Bruce Willis' family have announced his retirement from acting after being diagnosed with aphasia, a disease that has affected his "cognitive abilities".

Described by Johns Hopkins Medicine as "a language disorder caused by damage in a specific area of the brain that controls language expression and comprehension"; those afflicted have challenges effectively communicating with others.

“This is a really challenging time for our family and we are so appreciative of your continued love, compassion and support,” daughter Rumer Willis said in a statement. "We are moving through this as a strong family unit, and wanted to bring his fans in because we know how much he means to you, as you do to him."

According to those who have worked with Willis on his recent films, the actor has been exhibiting signs of decline in recent years. In interviews with The LA Times this month, nearly two dozen people who were on set with the actor expressed concern about Willis’ well-being. In 22 films made over the past four years, multiple crew members and actors allegedly witnessed his struggle to recall his lines.

The LA Times writes that this eventually led to an earpiece offered to the actor which fed the words to him, dubbed an "earwig". His earpiece actor, Adam Huel Potter, was allegedly paid $4,150 per week and got on-screen roles in each of the star's films. Willis’ longtime management team — including a powerhouse group of agents at the Creative Artists Agency — made sure that his film shoots were limited to two days. His handler, Stephen J. Eads, reportedly got a producing credit and $200,000 per film.

At 67 years-old, Willis has appeared in nearly 100 films across his 40 year career. Gaining popular acclaim for roles in Pulp Fiction and Sixth Sense, the actor has woven himself into popular culture — his name becoming virtually synonymous with the action movie scene.

His most notable role was in Die Hard, as the 'Yippie Ki Yay' yelling cop John McClane, who appeared in the five movies from 1988 to 2013.

A father to five children, Willis was married to fellow Hollywood star Demi Moore throughout the 1990s, until their divorce in 2000. They remained close after their breakup, raising their three children Rumer, Tallulah and Scout. In 2009, he married Emma Heming Willis, having children Evelyn Penn and Mabel Ray.

Tributes have been pouring out from people across the entertainment industry:

All my love and respect to my big brother Bruce Willis. I know his wonderful family is surrounding him with support and strength. He will always be that hero on that poster on my wall as kid.

— M. Night Shyamalan ⌛ (@MNightShyamalan) March 31, 2022

I am sending my very best wishes to #BruceWillis and his family during this tough time.

Thank you for so many great performances across a tremendous career including and especially for John McClain. pic.twitter.com/HW5iGfCsIx

— Don Winslow (@donwinslow) March 31, 2022

So sorry to hear the news about Bruce Willis. Worked with him on Death Wish and he was a lovely awesome badass man. Prayers for him and his family. Legend pic.twitter.com/28QKIoeMac

— Dean Norris (@deanjnorris) March 31, 2022

When Bruce Willis was on it, there were few who were better. An under appreciated dramatic force, an unlikely comedic presence, a sterling leading man. He could do anything and did everything in the movies. I’m going to miss seeing him on the silver screen.

— Robert Daniels (@812filmreviews) March 30, 2022

Bruce Willis has given us so many iconic characters and great performances across his career. Forever a legend. Wishing him all the best, and I hope he enjoys retirement. pic.twitter.com/Pof4ZwPB77

— Isaac Feldberg (@isaacfeldberg) March 30, 2022