ROLE OF SEROTONIN IN OBSESSIVE-COMPULSIVE DISORDER

Background Serotonin may play a role in the pathophysiology of obsessi ve-compulsive disorder (OCD) because of the anti-obsession ai effect o f selective serotonin reuptake inhibitors (SSRIs). Method The literatu re is reviewed on knowledge of the role of serotonergic neurons in bra in function, studies on monoamine metabolites in cerebrospinal fluid ( CSF), various stress neuropeptides, neuroendocrine and behavioural cha llenge after administration of direct and indirect serotomimetic compo unds, and neuroanatomical data on brain circuits organising behaviour. Results in most of the OCD cases analysed, CSF 5-hydroxyindoleacetic acid and homovanillic acid concentrations do not significantly differ from age-corrected controls. However, a relationship appears to exist between pre-treatment levels of these metabolites and clinical respons e to drugs acting on the serotonin transporter. Abnormalities in CSF a rginine vasopressin, corticotropin-releasing hormone, oxytocin and som atostatin levels have been reported in OCD. long-term treatment with h igh-doses of clomipramine, fluvoxamine, and fluoxetine tend to correct these neuropeptide abnormalities. Conclusions We hypothesise that con tinuous treatment with SSRIs alters serotonin turnover and neuropeptid e expression patterns in OCD-entertaining functional forebrain/midbrai n circuits.