CTE and Alzheimer’s: Overlapping Pathologies, Shared Challenges

For decades, Alzheimer’s disease has dominated the conversation around dementia. The hallmark signs of memory loss, cognitive decline, and the buildup of amyloid plaques and tau tangles are familiar to many families navigating aging and neurological illness. But as research evolves, another neurodegenerative condition is gaining long-overdue attention: chronic traumatic encephalopathy, or CTE.

Traditionally linked to professional athletes and military veterans, CTE is now recognized as a broader public health concern. And increasingly, scientists are discovering that CTE and Alzheimer’s disease are not entirely distinct. They may share overlapping pathology, similar symptoms, and a set of challenges that complicate how we diagnose and treat dementia-related diseases.

So what happens when the biological signatures of repeated head trauma and age-related cognitive decline intersect? And what can families, patients, and clinicians learn from the growing body of research connecting the two?

Pathology and diagnosis 

CTE is a progressive neurodegenerative disease believed to be caused by repeated head injuries, both concussive and sub-concussive. The condition is marked by the abnormal accumulation of tau protein, particularly in the depths of a part of the brain called the sulci and around small blood vessels. These pathological changes can lead to mood disorders, cognitive dysfunction, and, in many cases, full-blown dementia. 

Alzheimer’s disease, while also characterized by tau pathology, follows a different biological trajectory. It involves the buildup of both amyloid-beta plaques and tau tangles, disrupting memory and executive function.

The common link of tau means that clinically, the symptoms of Alzheimer’s and CTE can appear nearly indistinguishable in some patients. Both may involve memory impairment, mood disturbances, confusion, and difficulties with attention or problem-solving. However, the initial behavioral symptoms often differ: CTE may first appear as irritability, aggression, or depression; Alzheimer’s, on the other hand, typically emerges more gradually and often begins with subtle memory lapses.

Still, the overlap can confuse both patients and clinicians. A person with Alzheimer’s pathology may have also suffered repeated head injuries, muddying the clinical picture. Conversely, someone suspected of having CTE might later be found to also carry markers of Alzheimer’s disease. Complicating matters, at this time CTE remains impossible to confirm without a brain autopsy.

Diagnosis remains one of the most pressing challenges in navigating this overlap. While Alzheimer’s can often be supported with biomarkers, cognitive assessments, and brain imaging, CTE lacks a reliable diagnostic tool for living individuals. There are no FDA-approved blood tests or imaging protocols that can conclusively identify CTE while the person is alive. As a result, many clinicians must rely on symptom patterns and personal history to build a working diagnosis.

Contact sports and head trauma

When most people think about head injuries, they imagine the dramatic kind that involves loss of consciousness or needing to be rushed to the ER. But research increasingly shows that it’s the smaller, repeated hits over time that may quietly pose the greatest risk to long-term brain health. As neurophysiologist Alan Pearce told Being Patient, repetitive head trauma can put a person at greater risk for developing CTE and other neurodegenerative diseases. 

“Those with a history of repetitive impacts to the brain are more at risk [for developing neurodegenerative diseases],” Pearce said. “These impacts may not be diagnosed brain injuries or concussions, but rather non-concussive impacts (smaller hits that do not produce signs or symptoms of concussion).” 

According to Dr. Bruce Lamb, head of the Stark Neurosciences Research Institute at Indiana University, another shared concern is the role of genetic risk. 

The ApoE4 allele, often referred to as the “Alzheimer’s gene,” has also been associated with worse outcomes following brain injury. Research suggests that individuals with this gene variant may be more vulnerable to developing long-term cognitive issues after repeated head trauma. That means someone carrying ApoE4 who also played contact sports or served in the military may face compounded risks. 

As Lamb explained, recent studies into the allele suggest that “ApoE is potentially playing a role in the immune system, which I think previously, we didn’t appreciate. That is a brand new area, and you’re going to see a lot more relationships to brain injury and how the immune system is activated, but also in Alzheimer’s disease as well.”

Data from sports medicine and epidemiological studies support this concern. One study found that professional soccer players had a fivefold increase in Alzheimer’s risk compared to the general population. This suggests that the line between trauma-induced degeneration and Alzheimer’s disease might not be as clear as once believed.

Reducing dementia risk after trauma

Regardless of the perceived severity, anyone experiencing symptoms after a head injury should see a doctor right away for an examination, said Dr. Munro Cullum, a neuropsychologist at the University of Texas Southwestern Medical Center. After that, he recommended a slow recovery process.

“Light exercise after that initial day or two is good. Light exercise might be a brisk walk or riding a stationary bike,” Cullum said. “If symptoms get worse from activity, back off for the day, then progressively reengage in normal activities as symptoms [improve]. Most people recover from concussion. …A slow, progressive return to normal activity — without exacerbating symptoms — is the key.” 

Managing cardiovascular health, staying cognitively and socially active, getting good sleep, and avoiding further head injuries can also help mitigate long-term risk. 

Treatment and lifestyle interventions

While treatment remains largely focused on addressing symptoms for both conditions, lifestyle interventions such as sleep hygiene, cardiovascular fitness, cognitive engagement, and mood regulation are important regardless of the underlying pathology. 

Because tau plays a central role in both diseases, researchers have attempted to treat them together in clinical trials. At least one “basket” trial investigated a tau-targeting drug across multiple neurodegenerative conditions, including CTE. However, as of now both Alzheimer’s and CTE continue to evade curative treatment.

Ultimately, the intersection of CTE and Alzheimer’s is a reminder that the brain doesn’t segment its injuries neatly. A person’s risk for dementia may come from a complex interplay of genetics, life history, trauma, and aging. Understanding and acknowledging the overlapping pathologies is key to better diagnosis, smarter research, and more compassionate care.

CTE and Alzheimer’s: Frequently asked questions

What is the difference between CTE and Alzheimer’s?

CTE (chronic traumatic encephalopathy) is a neurodegenerative condition caused by repeated head trauma. Alzheimer’s disease is primarily driven by age-related biological changes, including amyloid-beta and tau protein buildup. While both involve tau pathology and result in dementia, their causes, progression, and diagnostic approaches differ.

Can a person have both CTE and Alzheimer’s?

Yes. Some individuals show pathology for both diseases, especially those with head trauma and a genetic predisposition like the ApoE4 allele. Mixed pathology is increasingly recognized in brain autopsies of dementia patients.

Is CTE considered a form of dementia?

Yes. CTE is a progressive brain disease that can lead to cognitive decline and dementia, particularly in later stages. Early signs may include mood changes, impulsivity, and memory issues.

Can CTE be diagnosed while a person is alive?

At present, CTE can only be definitively diagnosed through a post-mortem brain examination. Researchers are working on biomarkers and imaging tools, but no live diagnostic method is yet validated. 

How is Alzheimer’s diagnosed differently?

Alzheimer’s can be diagnosed during life using a combination of memory and cognitive tests, brain imaging (like PET scans), and biomarkers found in cerebrospinal fluid or blood. These tools are not yet available for CTE diagnosis.

Are Alzheimer’s treatments effective for CTE?

Currently, there is limited evidence that Alzheimer’s-specific medications are effective in treating CTE. Research is underway into tau-targeting drugs and their applicability across multiple neurodegenerative diseases, but currently most CTE treatment remains symptom-focused, addressing mood, behavior, and cognition as needed.