A link between traumatic brain injury and dementia?

A claim for provisional damages for epilepsy is now a well-established head of claim where there has been a moderate to severe one-off traumatic brain injury. In recent years there have been attempts to claim provisional damages to reflect the risk of developing post- traumatic brain injury (TBI), early-onset dementia.

There have been a number of studies purporting to find a link between TBI and the onset of dementia. This month, research was published by St Michael’s Hospital, Unity Health, affiliated to the University of Toronto, which analysed data in more than 260,000 adults aged over 65 years with and without TBI between April 2004 and March 2020. The study intended to look specifically at late-life TBI after age 65 and followed the participants until a diagnosis of dementia to March 2021 or death. It found that a TBI was associated with a 69% increased risk of subsequent dementia in the first five years following injury and a 56% increase beyond the initial five years. 

There are a couple of important points worth noting from the study. Firstly, the study highlights one of its limitations, namely, whether a person is more likely to sustain a TBI in the first place because they may already be suffering the early stages of dementia.

“We also could not assess the cyclical link between cognitive impairment and TBI, where sustaining a TBI increases dementia risk, and dementia, in turn, raises the likelihood of falls and subsequent TBIs. This complex interplay was beyond our study’s scope.”

Secondly, the study does not seem to use a standard classification of TBI, and it classified TBI severity as “noncomplex (≤ 3 d) or complex (> 3 d) based on length of hospital stay (including in the emergency department) using a pragmatic expert-consensus cut-off reflecting clinical complexity”. It found “Complex TBI patients made up 9.8% of the cohort” and “Patients with complex TBI had a significantly higher rate of all outcomes than those with noncomplex TBI.”

Risk factors

A TBI can trigger the formation of abnormal protein clumps such as amyloid and tau which are also hallmarks of some forms of dementia. These clumps can act as “seeds” that spread throughout the brain.

However, there are several risk factors (“dementia associated risk factors”) which can contribute to an increased risk of dementia. Advanced age, deafness, obesity, hypertension, the level of physical and mental activity, the level of education, alcohol use, depression, sleep deprivation/fatigue, social isolation, nutritional factors and other lifestyle choices can all be contributors. Age is a significant risk factor and 50% of those living to age 90 will have some form of dementia.

Symptoms of dementia can include memory loss, poor concentration, language and communication problems, confusion, mood changes, personality changes, withdrawal, delusions or hallucinations, lack of inhibition, sundowning (behaviours such as confusion, anxiety and aggression that occur in the late afternoon or evening) and changes in movement. Deterioration is a gradual process that can include “steps” or periods of more significant decline commonly known as “step down deterioration”.

There is no one test for dementia; it is a matter of clinical judgment taking into account a patient’s presentation, medical history and lifestyle choices. Dementia is a very individual disease caused, in many cases, by complex medical, environmental and interrelating factors.

Case law

In Mathieu v Hinds & Aviva [2022] EWHC 924 (QB) the 29-year claimant was crossing a road at a pedestrian crossing when he was struck by a moped being driven by the first defendant which he had stolen earlier that day. The moped was insured by the second defendant but the first defendant was not insured to drive it.

The claimant suffered a serious TBI but made a good recovery, although continued to suffer from headaches, fatigue and cognitive issues. He claimed provisional damages for the alleged risk of developing both epilepsy and dementia in the future because of his TBI.

The law relating to provisional damages is set out in section 32 of the Senior Courts Act 1981. A court can order that provisional damages can be paid where “there is proved or admitted to be a chance” that the injured person will develop some serious disease or deterioration in his/her physical or mental condition.

In 1991 in the case of Willson v Ministry of Defence [1991 ICR 595 the court identified three questions that needed to be determined in relation to an award of provisional damages:

1. Is there a chance of the claimant developing the disease or deterioration in question?
2. Is the disease or deterioration serious?
3. If so, should the court exercise its discretion to make an award of provisional damages?

The court considered that the chance referred to must be “measurable rather than fanciful”. It does not matter how small “measurable” might be. 

The claimant must establish on a balance of probabilities that there is a chance that, in the future, he/she will suffer some serious deterioration in his/her physical condition.

In Mathieu, the court awarded provisional damages for the claimant’s lifetime in respect of his chance of developing epilepsy following expert medical evidence from the claimant and because the second defendant’s medical experts assessed the risk of epilepsy at 8% and 5 – 7%, respectively; the risk being measurable.

The claim for provisional damages for the risk of dementia was far less straightforward. The claimant’s expert’s view was that there was growing evidence of a risk of developing dementia or similar following a TBI. The second defendant’s expert believed that there was insufficient evidence of such a risk.

