loosening of association


loos·en·ing of as·so·ci·a·tion

(lūs'en-ing a-sō'sē-ā'shŭn), A manifestation of a severe thought disorder characterized by the lack of an obvious connection between one thought or phrase and the next, or in response to a question.

derailment

A pattern of communication (speech or writing) in which a person's ideas slip off one track and onto another that is completely unrelated or only obliquely related. In moving from one sentence or clause to the next, the patient shifts topics from one frame of reference to another and things are said in juxtaposition that lack a meaningful relationship. This disturbance occurs between clauses, in contrast to incoherence, in which the disturbance is within clauses.
Aetiology
Organic brain disease, schizophrenia.

loosening of association

A sign of disordered thought processes in which the person speaks with frequent changes of subject and the content is only obliquely related, if at all, to the subject matter. This may be seen in mania or schizophrenia.