What is frontotemporal dementia and is there a cure for Bruce Willis's condition?

The Hollywood star's family has revealed his latest diagnosis in a heartfelt letter

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  US actor Bruce Willis at the European premiere of 'Glass' in central London. AFP

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  Bruce Willis in a scene from the movie 'Glass'. Photo: Universal Pictures

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  Bruce Willis in a scene from the 'Sixth Sense'. Photo: Spyglass Entertainment

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  Bruce Willis in 'Pulp Fiction'. Photo: Miramax

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  Bruce Willis in 'Breakfast of Champions'. Photo: Warner Bros

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  Bruce Willis in a scene from 'Motherless Brooklyn'. Photo: Warner Bros

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  Bruce Willis stars as Captain Sharp in Wes Anderson's 'Moonrise Kingdom'.

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  Bruce Willis in 'Die Hard' (1988). Photo: IMDb

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  Bruce Willis stars as the original GI Joe in this sequel. Photo: Paramount Pictures

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  From left, Steve Buscemi, Will Patton, Bruce Willis, Michael Clarke Duncan, Ben Affleck and Owen Wilson in 'Armageddon'. Photo: Touchstone Pictures

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  Bruce Willis attends the premiere of 'Motherless Brooklyn' during the 57th New York Film Festival. Invision / AP, File

Nearly a year after Bruce Willis’s family announced that he would step away from acting after being diagnosed with aphasia, they have posted an update to say the actor's “condition has progressed".

"We now have a more specific diagnosis: frontotemporal dementia, known as FTD. While this is painful, it is a relief to finally have a clear diagnosis," the family said on Thursday.

In a letter posted on the website for The Association for Frontotemporal Dementia, they thanked fans for "the outpouring of love and compassion for Bruce over the past 10 months".

"Your generosity of spirit has been overwhelming, and we are tremendously grateful for it," reads the letter, which has been signed by Willis's ex-wife Demi Moore, their children Tallulah, Scout and Rumer, as well as his current wife Emma Heming and her two children, Evelyn and Mabel.

Last March, the actor's family said his aphasia had affected his cognitive abilities. The condition causes loss of the ability to understand or express speech.

On Thursday, his family said communication challenges were only one symptom of frontotemporal dementia.

"FTD is a cruel disease that many of us have never heard of and can strike anyone. For people under 60, FTD is the most common form of dementia, and because getting the diagnosis can take years, FTD is likely much more prevalent than we know," the family said.

"Today there are no treatments for the disease, a reality that we hope can change in the years ahead. As Bruce’s condition advances, we hope that any media attention can be focused on shining a light on this disease that needs far more awareness and research."

What is frontotemporal dementia?

FTD or Pick's disease represents a group of brain disorders caused by degeneration of the frontal and/or temporal lobes of the brain, according to The Association for Frontotemporal Dementia. Subtypes of the disorder includes Behavioral Variant FTD and Primary Progressive Aphasia, a type of neurological syndrome in which language capabilities slowly and progressively become impaired.

How does FTD differ from Alzheimer's disease?

According to TAFD, the symptoms of FTD differ from those of Alzheimer's in that the former results in uncharacteristic personality changes, including unexplained struggles with decision-making, speaking or language comprehension.

FTD typically strikes younger people, with most cases occurring between ages 45 and 64. Symptoms of Alzheimer's typically appear in those aged 60 and above.

FTD is also lesser known, with TAFD estimating there are about 60,000 cases in the US. But that is also because many in the medical community remain unfamiliar with it. FTD is frequently misdiagnosed as Alzheimer's, depression, Parkinson's disease or a psychiatric condition, TAFD says. On average, it currently takes 3.6 years to get an accurate diagnosis.

How does FTD progress and what is the life expectancy?

The progression of symptoms varies by individual and the length of the disease's progress can range from two to more than 20 years, TAFD says.

As the disease progresses, the person affected may experience increased difficulty in planning or organising. They may also behave inappropriately in social settings and have trouble communicating.

Average life expectancy is 7 to 13 years after the start of symptoms, with the most common cause of death being pneumonia, as those with the disease are predisposed to infection and injury.

Can FTD be cured?

There is no cure for FTD, no treatments to slow or stop the progression of the disease. But TAFD says there are certain steps and treatments available to manage the symptoms.

In their letter, Willis's family appealed to fans to help raise awareness about FTD, saying it's what the Hollywood star would want.

"Bruce always believed in using his voice in the world to help others," they said. "We know in our hearts that — if he could today — he would want to respond by bringing global attention and a connectedness with those who are also dealing with this debilitating disease and how it impacts so many individuals and their families."

An extensive resource of tools are listed on TAFD's website www.theaftd.org

The ongoing appeal of Bruce Willis, archetypal action hero — in pictures

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  Bruce Willis in Detective Knight: Independence. Photo: Lionsgate

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  Willis in a scene from The Sixth Sense. Photo: Spyglass Entertainment

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  Willis in Pulp Fiction. Photo: Miramax

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  Brad Pitt, left, and Willis in 12 Monkeys. Photo: Universal Pictures

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  Jessica Alba as Nancy Callahan and Willis as John Hartigan in a scene from Sin City. Photo: Miramax Films

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  Bruce Willis in Die Hard with a Vengeance

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  Bruce Willis in Die Hard, 1988. Photo: Imdb

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  Willis as Detective John McClane fights off cyber-terrorists in Die Hard 4.0. AP Photo / Fox