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expert reaction to study investigating the long-term outcomes associated with traumatic brain injury in childhood

Researchers publishing in PLOS Medicine have assessed the long-term impact of traumatic brain injury (TBI) in young people and looked at the effect on early death, educational attainment, welfare requirements and need for psychiatric care. The study involved a large number of Swedish people who recorded a TBI (including concussion) before the age of 25 and compared them to siblings and others who had not had these injuries. These comments accompanied a briefing.


Prof. Tony David, Professor of Cognitive Neuropsychiatry, King’s College London’s Institute of Psychiatry, Psychology & Neuroscience, said:

“It is a very robust study that makes use of the enviable ability Scandinavian researchers have to link their various national records.

“The authors showed that having a head injury – one significant enough to lead to a hospital or specialist consultation – affects about 9% of the young population.

“When such people were followed up into mid-adult life, they were doing less well on a number of measures. Perhaps most surprising is that the chance of having to be admitted to a psychiatric hospital in the follow-up period was doubled. Needing a disability pension was also significantly increased.

“There are lots of things that put children and young people at increased risk of having a head injury – being unsupervised by parents and living in crowded conditions might be factors. However, the authors compared those with head injuries with their siblings – who were living under the same conditions – and the results remained just as strong.

“Other interesting findings included the fact that injuries in late teens and the early twenties had more impact on later adjustment than earlier injury – provided it is not too severe. Perhaps the young brain has more time and ability to compensate?

“One factor that this, and many similar studies, couldn’t quite take into account of is the fact that having a psychiatric condition (such as attention deficit hyperactivity disorder or even depression) might lead to having a head injury – because of carelessness or clumsiness or risk taking behaviour. That is to say it may be the psychiatric condition that is to some extent ‘causing’ the head injury rather than the other way round.

“All in all the study is a very strong demonstration of the interplay between psychosocial and neurological factors when it comes to the pathway to mental health problems.”


Prof. Michael Swash, Emeritus Professor of Neurology, Barts and the London School of Medicine, said: 

“This paper tells us what is already known but spells out some detail.

“There is a rather striking lack of detail about the head injuries. For example, the nature of the head injury, the degree of brain abnormality as shown by imaging (at least in more recent cases), the socio-economic class of those injured and the family history with regard to psychiatric illness are all not described. In addition there is a lack of information about those cases with head injury that did not have a recognised late consequence.

“I’m also somewhat disturbed by the highly speculative discussion regarding so-called prevention, which seems to suggest that almost all contact sports should be forbidden, including heading footballs. The paper does not provide any evidence with regard to these supposed risk factors other than collateral discussion with regard to the literature regarding sports in which there is a relatively high risk of head collisions. For the moment the evidence with regard to this issue relates almost entirely to American football (and of course historically to boxing).

“It would have been wiser if the authors had restricted the discussion to their own database.

“It should also be noted that there is no pathological data although some of these cases must have had autopsies.

“In my view it would be a mistake to use these data as a foundation for social policy changes, as suggested by the authors. The statistical data, however, is useful.”


Prof. Huw Williams, Associate Professor of Clinical Neuropsychology, University of Exeter, said:

“This is an incredibly strong study. They’ve taken huge care to try to manage a whole range of covariates and confounders and the story is very consistent with what is emerging across various areas (sports, crime and mental health) that traumatic brain injury (TBI), of various levels of severity, is problematic in the long term. The higher the dose (moderate to severe) and if an injury is repeated, the more problems present.

“The authors have very good controls (including recording other fall injuries and the impacts on siblings) so the data does look compelling.

“The odd finding is regarding younger age being less of an issue. The risk of a poorer outcome seems to be greater in those injured when 15 years old or older. It may be that neuro-plasticity is at work, protecting younger people from the effects, or it may be that Sweden’s education system is good at rehabilitation and keeping kids in school after injury, or a combination of both. In any case, I quite agree that neuro-developmentally appropriate public health systems should be put in place.

“We don’t know how the risk of TBI compares to other risks that children face. Issues such as adversity, poverty, abuse and neglect are all huge when it comes to brain development and all increase the likelihood of injury. Typically TBI happens more to those who are disadvantaged, so it may amplify the poorer outcomes one may expect from a person with fewer life chances.

