While it is difficult to definitively identify any specific causes of cognitive decline, studies have found an association between sleep-disordered breathing and cognitive function in children and middle-aged adults. Findings on the association between sleep-disordered breathing and cognitive decline in older adults have been mixed, however. A recent editorial (Canessa and Ferini-Strambi, 2011) in the Journal of the American Medical Association suggests that this may be a result of different methods used across the different studies, and describes some recent findings on the relationship between sleep disorders and cognitive decline in older adults (Yaffe, et. al., 2011).
One study (Yaffe, et. al., 2011) supports the hypothesis that sleep-disordered breathing can lead to mild cognitive impairment or dementia, and indicates that it is a condition called hypoxia (a low rate of oxygen intake and a high percentage of sleep time spent without breathing) that leads to impairment. In the study, which used data on the sleep of 298 older women without dementia, neither a shortage of sleep nor frequent sleep interruptions were associated with later cognitive impairment. Interestingly, previous research has suggested that children and younger adults are more sensitive to a lack of sleep, and also suggested that individuals can adapt over time to limited sleep.
The authors of the study report that their findings suggest that supplemental oxygen therapy might be useful for older adults who experience hypoxia, but that this has not been extensively tested by researchers. The authors also note that continuous positive air pressure (CPAP) devices have been found to slow cognitive decline, or even improve cognitive performance, for older adults with sleep-disordered breathing. Collectively, these findings suggest that clinical trials with CPAP and other oxygen therapy should be conducted with older adults, which may offer evidence for the treatment of cognitive impairment related to disordered sleep.
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