A little-known type of dementia leaves patients like Bruce Willis unrecognizable to their loved ones. These are the signs you have the gene… and why scientists believe one family holds the key to eradicating the disease

Before his diagnosis of frontotemporal dementia (FTD) in 2023, Bruce Willis had started to stutter again – a speech disorder he had overcome in childhood. His wife, Emma Heming Willis, told journalist Katie Couric they had dismissed those early symptoms, never thinking they could be a sign of the devastating brain disorder.

Other signs were equally difficult to pin down. His daughter Tallulah noticed his ‘vague unresponsiveness’ – something she blamed on ‘Hollywood hearing loss,’ adding that they assumed Die Hard had ‘messed with dad’s ears.’

As his cognitive abilities deteriorated, Demi Moore, the actor’s ex-wife who has remained close to him despite their divorce in 2000, described how hard it was to ‘see somebody who was so vibrant and strong and so directed, shift into these other parts of themself.’ 

Now, more than four years on from that diagnosis, Willis lives in a specialist care facility and earlier this month, to mark World FTD Awareness Week, Heming Willis paid tribute to her husband, describing him as a ‘legend’ and saying the family was living in a ‘constant state of grief.’

While FTD is extremely rare – it is estimated to affect around 50,000 people in the US – one family in Pennsylvania may hold the key to a cure. After decades of blind alleys, scientists believe the genetic mutation that has struck down multiple members of the same family might lead to a breakthrough in the prevention and treatment of all dementia – including the scourge of Alzheimer’s disease.

In the 1970s, in a small town in the foothills of the American Rust Belt, there lived a family with nine children.

The father, Ollie, was a successful civil engineer, and the mother, Jean, was a homemaker, filled with optimism and energy, reading, gardening and playing bridge.

Jean shopped for all the food on a strict budget, making all the calculations and lists in her head, and cooked everything for the family. She made her own donuts and pizza from scratch, and served up enchiladas when they were still considered an exotic foreign dish.

The older children remember their mother so differently from the woman she became. It was only in hindsight that they all saw what was happening – how Jean withdrew, fading into the background of her children’s lives like she was just part of the furniture.

All the things that made Jean so effervescent in those early years fell away. She played solitaire and watched television – Jeopardy, Wheel of Fortune, The Price is Right. A wife and mother not following through on even routine tasks like paying the bills or doing her hair or shopping for clothes was a woman who had given up on herself.

Her husband found her contemptible, and the children, more often than not, wrote her off in frustration. They were largely silent as she stopped dressing up each day, quit the hair salon, and even spoke less.

Where Jean used to be known as a library mom, now she’d be seen outside the local liquor store.

‘Our community was pretty small,’ an old family friend said. ‘She would be there even before it was open. It was something that would be whispered about.’

When Jean died of breast cancer at the age of 60, the children arrived at a shared understanding of the tragedy. They told themselves their mother had never really taken good care of herself – that she could have lived longer if she hadn’t smoked, or ever bothered to see a doctor.

None of them could fathom what it was about her that seemed so disconnected from the people she loved. And even then, there was no consensus on the reason – depression, alcohol, the demands of running such a large household.

It never occurred to any of them that Jean had early onset dementia.

Dementia may be the thing we all fear even if, technically, it is not one single thing at all.

Our ability to study the brain at the molecular and genetic level has allowed us to identify and differentiate countless new dementias. Some, like Alzheimer’s disease, are all too common, while others are rare.

All nine of Jean’s children, when they were born, inherited a 50 percent chance of carrying the genetic variety of frontotemporal dementia, or FTD – the condition geneticists have verified that she, too, suffered from in the years before cancer took her life.

Unlike more common brain disorders like Alzheimer’s, FTD emerges in the prime of one’s adult life – ages 45 to 55 – and relentlessly attacks the part of the brain responsible for planning, organizing, expressing language, understanding social cues and exercising judgment.

While most people associate dementia with memory loss and a decline in cognition, FTD seems to strike at the heart of human identity. There is something almost existential or metaphysical about what happened to Jean – and, now, at least five of her grown children – as if someone or something hit the reset button on their entire personality.

