Disease-specific attention impairment in disorders of chronic excessive daytime sleepiness

Patients with chronic excessive daytime sleepiness (EDS) complain of substantial attention deficits. However, their underlying neuronal dysfunction is largely unknown. Previous studies showed similar attention performances in central disorders of hypersomnolence suggesting that EDS-related cognitive impairment is independent of its cause. The aim of the current study was to further explore attentional profiles in disorders of chronic EDS.

Ten patients with narcolepsy type 1 (NT1; age 26.7 ± 9.3 years), 14 patients with idiopathic hypersomnia (IH; age 26.7 ± 9.3 years), 14 patients with subjective EDS (sEDS; age 31.4 ± 14.3 years), ie, a mean sleep latency >8 min in the multiple sleep latency test (MSLT), and 20 healthy controls (HC; age 32.6 ± 11.3 years) performed the vigilance task and the selective attention task of the test battery SLEEP^® (Vienna Test System Neuro^®). We assessed mean response time (RT) and standard deviation of RT separately for the first and the second half of the vigilance task to evaluate performance changes over time (time on task effect; TOT).

A significant interaction effect between group and TOT on the mean RT in the vigilance task suggests partly group-specific attention deficits. Combining paradigms of sustained and selective attention discriminated patients with NT1, IH, sEDS and HC. Behavioral results were unrelated to the mean sleep latency in the MSLT.

Discriminative performance of the sustained and selective attention tasks indicate disease-specific components of attention in NT1, IH, and sEDS. Different temporal dynamics of attentional control efficiency might be one factor underlying group differences.