that there must be more going on with the ducklings beyond their imprinting of sensory inputs such as shapes, colours or sounds.

The ability to differentiate the same from the different has previously been used as means to reveal the brain’s capacity to deal with abstract properties, and has been shown in other birds and mammals, such as parrots, pigeons, bees and monkeys. For the most part, these animals were trained, given guidance on how to determine sameness and differences between objects.

What makes Kacelnik’s ducklings special then, as the research showed, was that they were given no training at all in learning the relations between objects which are the same and object which are different.

“Other animals can be trained to respond to abstract relations such as same or different, but not after a single exposure and without reinforcement,” said Kacelnik.

Along with his fellow researcher Antone Martinho III, Kacelnik hatched and domesticated mallard ducklings and then threw them straight into an experiment. The ducklings were presented pairs of objects – either identical or different in shape or colour – to see whether they could find links and relations between the pairs.

The initial pairs they were presented served as the imprinting ones; it would be the characteristics of these pairs which the ducklings would first learn. The initial pairs involved red cones and red cylinders which the ducklings were left to observe and assimilate into their minds for 25 minutes. They were then exposed to a range of different pairs of objects: red pyramid and red pyramid, red cylinder and red cube.

What Kacelnik and his research partner found was that the ducklings weren’t imprinting the individual features of the objects but the relations between them; it’s why of the 76 ducklings that were experimented with, 68 per cent tended to move towards the new pairs which were identical to the very first pairs they were exposed to.

Put simply, if they initially imprinted an identical pair of objects, they were more likely to favour a second pair of identical objects, but if they initially imprinted a pair of objects that were different, they would favour a second pair of differing objects similar to the first.

The results from the experiment seem to highlight a misunderstanding of the advanced nature of this type of conceptual thought process. As science journalist Ed Yong suggests, there could be, “different levels of abstract concepts, from simple ones that young birds can quickly learn after limited experience, to complex ones that adult birds can cope with”.

Though the research doesn’t in any way assume or point towards intelligence in ducklings to rival that of humans, it seems that the growth in scientific literature on the topic continues to refute the notions that human being as somehow superior. Kacelnik told me: “The last few decades of comparative cognition research have destroyed many claims about human uniqueness and this trend is likely to continue.”