The claimant’s neurology expert estimated that the cumulative chance of dementia for the claimant would be around 20% at age 60 and around 55% at age 80 against background incidences of around 5% and 25% at these ages, respectively. He accepted that there was a wide range of opinion and uncertainty and suggested further expert evidence might be necessary.

The second defendant’s neurology expert accepted that there was a growing body of evidence suggesting a link between a TBI and dementia but described the literature as misleading, flawed and a “mess”. A number of the research papers cited were based on a very small cohort. He considered that the evidence was flawed and the judge agreed there was no evidence that a TBI was a risk factor in dementia nor that association necessarily means that one thing causes the other. Even if there existed a generalised enhanced risk of dementia, how any risk applied to an individual claimant was complex and unclear. The claimant’s own neurologist expert agreed with many of the criticisms made of the research.

Both parties’ experts agreed that other risk factors (such as obesity, depression etc) in individual cases can predict the onset of dementia even in the absence of a TBI.

The claim for provisional damages for the risk of dementia failed as the claimant could not show on the balance of probabilities, based on the current scientific evidence, that there existed a more than fanciful chance that the TBI would lead to him developing dementia.

The issue rose again in the case of the executors of the estate of the late Geoffrey Charles Ivory v Swale Borough Council. Based on the scientific evidence before it, the court upheld the findings in Mathieu. 

On 14 May 2014, the late Mr Ivory fell in a car park age 82, sustaining injuries to his head and face. The contemporaneous medical records recorded no loss of consciousness but there were reports that he had been “a little dazed” at first. Mr Ivory attended hospital and was discharged home the same night. Two months later he suffered a seizure and attended hospital where he was diagnosed with an “acute on chronic subdural hematoma”. He had two more similar episodes with the last being in September 2014. 

Mr Ivory had a number of dementia-related risk factors including cardiac problems, COPD and Type II diabetes. By the time the defendant’s experts examined Mr Ivory in 2018, he was suffering from dementia and was unable to provide details of the accident or his symptoms. Mr Ivory died of unrelated causes on 25 January 2020 aged 87.

His executors took over legal proceedings which included a claim for substantial care home fees as Mr Ivory had been unable to remain at home once his dementia progressed. Evidence was given by family members who reported a step-down deterioration in cognitive functioning after the seizure in July 2014 and brought the claim pleading that Mr Ivory’s dementia had been caused by the accident. However, there were pre-accident medical entries reflecting cognitive decline. 

The severity of any TBI, and whether in fact a TBI was sustained, was a key issue in Ivory. The judge found at para 353:

“This is not an easy dispute to resolve, but it seems to me that because of the two descriptions of him being "dazed"  Mr Ivory would probably have just satisfied most criteria for a mild TBI. It was not however the stated view of any expert that an injury at the lowest end of the mild TBI spectrum would necessarily entail any lasting harm to the brain. I am not persuaded that most clinicians would have regarded Mr Ivory as having a moderate to severe TBI.”

Whilst it was accepted the July 2014 subdural haematoma was related to the accident, the judge also did not find it was indicative of Mr Ivory suffering any lasting brain damage (paragraph 365):

“I am not persuaded on a balance of probabilities that the seizures suffered by Mr Ivory were either indicative or causative of brain damage, save in the limited sense mentioned in the previous paragraph, or that any of the seizures experienced after September 2014 were a result of the accident. Further, I do not see any basis in the expert evidence for saying that the seizures are likely to have caused or accelerated dementia.”

As to causation, the court confirmed that it had to determine whether the accident had caused or contributed to Mr Ivory’s dementia. The fact that Mr Ivory developed dementia was undisputed. It was necessary to consider how likely it was that the pre-accident history of memory problems was a symptom of an underlying progressive condition which eventually developed into dementia.

The court ultimately found that there was no causal link between the TBI and dementia. 

What does the future hold?

Strong medical evidence will be required to prove that a TBI has caused or contributed to, or has a real “measurable” chance of causing or contributing to, the onset of dementia. 

More research is likely to become available in the future which may provide stronger evidence of a link between TBI and early onset dementia.

If this happens, there is likely to be more litigation on the issue. Whilst the Canadian study is perhaps another small weapon in the armoury for those considering bringing a claim for TBI-related dementia, the courts are unlikely to tip the balance in favour of claimants anytime soon. The scientific evidence remains unconclusive. Until there is a body of cohesive scientific evidence that establishes a link between TBI and dementia and quantifies the associated measurable risks of dementia developing, separate from other known risk factors, the courts will be reluctant to move away from the stance taken in Mathieu.

This article has been brought to you from Fiona Constantine, a member of the Weightmans Brain Injury Technical Unit.