In a heartfelt Instagram post, Rumer Willis, the eldest daughter of Demi Moore and Willis, shared that her father's diagnosis "is impacting his cognitive abilities."
"To Bruce’s amazing supporters, as a family we wanted to share that our beloved Bruce has been experiencing some health issues and has recently been diagnosed with aphasia, which is impacting his cognitive abilities," she wrote, which was also signed by other members of the family: Emma, Demi, Scout, Tallulah, Mabel and Evelyn.
Moore also shared the post on her Instagram page.
"As a result of this and with much consideration Bruce is stepping away from the career that has meant so much to him."
Aphasia "is a condition that robs you of the ability to communicate. It can affect your ability to speak, write and understand language, both verbal and written," according to the Mayo Clinic.
It most commonly arises after a stroke or brain injury, though can also come on more gradually due to the growth of a brain tumor or a degenerative disease.
The family did not say what the cause is in Willis' case. They wrote that it is "a really challenging time" for them, but that they are "moving through this as a strong family unit."
"As Bruce always says, 'Live it up' and together we plan to do just that," the Instagram post concludes.
The news comes just weeks after Bruce Willis celebrated his 67th birthday. Moore shared a photo wishing Bruce Willis a happy birthday on March 19, writing she is "Thankful for our blended family."