OBJECTIVE: Obsessive-compulsive symptoms are induced or aggravated by stress, and the pituitary is a key component of the hypothalamic-pituitary-adrenal axis. We examined pituitary volume in drug-naive and medicated male patients with obsessive-compulsive disorder (OCD). 

METHODS: Volumetric magnetic resonance imaging studies were conducted on 62 male control subjects, medicated male patients (N=50) and drug-naive male patients (N=12) with OCD. 

RESULTS: Pituitary volume was significantly smaller in drug-naive patients with OCD (464.97+/-55.82 mm(3)) compared to medicated patients (577.84+/-129.11 mm(3), P=0.004) and control subjects (543.04+/-113.70 mm(3), P=0.027), and no difference between control subjects and medicated patients (P=0.174). 

CONCLUSION: The results indicate that drug-naive male patients with OCD exhibit decreased pituitary volume. This finding suggests that dysregulation of the HPA axis in OCD may influence pituitary volume. In addition, the increased pituitary volume in medicated patients may reflect the effect of drugs on the pituitary.