(The) pattern of manifestation of nocturnal hypoxia and its relationship with cognitive dysfunction in patients with amyotrophic lateral sclerosis

Abstract

Background: Amyotrophic lateral sclerosis (ALS) is a common neurodegenerative disease that leads to the progressive weakness of the respiratory muscles and limb muscles. Consequently, most patients with ALS exhibit progressive hypoventilation, which easily worsens during sleep. The aim of this study was to evaluate the effect of nocturnal hypoxia on the cognitive function of patients with ALS and assess the pattern of nocturnal hypoxia in the patients with ALS. Method: Twenty-three patients with either definite or probable ALS were recruited for the study. The patients were grouped on the basis of the presence of nocturnal hypoxia, and their clinical characteristics. Cognitive functions including attention, executive function, and memory were measured. Results: Ten of the 23 patients with ALS (43.5%) exhibited nocturnal hypoxia and a poor performance for memory retention (p = 0.039) and retrieval efficacy (p = 0.045). In addition, 7 patients in the nocturnal hypoxia group showed a cluster of desaturation pattern for hypoxia. Conclusions: Compared to a group of patients without nocturnal hypoxia, the ALS patients with nocturnal hypoxia showed significant defects in memory function tests. Further studies are required to examine the causal relationship of this phenomenon and to understand the mechanism underlying the intermittent hypoxia in these patients.