Obstructive sleep apnea may be linked to Alzheimer’s disease pathogenesis

Severe obstructive sleep apnea is a significant predictor of an increase in amyloid beta plaques and may accelerate Alzheimer’s disease pathogenesis, according to a study published in SLEEP.

“People with obstructive sleep apnea are more likely to develop Alzheimer’s disease in old age but it was not known why,” Stephen R. Robinson, PhD, professor in the school of health and biomedical sciences at RMIT University in Melbourne, Australia, told Healio Psychiatry. “Alzheimer’s disease is characterized by the pathological accumulation of amyloid plaques and neurofibrillary tangles in the brain, which begin in the vicinity of the collateral sulcus then spread through the hippocampus and then into adjacent areas of the brain.”

To study the underlying neuropathy of Alzheimer’s disease in association with obstructive sleep apnea (OSA), Robinson and colleagues analyzed the post-mortem hippocampi (n= 34) and brainstems (n= 24) of people with OSA for the presence of neurofibrillary tangles and amyloid beta plaques using quantitative immunochemistry. They also recorded continuous positive airway pressure use during sleep.

Study results showed OSA severity was a predictor of amyloid beta plaque burden and neurofibrillary tangle burden in the hippocampus. Further, although 71% of brainstems contained neurofibrillary tangles and 21% contained amyloid beta plaques, their burdens did not correlate with OSA severity.

The researchers speculated that episodes of hypoxia followed by re-oxygenation cause the oxidative stress that renders areas of the brain more vulnerable to Alzheimer’s disease-causative agents.

“Although we cannot prove that OSA causes Alzheimer’s disease, our findings establish that it is associated with the formation of the signature pathology of Alzheimer’s disease,” Robinson said. “Until now, no one knew what factors are responsible for triggering the pattern of plaques and tangles in Alzheimer’s disease, but our results narrow the field of potential factors to just a handful of likely candidates.”