“This does not mean we should be banning children from playing contact sports but care is needed, especially in managing a child’s return to play, so that they don’t get injured again when they are still suffering from an injury (as they are very vulnerable then), and managing their return to school. We also need to make sure the rules are followed – more than 20% of concussion injuries in rugby appear to happen during foul play. Unfortunately there isn’t enough of a shared understanding between educators and health professionals over what a concussion is and how it may be managed. But there are new systems, like post-TBI care coordinators, being developed that could improve outcomes. This might be a vital step to help link A&E departments, GPs and schools alongside online help, such as through England Rugby Union. But we can use the return to play/school guidelines that have been adopted in many US states (which in some places use apps to monitor symptoms).

“Vitally, one injury is a big risk for another injury, so we must do more to follow up TBI in kids more effectively, both nationally and globally. The economics of managing TBI are powerfully argued.”


Dr Alan Carson, Reader in Neuropsychiatry, Centre for Clinical Brain Sciences, University of Edinburgh, said:

“This study adds considerably to our understanding of the long term outcomes of traumatic brain injury (TBI) in childhood and adolescence. The study has been well conducted and has utilised the highly reliable national registers in Sweden. They followed up over a million children, of whom 9% had had a TBI. Childhood TBI was found be associated with a range of negative outcomes in adult life including increased rates of psychiatric disorder and uptake of disability pensions. They also found a weak effect on premature mortality.

“The key finding was that of a convincing dose response curve in which the more severe the injury in childhood the higher the rate of adverse outcome in adulthood. These findings will come as no surprise to anyone working in the field of brain injury and have been seen in a number of less well conducted studies- what this study does is to demonstrate the extent of the effect in a far more precise and reliable fashion. It provides a strong argument for the need to invest in rehabilitation services for brain injured children.

“However, one suspects the newsworthy aspect is the possible long term outcome of mild head injuries suggesting a slight but nonetheless significant effect on adult functioning. This is a current area of concern given high profiles claims, albeit unsupported by high quality scientific evidence, of the risks of such injury of causing neurodegenerative disease (dementias). This study does not address that topic directly but does suggest some long term effects in other domains of health function. However, interpretation of these findings is much less clear. The problem is that the risk of head injury is not evenly distributed in the population. A child with, say, ADHD is at significantly increased risk of head injury whilst playing in childhood and will, because of their ADHD, have poorer function in adult life. The authors have tried to control for this genetic effect using sibling controls- but siblings do not have similar genetics, nor risk of neurodevelopmental disorders such as ADHD, nor of psychiatric disorder. We see in table 5 that even this imperfect form of control explains some but not all of the effect. We are therefore left as readers not knowing whether this poor function in adult life is a marker of the ‘cause’ or the ‘effect’ of the mild head injury.

“The authors conclude ‘Currently most children with significant head injuries receive no systematic long-term follow-up. An implication of our findings is that this should change. Services should consider how to routinely and systematically review these children on a regular basis to allow the subtle but important neurological, cognitive, and psychiatric consequences of TBI to be identified.’ and I would fully endorse this statement.”

[For more info. on mild TBIs, Dr Carson was involved in the creation of this website: Head Injury Symptoms]


Long-Term Outcomes Associated with Traumatic Brain Injury in Childhood and Adolescence: A Nationwide Swedish Cohort Study of a Wide Range of Medical and Social Outcomes’ by Sariaslan et al. published in PLOS Medicine on Tuesday 23rd August. 


Declared interests

Prof. David: None received

Prof. Swash: “I confess to being involved in medicolegal cases with TBI. No other conflict.”

Prof. Williams: “I have put in a grant application with Sharp and Fazel to MRC (unfunded) and we collaborate on research occasionally (e.g. recently with Centre for mental health on economic impact of crime due to TBI) and I had discussed these data sets with him some time ago. I am vice chair of Division of Neuropsychology, Policy Group and vice chair of Criminal Justice and Acquired Brain Injury Group (CJABIG). I have consulted for England Rugby Union.”

Dr Carson: None received

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