It might start when a person stumbles over a word. Within as few as four years, a patient with primary progressive aphasia, a neurological language disorder, could go completely mute, said Maya Henry, ...

Imagine seeing a furry, four-legged animal that meows. Mentally, you know what it is, but the word "cat" is stuck on the tip of your tongue. This phenomenon, known as Broca's aphasia or expressive ...