Neuropsychological deficits in obstructive sleep apnea patients pre- and posttreatment

The effects of obstructive sleep apnea syndrome (OSAS) on cognitive functioning represents a recently studied area within sleep disorders medicine. The consequences of apneic events include severely fragmented sleep and a loss of deeper stages of sleep due to repetitive arousals. These consequences are manifest as symptoms of excessive daytime sleepiness (EDS) and impaired daytime functioning, as well as cognitive impairment.;The present study utilized a pre and post treatment design. Subjects ranged in the severity of OSAS in terms of amount of sleep fragmentation and hypoxia. Subjects were administered a neuropsychological battery pre treatment (baseline) and following six months of continuous treatment with either CPAP or an oral appliance. Measures of sleep fragmentation, respiratory disturbance and blood oxygen saturation level were used to illustrate the subsequent response to treatment.;Although at baseline testing the subject group demonstrated no impairment on the neuropsychological tests, significant improvement occurred post treatment for the group on tests of verbal fluency, cognitive shifting, short term visual memory and time estimation. These improvements suggest that treatment positively affected attentional abilities in the subjects. It is unclear, however, whether these improvements represent changes in executive functions or whether they reflect decreased daytime somnolence. Significant differences were also found between patients with different levels of respiratory disturbance on tests of verbal fluency, motor skill and inhibiting habitual responses. No relationship was found between the level of oxygen saturation and neuropsychological functioning. Evaluation over a longer period of treatment with a more sensitive battery of frontal related tests and a greater number of subjects may yield more significant findings.;Treatment of OSAS results in improved sleep and daytime functioning, however persistent neuropsychological deficits appear to remain after short-term treatment. These impairments have been classified as executive deficits and are usually associated with frontal dysfunction. The persistent deficits suggest that the intermittent nocturnal hypoxia associated with OSAS may be responsible for the neuropsychological deficits demonstrated by apneics. It is unclear whether long-term treatment might eventually improve these enduring deficits.