In a statement posted on Rumer Willis’ Instagram account, the family said: “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.
“As a result of this and with much consideration Bruce is stepping away from the career that has meant so much to him.
“This is a really challenging time for our family and we are so appreciative of your continued love, compassion and support.
“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.
“As Bruce always says, ‘Live it up’ and together we plan to do just that.”
Willis has starred in classic films such as the Die Hard series and Pulp Fiction since starting his career in 1980.
He also starred in TV shows such as Miami Vice and Moonlighting, as well as enjoying a music career.
Willis gained superstar status for his role as John McClane in Die Hard, but also went on to star in huge films such as The Fifth Element, The Sixth Sense, and Sin City.
He is known for his hard-man credentials, but also picked up a Golden Globe for his role as private detective David Addison in Moonlighting.
Aphasia is a condition which affects cognitive functions such as the ability to speak, write, and understand language.
The NHS website describes the illness as ‘when a person has difficulty with their language or speech’ and says it is ‘usually caused by damage to the left side of the brain’.
People with aphasia may have trouble reading, listening, writing, and speaking.
However, according to the website: “Speaking problems are perhaps the most obvious, and people with aphasia may make mistakes with the words they use.
“This could be sometimes using the wrong sounds in a word, choosing the wrong word, or putting words together incorrectly.
“Although aphasia affects a person's ability to communicate, it doesn't affect their intelligence.
“Aphasia can occur by itself or alongside other disorders, such as visual difficulties, mobility problems, limb weakness, and problems with memory or thinking skills.”
It is not known how long Willis has been suffering with the condition.