Aphasia Can Have Many Causes — an Expert Shares What to Know About This 'Complex' Condition

Last week, Bruce Willis' family shared that the actor is "stepping away from the career that has meant so much to him" after "experiencing some health issues." Willis has recently been diagnosed with aphasia, a language impairment that is "impacting his cognitive abilities," they said.

Affecting around 1 to 2 million Americans each year, aphasia, a communication disorder, is a common and difficult condition for patients and their families. It's also not a straightforward diagnosis — for some patients, aphasia develops after a traumatic brain injury, while for others, it's a sign of a degenerative brain condition.

Here, Dr. Prin Amorapanth, assistant professor of rehabilitation medicine at NYU Langone Health Rusk Rehabilitation, shares what to know.

What is aphasia?

"Aphasia broadly refers to an impairment of language that affects the production or comprehension of speech and can also affect the ability to read or write," Amorapanth tells PEOPLE.

There are two main types — fluent, also called receptive, and non-fluent, or expressive aphasia. Those with fluent aphasia have trouble understanding the content of words when people are speaking to them — "it kind of sounds like word salad," Amorapanth says — while those with non-fluent aphasia struggle to form words or have trouble stringing together a sentence. And the condition has "a spectrum of severity — it can be mild, moderate, severe."

How can a person develop aphasia?

There are two main causes: It can either develop after a traumatic brain injury such as a stroke or an aneurysm, or it could develop due to dementia or other degenerative diseases. (Willis is not known to have suffered a brain injury.)

How are aphasia and dementia related?

If a patient hasn't had a traumatic brain injury and develops aphasia, it can be "an initial presenting symptom" of dementia, and is typically called primary progressive aphasia (PPA), Amorapanth says. The communication issues that are trademarks of aphasia are "sometimes your only clue that there's something abnormal with the brain," he says, "and that can lead to a diagnosis of dementia."

What is aphasia like for patients and their families?

Aphasia can be "massively frustrating," Amorapanth says, particularly for people with non-fluent aphasia, who are able to understand what people are saying but unable to form a response. For those with fluent aphasia, it can be tougher on the people around them. Patients are often unaware "that their language function is compromised," he says, and may not realize they're not speaking the words that formed in their head.

"It's almost as if their version of reality is not in agreement with anyone around them."

Is there a cure for aphasia?

"There's no cure, unfortunately," for aphasia, says Amorapanth. But targeted speech and language therapy can help. Therapists can take patients through reading or speaking exercises and try role-playing scenarios like ordering from a store or doing video calls. Depending on the case, "it's possible to improve your language function significantly with therapy."

For more information on aphasia, the National Aphasia Association, at aphasia.org, can help.