Bruce Willis may not be aware that he has dementia, his wife says

Bruce Willis was diagnosed in February with frontotemporal dementia, a brain disorder that causes impaired communication and sometimes dramatic behavioral changes as it progresses.

The actor's wife, Emma Hemming Willis, spoke candidly about her family's struggles Monday in an interview on NBC's "Today." She said Willis, 68, may not be aware that he's suffering from dementia.

Frontotemporal dementia causes the brain's frontal and temporal lobes to shrink due to loss of nerve cells. The disease can have noticeable effects on personality, language and movement that family members often perceive to be unexplained.

Last year, Willis retired from acting after he was diagnosed with aphasia, a neurological condition that inhibits speech, writing and interoperation of language. The condition affects more than 2 million people in the U.S., often developing after strokes or injuries. It also can be part of a degenerative process called primary progressive aphasia, a type of FTD that gradually depletes communication skills. Sometime people who have aphasia are unable to realize that those around them can't make sense of the things they're saying.

Hemming Willis was joined on "Today" by Susan Dickinson, who leads the Association for Frontotemporal Degeneration. She explained that it's often difficult to assess how much awareness people have of the disease as they progress beyond a diagnosis.

"One of the things that the frontal lobe controls is self-insight, so we really don't know," Dickinson said. "Some people, the first thing they lose is any understanding that they themselves have changed. And other people retain that for a very long time."

Alzheimer's disease is the most common and widely known form of dementia, accounting for 60% to 80% of cases. FTD is sometimes mistaken for Alzheimer's, but it usually develops earlier in life, between ages 40 to 65, and is not associated with memory loss until its advanced stages. 

People who develop FTD symptoms, like language problems and personality changes, may be less likely to recognize they have a medical condition because they are often relatively young. Another common form of FTD is behavior variant, or bvFTD, which affects behavior and personality in ways that seem out of character. An estimated 50,000 to 60,000 people in the U.S. are believed to have some form of FTD. 

Since awareness of FTD is more limited in the medical community than other types of dementia, it's often a challenge for people to get answers about what's happening to them or their loved ones.

"Most doctors aren't familiar with it, so it can take almost four years to get diagnosed, on average," Dickinson said. "And (patients) accrue many misdiagnoses along the way — often depression, bipolar (disorder), Alzheimer's or even with some of the movement symptoms ... Parkinson's (disease) or ALS."

The National Institute of Aging notes that many loved ones of people with FTD are confused by their erratic behavior, which can lead to conflict and anger. These symptoms cannot be controlled by someone with FTD. Those who have not yet been diagnosed often have no way to explain the changes they are showing and may not be able to realize that they're changes at all.

"What I'm learning is that dementia is hard," Heming Willis said. "It's hard on the person diagnosed. It's also hard on the family. And that is no different for Bruce, or myself, or our girls. When they say that this is a family disease, it really is."

Willis, a New Jersey native, has two young daughters with Hemming Willis and three adult daughters from his prior marriage to actress Demi Moore. Hemming Willis said she has been up front with her daughters about what's happening to their dad.

"It was important that we let them know what it is because I don't want there to be any stigma or shame attached to their dad's diagnosis or for any form of dementia," Hemming Willis said.

There are no known causes for FTD, but Dickinson said about 20% to 25% of cases can be linked to genetic mutations that predispose people to it.

"In the majority of people, it's what we call sporadic," Dickinson said.

There are no cures or medications to halt the progression of FTD, although some medications can be used to manage symptoms. Some people can live with FTD for as long as 10 years after diagnosis. Others die within a few years. The progression of symptoms often requires constant care for people with FTD.

Hemming Willis said that she and her family work hard to be present and enjoy their time with Bruce as much as they can.

"There are so many beautiful things happening in our lives," she said. "It's just really important for me to look up from the grief and the sadness so that I can see what is happening around us. Bruce would really want us to be in the joy of what is."