Lack of speech or absence of speech can occur due to both medical and psychological conditions. Absent speech or mutism can occur as a sign of catatonia, a state in which one is unresponsive but otherwise awake. Catatonia can be a sign or schizophrenia or other psychiatric conditions involving psychosis. It may also be a sign of severe depression or other emotional disorders. The antipsychotic medications listed below are used in the treatment of emotional conditions that may manifest as catatonia with lack of speech.

Aphasia is a term used to describe the loss of language or the ability to communicate, typically due to brain damage. Mutism is a speech disorder characterized by the inability to speak. Lack of speech development in children can occur due to deafness or hearing problems. In people who have developed speech, the onset of inability to speak can signal a stroke or other type of brain damage. Head injury, dementia, and brain tumors may be associated with the loss of speech or language functions.

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