Emerging psychiatric disorders in Kleine-Levin syndrome

{In Kleine-Levin syndrome (KLS), episodes of hypersomnia and cognitive, psychiatric and behavioural disturbances alternate with asymptomatic periods in adolescents. We evaluated whether psychiatric disorders would emerge during asymptomatic periods in a naturalistic, uncontrolled clinical cohort. Patients with primary KLS underwent psychiatric interviews at diagnosis and every year for 1-10years, leading to diagnosis of former and present comorbid psychiatric disorders. Among the 115 patients (65.2% male and aged 16.1 +/- 4.8years at KLS onset), 19 (16.5%) had a history of psychiatric disorder prior to KLS onset, which persisted afterwards in 10. Twenty-five (21%) patients developed a new, comorbid psychiatric disorder 1-6years after KLS onset, during asymptomatic' periods, including mood disorders (n=14; including major depressive episodes