What to know about frontotemporal degeneration after NASCAR Hall of Famer Darrell Waltrip's diagnosis

NASCAR Hall of Famer Darrell Waltrip's family revealed over the weekend he has been diagnosed with frontotemporal degeneration (FTD) complicated by possible chronic traumatic encephalopathy (CTE).

In a statement, Waltrip's family said the possible CTE may be related to injuries sustained during his racing career. They said his symptoms are currently minor, but that he will step further away from public life as the disease progresses.

It remains unclear what symptoms Waltrip may have at this time.

ABC News has reached out to NASCAR for comment but has not yet heard back. 

Here's what to know about FTD and CTE, including how it's diagnosed and what treatments are available.

What is frontotemporal degeneration?

FTD refers to a group of progressive neurological disorders caused by damage to nerve cells, primarily in the frontal and temporal lobes of the brain which play an important role in behavior, personality, decision-making, language and emotions, according to the NIH.

Unlike Alzheimer's disease, which commonly begins with memory problems, FTD may initially cause changes in behavior or language while leaving short-term memory unaffected early in the disease.

The most common subtype of FTD is the behavioral variant, which presents as changes in behavior and personality, troubles in problem solving or lack of control in emotions, according to the Association for Frontotemporal Degeneration.

Other subtypes can include problems speaking or understanding language, or movement difficulties due to disorders such as but not limited to ALS.

FTD is a common cause of early-onset dementia, with around 60% of patients under the age of 65. There are between 30,000 and 60,000 estimated cases in the U.S., though it is challenging for patients to receive a formal diagnosis.

How is it diagnosed?

The diagnosis of FTD is made by a physician through gathering a history, looking for symptoms in keeping with the disease impacting day-to-day activities, according to the DSM5.

Physical exam, brain imaging, cognitive testing and other blood tests may support the diagnosis. FTD occurs without a family history in over 60% of people diagnosed.

The cause for most cases of FTD is unknown, though some risk factors such as prior brain trauma or rare genetic causes may be linked.

What treatments are available?

FTD is progressive, meaning symptoms worsen over time. Patients typically live six to eight years, according to the NIH, but doctors say prognosis and life expectancy can vary based on an individual’s disease and circumstances.

There is currently no treatment proven to cure or slow the disease, although medications may help troublesome behaviors, speech therapy may help language difficulties and physical therapy may help any mobility changes.

Doctors may also offer other treatment options to help manage individual symptoms.

What does "possible CTE" mean?

CTE is a progressive brain disease associated with a history of repetitive head impacts, according to the Centers for Disease Control and Prevention.

It is caused by the buildup of abnormal proteins in the brain, causing brain cells to die.

Symptoms can include problems with thinking, changes in mood or behavior, and difficulties with movement, all of which may affect daily activities.

In a recent study in the journal Alzheimer's & Dementia, CTE has been independently linked to a 4.5-times higher risk of developing dementia.

Currently, CTE cannot be diagnosed in a living person. Diagnosis requires examination of brain tissue after death, which is why Waltrip's family described CTE as "possible," rather than a confirmed diagnosis.

FTD and CTE can both affect thinking and behavior, but they are distinct neurodegenerative conditions with different underlying disease processes.

Doctors may use a patient's symptoms, medical history, neurological testing and brain imaging to evaluate the possible causes of progressive cognitive or behavioral changes.

Dr. Allen Chang is a Geriatric Medicine subspecialist at Dalhousie University and a member of the ABC News Medical Unit.