If you were told you had a “mild” brain injury—but it certainly didn’t feel mild—you’re not alone. For decades, concussions have been underestimated, both in how they’re diagnosed and understood. But that’s starting to change. In 2024, an international group of experts proposed a new classification model, which they referred to as “CBI-M,” a framework that replaces the outdated categories of “mild, moderate, and severe” with a more nuanced system built on clinical signs, biomarkers, imaging, and individual modifiers, such as injury history, age, and mental health. This new model gives clinicians better tools for diagnosis and treatment, and it also validates what so many survivors have been saying all along: concussion is a brain injury, and it deserves to be treated like one. We sat down with John Corrigan, PhD, National Director of Research at the Brain Injury Association of America, to hear his perspective on this new classification and what it means for diagnosing and treating concussion in the future.

For more than 50 years, traumatic brain injuries—including concussions—have been categorized using just three words: mild, moderate, and severe.

While these labels may seem helpful on the surface, they often oversimplify a condition that is anything but. The oversimplification of concussion can have real consequences, including delayed diagnoses and misunderstood symptoms. That, in turn, can create missed opportunities for care and plenty of stigma around the seriousness of concussion.

A global team of researchers and medical experts is working to change that. Earlier this summer, a new traumatic brain injury classification model, known as CBI-M (Clinical, Biomarker, Imaging, and Modifiers), was introduced. This framework expands how we define and diagnose brain injuries—including concussions—by adding both objective data and personal context to what historically has been a very narrow assessment.

For patients, providers, and advocates focused on concussion, this new model represents a meaningful shift in how we talk about concussion.

The origins of the CBI-M framework

The push for a new classification system began in earnest in 2022, when the National Academies of Sciences, Engineering, and Medicine released a report warning that the United States lacked a comprehensive framework for understanding and addressing traumatic brain injuries. That report called attention to widespread gaps in detection, treatment, rehabilitation, and public understanding—particularly for people whose symptoms continue long after the initial injury.

In response, a coalition of global experts—including scientists, clinicians, federal agencies, and patients—met at the National Institutes of Health in 2024 to lay the groundwork for what would become the CBI-M model. The framework was formally introduced in The Lancet Neurology in May 2025 and is now being phased in at trauma centers on a trial basis.

As the CBI-M model is still new, it will likely change as additional research emerges. But its purpose is clear: to move beyond the outdated “mild, moderate, severe” labels and give clinicians a better way to understand what’s really happening in the brain. By looking at data such as blood tests, scans, and personal history, and not just symptoms, CBI-M could help people with a concussion get the care they need, right from the start.

The four pillars of CBI-M

CBI-M is a four-pillar approach that replaces single-number evaluations with a more comprehensive profile of injury. Here are those pillars in more detail:

Clinical (C): For more than 50 years, doctors have relied on the Glasgow Coma Scale (GCS) to help assess the severity of a brain injury. The GCS is a tool that measures a patient’s consciousness by scoring a person’s ability to open their eyes, speak, and move in response to commands. It gives clinicians a number between 3 and 15, and that number has traditionally been used to classify brain injuries as mild, moderate, or severe.

In the new CBI-M classification, GCS is still an important part of assessment, but it doesn’t tell the whole story. The Clinical pillar of the CBI-M model keeps the GCS but adds more information—like whether someone has amnesia, is disoriented, or is experiencing symptoms such as headache, dizziness, or sensitivity to noise. Together, these details help build a more accurate picture of what’s happening in the brain right after the injury occurs.

Biomarkers (B): This pillar looks at substances in the blood that can show signs of brain damage—kind of like how a cholesterol test can tell you about your heart health. One of the key biomarkers is something called GFAP, which stands for glial fibrillary acidic protein. When certain brain cells are injured, GFAP gets released into the bloodstream.

Even if a person seems fine on the outside—talking clearly, remembering things, and walking normally—an elevated GFAP level can be a clue that their brain is still healing. In the future, tests like this could help doctors spot which concussion patients are more likely to have ongoing symptoms and who may need more follow-up care.

