For years, doctors have thought that concussions and serious head injuries (called traumatic brain injuries, or TBIs) might raise the risk of getting ALS, a serious brain disease also known as Lou Gehrig’s disease.
But now, a new study suggests it might be the other way around.
The research team, led by Dr. William Stewart from Queen Elizabeth University Hospital in Glasgow, believes that concussions might actually be an early warning sign of ALS. In other words, people who are already starting to develop ALS—before they even know it—might be more likely to fall or get hurt, leading to a concussion.
ALS affects the nerves that control muscles. Over time, people with ALS lose strength and find it harder to move. Even in the early stages, the disease can quietly affect balance and coordination, making falls more likely. That could explain why people with early ALS seem to get more concussions.
To test this idea, researchers studied over 85,000 people who had a traumatic brain injury. They compared them with more than 257,000 people who had never had a TBI. All of them were tracked for nearly six years. During that time, 150 people were diagnosed with ALS.
The study found that people who had a TBI were more than twice as likely to be diagnosed with ALS. But that increased risk only lasted for about two years after the injury. After that, the risk went back to normal.
Also, there was no difference in the age at which people were diagnosed or when they died, whether they had a TBI or not. This suggests that TBIs don’t cause ALS—they might just happen more often in people who already have the disease starting inside their body.
In other words, the brain injury may not lead to ALS. Instead, the early, hidden symptoms of ALS may lead to the injury.
Dr. Rosanna Sabini, who leads a concussion program at Northwell Health in New York, said the study is a good reminder for doctors to keep a close eye on people who’ve had a head injury. She said doctors should check on how their brains are doing even after the physical injury heals. Spotting problems early might help improve their health and life span.
ALS is a disease that usually develops as people get older. It damages parts of the brain and spinal cord that control movement. This leads to muscle weakness, making it harder to walk, move, and eventually breathe. Many people with ALS eventually need help from machines to breathe.
This study doesn’t prove that a concussion causes ALS. Instead, it suggests that for some people, concussions may be a sign that something more serious—like ALS—is already beginning to happen in the body.
If you care about stroke, please read research about Thanks to his wife’s quick reaction, postal worker fully recovered from a stroke and findings of new hope for people with irregular heartbeat to prevent stroke.
For more about stroke, please read research about Stronger high blood pressure treatment may help prevent stroke in older people and findings of Stroke death risk increases again after falling for 40 years.
The study is published in JAMA Network Open.
Copyright © 2025 Knowridge Science Report. All rights reserved.
