How to Know If You Have CTE | Clinical Signs and What Research Confirms

The honest answer first: you cannot know for certain whether you have CTE while you are alive. Chronic Traumatic Encephalopathy is diagnosed only after death, through examination of brain tissue. There is no blood test, no scan, and no clinical exam that confirms CTE in a living person.

What can be evaluated during life is a related condition called Traumatic Encephalopathy Syndrome (TES). TES is the clinical syndrome thought to be associated with CTE pathology, and in 2021 a panel of twenty expert clinician-scientists from eleven academic institutions published the first consensus diagnostic criteria for it through the National Institute of Neurological Disorders and Stroke (NINDS).

This article walks you through what those criteria actually say, what families often notice first, why so many conditions look like CTE, and what to do next if you are worried.

What CTE is, in one paragraph

Chronic Traumatic Encephalopathy is a neurodegenerative brain disease linked to repeated head impacts. It is defined by a specific pattern of abnormal tau protein that accumulates around small blood vessels at the depths of the brain's cortical folds. That pattern is what pathologists look for at autopsy. It is not the same as the changes seen in Alzheimer's disease, and it is not the same as ordinary aging. CTE has been documented in former contact-sport athletes, military veterans with blast exposure, victims of physical abuse, and others with histories of repetitive head trauma.

For a shorter overview of what doctors can and cannot confirm today, see our reference page: Can CTE Be Diagnosed?.

Why CTE cannot be diagnosed in a living person

The tau protein pattern that defines CTE can only be seen by examining brain tissue under a microscope. Current MRI and CT scans cannot reliably detect it. Experimental PET imaging is being studied, but no in-vivo biomarker has been validated for clinical diagnosis. Researchers are working on this, and the field will change in the coming years, but as of today CTE remains a postmortem diagnosis.

This is why the medical community developed a separate term for what can be evaluated during life: Traumatic Encephalopathy Syndrome.

What Traumatic Encephalopathy Syndrome (TES) is

TES is the clinical condition believed to correspond to CTE pathology. The 2021 NINDS consensus criteria define four requirements for a TES diagnosis. All four must be present.

1. Substantial exposure to repetitive head impacts. This means significant exposure from contact sports, military service (including blast exposure), domestic violence, or other causes. For organized American football as an example, the criteria reference a minimum of five years of play, with at least two of those years at the high school level or beyond.
2. Core clinical features. The person must show cognitive impairment in episodic memory (short-term memory) and/or executive functioning (planning, organization, judgment, multi-tasking), or neurobehavioral dysregulation (explosiveness, impulsivity, rage, emotional lability), or both.
3. A progressive course. The symptoms must worsen over time. A single episode of post-concussive symptoms that resolves is not TES.
4. Not better explained by something else. The clinical picture cannot be fully accounted for by another neurologic, psychiatric, or medical condition. Other conditions may exist alongside TES, but they must not fully explain what is happening.

TES: The Living Face of CTE

The criteria also assign a level of functional dependence (ranging from independent to severe dementia) and a provisional level of certainty that the underlying pathology is CTE, based on factors like duration of exposure, delayed symptom onset, and supportive features such as motor signs.

Why this matters for families

TES criteria are designed for research. They are not a checklist a family member should use to self-diagnose a loved one. But understanding the criteria does three useful things:

• It clarifies that exposure history matters. Without significant repetitive head impact exposure, CTE is not the most likely explanation, no matter how concerning the symptoms.
• It clarifies that progression matters. A bad week, a single episode, or symptoms that improve with treatment do not meet criteria.
• It clarifies that other conditions must be ruled out first. Depression, PTSD, sleep disorders, thyroid problems, medication side effects, and substance use can all produce overlapping symptoms.

What families often notice first

In documented CTE case series, the symptoms families report noticing earliest tend to fall into two broad categories.

Mood and behavior changes. Shorter fuse than usual, sudden emotional outbursts, increased impulsivity, depression that feels different from prior depression, withdrawal from people they used to enjoy, sleep changes, and apathy. Partners often describe these as "personality changes" before they describe memory problems.

Cognitive changes. Trouble holding onto recent information, repeating questions, getting lost in familiar places, difficulty managing tasks that used to be automatic (paying bills, following a recipe, organizing a day), and slower processing in conversation.

