April 10, 2018

expert reaction to study on traumatic brain injury and risk of dementia

A new study, published in The Lancet Psychiatry, examines the association between sustaining a traumatic brain injury and increased risk of developing both dementia and Alzheimer’s disease.

Prof Jonathan Schott, Professor of Neurology, University College London (UCL), said:

“This population based study of over 2.5 million people provides perhaps the best evidence yet that traumatic brain injury is a risk factor for dementia. Whilst the study shows that the number, severity, and timing of head injuries influences risk, further research is required to establish the extent to which specific types of head injury (e.g. sports concussions) are or are not implicated; and how head injury relates to the different brain pathologies that can cause dementia. These uncertainties notwithstanding, this study reinforces the importance of trying to prevent injury to the brain.”

Prof Tara Spires-Jones, UK Dementia Research Institute Programme Lead and Deputy Director, Centre for Discovery Brain Sciences, University of Edinburgh, said:

“Prof Fann and colleagues have conducted an impressive, large study of the relationship between traumatic brain injury (TBI) and dementia.  Their data from 2.8 million people strongly supports the conclusion that TBI is associated with increased risk of dementia.  While observational studies like this cannot conclusively prove that TBI leads to dementia in some people, this study is strong because the scientists looked at a very large sample size from the Danish population and followed their health outcomes for many years after TBI.  There are other studies in the field of neuroscience suggesting that TBI causes some of the same pathological changes in the brain that are seen in Alzheimer’s disease, providing a potential biological link between TBI and dementia.”

Prof Martin Rossor, NIHR National Director for Dementia Research, University College Hospitals and Professor of Clinical Neurology, UCL, said:

“There have been many reports of an association between head injury and the later development of dementia and specifically Alzheimer’s disease.

“The additional value of this study is the sample size which provides assurance that the observation is genuine. As the authors point out, there is a significantly increased relative risk but the absolute risk of developing later dementia is small. Association cannot prove causation but head injury is cognitively bad in the short term and this adds to the evidence that it is also bad in the long term; and it is potentially preventable.”

Dr Carol Routledge, Director of Research at Alzheimer’s Research UK, said:

“This well-conducted study adds significant weight to previous evidence of a link between head injury and an increased risk of dementia. The researchers were able to take advantage of comprehensive health records from nearly 3 million people in Denmark to explore dementia risk at a national scale and shed more light on the long-term health effects of head injuries.

“While there is growing interest in the question of whether collisions in sports like rugby or football might affect dementia risk, this study only looked at head injuries that required hospital treatment and doesn’t tell us anything about the impacts you’d normally expect to see on the sports field.

“The study was not designed to be able to pick apart the biological processes that link head injury and dementia but this a key question facing dementia researchers. Alzheimer’s Research UK is supporting pioneering research to investigate the brain changes that underlie the link between head injury and dementia and this understanding will be crucial in developing new ways to minimise the long-term health effects of a head injury.

“While no one sets out to sustain a serious head injury, there are other risk factors for dementia that we can address through our lifestyle. Eating a healthy diet, not smoking, only drinking in moderation, controlling blood pressure and cholesterol, and  staying mentally and physically active can all help to maintain a healthy brain as we age.”

Dr Mahmoud Maina, Research Associate, University of Sussex said:

“The findings are truly novel due to the large sample size employed, in-depth history collected and follow-ups. Although the results are not surprising, it instead further confirms the link between traumatic brain injury (TBI) and dementia which has been a hot area of debate in recent years.

“This study certainly reinforces the fact that sports in which head injury occurs are dangerous and may make us susceptible to dementia. However, it is important to note that TBI is not specific to head injuries from sports. Previous studies on war veterans with head injuries came to a similar conclusion that about its risk for dementia.

“Dementia is an umbrella term for many brain diseases that have a wide range of causes. The findings described in this study further confirms that concussion is a risk factor for dementia. However, whether concussion possesses risk for a specific type of dementia, such as Alzheimer’s disease is still a question to be resolved by future studies.”

* ‘Long-term risk of dementia among people with traumatic brain injury in Denmark: a population-based observational cohort study’ by Jesse Fann et al. published in The Lancet Psychiatry on Tuesday 10 April.

All our previous output on this subject can be seen at this weblink: http://www.sciencemediacentre.org/tag/dementia/

Declared interests

Prof Tara Spires-Jones: No conflicts of interest

Dr Carol Routledge: No conflicts of interest

None others received.