The study, published today by the University of California, San Francisco, tracked more than 350,000 US veterans for four years, showing even the most mild injuries sewed the seeds for brain diseases in later life.
Concussions more than double the risk of dementia – whether the sufferer lost consciousness or not, a new study warns. It is the last in a swell of research over the last few years linking milder head-hits to neurodegenerative disorders.
Last month, the same research team reported a link between concussion and Parkinson’s disease – putting yet more pressure on the Army and sports leagues to confront the life-threatening damage of head hits.
The study, published today by the University of California, San Francisco, tracked more than 350,000 US veterans for four years, showing even mild injuries lead to brain diseases
‘Our results show that more needs to be done to reduce the likelihood of traumatic brain injuries,’ said first author Deborah Barnes, PhD, MPH, professor in the UCSF departments of psychiatry, and epidemiology and biostatistics.
‘In older adults, exercise and multifactorial interventions may limit the risks of falls, which are a leading cause of head injury.
‘For those who experience a concussion, get medical attention, allow time to heal and try to avoid repeat concussions. Although our study did not directly examine this issue, there is growing evidence that repeated concussions appear to have a cumulative effect.’
The four-year study, published in JAMA Neurology, involved 357,558 US veterans with an average age of 49; 91 percent were male and 72 percent were white.
The participants were gathered from two databases.
The first listed all-era veterans whose traumatic brain injuries (concussion or worse) could have occurred during civilian or military life. The second involved veterans serving in Iraq and Afghanistan, who suffered injuries in combat, for example from shockwaves in blasts.
Half of them had suffered a traumatic brain injury. Of those, 54 percent had also been diagnosed with a concussion. Concussion was defined as mild traumatic brain injury which affected their consciousness and gave them amnesia for a day or less.
After adjusting for age, sex, race, education and other health conditions, they found that concussion without loss of consciousness led to 2.36 times the risk for dementia.
These risks were slightly elevated for those in the loss-of-consciousness bracket (2.51) and were nearly four times higher (3.77) for those with the more serious moderate-to-severe traumatic brain injury.
‘The findings in both groups were similar, indicating that concussions occurring in combat areas were as likely to be linked to dementia as those concussions affecting the general population,’ Barnes said.
Senior author Kristine Yaffe, MD, a neurology professor at UCSF, added: ‘There are several mechanisms that may explain the association between traumatic brain injury and dementia.
‘There’s something about trauma that may hasten the development of neurodegenerative conditions.
‘One theory is that brain injury induces or accelerates the accumulation of abnormal proteins that lead to neuronal death associated with conditions like Alzheimer’s disease.
‘It’s also possible that trauma leaves the brain more vulnerable to other injuries or aging processes,’ said Yaffe, ‘but we need more work in this area.’