Motor symptoms (tremor, balance problems, slowed movement) tend to appear later if they appear at all. Headache patterns may also change.

None of these symptoms on their own confirms anything. All of them have other possible causes. But a pattern of progressive change in someone with significant head impact exposure is what brings families to a neurologist.

What CTE looks like is not always what CTE feels like

One of the hardest parts of suspected CTE is that the person living with it often does not perceive the changes the way the family does. Insight (the awareness of one's own cognitive or behavioral changes) is frequently affected in frontal-lobe conditions. A person can be genuinely unaware that they repeated the same story three times in an afternoon, or that their reaction to a small frustration was disproportionate. This is not denial. It is part of the neurology.

For caregivers, this is one of the most painful realities. We have a separate caregiver-focused article on this dynamic if you want to read more.

If you are worried, what to do next

1. Document what you are seeing. Write down specific examples with dates. "He forgot our anniversary" is harder to evaluate than "On March 14 he did not recognize that it was our anniversary, then on March 21 he could not remember the conversation we had that morning about it." A behavior log is one of the most useful things a family can bring to a neurology appointment.
2. Document exposure history. Years and level of contact sport participation, military service with blast or breaching exposure, any documented concussions or loss-of-consciousness events, and any history of physical assault or domestic violence.
3. Request a referral to a behavioral neurologist or neuropsychologist. Primary care can start the process. A neuropsychological evaluation establishes a baseline that any future evaluations can be compared against.
4. Ask for a workup that rules out treatable causes. Thyroid panel, B12, sleep evaluation, medication review, mood assessment. Many things that look like dementia or CTE are actually treatable.
5. Connect with a research-affiliated center if exposure history fits. The Boston University CTE Center, the Concussion Legacy Foundation, and the VA's Translational Research Center for TBI and Stress Disorders all maintain research programs that evaluate living individuals at risk.

A note on fear, and on hope

If you or someone you love has a significant head impact history and is now experiencing the kinds of changes described above, the fear of CTE is rational. It is also not the only possible explanation, and in many cases it is not the most likely one. Treatable conditions are common. So is post-traumatic stress disorder, which can look strikingly similar in veterans. So is depression. So are sleep disorders. So are medication interactions.

What you do next is the same regardless of the eventual diagnosis: get a thorough evaluation, document the changes, and connect with people who understand brain injury. Robbins Nest Alliance exists to help families do exactly that.

Continue learning

• Understanding CTE: the full hub
• CTE Symptoms and Warning Signs
• Early Warning Signs Families Often Notice First
• CTE vs PTSD and Depression: Why They Overlap
• CTE in Veterans
• CTE Caregiver Support

Free resource for caregivers

If you are caring for someone with suspected CTE, our free CTE Caregiver Guide walks you through what to track, what to bring to appointments, and how to navigate the diagnostic process. No cost. No sign-up wall. Just the information families need.

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Sources and further reading

1. Katz DI, Bernick C, Dodick DW, et al. National Institute of Neurological Disorders and Stroke Consensus Diagnostic Criteria for Traumatic Encephalopathy Syndrome. Neurology. 2021;96(18):848-863. doi:10.1212/WNL.0000000000011850
2. McKee AC, Cairns NJ, Dickson DW, et al. The first NINDS/NIBIB consensus meeting to define neuropathological criteria for the diagnosis of chronic traumatic encephalopathy. Acta Neuropathologica. 2016;131(1):75-86. doi:10.1007/s00401-015-1515-z
3. McKee AC, Stern RA, Nowinski CJ, et al. The spectrum of disease in chronic traumatic encephalopathy. Brain. 2013;136(1):43-64. doi:10.1093/brain/aws307
4. Mez J, Daneshvar DH, Abdolmohammadi B, et al. Duration of American football play and chronic traumatic encephalopathy. Annals of Neurology. 2020;87(1):116-131.
5. Stern RA, Daneshvar DH, Baugh CM, et al. Clinical presentation of chronic traumatic encephalopathy. Neurology. 2013;81(13):1122-1129.

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Medical disclaimer: This page is educational and is not a substitute for professional medical evaluation. If you are concerned about cognitive or behavioral changes in yourself or a loved one, please consult a qualified healthcare provider.

Robbins Nest Alliance is a 501(c)(3) educational nonprofit. EIN: 39-2763662. We publish free, medically-cited brain injury education for caregivers and families.