Neurocognitive function in patients with residual excessive sleepiness from obstructive sleep apnea: a prospective, controlled study

Abstract Objective This study aimed to evaluate neurocognitive function in adult patients with residual excessive sleepiness (RES) after appropriate treatment of obstructive sleep apnea (OSA) with CPAP and good adherence to treatment. Methods This was a prospective controlled study. We included patients of both sexes, aged 35–60 years with OSA and an apnea–hypopnea index >20 ev/h, effectively treated with CPAP, but with a residual Epworth Sleepiness Scale score ≥11. The control group consisted of OSA patients adequately treated with CPAP who did not present with excessive sleepiness after treatment. Both groups underwent the following evaluations: polysomnography, multiple sleep latency testing, depression symptoms, and cognitive assessment. Results Regarding baseline characteristics, the data were matched for age, years of study, and body mass index. Long-term memory result did not show a significant difference between the two groups (RES group 4.7 ± 2.0; control group 6.5 ± 1.9; p  = 0.08). The executive functions were the most affected, with alterations in Wisconsin test, number of categories (RES group: 1.6 ± 1.4; control group: 3.0 ± 1.4; p  = 0.01), and semantic verbal fluency test (RES group: 13.6 ± 3.3; control group: 16.9 ± 4.3; p  = 0.04). Conclusion In summary, the mean depression scale score in the group with residual excessive sleepiness was significantly higher than that in the control group. Patients with residual excessive sleepiness showed impairment of executive functions but no impairments in other cognitive domains.