Derailment (thought disorder)


In psychiatry, derailment is a thought disorder characterized by discourse consisting of a sequence of unrelated or only remotely related ideas. The frame of reference often changes from one sentence to the next.
In a mild manifestation, this thought disorder is characterized by slippage of ideas further and further from the point of a discussion. Derailment can often be manifestly caused by intense emotions such as euphoria or hysteria. Some of the synonyms given above are used by some authors to refer just to a loss of goal: discourse that sets off on a particular idea, wanders off and never returns to it. A related term is tangentiality—it refers to off-the-point, oblique or irrelevant answers given to questions. In some studies on creativity, knight's move thinking, while it describes a similarly loose association of ideas, is not considered a mental disorder or the hallmark of one; it is sometimes used as a synonym for lateral thinking.

Examples

Entgleisen was first used with this meaning by Carl Schneider in 1930. The term asyndesis was introduced by N. Cameron in 1938, while loosening of association was introduced by A. Bleuler in 1950. The phrase knight's move thinking was first used in the context of pathological thinking by the psychologist Peter McKellar in 1957, who hypothesized that individuals with schizophrenia fail to suppress divergent associations. Derailment was used with this meaning by Kurt Schneider in 1959.