Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative brain disease associated with repeated head impacts. It has been identified in individuals with histories of repetitive brain trauma, including athletes involved in contact sports and military veterans exposed to blast injuries or repeated concussions. CTE is characterized by abnormal deposits of a protein called tau in the brain, which interfere with normal brain function and can lead to changes in behavior, mood, thinking, and memory.

Video: What chronic traumatic encephalopathy (CTE) symptoms can look like for patients and caregivers in everyday life.

Seeing how symptoms appear in real life can help families recognize the early warning signs of neurological injury.  Understanding how CTE develops begins with examining the primary cause: repeated head trauma. 

Research over the past two decades has increased awareness of CTE, particularly in athletes and veterans. However, many questions remain about who develops the condition, how symptoms progress, and how families can navigate the challenges that come with neurological injury.

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What Causes CTE

The primary risk factor associated with CTE is repeated head trauma. This trauma may occur through diagnosed concussions or through repeated smaller impacts that do not always produce immediate symptoms.

Examples of repeated brain trauma include:

• Contact sports such as football, boxing, hockey, and soccer

• Military blast exposure

• Repeated head injuries in accidents or combat

• Subconcussive impacts (smaller hits that do not cause a concussion but still affect the brain)

Research indicates that repetitive brain trauma may trigger changes in brain cells that lead to abnormal accumulation of the tau protein. Over time, these changes can spread through the brain and disrupt communication between neurons.

Importantly, not everyone who experiences repeated head trauma develops CTE, and scientists are still studying why some individuals are more vulnerable than others.

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Who Is Most At Risk

CTE has been most commonly identified in people with long histories of repetitive head impacts.

Groups that have received the most research attention include:

Contact sport athletes

Professional and amateur athletes in sports with frequent head impacts have been studied extensively. This includes American football players, boxers, hockey players, and others involved in collision sports.

Military veterans

Military service members may experience repeated blast exposure or traumatic brain injuries during training or combat. Research has explored possible links between these exposures and long-term neurological conditions.

Individuals with repeated head injuries

CTE has also been observed in people with repeated traumatic brain injuries unrelated to sports or military service.

It is important to emphasize that CTE is not limited to professional athletes, and researchers continue to study how different types of head trauma contribute to risk.

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Symptoms Associated With CTE

Symptoms of CTE often develop years or even decades after the initial brain injuries. Because of this delay, early signs may be difficult to recognize.

Common symptoms reported in individuals later diagnosed with CTE include:

Cognitive symptoms

• Memory problems

• Difficulty concentrating

• Impaired judgment

• Slowed thinking

Emotional and behavioral symptoms

• Irritability

• Mood swings

• Depression

• Aggression or impulsivity

Neurological symptoms

• Problems with balance or coordination

• Parkinsonian symptoms in some cases

• Progressive cognitive decline

Not every person with repeated head trauma develops these symptoms, and many symptoms overlap with other neurological or psychiatric conditions.

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How CTE Is Diagnosed

Currently, chronic traumatic encephalopathy (CTE) cannot be definitively diagnosed in a living person. 

Many families ask: “Can CTE be diagnosed in living patients?” At this time, the disease can only be confirmed through post-mortem examination of brain tissue, where doctors can identify the characteristic pattern of abnormal tau protein deposits.

Researchers are actively working to develop methods that may allow doctors to identify CTE during life using:

• Brain imaging techniques

• Biomarkers in blood or spinal fluid

• Improved clinical diagnostic criteria

However, these tools are still under investigation.

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Why CTE Research Matters

CTE has gained significant attention because it highlights the potential long-term effects of repeated brain trauma. Increased awareness has led to:

• Improved concussion protocols in sports

• Greater attention to brain injury prevention

• Expanded research into traumatic brain injury and neurodegenerative disease

At the same time, researchers emphasize that much remains unknown about the disease, including exactly how it develops and why some individuals are affected while others are not.

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Living With the Impact of Brain Injury

While CTE itself can only be confirmed after death, many families are living with the real-world effects of traumatic brain injury, cognitive decline, and neurological changes.

Caregivers often face challenges such as:

• Behavioral and personality changes

• Memory loss

• Emotional volatility

• Increasing caregiving responsibilities

Education and support can make a significant difference for families navigating these conditions.

Organizations like Robbins Nest Alliance focus on providing resources, education, and community support for individuals and caregivers affected by neurological injury and neurodegenerative conditions.

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Conclusion

Chronic traumatic encephalopathy is a complex brain disease linked to repeated head trauma. Although research has made important advances in understanding the condition, many aspects of CTE remain under investigation. What is clear is that repeated brain injury can have lasting effects on brain health, behavior, and cognition.

Continued research, awareness, and support for affected families are essential as scientists work toward better prevention, diagnosis, and treatment strategies.

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Sources

1. McKee AC et al. “Chronic Traumatic Encephalopathy in Athletes: Progressive Tauopathy After Repetitive Head Injury.” Journal of Neuropathology & Experimental Neurology, 2009.

2. Mez J et al. “Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football.” JAMA, 2017.

3. Centers for Disease Control and Prevention (CDC). “Traumatic Brain Injury & Concussion.”

4. National Institute of Neurological Disorders and Stroke (NINDS). “Chronic Traumatic Encephalopathy Information Page.”

5. Boston University CTE Center – Research on CTE and Repetitive Head Impacts.