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Traumatic Brain Injury Increases Risk of Dementia #Updated 04.05.18

04 May 2018
Ian Slater discusses a Danish study on the link between traumatic brain injury and dementia.

A study published in the Lancet Psychiatry on Tuesday 10th April suggested that people who have sustained a TBI have a higher risk of developing dementia and Alzheimer's diseases in later life.


This is an argument which we sometimes see put forward in relation to personal injury claims. In the past it has prompted considerable debate with evidence both 'for' but, in the main, 'against'.


Is that about to change with the publication of this latest study?


The Study itself took place in Denmark: it is one of the first to have a sufficient sample size and follow-up time to assess the effects of TBI. Data was captured on almost 2.8 million people living in Denmark on 01.01.95 who then turned 50 at some point in the period 1999 – 2013.


People who had sustained a TBI between 1977 and 2013 were identified. Over the 36 year period 132,093 [4.7%] sustained at least one TBI and 126,734 [4.5%] had dementia diagnosed during 1999 – 2013.


The headlines are that analysis of the data showed that people who sustained at least one TBI were 24% more likely to have dementia diagnosed than those without a TBI and 16% more likely to have Alzheimer's diagnosed.


The risk of dementia further rose with the number of TBI's sustained and the severity of the TBI. Even a single mild injury (concussion) was linked to a 17% increase.


Interestingly dementia risk was highest in the first 6 months after injury and decreased with time. The younger the person at the time the higher the hazard risk for dementia when stratified over time.


The problem with many previous studies has been the length of time required to assess the effects of a TBI. The Denmark study begins to address that issue but, as Carol Brayne from the University of Cambridge School of Clinical Medicine commented:


"It will be many years before the outcomes of the mildest traumatic brain injuries studied in younger adults will become known, as it will be decades before the age groups reach the age of highest dementia risk."


Clearly more work to be done but remember that forewarned is forearmed. Insurers need to be aware of the Study and the growing debate which is likely to develop. Consideration needs to be given to the effect on such factors as life expectancy; care costs and general damages.



#UPDATE 04.05.18


Dr Andrew Auty of Liability (Oxford) Ltd has contacted us to point out that:


"The authors are to be congratulated on preparing a potentially very useful study.


Around 70% of the association is probably due to reverse causation. That is, un-diagnosed dementia was the cause of the accident. There is also very good reason to suppose that the remaining 30% included a contribution from systematic study bias.


These criticisms were not addressed in the paper or in any press release. They should have been."


At the very least, therefore, it seems that notwithstanding the sample size further research is required before the link between TBI and dementia can be established.


For any insurer faced with this argument it is suggested that their independent expert review the study in question and query whether or not the study deals with the issue of whether or not the participant's reported TBI could itself have been caused by early onset or undiagnosed dementia.


DWF's Bodily Injury Research Garage will continue to follow the story and update as appropriate. 


Last but by no means least, a plea, if you have the opportunity please follow our new Twitter page @BIRGarage

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