This disturbance occurs between clauses, … 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. It happens when there's disconnect between who you feel you are today, and who you believe you used to be. 'Derailment' Is the Latest Theory Psychologists Have to Explain Depression . Psychology Definition of DERAILMENT: Thought disorder symptom marked by interruptions to thought and jumping from one though to another disconnected thought. Derailment Described as a "loosening of association" or tangential thinking, speech exhibiting derailment is composed of ideas or statements that are completely unrelated to each other but are connected as if in a legitimate conversation. See cognitive derailment- derailme 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.