Obsessive-compulsive disorder and spectrum across the life span.
An obsessive-compulsive disorder (OCD) spectrum has been proposed, which includes a group of disorders that share certain features with OCD including clinical symptoms (repetitive behaviours and thoughts), neurobiology (e.g. neurotransmitters) and preferential response to anti-obsessional treatments, such as the selective serotonin reuptake inhibitors (SSRIs). Three distinct clusters have been identified within the OCD spectrum, i.e. disorders concerning preoccupations with bodily sensations or appearance, impulsive disorders, and neurologically based disorders, and these share phenotypic features. Using one example from each of these clusters, body dysmorphic disorder (BDD), pathological gambling (PG) and autism, respectively, the phenomenology, neurobiology and pharmacotherapy indicates that specific biological factors are shared by OCD and by these disorders and correlate with the severity of repetitive behaviours. Thus, in common with OCDs, in BDD there is increased activity in the limbic regions; in PG there is evidence of deficiencies in 5-HT function and receptors; and in autism there are restricted interests and repetitive behaviours which may be influenced by serotonergic mechanisms. Our findings support the notion that targeted treatments, for example using SSRIs, for the behaviours associated with these disorders are effective. Our review considers one SSRI treatment in particular, fluvoxamine, and conclusions should be drawn in light of this. Further testing of our hypothesis would be prudent to confirm its validity.