Pattern & Correlates of Neurocognitive Dysfunction in Asian Indian Adults with Severe Obstructive Sleep Apnoea (Report‪)‬

Obstructive sleep apnoea (OSA) is characterized by recurrent sleep disruption and hypoxaemia due to collapse of the upper airway during sleep. It is known to be associated with various cognitive defects since its first description. Cognition comprises of the ability to register, remember, develop abstract concepts, plan, decide and foresee. Cognitive areas most frequently reported to be affected by OSA are general intelligence, attention, memory, executive function, and motor functioning (1). Subjects with OSA suffer from fragmented sleep due to recurrent effort related arousals (to overcome airway obstruction) and nocturnal hypoxaemia due to airway obstruction with consequent hypoventilation. These two factors are differentially related to the neurocognitive deficits observed in OSA (2). Recent population-based studies have found the prevalence of OSA among Indians to be comparable to the Western populations (3,4). However, no data are available on the cognitive impairment in Indian subjects with OSA. Studies from Western populations had heterogenous subjects and used varied psychometric tests focused on different cognitive domains, making the results difficult to aggregate and analyse (5,6). There are only a few studies focusing on impairment of "executive" or so-called "higher mental" functions in patients with OSA with differing conclusions (7-11). We hypothesised that patients with OSA suffer from excessive sleepiness and slowed information processing, without any independent impairment in higher mental or 'executive functions'. A systematic study adjusting for the pervasive effects of slowed information processing on any sort of cognitive assessment is essential for proper profiling of cognitive impairment. Hence, we sought to study the various domains of cognitive function in a homogenous population of Asian Indian patients with OSA, to gain insight into the profile and correlates of cognitive impairment. Material & Methods