Psychopathology and personality characteristics in relation to blood serotonin in Tourette's syndrome and obsessive-compulsive disorder

Family studies suggest an interrelationship between Gilles de la Tourette S yndrome (GTS) and some forms of obsessive-compulsive disorder (OCD). Some a uthors consider GTS to be part of a serotonergically mediated cluster of OC D spectrum disorders. The present study was undertaken to compare measures of psychopathology, personality and blood serotonin between GTS and OCD (wi thout ties), and to investigate whether an OCD spectrum hypothesis is suppo rted for GTS. Fifteen GTS without OCD subjects, 21 tic with (+) OCD subject s, 15 OCD without tie subjects and 26 controls tall without serotonergic me dication) were evaluated with self-rated and clinician-rated measures of ps ychopathology and personality. Whole blood serotonin (5-HT) and platelet mo noamine oxidase activity (MAO) was measured, and Spearman's correlations we re calculated between whole blood 5-MT, MAO and rating scale scores within the entire sample and within subgroups. There were main effects of OCD on a nxiety, obsessive-compulsive, neuroticism and extraversion scores. There we re main effects of ties on depression, obsessive-compulsive, trait anxiety and neuroticism scores, and on platelet MAO. There were interaction effects on platelet MAO, 5-MT, Yale-Brown Obsessive-Compulsive Rating Scale severi ty, trait anxiety and Eysenck Personality Questionnaire neuroticism scores. Platelet MAO activity was elevated in tie-free OCD subjects when compared to tie + OCD, GTS without OCD and controls. Whole blood 5-HT was lowered in tie + OCD patients in comparison to GTS without OCD and tie-free OCD subje cts. Whole blood 5-HT and obsessive-compulsive severity were negatively cor related within OCD without tie patients and MAO and Leyton Obsessive Invent ory scores were negatively related within GTS without OCD patients. The bio chemical data of this study suggest that in tie + OCD and in tie-free OCD p atients, 5-HT dysregulations play a role, but not necessarily in pure GTS. Serotonergic dysregulations within tie c OCD and tie-free OCD patients are distinct, suggesting differences in underlying pathophysiology. The finding that obsessions and compulsions can be associated with either 5-HT hypofun ctionality or hyperfunctionality reveals a major weakness in the OCD spectr um theory, i.e. that the associations between obsessive-compulsive behaviou rs and 5-HT abnormalities are less specific than suggested by the original obsessive-compulsive spectrum model.