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Teen brains and driving: One ‘request’ all parents should ask of P-platers

As the eldest of three sons, I was the first to get my driver’s licence. After the initial shock that I actually passed my test the first time (I’m a terrible driver – my father says I don’t drive a car, I aim it!), Dad sat my brothers and I down and shared with us his one rule when it came to driving, i.e., he never wanted for one of us to be behind the wheel and the other two to be passengers in the car. His explanation was simple – young drivers aren’t experienced and accidents happen, to have one of his sons in a car crash would be bad enough, to have all three in that vehicle would be devastating. Over 4 decades later I can’t think of a time when the three of us have ever been in a car together with one of us driving. For some reason the discussion we had all those years ago just stuck. The rule certainly didn’t come about as a result of my Dad’s extensive knowledge of research in the area (in fact, I doubt whether any really existed back then), it simply came out of his love for his kids and awareness that young drivers are more likely to make mistakes. In recent years we’ve seen so much research conducted in this area and when you look at what we know now my Dad was away ahead of his time.

When you look at the Australian statistics around young drivers, and particularly P-platers, it’s no surprise that parents are concerned:

  • 45% of all young injury deaths are due to road traffic crashes
  • almost half of all hospitalizations of young people are drivers, another quarter are passengers
  • young drivers (17-25 years) represent one-quarter of road deaths, but are only 10-15% of the licensed driver population
  • a 17-year-old with a P1 licence is 4 times more likely to be involved in a fatal crash than a driver aged over 26

Most importantly, studies have now identified passengers and number of passengers as key factors associated with increased fatal crash risk for young drivers, with one US study’s (Chen et al, 2000) results bound to cause great concern for any parent of a P-plater. As shown in the infographic above, compared to driving with no passengers, a 16- or 17-year-old driver’s risk of death per mile:

  • increases 44% when carrying one passenger younger than 21
  • doubles (increases 102%) when carrying two passengers younger than 21
  • quadruples (rising 339%) when carrying three or more passengers younger than 21

Interestingly, having an older person in the car seems to have the reverse effect, decreasing the risk of death by 62 per cent when passengers aged 35 or older are present. These findings mirror those tragic stories of groups of Australian teens being killed in car crashes involving P-platers. Too often these involve three or four young people being in the car when the accident happened. As a result of growing research, as well as in response to the deaths that have occurred, we have seen some countries, including Australia, impose restrictions on the number of peer passengers young drivers are permitted.

Years ago, I fought hard against proposed legislation the NSW Government was planning to introduce limiting the number of passengers P-platers were allowed to have in their car. In my dealings with young drivers, particularly around drink driving, I’ve always heavily promoted the concept of the ‘designated driver’ and believed then (and still do) that the vast majority of teens would never even consider driving home from a party after drinking. It’s important to acknowledge that some studies have found that having passengers in a car can have positive effects on drivers, although these are reduced the younger they are. Passengers can help keep drivers alert, help them navigate, operate the radio or other communication devices such as mobile phones and even take over driving when necessary. Limiting the number of passengers P-platers were allowed to transport seemed incredibly unfair to me. I then attended a conference in Geneva and heard about some research that changed everything.

A Dutch study found that the older a driver gets their driving licence, the lower the initial risk (Vlakvled, 2004). You could have as many lessons as you wanted but the earlier you started driving, the more likely you were to have a crash. If you started driving after 21, with fewer lessons, your risk of a crash dropped and further reduced the older you got. There was something about young drivers that put them more at risk. Experience certainly mattered (and that’s why we’re seeing many jurisdictions continue to increase the number of hours learner drivers must complete before getting their licence), with crash rates over time being lowest for those who got their licence at age 18 and highest for drivers licensed at ages 30–40 (i.e., if you got your licence early you were less likely to have a crash later in life), but why was there this initial ‘high risk’ time?

There’s growing evidence to suggest that this could be due to brain development. Recent research has found that between the ages of 18-19 and 21-22 there is a 10 per cent reduction in accident rates, even when driving experience is taken into account. Gender also appears to be a factor, with three times as many males being involved in crashes. When you look at this data and match it to what we know about adolescent brain development, it clearly matches up. We now know that the brain doesn’t finish developing as early as we once thought, with females fully developed at around 21-22 years and males much later (at around 25-26 years at the earliest). When you look at the crash data, it’s at that age when you start seeing rates of crashes and casualties/fatalities significantly decrease. Yes, they’re becoming more experienced drivers but they’re also getting a fully developed brain.

We know that several parts of the brain are used when driving. These include:
  • frontal lobe – dealing with judgement and decision making
  • parietal lobe – managing information from all the senses
  • occipital lobe – the visual cortex, interpreting visual information the driver receives
  • temporal lobe – dealing with sounds heard by the driver
  • cerebellum and other areas outside the cortex – controls muscle movement and balance

The brain develops in a back to front pattern, with the frontal lobe the last to ‘complete’. With that in mind, one recent study examined the impact of this development, particularly the prefrontal cortex (PFC), had on driving (Foy et al, 2016). They found that younger drivers had reduced PFC activity compared to older drivers and concluded that “the reduced activation in younger drivers may be related to prefrontal maturation which could contribute to the increased crash risk seen in this population.” What’s particularly interesting and important when it comes to messages for parents of P-platers is that this ‘increased crash risk’ was not necessarily due to less impulse control but insufficient perception and attention leading to driver error – i.e., driving had not yet become an “automatic task”. Most adults can relate to driving on ‘auto-pilot’ at some time or another, i.e., you’re driving and suddenly realize you’re in the next suburb and you can’t quite remember those three sets of traffic lights you must have gone through. As experienced drivers with fully developed brains, we’re able to drive on ‘auto-pilot’ and still react to sudden or unexpected events – young drivers are unable to do this.

