Teenagers have got a fully developed immune system and are unlikely to suffer from older-age related diseases so they should enjoy incredibly low rates of mortality. However, their behaviour and decision making leads to an increase in potentially preventable deaths in this stage of life.
Indeed, studies of deaths amongst teenagers in the USA have consistently found that accidental deaths account for nearly 50% of all teenage deaths.
Looking at the data more carefully, accidents lead the way causing 48 percent of deaths, then homicide is the next most common cause of death (13 percent), closely followed by suicide (11 percent).
Tragically, nearly three-quarters of all accidental teenage deaths are as a result of car accidents. While many teenagers have the skills to pass their driving test, they are less likely to have the judgement and impulse control to drive a car safely. Teenagers are more likely than adults to be overconfident and irresponsible.
Many scientists have tried to look at why this preponderance for dangerous behaviour occurs in the teenage years.
Professor Yurgelun-Todd and her colleagues have long been interested in the teenage brain and has carried out meticulous and ground-breaking brain imaging studies.
She and her colleague Marisa Silveri have concluded that the source of poor judgment in teenagers might be found in the white matter microstructure in the brain’s prefrontal cortex. The entire frontal cortex (at the top and front of the brain) is associated with executive functions like:
Through diffusion tensor imaging (DTI), Yurgelun-Todd, Silveri, and their colleagues examine white matter microstructure, the part of the brain that’s responsible for relaying signals between neurons in the gray matter.
During adolescence lots of unneeded gray matter, in the frontal cortex, is pruned away while white matter (fast myelin-covered neurons), increases. This myelination is like insulation of electrical wires and speeds up and improves connectivity,
“Myelination, or the insulating of axons, allows more rapid and efficient communication between neurons,” says Silveri.
The research team found the more integrated and connected the prefrontal white matter, the stronger the impulse control in teenage boys and girls. This study may point to how full maturation of the frontal and prefrontal cortex may lead to improved impulse control in adults.
In an earlier study of teenagers by Yurgelun-Todd when she was based at Harvard Medical School, she reported that three-quarters at the teenagers did not recognise fearful faces and were significantly less able than adults to read emotions in faces.
This is a staggering finding. Reading fear in the faces of other people is referred to as ‘social referencing’ and is an important way by which we judge how safe a situation is. If teenagers are struggling to see that other people find a situation fear-inducing, they may be less able to make a judgement to avoid danger and this, along with other executive brain function immaturity may go some way to explaining the startling statistics around teenage accidents and homicides.
Teenagers are still waiting for the crucial final part of their brain to be rewired and during this time they have trouble controlling themselves. The frontal cortex helps us to assess all kinds of risks and control impulses and urges.
Teenagers have not yet got a fully developed frontal and prefrontal cortex and are more likely to engage in other risky behaviours too (compared to adults and children), such as binge drinking, unprotected sex, and drug use.
The causes and patterns of teenage risk-prone behaviour are multi-faceted and complex – including reduced impulse control, reduced ability to read emotions and situations, and the effects of hormonal increases.
It’s important to remember that although teenagers are physically as big and tall as adults, their brains are not fully matured. Indeed, the human brain doesn’t go through its final stage of development till the very end of the teenage years – perhaps this is why 21 years of age is often referred to as adulthood. In the USA, this is when alcohol can be legally drunk and is celebrated in the UK as the ‘key to the door’ of adulthood. That said – the brain might not reach maturity until several years later!
Teenagers are not adults. The good news is that most teenagers do survive the adolescent years, usually with nothing more than a few scrapes and bruises, but expecting teenagers to act like mini-adults is unrealistic.
Giving your teenager relatively safe outlets for their impulsive and thrill-seeking behaviour may help, e.g., youth initiatives* and skating parks. Activities that encourage discipline and self-control can also help such as martial arts and dancing.
*A youth programme based in Manchester saw crime amongst teenagers reduced by 60% (source – BBC series Teen Species)
Arialdi & Miniño (2010) Mortality Among Teenagers Aged 12-19 Years: The United States, 1999-2006 NCHS Data Brief No. 37, May 2010
Rosso, I.M., Young, A.D., Femia, L.A. & Yurgelun-Todd, D.A. (2004). Cognitive and emotional components of frontal lobe functioning in childhood and adolescence. Annals of the New York Academy of Sciences, 1021, 355-362.
Yurgelun-Todd, D.A. & Killgore, W.D.S. (2006) Fear-related activity in the prefrontal cortex increases with age during adolescence: A preliminary fMRI study. Neuroscience Letters, 406, 194-199.
Yurgelun-Todd, D. (2007) Emotional and cognitive changes during adolescence. Curr Opin Neurobiol, Apr;17(2):251-257.
Xu, Murphy, Kochanek, Brigham & Bastian (2016) Deaths: Final Data for 2013. National Vital Statistics Reports Volume 64, Number 2 February 16, 2016