FTD is confoundedly rare; perhaps a few hundred thousand people have it worldwide, though that estimate is complicated by how difficult it is to diagnose. The Hollywood star Bruce Willis has it, though it is not clear if his condition is inherited or sporadic.

What happens with FTD is so unlike what’s commonly thought of as dementia that it’s quite often mistaken for something else, like depression or schizophrenia. Jean’s family, their surname is withheld for privacy, went unnoticed and then misdiagnosed for so long that their torturous history of missed connections doubles as the story of science’s struggle to understand the nuances of dementia.

The paradox of rare dementias is that, despite seeming so unusual, taken together they might amount to more than 40 percent of all dementias. Researchers believe the epidemics of addiction and homelessness may be intertwined with undiagnosed dementia.

The challenge for researchers and others desperate for new treatments is to convince doctors and families to be on the lookout for dementia as a possible explanation for strange new behavior. In too many cases, the culprit isn’t severe mental illness or menopause or a mild case of depression. It’s dementia.

Christy was the next to change. She was the second oldest of Jean’s children and one of the family’s superstars. She was a married mother of two and a high-powered pharmaceutical company marketing executive, traveling the world and living in a wealthy New York suburb.

Then one day, in her mid-thirties, she left her job. No one could tell if she was laid off or fired.

Christy announced she was going to stay home now. But her husband Don had noticed peculiarities – a certain thoughtlessness about the kids. They drifted apart and divorced. And Christy seemed more withdrawn, less interested in her children or anyone or anything except what was on TV.

At the time, everyone was willing to consider that Christy was in some sort of funk, but not that she was in serious trouble. It was hard for anyone in the family to imagine her as anything other than capable. Better, perhaps, to think that she would steer herself out of the skid and get back on the road before long.

After a few months, Don couldn’t help but notice an escalation. Once, he and his brother came by and saw garbage all over the floor. As they went through and tossed stuff away, Christy largely ignored them both, staring at the TV.

Soon after, she was hospitalized and misdiagnosed with depression and then schizophrenia. But even on medication, Christy still seemed checked out, removed emotionally.

Her brothers and sisters were baffled. It was as if someone had taken away the savvy, self-possessed older sister they once adored and replaced her with a person they didn’t recognize, someone almost impossible to talk with.

Though the idea shook them, they couldn’t help but think of their mother.

It would take several years for doctors to finally diagnose Christy with FTD. By then another sister, Mary, had fallen prey to the same symptoms – and again, they were misdiagnosed at first.

Mary’s husband, Fred, had been at his wit’s end. Mary had never really bonded with their two-year-old son. She didn’t work. She never showered. She slept in until 11am every day. The old Mary was disappearing, with nothing to replace her.

Fred divorced Mary and fought for full custody of their son. When Mary’s family argued that she had FTD, Fred dismissed the claim as a courtroom ploy. It took Mary’s family to secure visitation rights for Mary. But even she never believed she had FTD.

The refusal to believe these behavioral symptoms were dementia is so commonplace that even more scientifically minded members of this family had a hard time accepting what was happening.

Another sister, Peggy, would not acknowledge her changes. Neither would a brother, Dutch, and another sister, Jenny.

By then, it became impossible for anyone in the family to decide which would be worse – having the illness, or being the only one in her family without it, watching the others vanish.

If there is a sliver of hope that families like Jean’s can hang on to, it is this: The genetic clarity of their condition.

We’re at the dawn of the genetic-editing revolution, when researchers are promising to be able to snip out offending mutations and wipe out genetic diseases forever. If scientists can slash a path through the bureaucratic and financial hurdles of drug development and find a gene therapy for FTD, the family might be saved.

Even more tantalizing is that their particular genetic mutation also plays a part in many other types of dementia, including Alzheimer’s. Many researchers believe that a solution to their disease could offer a playbook, or the beginnings of an answer key, for others.

So we can add this to the mix of things this family finds themselves ruminating over late at night: The possibility that, as monstrous as their dementia is, it may provide a back door for researchers to treat the 55 million people who suffer from Alzheimer’s around the world.

Robert Kolker is an award-winning journalist and the author of The Vanishing Family: Love, Fate, and the Quest to End Dementia, recently published by Quercus.