Sleep-disordered breathing and cognition in older adults

Both sleep-disordered breathing (SDB) and cognitive impairment are common among older adults, yet few studies have examined their relationship within this population to determine whether the effect of SDB on cognition is of a magnitude similar to or greater than that observed in younger and middle-aged adults. Here, we review the extant literature and report that studies are largely supportive of an association between SDB and cognitive impairment in older adults, particularly in the domains of attention/vigilance, executive function, and verbal delayed recall memory. Presence of the APOE4 allele may confer increased vulnerability to SDB-associated cognitive dysfunction among elderly individuals. Although findings are mixed, there is strong evidence to suggest that SDB-related intermittent hypoxemia is the primary mechanism through which SDB exerts its adverse effects on cognition. We propose a microvascular model in which chronic intermittent hypoxemia causes vasculopathy that ultimately is expressed as cognitive impairment in the older adult. However, it remains unclear whether the effects of SDB on cognition are the same regardless of age or whether there is a synergistic interaction between age and SDB.