The family of Bruce Willis shocked his fans Wednesday when they announced the actor is "stepping away" from his career after being diagnosed with aphasia, a disorder that affects a person's ability to speak or comprehend language.

"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," Willis's wife, Emma Heming Willis; his ex-wife, Demi Moore; and his daughters shared on Instagram. "As a result of this and with much consideration Bruce is stepping away from the career that has meant so much to him."

With his diagnosis, Willis, 67, joins a community of around 200,000 people in the United States who develop aphasia every year, according of the National Institutes of Health .

Aphasia is a disorder that affects people of all ages, although Willis represents the most common population, people who are middle-aged or older.

Willis's family did not provide further details on his current condition or future prognosis, writing only that this is a "really challenging time."

Here are five things to know about aphasia.

1. Aphasia affects language.

According to the NIH, aphasia results from damage to the parts of the brain that process language, typically the left side of the brain.

The disorder can make it harder to speak, write, read and comprehend.

2. Aphasia is caused by brain damage.

In most cases, aphasia comes on suddenly, like after a stroke or a traumatic brain injury, according to the NIH.

If a person has a brain tumor or a progressive neurological disease, aphasia may develop more gradually.

Aphasia is typically diagnosed if a person is having trouble speaking or understanding words. A speech-language pathologist can then test for speech and language skills, according to the American Speech-Language-Hearing Association

3. It does not affect a person's intellect.

While people with aphasia have difficulty communicating, the disorder itself does not affect their intelligence, according to the National Aphasia Association.

"For people with aphasia it is the ability to access ideas and thoughts through language – not the ideas and thoughts themselves- that is disrupted," according to the NAA.

4. There are different types of aphasia.

There are different types of aphasia depending on which area of the brain sustained damage.

In Broca’s aphasia, which is caused by damage to the frontal lobe of the brain, a person may be unable to produce words or full sentences despite being able to completely understand speech, according to the NIH.

In Wernicke's aphasia, which is caused by damage to the temporal lobe of the brain, a person may speak in long, often made-up sentences, and may have difficulty understanding speech, according to the NIH.

With another type, global aphasia, there is more extensive damage across the language portions of the brain, leaving a person potentially unable to both speak and understand, according to the NIH.

With conduction aphasia, a person may have difficulty repeating words, even though they understand them, while anomic aphasia, a person may have difficulty naming objects, even though they know what the object is.

5. Speech-language therapy is the go-to treatment.

Some people with aphasia can see improvements even without treatment as their brain recovers, according to the NIH.

For others, speech-language therapy is required to help regain the ability to communicate.

How much of their language abilities a person can recover depends on the cause of the brain injury, the extent of the injury and where in the brain the damage occurred and the person's age and health, according to the NIH.

In addition to speech-language therapy, social activities like book clubs and support groups can also be helpful for treatment, as is family involvement, according to the NIH.