June 12, 2017

Sleep-Disordered Breathing Linked to Cognitive Decline, Dementia

By Lorraine L. Janeczko

BOSTON -- June 12, 2017 -- Sleep-disordered breathing is linked with higher risk of cognitive decline or dementia, researchers reported here at SLEEP 2016, the 31st Annual Meeting of the Associated Professional Sleep Societies (APSS).

“By summarising findings from 14 published studies covering more than 4 million participants in total, we found that those with sleep-disordered breathing were more likely to develop cognitive impairment, especially in the domain of executive function,” said lead author Yue Leng, PhD, University of California San Francisco School of Medicine, San Francisco, California.

“Growing evidence suggests an association between sleep-disordered breathing and cognitive decline in the elderly,” the authors wrote in their presentation. “However, existing population-based studies have been conflicting and few have considered differential effect on cognitive domains.”

The researchers conducted a systematic search of publications in English using PubMed, EMBASE, and PsychINFO, including cross-sectional and prospective studies with 200 or more participants aged 40 years and older.

Sleep-disordered breathing was defined according to the apnoea-hypopnea index (AHI) or clinical diagnosis, and cognitive outcomes were based on standard tests or cognitive impairment diagnosis. A total of 14 studies comprising 4,288,419 adults were included; 6 studies were prospective.

The authors considered three cognitive domains: global cognition, executive function, and delayed memory. They used the I2 statistic to test heterogeneity between studies, and they assessed publication bias by the Egger test and funnel plot asymmetry.

They extracted and pooled adjusted risk ratios from prospective studies as well as standard mean differences (SMD) from cross-sectional studies.

Pooled analysis of the 6 prospective studies suggested that patients with an AHI of 15 or higher were 26% more likely to decline cognitively or to develop dementia.

After the researchers eliminated 1 study that introduced significant heterogeneity, the pooled RR increased to 1.35 (95% CI, 1.11-1.65).

Pooled analysis of 7 cross-sectional studies indicated that patients with sleep-disordered breathing had significantly poorer executive function.

“The link between sleep and the aging brain is receiving increasing interest, and we think it’s important to continue this effort,” said Dr. Leng.

She recommended further studies to explore whether treating sleep-disordered breathing can improve cognition and to explore the underlying mechanisms involved.

[Presentation title: Sleep-Disordered Breathing, Cognitive Function and Risk of Cognitive Decline: a Systematic Review and Meta-Analysis. Abstract 0468]
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