Tangential speech or tangentiality is a communication disorder in which the train of thought of the speaker wanders and shows a lack of focus, never returning to the initial topic of the conversation.
Specific thought disorders include derailment, poverty of speech, tangentiality, illogicality, perseveration, and thought blocking. ... However, formal thought disorder is not unique to schizophrenia or psychosis. It is often a symptom of mania, and less often it can be present in other mental disorders such as depression.
