ABSTRACT
Obsessive-compulsive disorder (OCD), Tourette’s syndrome, complex repetitive rituals, hair pulling (trichotillomania), nail biting, simple motor and vocal tics, and isolated compulsions and obsessions collectively form part of a spectrum of psychological problems where the central psychological concern is the fact that adjustment is compromised by the execution of repetitive actions. The way in which these difficulties are classified in DSM IV and ICD-10 is presented in Figures 13.1 and 13.2. From these figures it is clear that despite their similarity from a behavioural perspective, they have been classified within these systems as if they form discrete clusters of problems associated with anxiety, impulse control and childhood movement difficulties. Genetic evidence supports the view that these disorders probably fall along a continuum (Leonard et al., 1994; Leckman and Cohen, 1994; Rapoport et al., 1994). For example, there is a preponderance of OCD and Tourette’s syndrome within families where one or the other disorder is diagnosed. Hair pulling, an excessive grooming behaviour, has ethological similarities to compulsive cleansing behaviours associated with cases of OCD where obsessions about contamination are a central feature. The tics that characterise Tourette’s syndrome are similar to those which occur in isolation. And the movements which typify chronic movement disorder are probably subserved by the same structures within the basal ganglia as those which underpin compulsive behaviours and complex tics.
