The impact of obesity in cognitive and memory dysfunction in obstructive sleep apnea syndrome

Obstructive sleep apnea (OSA), a sleep disorder, results in decreased daytime alertness and neurocognitive dysfunction. Obesity is considered a major risk factor for the development and progression of OSA and the resulting cognitive dysfunction. However, the effect of obesity on neurocognitive dysfunction in OSA has been rarely investigated. Eighty-three patients with moderate to severe OSA syndrome were recruited in our study. After matching for education, age, and body mass index (BMI), 40 patients were enrolled into our study with matched obese (BMI ≧ 30) and non-obese (BMI < 30) groups. All enrolled patients completed a polysomnographic study, sleepiness questionnaires, and attention, cognitive, and memory function tests. Compared to obese OSA patients, non-obese OSA patients had shorter reaction times in the psychomotor vigilance task but not the Flanker or Stroop cognitive tasks. Additionally, obese OSA patients had a reduced capacity for working memory relative to non-obese OSA patients. Obesity had a significant effect on OSA patients in our study, including delayed reaction times in the psychomotor vigilance task and a decrease in working memory.