The effect of continuous positive airway pressure (CPAP) treatment on the neurocognitive function of patients with obstructive sleep apnea

Abstract

Obstructive Sleep Apnea (OSA) affects up to 5% of the population in Western countries but as many as 80% of cases remain undiagnosed (1). OSA is characterized by repeated cessation of breathing during sleep and is recognized as a significant public health problem which imposes substantial neurocognitive morbidities (2). Several studies in patients with OSA demonstrated the presence of cognitive deficits concerning memory, attention, executive functions, motor abilities (3), concentration, verbal and visuospatial memory, constructional abilities, and psychomotor functioning (4). The negative effect of the cognitive dysfunction greatly affects the quality of life of these patients. There is growing evidence that intermittent hypoxia is more damaging than the sustained condition. OSA patients experience this intermittent hypoxia while sleeping, during periods of apnea- hypopnea. To address this problem, the gold standard treatment for OSA is continuous positive airway pressure (CPAP). It is said that CPAP reduces hypoxia, normalizes blood-oxygen saturation and reduces sleep fragmentation thereby improving a majority of the effects of OSA including the neurocognitive domain (4). This study aimed to determine the neurocognitive function of patients with Obstructive Sleep Apnea (OSA) and assess the effectiveness of two weeks Continuous Positive Airway Pressure (CPAP) treatment in patients with OSA in a tertiary hospital from January 1, 2012 to June 30, 2012 as measured by improvement in results in the Montreal Cognitive Assessment (MoCA) test and the Rey Osterrieth Complex Figure Test. This study employed a quasi-experimental study design. Fifteen patients (15) who presented with symptoms suggestive of OSA and confirmed by polysomnography were included in the study. The patients’ demography as well as the OSA severity, number of hours of CPAP use, Epworth Sleepiness Scale score and other co morbid conditions were assessed using a data sheet. The Montreal Cognitive Assessment Test was used to evaluate the following cognitive domains: attention and concentration, executive functions, memory, language, visuoconstructional skills, conceptual thinking, calculations, and orientation. To assess visuospatial processing, memory and certain executive functions, which are based on the incidental-learning paradigm, the Rey–Osterrieth Complex Figure Test was used. Only nine subjects had information on the ESS, MoCA and CFT scores both at the initial and follow up periods. Of these, seven patients who were able to use CPAP served as the treatment group, while the other two served as the control group. All patients who used CPAP had a notable increase in MoCA scores, from a median score of 24–30. Those who did not use CPAP had no notable change in MoCA score ( p = 0.037). Changes in score in both the copy and recall portions of the CFT was statistically significant ( p = 0.037). This study conducted in our setting demonstrated that patients with OSA have impairment in different domains of cognitive function. This includes attention, concentration, executive function, visuoconstructional skills, conceptual thinking, language and memory. This study also proved that CPAP improves these cognitive impairments as shown in the improvement of scores in both the MoCA and CFT. Neurophysiology and Sleep Disorders Laboratory , Makati Medical Center Department of Neurosciences , Section of Neurology, Makati Medical Center .