After being diagnosed with the language condition aphasia, Bruce Willis' family announced his retirement from acting on Wednesday.
According to the American Speech-Language-Hearing Association, aphasia is a "acquired neurogenic language disease" that affects the understanding and expression of written and spoken language and commonly happens after a stroke or a brain injury. While speech and language treatment can help persons with aphasia restore their language abilities, it is "typically a rather slow process," and while "most people make considerable improvement, few people reach their pre-injury communication levels," it is "generally a relatively slow process."
It's unknown what caused Willis' aphasia or if the "Die Hard" star has any additional disabilities.