We tend to believe that the multiple deaths that occur on the roads with P-platers behind the wheel are simply the result of passengers urging the driver to take greater risks, or being distracted by talking, movement or some other activity. Certainly, research has shown that 6 out of 10 young driver crashes are due to distraction of some kind, but it’s now becoming more evident that brain development may also be playing a role in these tragic events. It doesn’t necessarily have to be a group of ‘lads’ in a car that leads to an accident, having any same-age peers (no matter how responsible they may be) increases the risk of a crash because a P-plater does not have a fully developed brain and driving has not yet become ‘automatic’.

By the time your child starts driving they’re well and truly becoming young adults. If they’re living in your home, they should still abide by your rules, but when it comes to driving, there’s very little you can do to control what they do behind the wheel of a car once they leave your driveway. I reckon my Dad got it right, at least to some degree – he was thinking of his family and ensuring that if something went wrong he didn’t lose all of us, what we know now is a little more complex. For parents of P-platers I would recommend that you try to get them to agree to just one simple request when they start driving and that’s as follows – “Whenever possible, never drive with anymore than one passenger whilst on your P-plates.”

Now I realize that this could be a hard-ask but it’s certainly worth a try. When you look at the figures trying to push them in this direction is well worth the effort. The vast majority of P-platers wouldn’t even consider drink driving (their parents are more likely to do that than they are) but they think nothing of having a couple of friends in the car and the evidence is clear that this is a significant risk.

Chen, L., Baker, S., Braver, E., & Li, G. (2000). Carrying passengers as a risk factor for crashes fatal to 16- and 17-year-old drivers. JAMA 283, 1578-1582.
Foy, H.J., Runham, P. & Chapman, P. (2016). Prefrontal cortex activation and young driver behaviour: A fNIRS study. PLoS ONE 11
Vlakveld, W.P. (2004). New policy proposals for novice drivers in the Netherlands. Behavioural Research in Road Safety: Fourteenth Seminar, 194–204.

Published: August 2017

3 thoughts on “Teen brains and driving: One ‘request’ all parents should ask of P-platers”

  1. Thanks Paul, I found your piece very insightful and feel parents should consider implementing same-aged peer passenger restrictions – especially during the first 6 months of unsupervised licensure.

    Research shows that adolescents do take more risks than any other age demographic, but not because they are ignorant. In fact, if anything, they often overestimate risks but choose to take them anyway.

    The mid-adolescent years are particularly tricky, because as you referenced, the prefrontal cortex area of our brain that enables us to determine when risk outweighs reward is not yet fully developed – so basically we have the impulsive “GO” part (the accelerator pedal); but not the higher cognitive part – the ‘BRAKE’ pedal.

    A few years ago the psychology department at Temple University in Philadelphia conducted a study into adolescent development and decision making. They created a driving test simulator to study the risk behaviour of adolescents and adults, both when alone and when being observed by a group of their peers.
    When not being watched by their friends the adolescents took no more risks than the adults; but when being observed, they did. Where it gets interesting though is they then conducted brain imaging tests to compare brain activity when completing the tasks alone and when their friends were viewing via a monitor in another room. When being observed by friends it activated the reward centre of their brain, despite not even seeing their peers – (simply believing they were being watched was enough). When the adults’ brain activity was monitored there was no change in the reward centre of the brain when told they were being watched by their friends.

    Their lab then decided to conduct an experiment with mice. They took a group of new-borns from different litters and created individual peer groups by raising them in separate cages with the intention of learning how much alcohol the different groups would consume.
    They conducted the test with half of the mice being adolescents and the other half adults. And, they tested half of each group both alone and with their friends. They found the adolescent Mickeys drank more when with their friends compared to when they were alone. The adult mice on the other-hand consumed the same amounts whether by themselves or partying with their peer group.

    Perhaps rather than deny that risk-taking is simply an inherent part of an adolescent’s pathology, we parents could manoeuvre our way around it by managing the ‘opportunity for risk’.

  2. Thanks for the comment Mal – I know the study well (I think it was led by Laurence Steinberg – one of my 'gurus'! The material he has published on adolescents and 'risk-taking' is amazing). My whole philosophy around working with adolescents is based on what you call "managing the 'opportunity for risk'". When I speak to parents, I often refer to it as 'putting pillows around young people'. You can give them all the information around the risks and dangers but they are 'wired' to weigh-up risk and reward in a different way to adults. When you look at the evidence around driving and young people it is frightening – the study you refer to only reinforces the message … Paul

  3. Yes Paul, the study was led by Laurence Steinberg. I'm also a fan and feel his book 'Age of Opportunity' successfully challenges several myths surrounding adolescence — Mal

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