International Swiss Primary Hypersomnolence and Narcolepsy Cohort Study (iSPHYNCS): the impact of psychiatric comorbidities on daily life in central disorders of hypersomnolence-a vicious circle.

Presence of psychiatric comorbidities is well documented in narcolepsy type-1 (NT1) but there are limited data on patients with 'other central disorders of hypersomnolence' (OCH). This study aimed to investigate frequency of psychiatric comorbidities in patients with NT1 and OCH, and to evaluate their impact on quality of life and sleep as an additive factor in combination with hypersomnolence-related symptoms. This study was conducted within the scope of the international Swiss Primary Hypersomnolence and Narcolepsy Cohort Study (iSPHYNCS), which aims to find new biomarkers in central disorders of hypersomnolence (CDH). Study participants underwent Mini International Neuropsychiatric Interview and completed questionnaires related to quality of life and sleep. Comparative analysis was conducted to investigate group differences, and multivariable regression models were used to reveal the impact of psychiatric comorbidities. Among a total of 90 patients, 26 were diagnosed with NT1 and 64 with OCH. In all, 38 patients showed at least one psychiatric disorder, 27% of NT1 and 48% of OCH, with female dominance (50% in females versus 23% in males, p < 0.02). Major depressive episodes (n = 29) were most common, followed by suicidality (n = 13). Patients with a psychiatric diagnosis were more fatigued (β = 0.70, p < 0.05), apathic (β = -5.41, p < 0.002), had more disturbed sleep (β = 0.55, p < 0.02), worse sleep (β = 1.89, p < 0.001) and general health (β = -12.55, p < 0.02) quality. Comorbid psychiatric disorders are frequent in patients with CDH and worsen the impact of hypersomnolence-related symptoms on daily activities regardless of the type of CDH. Psychiatric comorbidities may create a vicious circle with fatigue and avoidance of physical activities, which aggravates hypersomnolence-related symptoms.