The Perception and Attention Functions test battery as a measure of neurocognitive impairment in patients with suspected central disorders of hypersomnolence.

The aim of the current study was to evaluate an attention test as a discriminative tool to measure neurocognitive impairment in patients with disorders of hypersomnolence. Chronic excessive daytime sleepiness is the main symptom in central disorders of hypersomnolence. For diagnostic purposes and treatment evaluation, reliable assessment of excessive daytime sleepiness is required. Thirty-six patients with central disorders of hypersomnolence were compared with 20 healthy controls. All participants performed the 'Perception and Attention Functions' (WAF) of the Vienna Test System. Patients underwent polysomnography, Multiple Sleep Latency Test and Maintenance of Wakefulness Test. Patients were divided into two groups: (i) patients who met the criteria of disorder of hypersomnolence (objective excessive daytime sleepiness); and (ii) patients with subjective excessive daytime sleepiness, i.e. with normal Multiple Sleep Latency Test results. Group 1 consisted of 23 patients with objective excessive daytime sleepiness (11 with idiopathic hypersomnia, nine with narcolepsy type 1, three with narcolepsy type 2); group 2 included 13 patients with subjective excessive daytime sleepiness. The results showed cognitive impairment in patients with objective excessive daytime sleepiness and even in patients with subjective excessive daytime sleepiness. WAF tests identified distinct attention profiles in patients with narcolepsy type 1, idiopathic hypersomnia/narcolepsy type 2, and patients with subjective excessive daytime sleepiness. WAF test measures correlated with Maintenance of Wakefulness Test and the Epworth Sleepiness Scale, but not with Multiple Sleep Latency Test and the Fatigue Severity Scale. In conclusion, the multidimensional WAF test battery detects cognitive impairment even in patients that complain of excessive daytime sleepiness but have normal Multiple Sleep Latency Test results. WAF tests offer valuable information that adds to the existing polysomnographic measures in discriminating patients with different types of chronic excessive daytime sleepiness. The results provide new insights into cognitive dysfunction underlying different types of chronic excessive daytime sleepiness.