Teen brains are more impulsive

4th November 2011 at 00:00
Neuroscience explains why adolescents are vulnerable to drugs and take rejection badly, says Dr Ellie Dommett

To date, the majority of neuroscience applied to education has focused on the role of educators in teaching academic content to pupils. But the school environment is far more than a seat of learning. In particular, schools provide essential pastoral care, especially during adolescence.

Two main topics this pastoral care may touch on are use of addictive substances and bullying. Both are crucial issues at this stage of life. For example, anti-drugs literature is commonly targeted at adolescents, with advocates of this approach believing this age range is particularly at risk. And research has found that around one quarter of adolescent girls report social rejection from their peers, which is associated with decreased academic achievement and negative effects on psychological well-being.

Neuroscience can shed some light on these issues. Psychologists believe adolescents are more vulnerable than other age groups to developing addictions because they display greater impulsivity and novelty-seeking behaviour. Adolescents are not only more sensitive to the positive effects of the drugs, but also less sensitive to the negative effects when compared to adults, both of which may add to increased drug-taking.

In addition to psychosocial explanations, neuroscientists have put forward two reasons for this increased vulnerability. The first is that the specific pathway in the brain that is important in addiction (as well as motivation in general) is more active during adolescence. The second is that the prefrontal cortex, a region of the brain involved in self-regulating behaviour - that is, stopping an individual acting on every impulse - is slower to mature. The combination of strong motivation and weak self-regulation might explain why adolescents are at risk of addictions. Anything done to reduce that motivation or increase control would, perhaps, be beneficial.

However, the prefrontal cortex is more than just an elaborate impulse controller; it has recently been implicated in reactions to bullying. Using brain-scanning techniques such as functional magnetic resonance imaging, it is possible to investigate the brain basis of social rejection. This technique detects increased blood flow to parts of the brain, indicating activity, while participants perform a task. In this case, the task is commonly a cyber ball game, in which the participant believes they are playing with two other people who then deliberately leave them out of the activity.

Research has previously shown that social rejection in adults is associated with increased activity in regions of the brain that are linked to processing physically painful stimuli, and that pain-relieving drugs can reduce feelings of rejection and brain activity in these regions. This research has, however, been conducted using adult participants. Because of changes in the maturation rates of brain regions, it is important to also investigate responses in adolescents.

Research has already shown that adolescents report such rejection as more distressing than adults, so it is likely there will be a difference in brain responses. Research just published by scientists at University College London, led by Sarah-Jayne Blakemore, has shown that the prefrontal cortex responds to social exclusion. The researchers suggest that the regulatory control normally exerted by this region is reduced in adolescents during a social rejection task, in contrast to adults doing the same task.

This research tells us that an adolescent's reaction to drugs or being socially rejected is different from that of an adult and, therefore, while their responses may seem disproportionate for teachers or parents, they are appropriate for the individual. Of course, the neuroscience does not necessarily tell us how to reduce the impact of these events on an adolescent, but it does indicate that teaching self-awareness and emotion regulation could be useful.

Dr Ellie Dommett is a lecturer at the Open University and a co-author of the Learning and the Brain Pocketbook


"Behavioural Problems and Bullying at School: can cognitive neuroscience shed new light on an old problem?", Viding E, McCrory EJ, Blakemore SJ, Frederickson N, Trends in Cognitive Sciences, July 2011. http:bit.lyoQu2b6

"Developmental Influences on the Neural Bases of Responses to Social Rejection: implications of social neuroscience for education", Sebastian CL, Tan GCY, Roiser JP, Viding E, Dumontheil I, Blakemore SJ, NeuroImage, August 2011. http:bit.lyjhlUCL.

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