5. Calling for high quality research into head injury and dementia
Research into head injury in this context is particularly difficult because of the long timeframe between playing sport, sustaining a head injury and the subsequent development of dementia. Further, many mild episodes of head injury are not recorded. Rigorous prospective studies, where people are followed from the point of sports-related head injury, will therefore take many decades. Retrospective studies, where people who developed dementia are asked about head injury or concussion during lifetime, rely on people self-reporting their experiences as minor head injuries are rarely put into healthcare records. These self-reported studies are subject to bias as people may not recall the exact details of when they received an injury or how severe it was.
The round table made a number of recommendations for research studies that are required to address this issue:
- The expert group recognised that prospective studies will need to rely on finding accurate biomarkers which can indicate the start of neuropathological processes in the brain. These could include magnetic resonance imaging (MRI) scans, with measurement of key indicators of dementia in the brain (such as hippocampal volume); positron emission tomography (PET) studies to detect the hallmark amyloid or tau proteins in living people; and cerebrospinal fluid (CSF) analysis for proteins and signals related to dementia. However, many of these techniques are still undergoing evaluation as markers of neurodegeneration and are not able to give definitive answers at the moment.
- There are a number of ongoing studies that are following large numbers of people for a long period of time. These studies could seek to collect retrospective information about a person’s history of head injury or concussion. These records are still subject to bias. For example people will make different (and inconsistent) judgements as to the severity of their head injury. There seems to be a range of different questions and scales used to ascertain exposure to head injury/ previous concussions, and there is an opportunity to further develop, validate and standardise these between studies.
- Neuropathological studies will remain at the core of understanding possible mechanisms between sport, head injury and dementia risk. Helping retired sportsmen or veterans to understand the value of brain donation could make a valuable contribution. The presence of CTE-like pathology in the general population should be characterised in a large number of brains.
- Whilst it is clear that not everyone develops CTE or dementia following a head injury, little is known about the risk factors that affect this. It seems likely that the risk of developing CTE might be mitigated by other genetic and lifestyle factors, for example how highly educated a person is or whether they have an active, healthy lifestyle. Risk factors for CTE following head injury are an area for more investigation.
- Another key issue is that head injury – particularly head injury that does not result in loss of consciousness – is often not recorded in people’s medical records. This is because people often don’t feel the need to visit their GP after a minor head injury, and sporting bodies often do not record minor injuries. In order to fully understand the risks of head injury, these data need to be included in official healthcare records, which can then be used for data analysis in the future. This should include whether someone receives a head injury through playing sport.
- We need patient and public involvement, particularly through engagement with current and former professional sportsmen and sportswomen, to determine whether they want to take part in research of this nature. This engagement could include making medical records relating to their period of professional sport available to researchers after players have retired, or having regular follow-up to assess their cognitive health over a long period of time.