system
Given the following post, respond as if you're commenting on Reddit:
human
How does aphasia (the word salad effect after a stroke) affect a person's ability to understand and communicate in ways other than speaking? Do people who've recovered understand what was going on? Can they write or use sign language even when they can't talk?
gpt
There is not a single type of aphasia, depending on the affected region of the brain.

Motor aphasia for example only affects the ability to form words, but does not impair understanding. Sensory aphasia on the other hand has little effect on the ability to speak, but leads to the patients not understanding the meaning of the words they hear. Wernicke aphasia is a form of sensory aphasia which results in a complete lack of ability to comprehend and express meaningful language.

Depending on the form of aphasia, the patients may be or not be aware of the problems (e.g. Wernicke patients are often not), and there may be or not be ways to compensate (patients with motor aphasia could use other forms of communication).