Imaging (I): CT and MRI scans continue to play a role, particularly when evaluating whether a concussion may have resulted in lesions or bleeding. Under the new model, even subtle imaging abnormalities are taken into account.

Modifiers (M): This is where the model gets deeply personal. Modifiers consider the context of the injury: Was it a fall or a blast? Did the person have a prior TBI? Are they on medications, living in a rural area, or managing mental health challenges? These details help clinicians move from a “one-size-fits-all” treatment to targeted, proactive care.

Why CBI-M matters for concussion diagnosis and care

For those recovering from concussion, CBI-M offers something the old classification system never could: validation.

“I could almost make the case that [CBI-M] has the most to say about concussion,” said John Corrigan, PhD, National Research Director at the Brain Injury Association of America. “Concussion is still on the less severe end of the spectrum, but now we’ll be much more detailed about how we capture what’s happening to the brain in the first hours and days.”

John Corrigan, PhD, explained that the model can help identify concussion cases where risk factors are present but symptoms are still evolving, giving providers a clearer window to intervene early. For example, a patient with a GCS score of 15 (indicating they are alert and responsive) might still show elevated GFAP levels, suggesting hidden damage. Another patient with a history of multiple concussions may appear fine clinically, but be at high risk for prolonged recovery.

“These are the people we might want to give more attention to early on,” John Corrigan, PhD, said, “instead of waiting for them to come back later when they’re struggling.”

Moving from reactive to proactive care

Historically, concussion care has been reactive: wait-and-see, rest-and-hope. The CBI-M model supports a shift toward proactive intervention by providing a richer set of data that can help predict who’s likely to benefit from closer follow-up or specialist care.

This shift is especially valuable in rural or under-resourced areas, where health systems may lack the ability to offer specialist evaluations across the board. John Corrigan, PhD, noted that by combining electronic symptom tracking with CBI-M-informed triage, systems can begin to act earlier—and smarter.

“You can’t throw an interdisciplinary team into every case—the resources just aren’t there in many areas of the country,” he said. “But if we can better predict who’s likely to need more support, we can step in sooner and provide it more efficiently.”

A reframe of concussion language

While CBI-M is a clinical framework first and foremost, its introduction also gives the concussion community an opportunity to rethink how we talk about concussion—not just in medical records, but in everyday conversations, awareness campaigns, and public health messaging.

For years, “concussion” and “mild TBI” have been used interchangeably. But as John Corrigan, PhD, explained, dropping the word “mild” doesn’t fix the problem—especially if the word “concussion” continues to be misunderstood or downplayed.

“We can’t just replace ‘mild’ with ‘concussion’ and assume the stigma will disappear,” he said. “We have to consciously change how we communicate—especially to the public. Otherwise, we risk downplaying the seriousness of concussion all over again.”

In fact, John Corrigan, PhD, shared that the term “concussion” was originally used in part to avoid alarming patients—especially in emergency settings where providers might have hesitated to label something as a “traumatic brain injury.” But that softer language has come at a cost. Today, that neutrality can be confusing. Patients may not realize a concussion is a brain injury, or that it can lead to long-term effects. In a recent public awareness poll conducted by the Brain Injury Association of America, eight out of 10 people didn’t connect concussion with traumatic brain injury at all.

That’s why, alongside this new classification, public education remains critical. Recognizing the signs and symptoms of concussion is still essential. But now, clinicians may have additional tools to confirm and contextualize those experiences using imaging, biomarkers, and personal history.

Looking ahead with CBI-M

CBI-M isn’t perfect, and it isn’t final. Experts are already discussing how to adapt the model for long-term concussion effects, retrospective evaluations, and post-acute care pathways. But even in its early form, it signals a critical shift.

It acknowledges what survivors have long known: concussion is complex. Outcomes aren’t dictated by a number on a scale. And recovery depends not just on what happened during the injury, but who it happened to.

With the CBI-M framework, we finally have a chance to move beyond a one-word label—and toward an improved standard of care.