Obstructive sleep apnea (OSA) is associated with impairments in cognitive functioning. Although cognitive complaints are related to quality of life, work productivity and health care expenditures, most research and all reviews have focused exclusively on objective cognitive functioning so far. In this systematic review, we assessed the available literature on subjective measures of cognition in adult OSA patients. Concentration complaints were consistently found to be more severe in untreated OSA patients as compared to primary snorers and healthy controls. The same seems to be true for memory and executive function problems, but firm conclusions cannot be made as of yet, due to methodological limitations of the available studies. Cognitive complaints appear to be at least partially related to subjective sleepiness. Importantly, they are not necessarily a sign of objective cognitive impairment. Additional research is needed to explore the relation between cognitive complaints, sleepiness and mood problems using validated and norm-referenced questionnaires for cognitive complaints. In addition, the impact of continuous positive airway pressure (CPAP) treatment on cognitive complaints in OSA warrants further study.
Keywords: Cognition; Cognitive complaints; Depression; Memory; Obstructive sleep apnea; Sleep disordered breathing; Sleepiness.
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