Editors' ChoiceSleep

Sleep well, breathe well, age well

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Science Translational Medicine  29 Apr 2015:
Vol. 7, Issue 285, pp. 285ec68
DOI: 10.1126/scitranslmed.aab3134

Sleep-disordered breathing such as that occurring during obstructive sleep apnea is the most common sleep disorder and has been linked to dementia, including Alzheimer’s disease (AD). In a small cohort of elderly women, sleep-disordered breathing was shown to increase the prospective risk of cognitive decline. However, any contribution of sleep-disordered breathing to dementia risk at a younger age, as well as the effect of treatment of sleep-disordered breathing using positive airway pressure (PAP), has not been explored. Osorio and colleagues now examine data from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) to determine the effect of sleep-disordered breathing on the age of onset of mild cognitive impairment (MCI) and AD.

They analyzed three groups from the ADNI data set: those with self-reported sleep-disordered breathing, those reporting no sleep-disordered breathing, and those with self-reported sleep-disordered breathing who undertook PAP treatment. Due to the nature of the ADNI data set, which is collected from many sites, the investigators performed their analysis three times, each time with increasingly stringent entry criteria. They used Kaplan-Meyer survival analysis, with Cox regression for covariates that may affect AD risk, to compare the age of MCI and AD onset in the three groups.

The mean age of MCI onset was much earlier in those with sleep-disordered breathing, remarkably 11 to 12 years earlier than for those without sleep-disordered breathing. The age of onset of AD was about 5 years earlier in the sleep-disordered breathing group, in the most stringent analysis. However, those with sleep-disordered breathing who undertook PAP treatment showed a 10-year delay in onset of MCI compared with those with sleep-disordered breathing who did not have treatment. This suggested that PAP treatment neutralized the effect of sleep-disordered breathing on the risk of developing MCI and AD.

Brain changes seen in AD such as the accumulation of amyloid plaques are present years before any symptoms emerge. The data of Osorio et al. suggest that sleep-disordered breathing accelerates the progression from asymptomatic brain change to MCI, and then in some cases to AD. More importantly, these are the first data suggesting that treatment with PAP can “rescue” the sleep-disordered breathing group from early cognitive decline. The study is limited by using self-reporting to define sleep-disordered breathing and PAP usage; however, this would have biased the study towards the null. Additionally, due to missing data, 69% of potential participants were excluded from even the most permissive analysis. Even so, the study provides clinically useful evidence to support PAP treatment for sleep-disordered breathing, specifically to reduce the risk of cognitive decline.

R. S. Osorio et al., Sleep-disordered breathing advances cognitive decline in the elderly. Neurology 10.1212/WNL.0000000000001566 (2015). [Full Text]

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