Bruce Willis was diagnosed frontotemporal dementia. What is it ...

Bruce Willis' family gave an update on the actor's health Thursday, announcing his condition has progressed and has been diagnosed as frontotemporal dementia. 

"Since we announced Bruce’s diagnosis of aphasia in spring 2022, Bruce’s condition has progressed and we now have a more specific diagnosis: frontotemporal dementia," his family said in a statement. 

"Unfortunately, challenges with communication are just one symptom of the disease Bruce faces. While this is painful, it is a relief to finally have a clear diagnosis.  

The news comes after his family said in March 2022 Willis would be stepping away from acting due to health issues.

Frontotemporal dementia is a brain disorder, but it differs from Alzheimer's disease. It is less common and known, according to the Association for Frontotemporal Degeneration. Here's what to know about frontotemporal dementia:

A 'cruel disease': Bruce Willis diagnosed with frontotemporal dementia, family announces

What is frontotemporal dementia?

Frontotemporal dementia, or FTD, represents a group of brain disorders cause by the degeneration of the frontal and/or temporal lobes of the brain, the AFTD says. Those parts of the brain are generally associated with personality, behavior and language, the Mayo Clinic says.

The disorder has various subtypes and differs from Alzheimer's, as people diagnosed with frontotemporal dementia are typically younger. Most people with frontotemporal dementia are diagnosed in their early 40s through early 60s, according to the Alzheimer's Association. Willis is 67.

"FTD has a substantially greater impact on work, family, and finances than Alzheimer's," the AFTD says, as the age of onset ranges younger.

How common is frontotemporal dementia?

The AFTD estimates there are around 50,000 to 60,000 people diagnosed with frontotemporal dementia in the U.S. The organization adds it is frequently misdiagnosed as Alzheimer's, depression, Parkinson's or a psychiatric condition, and it typically takes over three years to get accurately diagnosed.

Willis' family said the actor was initially diagnosed with aphasia, a different type of brain disorder. 

What causes frontotemporal dementia?

The exact cause of frontotemporal dementia is currently unknown, but several medical organizations say there are genetic mutations that are linked to the disorder. 

"Some people with FTD have tiny structures, called Pick bodies, in their brain cells. Pick bodies contain an abnormal amount or type of protein," Johns Hopkins Medicine says. 

There is no known risk factor of developing the disorder, but the Mayo Clinic says your risk of developing frontotemporal dementia could be higher with a family history of dementia, but the AFTD disease is "sporadic." 

What are symptoms of frontotemporal dementia?

Frontotemporal dementia affects a person's behavior and personality, can cause speech problems and, in rare cases, can cause motor related problems. Common symptoms include, but not limited to, are:

• Increasingly inappropriate social behavior that can be impulsive or repetitive 
• Repetitive compulsive behavior, such as tapping, clapping or smacking lips
• Loss of empathy and other interpersonal skills, such as having sensitivity to another's feelings
• Frequent mood changes
• Lack of judgment and apathy
• Changes in eating habits, usually overeating, developing a preference for sweets and carbohydrates, or eating inedible objects
• Distractibility 
• Difficulty in using and understanding written and spoken language, such as having trouble finding the right word to use in speech or naming objects
• No longer knowing word meanings
• Making mistakes in sentence construction

The Mayo Clinic says symptoms typically get progressively worse over time. The length of progression varies from 2 to over 20 years, the AFTD says.

Can you recover from frontotemporal dementia?

There is no cure from frontotemporal dementia, as the AFTD says there are no treatments that can slow or stop the progression of it. Patients are often prescribed medication to treat symptoms.

The AFTD adds frontotemporal dementia can lead to life-threatening issues like pneumonia, infection or injuries from fall. Pneumonia is the most common cause of death in people with frontotemporal dementia.

The average life expectancy from the start of symptoms is 7 to 13 years. 

Follow Jordan Mendoza on Twitter: @jordan_mendoza5.