Millions of Americans get a concussion every year. While often associated with blows to the head during contact sports, concussions are common at all ages. Thirteen percent of older adults have experienced a traumatic brain injury — most often caused by falls — and more than 80 percent of traumatic brain injuries are concussions.
Though concussions are commonplace and often perceived to have short-term effects, they can involve real, long-term risks to the brain that should not be ignored.
“A concussion is often referred to as a minor or a mild traumatic brain injury,” said Brian Christie, a professor and associate dean in the school of medical sciences at the University of Victoria in Canada. “You still have those three words: traumatic brain injury.”
Traumatic brain injuries are associated with faster cognitive decline. They’re a risk factor for dementia, potentially leading to an earlier onset by two to three years. Concussions are also associated with an 18 percent increase in relative risk of Alzheimer’s disease, according to a 2022 meta-analysis of five studies.
Getting multiple concussions — or getting one while you’re still recovering from another — is the greatest concern for long-term brain health, Christie said.
But you can protect yourself by following a few simple tips to prevent falls and potential concussions, and getting proper treatment if a concussion does happen.
“A brain injury can change the probability of dementia,” Christie said. “It doesn’t determine the individual’s destiny.”
How concussions impact your brain
Encased in our skull, our brain is soft and squishy with a consistency akin to warm Jell-O. A big hit to the head sets off a shock of biological consequences that can lead to short-term amnesia, headaches, confusion or unconsciousness.
The brain doesn’t move in a uniform way. When you get hit, the force moves along where white matter — bundles of neural connections — are densest, causing the white matter to twist and shear. Blows to the head can also damage the small blood vessels that supply the brain with needed nutrients and oxygen.
At the same time, the hit can also set off a “neurometabolic cascade,” said Benjamin Brett, a clinical neuropsychologist by training and associate professor in the department of neurosurgery at the Medical College of Wisconsin.
After a blow to the head, glutamate — a neurochemical that activates neurons — is spewed out, making large areas of the brain more active than they should be. As a result, cells need to compensate to return to their baseline — an energy-intensive process that causes a drop in blood flow and a “metabolic crisis” in the brain, Brett said.
In a concussion, it isn’t possible to detect these biological changes using conventional neuroimaging techniques. (A noticeable brain bleed would bump up the diagnosis to a moderate or severe traumatic brain injury.)
But more advanced techniques have revealed that concussions cause injury to white matter. Long tracts of white matter, such as the corpus callosum, which connects the brain’s left and right hemispheres, are most vulnerable, Brett said.
These brain changes typically resolve within six months, though that may vary, Brett said.
The good news is that “the majority of people recover and have no perceptible difference in function after a concussion,” Christie said. However, over 13 percent of patients still had poor cognitive outcomes one year after a concussion, a 2022 study of more than 600 adults reported.
And having multiple concussions or experiencing another concussion while still recovering may result in a different brain trajectory.
How many concussions is too many?
Overall, one mild traumatic brain injury, by itself, probably does not increase dementia risk. “A single concussion is something you should always take seriously, but it’s not a forecast for dementia,” Christie said.
Concussions, however, can prime the brain to be more vulnerable to other harms such as infection or cardiovascular events. This “double-hit hypothesis” suggests that one risk factor, such as a concussion, isn’t enough to cause dementia but, when combined with others, is more likely to cause problems, Brett said.
This could be why older adults may be at a particularly high risk for dementia following a concussion or traumatic brain injury, with falls being the most common cause, Brett said.
In fact, a 2026 study tracking more than 10,000 people across 74 years found that concussions were associated with a 60 percent increased risk of dementia-related mortality. (Moderate and severe traumatic brain injuries were linked to a 267 percent increase.)
The relationship between traumatic brain injuries and dementia is complex and still being investigated, but it seems the number of concussions that puts people at long-term risk may be relatively high.
“The people in our cohort who are having the most difficulties tend to occur at honestly a very high number, around like six to nine [concussions],” with higher rates of cognitive impairment, stroke and depression, though there’s a lot of variability, said Brett, who wrote a 2024 review on the consequences of concussion in athletes.
Repetitive head injuries that don’t cause concussion, such as from heading soccer balls or playing contact sports such as football, can also produce cognitive issues, and in extreme cases, chronic traumatic encephalopathy, or CTE — the degenerative brain disease common among football players.
How to avoid and treat concussions
To prevent concussions, wear the recommended protective gear when playing contact sports or bicycling, which produces the highest number of sports-related emergency room visits for traumatic brain injuries in the United States.
For older adults, avoiding falls is key. Training balance pays great dividends and can be incorporated into your day, such as standing on one leg while brushing your teeth or practicing standing up from the floor. Using mobility assistive devices, such as canes or walkers, and getting rid of trip hazards around the home may also be beneficial, Brett said.
After getting a hit to the head, if you or someone else notices that you have an altered state of mind, it’s a good idea to get evaluated by a medical professional. Watch out for more severe symptoms such as loss of consciousness, seizures or severe headaches as well.
Treatment for a concussion has changed. People aren’t told to stay in a dark room with low stimulation. Doctors now encourage people to gradually return to physical and mental activity after some rest.
“You need to have activity,” Christie said. “Returning to function in that graduated fashion is important to help reestablish your normal brain,” while paying attention to worsening symptoms, such as sensitivity to light or sound, as a guide on how much activity is appropriate.
If you’ve had a concussion, “you can’t do anything about your history of head injury,” but there are still many ways to mitigate your dementia risk, Brett said.
That includes staying connected with others, whether it’s your family, friends or neighbors. Regular exercise — even running or walking a few minutes a day — can help protect the brain, cutting down cardiovascular risk factors such as hypertension.
Vaccines, such as for shingles and flu, have been linked to a 20 and 17 percent lower risk, respectively. Keeping your brain stimulated through activities such as learning a new language, reading fiction or certain brain games — including video games — can also help, as can cutting down on alcohol.
Do you have a question about human behavior or neuroscience? Email [email protected] and we may answer it in a future column.
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