Bruce Willis has lost his “joie de vivre” and some “language skills” since being diagnosed with frontotemporal dementia, according to “Moonlighting” creator Glenn Gordon Caron.

Willis’ family shared in February that the “Die Hard” star has been diagnosed with the degenerative condition that can have similar signs to Alzheimer’s, including memory loss and communication challenges.

Caron, who worked with Willis on the Emmy-nominated ABC detective series in the late 1980s, gave an update about the actor’s condition to The New York Post on Tuesday.

In the interview, Caron said that he tries to visit the “Looper” actor once a month at his home and he has “tried very hard to stay in his life.”

Bruce Willis’ illness

“My sense is the first one to three minutes he knows who I am,” Caron said. “He’s not totally verbal; he used to be a voracious reader — he didn’t want anyone to know that — and he’s not reading now. All those language skills are no longer available to him, and yet he’s still Bruce.”

“When you’re with him you know that he’s Bruce and you’re grateful that he’s there, but the joie de vivre is gone,” he added. “If you’ve ever spent time with Bruce Willis, there is no one who had any more joie de vivre than he.”

Caron said that Willis “just adored waking up every morning and trying to live life to its fullest,” but now he lives as though “seeing life through a screen door.”

The 68-year-old actor is being cared for by his wife Emma Heming Willis, to whom he’s been married since 2009. The 45-year-old model, with whom Willis shares two daughters, has been documenting some of her experience caring for her husband amid his condition on social media.

Last month, Heming Willis appeared on “Today” to speak about her husband’s condition and said that it’s “hard to know” if Willis is aware of his dementia.

FTD is the most common type of dementia in people under 60

Frontotemporal dementia, also known as FTD, is a degenerative condition that is the most common form of dementia in people under 60, and often begins between the ages of 40 and 65, according to the Mayo Clinic.

FTD occurs when nerve cell damage begins to affect areas of the brain behind the forehead (the frontal lobe) and behind the ears (the temporal lobes). These are the parts of the brain that control language, behavior, and personality.

What causes the damage is unknown, but there is often a genetic link, with around one in eight people who develop FTD having relatives also affected by the condition, according to the UK’s National Health Service.

Symptoms vary depending on which areas are affected and worsen over time. These can include dramatic personality changes, socially inappropriate behavior, a lack of emotion and empathy, changes in eating habits and trying to eat inedible objects, and speech and language problems, according to the Mayo Clinic.

In a statement posted on The Association for Frontotemporal Degeneration’s website, Willis’ family wrote that it can be hard to get a diagnosis, so FTD is likely more common than we know.

There are currently no current treatments for the disease, according to The Association for Frontotemporal Degeneration.

However, in June 2023, Willis’ family said they “will never lose hope” that scientists will discover a cure for dementia.