Pineal gland abnormality in major depressive disorder.

• Circadian rhythm alteration and sleep disturbance are common in depression patients. • Pineal gland regulates circadian rhythm and sleep by secretion of melatonin. • Depression patients had higher prevalence of pineal cyst than healthy controls. • Depression patients had smaller pineal parenchymal volume than healthy controls. • Pineal abnormality might play a critical role in depression. Patients with major depressive disorder (MDD) often have circadian rhythm alteration and sleep disturbance. The pineal gland regulates the circadian rhythm and sleep by the secretion of melatonin neurohormone. However, the relationship between pineal abnormality and MDD remains elusive. 50 patients with MDD and 35 gender- and age-matched healthy controls underwent high-resolution structural MRI. Pineal parenchymal volume (PPV) was measured manually. Inter-group differences in prevalence of pineal cyst and PPV were examined. In addition, we investigated the correlations between PPV and symptom severity as well as sleep variables in the patient group. Compared to healthy controls, patients with MDD had a higher prevalence of pineal cyst. Moreover, patients had significantly decreased PPV relative to controls. However, no significant correlations were observed between PPV and symptom severity as well as sleep variables. Our findings suggest that pineal abnormality may play a critical role in depression. [ABSTRACT FROM AUTHOR]