Prevalence of cognitive impairment in patients with obstructive sleep apnea.

Abstract

Aim: To study the prevalence of neurocognitive impairment and its association with the severity of OSA in untreated OSA patients from India. Materials and Methods: Forty Seven polysomnography (PSG) proven OSA patients were compared with 47 age, gender and education matched controls without OSA on the NIMHANS validated neurocognitive battery and their respiratory parameters obtained from PSG were analyzed. Results: Of the 15 cognitive function tests, a greater number of errors (>6 errors) were seen in OSA patients compared to controls (45% vs 2%; p<0.001). Working memory and executive function were more significantly impaired in the OSA group than in non-OSA group (p<0.001). Desaturation Index and duration of SpO2 <90% were higher while mean SpO2 was lower in subjects with greater cognitive impairment. Severity of cognitive impairment did not correlate with the severity of OSA, but was more common. Conclusions: Neuro-cognitive impairment is more commonly seen in patients with OSA, especially severe OSA. Hypoxia appears to play a role in cognitive decline in OSA. We recommend all patients with cognitive impairment should be screened for underlying OSA and vice-versa. Early initiation of CPAP may reverse the cognitive dysfunction.