Depressive and Attentional Symptoms in Narcolepsy: Findings From Patients, First-Degree Relatives, and Controls

Background and Objective Depression and attentional difficulties are prevalent in narcolepsy. Although depression has been noted in first-degree relatives, the impact of sleep disturbances on these self-reported symptoms remains unclear. We investigated depressive symptoms and attention-deficit/hyperactivity disorder (ADHD)-related traits in patients and their relatives, while controlling for sleep quality and sleepiness.Methods A cross-sectional study included 613 participants: narcolepsy patients (n=253), first-degree relatives (n=156), and healthy controls (n=204). We measured symptoms using the Beck Depression Inventory-II (BDI-II), Adult ADHD Self-Report Scale (ASRS), Pittsburgh Sleep Quality Index (PSQI), and Epworth Sleepiness Scale (ESS). We analyzed group differences using ANCOVA, adjusting for age, sex, body mass index, PSQI, and ESS.Results Patients exhibited significantly high unadjusted scores for depression (mean, 27.51) and attentional symptoms (mean, 11.47). After controlling for covariates, group status remained significantly associated with BDI-II total scores (F=25.03, p<0.001), with both patients and relatives reporting higher levels of depression than controls. Notably, affective-cognitive items on the BDI-II remained elevated. However, the group effect on the ASRS was no longer significant after adjustment (F=1.45, p=0.236).Conclusions Depressive symptoms were consistently elevated in both patients and first-degree relatives, even after accounting for sleep quality and daytime sleepiness, indicating a potential shared familial vulnerability. In contrast, ADHD-like symptoms appeared to be largely influenced by sleep quality and excessive daytime sleepiness, indicating they may be state-dependent.