Sleep-disordered breathing and the risk of cognitive decline: a meta-analysis of 19,940 participants

Sleep-disordered breathing (SDB) is related to the incidence of cognitive decline. However, results of cohort studies were inconsistent. We performed a meta-analysis of cohort studies to evaluate the sequential association between SDB and cognitive decline. Cohort studies were identified by the searching of PubMed and Embase databases. A random effect model was applied to combine the results. Nineteen thousand nine hundred forty participants from six cohort studies were included. Participants with SDB at baseline had significantly higher risk of cognitive decline, as indicated by a combined outcome of mild cognitive impairment (MCI) or dementia (RR = 1.69, p < 0.001; I (2) = 60%). The association between SDB and the subsequent risk of cognitive decline remains in older people (RR = 1.70, p < 0.001; I (2) = 66%). Results of subgroup analyses indicated consistent results regardless of whether SDB was confirmed by PSG or whether the apolipoprotein E4 allele was adjusted. However, participants with SDB at baseline were with higher risk for developing MCI (RR = 2.44, p < 0.001) than dementia (RR = 1.61, p < 0.001; p for subgroup difference = 0.04). Moreover, SDB was associated with a significantly higher risk of cognitive decline in female participants (RR = 2.06, p < 0.001), but not in the males (RR = 1.18, p = 0.19; p for subgroup difference = 0.03). SDB may be an independent risk factor for the developing of cognitive decline, and gender difference may exist regarding this association.