New research has suggested that concussion could lead to changes in the brain that are associated with Alzheimer's disease.
A study at the Mayo Clinic in the US recruited 448 over-70s without any memory problems and 141 people of similar ages who had memory and thinking problems called mild cognitive impairment.
Each one was given a brain scan and also asked about their history of head injuries that involved loss of consciousness or slips in memory.
It was found that those with cognitive impairments and a history of trauma had levels of amyloid plaques - substances commonly associated with Alzheimer's - that were 18 per cent higher than those with no head trauma history.
Interestingly, differences in the amount of brain plaques were only found in people with memory and thinking problems, not patients who were cognitively 'normal'.
Lead author Michelle Mielke said in the journal Neurology that even momentary losses of consciousness may be enough to allow plaques to build up.
'Our results add merit to the idea that concussion and Alzheimer's disease brain pathology may be related,' she added.
Earlier this year, researchers at the University of New Mexico found the damage caused by concussion could last much longer than previously thought.