Sleep Disorder Breathing Linked to Cognitive Function
Sleep-disordered breathing (SDB) might be a modifiable risk factor for dementia, according to a recent study.
The study included 1752 participants who underwent Type 2 in-home polysomnography, which included measurements of % sleep time <90% oxyhemoglobin saturation (%Sat<90%) and apnea-hypopnea index. In addition, researchers assessed Epworth Sleepiness Scale (ESS) scores and the presence of sleep apnea syndrome (SAS). Cognitive function was evaluated using the Cognitive Abilities Screening Instrument, Digit Symbol Coding Test (DSC), and the Digit Span Tests (DST) Forward and Backward.
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Approximately 9.7% of participants had SAS, and 26.8% of participants had at least one copy of the apolipoprotein ε-4 (APOE-ε4) allele.
One standard deviation increase in %Sat<90% and in ESS score were associated with poorer attention and memory on the DST Forward. Likewise, SAS and higher ESS scores were associated with poorer attention and processing spend on the DSC.
Additionally, the presence of the APOE-ε4 allele modified the associations between %Sat<90% and DST forward scores and ESS scores and DSC scores.
“Overnight hypoxemia and sleepiness were associated with cognition. The average
effect estimates were small, similar to effects estimated for several other individual dementia risk factors. Associations were strongest in APOE-ε4 risk allele carriers,” the researchers concluded. “Our results: 1) suggest that SDB be considered among a group of modifiable dementia risk factors; and 2) highlight the potential vulnerability of APOE-ε4 risk allele carriers with SDB.”
—Melissa Weiss
Reference:
Johnson DA, Lane J, Wang R, et al. Greater cognitive deficits with sleep-disordered breathing among individuals with genetic susceptibility to Alzheimer’s Disease: the Multi-Ethnic Study of Atherosclerosis [published online July 21, 2017]. Ann Am Thorac Soc. https://doi.org/10.1513/AnnalsATS.201701-052OC