Until about 15 years ago, it was widely assumed that the majority of brain development occurs in the first few years of life. But recent research on the human brain has demonstrated that many brain regions undergo protracted development throughout adolescence and beyond in humans. This advancement in knowledge has intensified old worries and given rise to new ones. It is hugely worrying that so many teenagers around the world don't have access to education at a time when their brains are still developing and being shaped by the environment. We should also worry about our lack of understanding of how our rapidly changing world is shaping the developing teenage brain.
Decades of research on early neurodevelopment demonstrated that the environment influences brain development. During the first few months or years of life, an animal must be exposed to particular visual or auditory stimuli for the associated brain cells and connections to develop. In this way, neuronal circuitry is sculpted according to the environment during 'sensitive periods' of brain development. This research has focused mostly on early development of sensory brain regions. What about later development of higher-level brain regions, such as prefrontal cortex and parietal cortex, which are involved in decision-making, inhibitory control and planning, as well as social understanding and self-awareness? We know these brain regions continue to develop throughout adolescence. However, we have very little knowledge about how environmental factors influence the developing teenage brain. This is something that should concern us.
There is some recent evidence from the Dunedin Longitudinal Study that adolescence represents a period of brain development particularly sensitive to environmental input. This study reported that persistent cannabis use in adolescence had long-lasting negative consequences on a broad spectrum of cognitive abilities later in adulthood. In contrast, this was not the case if cannabis use started after the age of 18. Could the same be true for other environmental factors? Alcohol, tobacco, drug-use, diet, medication, Internet usage, gaming… these are all likely to affect the developing brain. The question is how, and we simply don't know the answer.
There's a lot of concern about the hours some teenagers spend online and playing video games. But maybe all this worry is misplaced. After all, throughout history humans have worried about the effects of new technologies on the minds of the next generation. When the printing press was invented, there was anxiety about reading corrupting young people's minds, and the same worries were repeated for the invention of radio and television. Maybe we shouldn't be worried at all. It's possible that the developing brains of today's teenagers are going to be the most adaptable, creative, multi-tasking brains that have ever existed. There is evidence—from adults—that playing video games improves a range of cognitive functions such as divided attention and working memory as well as visual acuity. Much less is known about how gaming, social networking and so on, influence the developing adolescent brain. We don't know whether the effects of new technologies on the developing brain are positive, negative or neutral. We need to find out.
Adolescence is a period of life in which the brain is developing and malleable, and it represents a good opportunity for learning and social development. However, according to Unicef, 40% of the world's teenagers do not have access to secondary school education. The percentage of teenage girls who have no access to education is much higher, and yet there is strong evidence that the education of girls in developing countries has multiple significant benefits for family health, population growth rates, child mortality rates, HIV rates as well as for women's self-esteem and quality of life. Adolescence represents a time of brain development when teaching and training should be particularly beneficial. I worry about the lost opportunity of denying the world's teenagers access to education.