Is dementia more common in people with traumatic brain injury? Yes, research shows that people who have had a traumatic brain injury, or TBI, face a higher risk of developing dementia compared to those without such injuries. A TBI happens when a sudden blow or jolt to the head disrupts normal brain function, and studies link it to brain changes that can lead to memory loss and thinking problems over time.
Scientists have found strong evidence for this connection. For example, people with a TBI are about 50 percent, or 1.5 times, more likely to get dementia than people without one. This comes from large reviews of studies on groups of people over many years. Experts estimate that TBIs account for around 3 percent of dementia cases around the world. In older adults, the risk grows even more. One big study of over 23,000 TBIs in people aged 65 and up showed that those with dementia before their injury had much higher death rates in the months after, pointing to how TBI worsens brain health issues.
Even mild TBIs can play a role. In military service members with mild head injuries, some groups developed serious thinking problems years later, raising worries about dementia risk. Brain scans in these cases showed differences in areas like the cerebellum, which handles learning and emotions. Repetitive head impacts, such as in sports like football or boxing, link to a rare dementia type called chronic traumatic encephalopathy, or CTE. Each extra year in such sports raises the CTE risk by 15 percent.
Why does this happen? A recent finding suggests TBIs might block the brain’s natural drainage system, speeding up buildup of harmful proteins seen in Alzheimer’s disease. Pre-existing dementia also makes outcomes worse after a TBI, with higher long-term risks. While not everyone with a TBI gets dementia, the pattern holds across many studies, and experts call for better prevention like helmet use and recovery protocols.
Sources
https://pmc.ncbi.nlm.nih.gov/articles/PMC12676572/
https://www.alzheimersresearchuk.org/about-us/our-influence/policy-work/position-statements/sport-and-dementia/
https://newsroom.uw.edu/news-releases/mild-traumatic-brain-injury-outcomes-vary-significantly
https://www.gbhi.org/news-publications/developing-topics-8
https://dukespace.lib.duke.edu/items/ef69d738-cd87-4653-b635-6aed2de1bf60
https://www.news-medical.net/news/20251216/Traumatic-brain-injury-disrupts-brain-drainage-and-accelerates-Alzheimere28099s-risk.aspx
