People who suffer repeated blows to the head are more likely to develop Alzheimer’s disease, new research suggests.
Possible links between contact sports and an increased risk of developing dementia have previously been identified but no firm scientific ties have been established.
Now, researchers from the University of Cambridge have developed a more detailed picture of how the disease takes root, which could provide a better understanding.
They used laser imaging to identify clusters of a protein, called tau, on the brains of sufferers and found possible links to neuronal damage, for example through head injuries inflicted during sport.
Dr Simon Ridley, head of research at Alzheimer’s Research UK, welcomed the development.
He said: ‘The state-of-the-art technology used by this research team allows a unique insight into the molecular events that occur in Alzheimer’s.
‘Investigating how the tau protein spreads between nerve cells can help researchers better understand what causes the disease and offer new approaches for treatments.
‘It is unclear from this study whether head injury could trigger this molecular process, but it is a risk factor for dementia that needs to be investigated further.’
The study, reported in The Journal of Biological Chemistry, focused on the tau protein.
This is found inside healthy brain cells but clusters of malfunctioning tau, which prevent brain cells from working properly, are found in the brains of those who have died with Alzheimer’s.
When small quantities of the protein were added to the outside of brain cells, the cells immediately started to ingest it, the study found.
The resulting clumping caused healthy proteins to misbehave.
In real life such clumping could be triggered by repeated head injuries, such as those suffered in contact sports.
Researchers urged caution, saying that their study used a model cell culture and the processes which enable the disease to take root and develop in the brain could be far more complicated.
Clemens Kaminski, professor of chemical physics at the University of Cambridge, who led the research, said: ‘These are molecular-level glimpses of what may be going on.
‘We are just beginning to see the molecular steps that may provide an explanation for what we see in the brains of patients who have died of Alzheimer’s.
It was revealed in September that former footballer Jimmy Hill has Alzheimer’s disease
‘The study underlines how significant the uptake of small quantities of tau might be as an initiator for the conditions that then prevail in the brains of Alzheimer’s sufferers.
‘It is one piece in the puzzle that could provide us with an explanation as to why head injuries may be connected to the disease. It’s not necessarily correct – but it is plausible.’
Although links between Alzheimer’s and contact sport are yet to be firmly established, previous studies have found professional American footballers are three times more likely to have neurodegenerative diseases compared with the general public.
Earlier this year the NFL reached a multimillion-pound settlement to compensate more than 4,500 retired players diagnosed with conditions including dementia, depression or Alzheimer’s which they blamed on blows to the head.
Researchers trying to find a cure for Alzheimer’s have long focused on the role of tau – an abbreviation of Tubulin Associated Protein Unit – and this is the first insight into how the dysfunctional protein emerges and spreads.
Dr Gabriele Kaminski-Schierle, who led biological aspects of the research, said: ‘We still do not know if we can stop cells from ingesting tau, or whether we can somehow wash tau out of the brain fluid.
‘Answering these questions is key to developing future therapies to treat what remains, at the moment, a terrible and incurable disease.’