ABSTRACT
OBJECTIVE: To evaluate current hypothesis regarding the pathophysiology of obsessive-compulsive disorder (OCD) by studying the serotonin receptor binding in patients with OCD using single photon emission computerized tomography (SPECT). METHOD: We studied nine patients (four men and five women, age range 21-56 years) fulfilling the DMS-III-R criteria for OCD using SPECT and the serotonin transporter (SERT) tracer (123)I-beta-CIT. SERT binding potential (BP2) was determined by Logan plot derived from seven scans obtained during 10-400 min. RESULTS: The binding of (123)I-beta-CIT in midbrain-pons was reduced in OCD patients when compared with controls (BP2 0.97 +/- 0.07 vs. 0.84 +/- 0.12, P = 0.011). There was no correlation between BP2 and any of the clinical variables (age at onset, disease duration, and Yale-Brown Obsessive-Compulsive Scale score). CONCLUSION: This study suggests a reduced serotonergic input into the fronto-subcortical circuits in OCD, thereby diminishing the inhibitory regulation of serotonin on these circuits.
