- Sleep disorders increase the risk of Alzheimer's disease, finds a new study
- Sleep apnea causes less attention and thinking in individuals who carry Alzheimer's gene
- The findings of the study support sleep therapy to prevent Alzheimer's disease
People who are at risk of Alzheimer's disease may be at greater risk of diminished cognition from sleep-disordered breathing than those without the susceptibility, finds a study published in the Annals of the American Thoracic Society.
Sleep Disorders Linked to Alzheimer's Disease
‘Difficulty breathing while asleep accelerates memory decline in people at-risk of Alzheimer's disease.’
The study participants carrying the apolipoprotein £`-4 (APOE-£`4) allele showed greater cognitive deficits with the various indices of sleep-disordered breathing compared to those without the allele.
APOE is a cholesterol carrier that supports injury repair in the brain. Studies have shown that people carrying the alternate form of the gene £`4 allele, are at increased risk of Alzheimer's disease. About 20 percent of the population carries the £`4 allele.
"Previous studies have shown inconsistent findings between sleep-disordered breathing and cognition, which may be due to the different tests used," said lead study author Dayna A. Johnson, instructor of medicine at Brigham and Women's Hospital and Harvard Medical School.
The research team investigated the association in a diverse sample using several indicators of sleep-disordered breathing and cognition. They also examined whether APOE-£`4 allele influenced the link between sleep-disordered breathing and cognition.
The research team analyzed 1,752 people with an average age of 68 in the Multi-Ethnic Study of Atherosclerosis (MESA) The participants took part in a sleep study, completed sleep questionnaire and tests to measure their cognition.
Sleep-disordered breathing is defined as having more than 15 stopped or shallow breaths per hour as well as loud snoring.
The study found:
- Increased overnight hypoxemia (oxygen saturation below 90 percent) or increased daytime sleepiness was associated with poorer attention and memory
- More daytime sleepiness was also associated with slower cognitive processing speed
- Sleep apnea syndrome was associated with poorer attention and processing speed
- These associations were strongest in APOE-£`4 carriers
- The researchers adjusted for race, age, body mass index, education level, smoking status, hypertension, diabetes, benzodiazepine use, and depressive symptoms
"The effects of the various sleep factors they measured on cognition were small, but in the range previously reported for several other lifestyles and health risk factors for dementia," said Johnson.
Regular screening and treating sleep-disordered breathing may help reduce a person's risk of dementia, especially if the individual carried APOE-£`4.
The findings of the study provide evidence that sleep-disordered breathing negatively affects attention, processing speed and memory, which are robust predictors of cognitive decline, said Susan Redline Professor of Sleep Medicine, Harvard Medical School.
"Given the lack of effective treatment for Alzheimer's disease, our results support the potential for sleep-disordered breathing screening and treatment as part of a strategy to reduce dementia risk."
Dayna A Johnson, Jacqueline Lane, Rui Wang, Michelle Reid, Ina Djonlagic, Annette L Fitzpatrick, Stephen R Rapp, Luenda E Charles, Ruth O'Hara, Richa Saxena, Susan Redline. Greater Cognitive Deficits with Sleep-Disordered Breathing among Individuals with Genetic Susceptibility to Alzheimer's Disease: The Multi-Ethnic Study of Atherosclerosis. Annals of the American Thoracic Society(2017) https://doi.org/10.1513/AnnalsATS.201701-052OC