Is traumatic brain injury a common cause of dementia? Traumatic brain injury, or TBI, raises the risk of dementia, but it is not among the most common causes. Experts estimate it accounts for about 3 percent of dementia cases around the world.
TBI happens when a hit to the head messes up how the brain works. It can range from mild, like a concussion, to severe. People who have had a TBI are about 50 percent, or 1.5 times, more likely to get dementia later than those who have not. In some groups, like older military veterans from recent wars, the risk can double after even a mild TBI.
One rare type of dementia tied to repeated head injuries is chronic traumatic encephalopathy, or CTE. This shows up in brains of former athletes from contact sports like boxing or football after many impacts. A single moderate to severe TBI can also lead to long-term brain changes that look like Alzheimer’s disease, with plaques and tangles building up over time.
Still, TBI is just one of many factors. Things like high blood pressure, smoking, and lack of exercise play bigger roles in most dementia cases. Up to 45 percent of all dementia might be stopped or slowed by fixing 14 changeable risks, and TBI makes up only a small part of that. Sports that risk head injuries need balance with the brain benefits of staying active.
Genes can make the link stronger. For example, a version of the APOE gene raises the chance of poor thinking skills after TBI. Studies on mice show that certain brain signals, when weak, make TBI trigger more Alzheimer’s-like damage.
Researchers are working to understand this better through projects like TBI-REPORTER in the UK. It studies TBI in all ages and groups, from kids to prisoners, to cut future dementia risk.
Sources
https://www.alzheimersresearchuk.org/about-us/our-influence/policy-work/position-statements/sport-and-dementia/
https://pmc.ncbi.nlm.nih.gov/articles/PMC12755970/
https://www.pnas.org/doi/10.1073/pnas.2100986118
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2842588
https://neurologytoday.aan.com/doi/10.1097/01.wnt.0001175652.03888.15
https://onlinelibrary.wiley.com/doi/10.1002/ana.78132?af=R
https://pmc.ncbi.nlm.nih.gov/articles/PMC12730488/
