When you’re recovering from a mild traumatic brain injury (mTBI) after a bicycle crash, you might be led to believe that healing up will be simple because it’s categorized as “mild”, and that once resolved, life will continue as normal.
New research shows that might not be the case for some people with mTBIs.
Published in December in JAMA Network Open, researchers from the University of Washington found in a 10-year follow-up study that long-term outcomes of combat veterans who experienced an mTBI had varying outcomes years after the event.
“We found that service members who had mild traumatic brain injury fell into different TBI subtypes, with many showing resiliency but important subgroups at risk for later decline,” said the study’s lead researcher, Christine Mac Donald, PhD, professor of neurosurgery at the University of Washington School of Medicine, in a news release.
While this research focused exclusively on combat veterans, the findings could be helpful outside of that population as well. This work “might help identify patients at high risk of developing psychological, neurobehavioral, or cognitive problems before they manifest,” Mac Donald said.
What is a mild TBI?
Traumatic brain injuries occur when there is a blow or jolt to the head. External forces, such as hitting hard concrete, can result in symptoms that range from mild to extreme. In bicycle cases, factors such as speed can affect the severity of a TBI.
The UW study used the Department of Defense definition of mTBI: exposure to blast or blunt trauma resulting in loss of consciousness of less than 30 minutes, alteration of consciousness of less than 24 hours, post-traumatic amnesia of less than 24 hours and a normal CT scan at the time of injury. This is also a common definition used among the general population and could apply to cyclists, too.
Mild traumatic brain injury symptoms include:
- Headache
- Sensitivity to light and/or noise
- Vision issues and/or dizziness
- Sleeping disturbances
- Issues with concentration
- Issues with memory
- Nausea or vomiting
- Changes in mood
- Feeling more anxious, sad, or nervous than usual
Sometimes these symptoms will resolve on their own, and doctors often prescribe rest for mTBIs (sometimes referred to as concussions). However, research is increasingly finding that even mild brain injuries can have lasting impacts on a person.
These impacts may not always be strictly physical symptoms, such as headache or nausea, but issues with cognition that show up years later.
Varying outcomes a decade later
The UW study followed 288 service members from the time of their deployment in Iraq or Afghanistan, and followed up one, five, and ten years later to evaluate for cognitive and neurobehavioral decline. Each visit included an MRI scan and an assessment of 34 psychological, cognitive, and neurological/neurobehavioral functions.
Of these members, 137 experienced blast exposure that caused an mTBI and 21 had a blunt trauma.
“One group was designated as resilient because they had no significant cognitive dysfunction or neurobehavioral or psychological symptoms after 10 years,” researchers note. “Most people in the resiliency subtype were part of the control groups, but 36% were service members with mild TBI. This observation suggests that mild TBI does not necessarily result in a poor long-term outcome.”
The three other subgroups the researchers found among services members who did have long-term impacts were 1.) those who did not have cognitive dysfunction but did have mild neurobehavioral and psychological symptoms 2.) those who had moderate cognitive dysfunction with substantial neurobehavioral and psychological symptoms and 3.) those who had severe cognitive dysfunction and moderate neurobehavioral and psychological symptoms.
It wasn’t until later in the study that these subtypes actually started to take shape, Mac Donald said. This highlights why it can be so vital to engage in long-term research, especially for mTBIs.
Additionally, brain imaging helped researchers determine differences among the groups. Those who developed severe cognitive dysfunction, for example, were more likely to show differences in key brain structures that are responsible for learning and emotion.
“…We identified neuroanatomical regions, specifically the cerebellum and brainstem, that may provide greater sensitivity in identifying individuals at highest risk of decline earlier on, as these regional differences were evident years before when stratified by 10-year follow-up cluster,” researchers wrote in their paper.
Evolving research: the TBI-mental health connection
The wide differences in outcomes presents important findings for service members and for the general population, including cyclists who experience blunt trauma from a crash. While many will go on to have normal lives, some may experience cognitive, psychological, and neurobehavioral dysfunction years after the initial injury.
Other studies in recent years have also made connections between mTBI and mental health. In 2024, researchers discovered that “sustaining a mild TBI significantly increased the risks of having a new affective or behavioral disorder up to four years after injury” in children.
Affective disorders, which include depression, anxiety, posttraumatic stress disorder, acute stress, and adjustment disorders, can have a significant impact on daily life.
For cyclists involved in a crash that leaves them with an mTBI, moving forward can be challenging, especially when some symptoms can resolve but others can show up years later.
This is why it’s important to find the right care, to document symptoms, and to work with a legal team that specializes in cycling and brain injury cases: there’s no guarantee that any cyclist’s mTBI will completely resolve and cognitive or behavioral dysfunction won’t play a part later on in life.
The good news is that as researchers learn more, policy responds. In 2024, the U.S. Centers for Medicare and Medicaid Services (CMS) began recognizing TBI as a chronic condition that may require specialized and prolonged care.
For cyclists who experience a TBI, it’s important that this work continues, as it ultimately will improve their experiences post-crash, too.
Involved in a crash and experiencing TBI symptoms or other injuries? After immediate health care, get in touch with our office. We can help you navigate the legal process. Start here and reach out for a free consultation.