The Study: What Happens to the Brain After Repeated Concussions?

The study “Concussion in Chronic Traumatic Encephalopathy” looks at what happens to the brain after repeated mild traumatic brain injuries, something incredibly common in military and special operations populations. 

Key takeaway:

Even “mild” or repeated impacts over time can lead to progressive changes in brain structure and function, not just short-term symptoms.

In the 2015 review article, “Concussion in Chronic Traumatic Encephalopathy,” researchers Thor Stein, Victor Alvarez, and Ann McKee examined what the existing research showed about chronic traumatic encephalopathy, or CTE, in relation to repetitive mild traumatic brain injury. CTE is described as a progressive neurodegenerative disease associated with repeated head trauma, with symptoms that can affect mood, behavior, cognition, and motor function. 

This was not a treatment study. It was a scientific review of the known exposure patterns, clinical symptoms, and brain pathology seen in confirmed CTE cases. The purpose was to better understand what types of repetitive trauma appear connected to CTE, what changes are seen in the brain, and how symptoms tend to show up over time.

One of the most important findings is that CTE is not simply about “how many concussions” someone remembers having. In published cases reviewed by the authors, the average exposure to repetitive head trauma was 15.4 years, symptoms began after an average latency of 14.5 years, and the mean age of death was 59.3 years. The study also reported that 16% of confirmed CTE cases had no known concussion history, suggesting that repeated subconcussive hits may be enough to contribute to disease development. 

Practically, this matters because many people in high-exposure environments do not recognize every hit, blast, impact, or neurological stressor as a “brain injury.” For military personnel, first responders, breachers, athletes, and others exposed to repetitive force, the concern is not always one dramatic injury. Often, it is the cumulative load over time.

The authors describe a distinct pattern of abnormal tau protein accumulation in CTE. This tau pathology tends to appear around blood vessels and deep within the folds of the brain, areas believed to experience higher mechanical stress during trauma. In more advanced stages, the pathology can spread more broadly through the cortex and into deeper brain structures.

Functionally, these changes can feel very different from the way they sound in a research article.

A person may not say, “I have a neurodegenerative process.” They may say:

“I am not as sharp as I used to be.”

“My mood changes faster than it should.”

“I cannot focus the way I used to.”

“I feel flat, irritable, or disconnected.”

“My memory is slipping.”

“I am exhausted, but I cannot fully rest.”

“I do not feel like myself.”

The study notes that clinical symptoms of CTE can involve several domains: mood symptoms such as depression, suicidality, and irritability; behavioral changes such as impulsivity or explosivity; cognitive changes such as impaired memory, executive dysfunction, and poor concentration; and motor symptoms such as gait changes, weakness, or parkinsonism.

For veterans and special operations families, this is especially important. The study specifically notes that CTE has been found in military personnel exposed to explosive blast, and that hundreds of thousands of service members experienced brain trauma from conventional and improvised explosive devices during Iraq and Afghanistan-era deployments.

At Brain Treatment Center NoVa, we do not diagnose CTE, and CTE can currently only be definitively diagnosed after death through autopsy. But we do work with many patients who have histories of repetitive head trauma, blast exposure, PTSD, TBI, sleep disruption, fatigue, mood changes, and cognitive decline.

Our role is to look at the whole picture.

That may include MeRT/rTMS to support brain communication and regulation, functional health evaluation to assess inflammation, nutrient status, hormones, toxins, gut health, and cellular resilience, mental health counseling to support identity and transition, SPIN/occupational therapy to help regulate the nervous system and restore brain-body balance, and additional integrative services when appropriate.

The main takeaway from this study is not fear. It is awareness.

Repeated brain stress matters. Subconcussive exposure matters. Years of accumulated impact matter. And for many patients, the symptoms they are experiencing are not weakness, poor motivation, or “just stress.”

There may be signs that the brain and body need a more comprehensive level of support.

At Brain Treatment Center NoVa, we help patients explore what is contributing to their symptoms and build a plan that supports the brain, body, and nervous system together.

Brain Treatment Center NoVa

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