Provisional damages and mitigation where claimant at risk of dementia considered

  • 27 April 2022 27 April 2022
  • UK & Europe

  • Insurance

The High Court has considered mitigation of loss and provisional damages in relation to the chance of developing dementia after the claimant suffered a traumatic brain injury.

Provisional damages and mitigation where claimant at risk of dementia considered

The judge found that the defendant had not proved the claimant had acted unreasonably nor proved that he had failed to mitigate his loss. The defendant’s evidence was preferred, however, in relation to the issue of dementia risk, with the judge finding that the claimant could not show on the balance of probabilities the existence of a more than fanciful chance that traumatic brain injury will lead to him developing dementia.

Mathieu v (1) Hinds (2) Aviva PLC [2022] EWHC 924 (QB)


In November 2015 the claimant was crossing the road at a pedestrian crossing when he was struck by a moped driven by Tony Hinds. Aviva (the defendant) insured the moped but Hinds, who had stolen it, was not insured to drive it. The defendant admitted liability, but quantum remained in issue and the matter progressed to trial.

The claimant sustained a serious brain injury in the accident, but the experts agree he has made a very good recovery from his injuries. His case is that he continues to suffer from headaches, fatigue and cognitive issues which hamper his productivity as an artist. As a result, he is not able to produce and sell as much art as he otherwise would have been able to. The claimant claimed over GBP 33.6 million in damages.

The defendant disputed the effect on the claimant’s productivity and argued that he had not mitigated his loss. The defendant’s Counter Schedule of Loss proposed GBP 49,500 for past losses and nothing for future loss.

The claimant gave evidence that he was suffering from a range of neuropsychological issues including difficulties with memory and concentration; fatigue; PTSD symptoms; anxiety, low mood and loss of confidence and insomnia. There was a consensus among the experts that the claimant's brain injury falls within the most severe category in the Mayo Classification System for Traumatic Brain Injury (TBI).

Mitigation of loss

The defendant argued that the claimant had failed to mitigate his loss as he had refused to take medication to help his headaches and he had failed to undergo the full recommended course of psychological therapy.

The experts agreed that amitryptiline is a tried and tested preventative medication for headaches. However, the claimant refused to trial it because the drug may contribute to fatigue and cause him to feel drowsy and interfere with his creative process. He stated that he refused to engage with “the lethargic state that comes with it”. He did confirm that he would try medication if there were no side effects.

Mrs Justice Hill described the claimant as “a person whose raison d’être is his art”, and therefore his concern that the medication would dampen his creativity was understandable.

Per the case of Payzu v Saunders [1919] whether a claimant has mitigated their loss is a question of fact not law. Hill J found that as one of the experts thought the claimant was acting reasonably then it is “harder to find that the claimant is acting unreasonably.” The judge concluded that the claimant has “made a careful decision about this issue, his anxieties about it are understandable”. She therefore found that the defendant had not discharged the burden of proving that the claimant was acting unreasonably. Furthermore, she stated that even if she had found that the claimant had acted unreasonably the defendant had not discharged the burden of showing what difference taking the medication would have made.

With respect to the further fatigue management sessions, the defendant’s case on mitigation of loss also failed as the defendant had not advanced any “clear evidence of what the impact of any further fatigue management sessions at this stage would be on the claimant’s loss”. Hill J accepted the claimant’s expert’s evidence that the claimant has “done very well” with his input.

Dementia risk

The claimant contended that provisional damages should be awarded for a risk of dementia arising from traumatic brain injury. Scott Baker J considered provisional damages in Willson v Ministry of Defence [1991] and identified three questions to answer:

1) is there a chance of the claimant developing the disease or deterioration in question?

2) is the disease or deterioration serious? and

3) if so, should the court exercise its discretion to make an award of provisional damages?

After considering the evidence before her Mrs Justice Hill preferred the evidence of the defendant’s expert. She agreed that an “association between two things does not necessarily mean that one thing has caused the other” and in this case especially, as there “is no clear understanding of what the causative “route” may actually be.”

On the current state of the science the claimant could not show on the balance of probabilities “the existence of a more than fanciful chance that TBI will lead to him developing dementia.” The claimant could therefore not meet the requirement of Willson question 1 and this aspect of his claim failed.

The judge continued to discuss post-TBI dementia finding that it is not clearly diagnosable, and that “on the basis of the current scientific evidence, any post-TBI dementia that develops would not be "reasonably clear-cut"”. On the current state of scientific knowledge, a post-TBI dementia is often not severable from the consequences of the initial TBI. In addition, she accepted defendant counsel’s submission that post-TBI dementia is akin to osteoarthritis or certain psychiatric condition, which were considered by Irwin J in Kotula v EDF Energy Networks PLC [2011] to be unsuitable for provisional damages.

The claimant was, however, awarded provisional damages for an increased risk of developing epilepsy, assessed by the experts at between 5% and 8%. 

Other issues

The defendant submitted that the assessment of past and future loss of income should be undertaken using the Blamire approach. However, Hill J noted that judges should “be slow to resort to the broad-brush Blamire approach”, and instead use the conventional approach which was appropriate here.

The claimant claimed his loss of income on a gross basis, as he claimed that he would be subject to taxation in accordance with Canadian and Quebecois tax laws. Hill J said the taxation position was unclear and therefore awarded the claimant lost income on a gross basis.


Mrs Justice Hill accepted that the claimant produces less art than he would have but for the accident because “he needs to take more regular breaks in the day than he would otherwise do” and that the accident has had a “life-changing impact on the claimant and his career.”

He was awarded GBP 3,178,741.64 in damages, of which over GBP 2.1 million is for future lost income. A detailed breakdown of the damages can be found in the judgment here.

What can we learn

  • This is the second time in recent High Court brain injury decisions a defendant’s argument of failure to mitigate has been rejected. In Stansfield v BBC [2021], a similar argument was advanced, this time over failing to follow medical advice to be treated with anti-depressants.
  • As in Stansfield, the defendant’s arguments here did not discharge the burden and show the claimant’s failure to mitigate was unreasonable.
  • In both cases, even if a prima facie case of failure to mitigate was established, it was not demonstrated how taking the recommended medication might have alleviated the claimant’s symptoms so that the failure to mitigate could be quantified (had it been established).
  • Practitioners who wish to run such arguments would be advised to have clear evidence as to both the (un)reasonableness of the claimant’s action or inaction as well as the alleged outcome had the claimant mitigated his loss.
  • As per the case of Hibberd-Little v Carlton [2018] it was argued by the claimant that an award of provisional damages should be made on the basis of the risk of the claimant developing dementia post the TBI. As in Hibberd-Little this was rejected but with a more clear and reasoned rationale, confirming, on the evidence available, that a more than fanciful chance of developing post-TBI dementia could not be established.
  • Defendants should be mindful of this ever-evolving area however. The defendant’s own expert accepted future diagnostic developments may lead to clearer evidence of post-TBI dementia.
  • It is likely therefore this type of argument will continue to be advanced by claimants as the science continues to develop.


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