Does sleep apnea in the elderly increase the risk of Alzheimer's disease?

Researchers are investigating the relationship between sleep apnea and Alzheimer's disease

Obstructive sleep apnea may increase the risk of developing Alzheimer's disease in the elderly. Amyloid beta biomarkers increase over time in older adults with sleep apnea. The more pronounced the sleep apnea is, the more the values ​​of these biomarkers increase. Thus, when people suffer from more apneas per hour, this leads to a greater accumulation of brain amyloid.

The scientists from the New York University School of Medicine found in their current study that people with sleep apnea are at an increased risk of developing Alzheimer's. The physicians published the results of their study in the journal "American Journal of Respiratory and Critical Care Medicine".

Many people suffer from respiratory disorders during sleep at night. A so-called CPAP device can provide a remedy. Physicians found in an investigation that sleep apnea seems to increase the risk for Alzheimer's. (Image: kudosstudio / fotolia.com)

Causality for links between Alzheimer's and sleep apnea has been difficult to verify

Alzheimer's is a so-called neurodegenerative disease that affects about five million older Americans alone. Sleep apnea is more common and affects 30 to 80 percent of older people, depending on the definition of sleep apnea, say the authors. Several studies have already concluded that sleep disorders can contribute to amyloid deposition and can accelerate cognitive decline in people at risk for Alzheimer's disease. Ricardo S. Osorio of New York University School of Medicine. So far, however, it has been difficult to test the causality for this compound because Alzheimer's and sleep apnea share certain common risk factors and often coexist, the expert adds.

Physicians are studying amyloid deposition in people with sleep apnea

The purpose of the current study was to investigate the associations between the severity of sleep apnea and changes in Alzheimer's biomarkers. It was particularly interesting for the researchers, whether the so-called amyloid deposits increase in the course of time in healthy elderly participants with sleep apnea.

Researchers examine 208 subjects

For their study, the experts examined 208 participants aged 55 to 90 years with normal cognition, which was measured by standardized tests and clinical reviews. The participants were not referred from a sleep center, did not use CPAP ventilation, were not depressed or suffered from medical conditions that impair brain function, the researchers explain.

104 subjects participated in the two-year longitudinal study

The study found that more than half of the participants suffered from sleep apnea, including 36.5 percent with mild sleep apnea and 16.8 percent with moderate to severe sleep apnea, the researchers say. 104 of the subjects then took part in a two-year longitudinal study. The results of this study showed an increase in amyloid deposits in the brain.

Changes take place in the preclinical stages of Alzheimer's disease

Surprisingly, this study did not find that the severity of sleep apnea can predict cognitive decline in healthy older adults, author Dr. Andrew Varga of the Icahn School of Medicine, Mount Sinai, New York. This finding suggests that these changes occurred in the preclinical stages of Alzheimer's disease.

Results may be due to limitations of the study

The relationship between amyloid burden and cognition is probably not linear and depends on additional factors, the expert further explains. This study finding may also be due to the relatively short duration of studies, highly educated participants, and the use of tests that fail to detect subtle or sleep-dependent changes in cognitive abilities.

The benefit of better screening tools would be enormous

The results from this and other studies suggest that sleep apnea, cognitive decline, and Alzheimer's are related. Perhaps the known effects of sleep apnea such as somnolence, cardiovascular and metabolic dysfunction are the cause of increasing brain impairment in old age, explains Dr. med. Osorio. If so, the potential benefits of developing better screening tools to diagnose sleep apnea in the elderly would be enormous, the expert adds. (As)