Obstructive Sleep Apnea Syndrome and Neuropsychological Dysfunction: Understanding the Impact of Obesity

Obesity is the largest risk factor for the development of obstructive sleep apnea syndrome (OSAS), which is a common sleep-related breathing disorder that is associated with cognitive dysfunction. A growing body of literature suggests that obesity is related to negative neuropsychological outcomes independent of other health problems known to impact cognitive functioning (e.g., type II diabetes, cardiovascular disease). The purpose of this study was to investigate the impact of obesity on the cognitive functioning of individuals with OSAS. Specifically, this study aimed to examine whether or not differences existed between obese and non-obese persons with OSAS on a battery of cognitive tests that assessed memory, attention, and executive functions both at baseline and over six months of continuous positive airway pressure (CPAP) treatment. This study utilized data from Project Breathe, which was a study conducted at National Jewish Health. It was hypothesized that obese participants with OSAS would demonstrate poorer baseline performance on tests of memory, attention, and executive functioning, and they would show lesser improvement in these cognitive domains over six months of CPAP treatment compared to non-obese participants. Analysis of covariance (ANCOVA) and repeated measures analysis of covariance (RM-ANCOVA) tests were used to analyze the data. Results indicate that obese and non-obese participants did not demonstrate differences in neurocognitive functioning at baseline or following six months of CPAP treatment after adjusting for age and hypertension. Several limitations, including how obesity was measured, analyses used, and low statistical power may have contributed to the lack of significant findings in the predicted direction. Future research should focus on the following: larger sample sizes; using measures of obesity other than or in addition to body mass index (BMI); and examining the moderating impact of sex on neurocognitive functioning in this population