Actor Bruce Willis’ diagnosis of frontotemporal dementia has brought renewed attention to the disease, whose symptoms include changes in behavior, language and communication.

Willis’ family, including ex-wife Demi Moore, said in a statement on Thursday that his aphasia diagnosis, which the family announced in March, had progressed to frontotemporal dementia. Willis is 67.

Frontotemporal dementia, or FTD, refers to a collection of disorders that primarily affect the frontal and temporal lobes of the brain. The diseases that fall under this umbrella are neurodegenerative, meaning they get worse over time.

Generally, there are two subdiagnoses, according to Dr. Paul Barton Rosenberg, a professor of psychiatry and behavioral sciences at the John Hopkins School of Medicine.

“One is a behavioral variant, where people can have a change in their personality and lose their inhibitions and social graces,” Rosenberg said. “Another is primary progressive aphasia, where people have trouble finding words or expressing themselves.”

In their Thursday statement, the Willis family said that “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 family wrote in its Instagram post, which was signed by the “Ladies of Willis/Moore” family.

Symptoms and causes of frontotemporal dementia

Frontotemporal dementia results from a buildup of proteins in the brain, which can damage and shrink the frontal and temporal lobes.

Because these areas of the brain are associated with personality, behavior and language, the symptoms of a particular case of FTD vary depending on which area is most affected, according to Dr. Gregg Day, a neurologist at the Mayo Clinic’s campus in Florida.

“Difficulty with language and understanding, as well as misinterpreting instructions could be symptoms of FTD,” Day said. “But when the proteins build up in parts of the brain that govern social cognition, unusual behavior, such as acting out, disrespecting loved ones, losing empathy, motivation and understanding can all be symptoms as well.”

Abnormal motor functions, such as problems with balance, vision or moving one side of the body, can also be symptoms.

Overall, many symptoms of FTD can be hard to recognize in patients, and the behavioral ones in particular can be difficult to separate from psychiatric diseases, Day said.

“It makes sense why the Willis family, who has been open about Bruce’s condition, is just learning more specific info about the aphasia months later themselves,” he said.

Who is most likely to get FTD?

This type of dementia tends to present in younger people, specifically those in their 40s, 50s and 60s, the two experts said.

“This disease is seen a little earlier in life, which can make it harder because it’s an age where people have a lot of demands and responsibilities,” Day said. “They might have full-time jobs, partners, be caring for young kids. And when it affects language for someone who relies on it to make a living, it’ll make an impact.”

FTD is relatively rare,”with an estimated lifetime risk of 1 in 742,” according to a 2019 study. The Mayo Clinic estimates that FTD is the cause of “approximately 10% to 20% of dementia cases,” making it rarer than Alzheimer’s.

Little is known about the causes or risk factors associated with FTD.

“The reality is, we don’t have a full grasp of what causes FTD,” Day said. “Causes can generally be genetic, but then we have exposures, things that happen to us, or habits we have.”

Rosenberg said it can sometimes seem to “strike out of the blue.”

Are there cures or treatments?

There are no medications that can stop or slow the progression of FTD. Instead, treatments focus on helping people manage the symptoms, Rosenberg said.

“The main treatment for aphasia is speech therapy, which can be helpful,” he said.

It also helps to keep a patient stimulated, Day said.

“For families, interacting with the loved one, engaging them in activities and keeping them stimulated is the best they can do for them,” he said.

In general, the risk of FTD is lower among people who stay physically active, keep their brains regularly engaged and stimulated and maintain healthy blood pressure and cholesterol levels, Day said.

He added that although research about frontotemporal dementia is ongoing, much more needs to be done to better understand the disease and to raise public awareness. In that sense, he said, the Willis family’s announcement is helpful.

“The family has used this opportunity to do something caring, compassionate and altruistic in spreading news about the disease,” Day said. “It’s a disease not a lot of people have ever heard of, and maybe this can now help others get diagnosed sooner.”