Following a diagnosis of aphasia, Bruce Willis' family revealed on Instagram on Wednesday that the acclaimed actor is retiring from the industry, raising questions about the communication disease that affects as many as 2 million Americans, according to the National Aphasia Association. It may also affect as many as 25% to 40% of stroke survivors, per the association.

Here's what you should know about aphasia if you've never heard of it.

What is aphasia, and how does it affect people?

Aphasia is the inability to speak or use language as a result of brain impairment caused by disease or accident. Although neurological disease can be a cause of aphasia, it is not the same as Alzheimer's disease or dementia.

People with aphasia may have difficulty finding words, speak in a choppy, halting manner, or use brief snippets of speech. According to the American Speech-Language-Hearing Association (ASHA), they can even make up meaningless words and use them in their speech and writing.

Grammatical errors and run-on phrases are common in written communications. A person with aphasia may also have difficulty accurately duplicating letters and words, according to ASHA.

What are the symptoms of aphasia?

The symptoms of aphasia might vary depending on the type of aphasia and the location of the injury in the brain. According to the Mayo Clinic:

Broca or expressive aphasia is characterized by a person's ability to understand but not speak. They may speak in short phrases and omit words, and they may become frustrated by the lack of communication. They may also have right-side paralysis or weakness.

Comprehensive aphasia, also known as Wernicke aphasia, is characterized by a pattern of extended phrases with excess or unneeded words, which might be confusing to the listener. A person with comprehensive aphasia may have difficulty understanding language and may be unaware that others are unable to understand them.

Global aphasia is characterized by poor understanding and difficulties formulating words or sentences. This disorder causes substantial damage to the parts of the brain that handle language, and people with it may have difficulty expressing or understanding language.

Primary progressive aphasia is another kind of aphasia, according to the National Aphasia Association. This type is caused by tissue loss caused by a neurodegenerative disease such as Alzheimer's.

Is there a cure for aphasia?

Speech and language therapy may be advised for someone who has been diagnosed with aphasia, but symptoms of aphasia can sometimes improve without treatment.

Complete recovery from aphasia is improbable if symptoms do not improve within two or three months of a stroke. Some people, on the other hand, continue to improve for months or even years.

According to the Mayo Clinic, medications for aphasia that enhance blood flow to the brain are being researched. Although several have shown potential, more research is required before they may be recommended for treatment.