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Behavioural Neurology
Volume 11, Issue 4, Pages 245-250

An Evolutionary Hypothesis for Obsessive Compulsive Disorder: A Psychological Immune System?

Riadh T. Abed1 and Karel W. de Pauw2

1Rotherham District General Hospital, Moorgate Road, Rotherham S60 2UD, UK
2St James's University Hospital, Leeds LS9 7TF, UK

Received 1 April 1999; Accepted 1 April 1999

Copyright © 1999 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A new hypothesis is presented within the framework of evolutionary psychology that attempts to explain the origins of obsessive-compulsive disorder. It is suggested that obsessions and compulsions originate from the overactivity of a mental module that the majority of humans possess and has the function of generating risk scenarios without voluntary intervention. It is hypothesised that obsessional phenomena function as an off-line risk avoidance process, designed to lead to risk avoidance behaviour at a future time, thus distinguishing it from anxiety and related phenomena as on-line emotional states, designed to lead to the avoidance of immediate and direct risks. Finally, the hypothesis makes a number of specific predictions that are testable and refutable. It is contended that the present hypothesis if supported by empirical evidence could serve as a basis for future research on this important disorder.