Cognitive executive dysfunction in patients with obstructive sleep apnea syndrome (OSAS) after CPAP treatment

We have previously described impairments of cognitive executive functions in 17 patients with OSAS in comparison with 17 normal controls, as assessed by various frontal-lobe-related tests. In the present study, 10 of these OSAS patients treated with continuous positive airway pressure (CPAP) were reevaluated after 4-6 months of treatment. Neuropsychological tasks explored attention, short-term memory span, learning abilities, planning capacities, categorizing activities, and verbal fluency. Patients were found to have normalized most of their cognitive executive and learning disabilities, but all the short-term memory tests remained unchanged. These findings are discussed in light of the contribution of the frontal-lobe-related systems to short-term memory functions, and the eventual pathogenic role played by sleep fragmentation and nocturnal hypoxemia, which are related to the occurrence of apneic and hypopneic events. In conclusion, short-term memory impairment was persistent in OSAS patients despite CPAP treatment for 4-6 months.