Sleep Apnea and Alzheimer’s

Sleep apnea affects many Americans, with more than 3 million new cases each year.  Sleep apnea is a sleep disorder in which breathing becomes shallow, infrequent, and may even stop during sleep.  It has been recognized for quite some time as being a fairly serious disorder, with complications including heart problems and high blood pressure.  New research, however, has shown that sleep apnea has more complications than previously thought.  Sleep apnea may contribute to another serious disease: Alzheimer’s.

A study published recently suggests that sleep apnea hastens cognitive decline, leading to earlier diagnoses of Alzheimer’s and dementia.  Researchers reviewed the medical histories of more than 2,000 people aged 55 to 90 who had participated in a previous study on onset of Alzheimer’s.  At the beginning of the study, none of the participants showed any sign of cognitive decline or Alzheimer’s.  The results showed that on average, participants who suffered from sleep apnea received a diagnosis of mild cognitive impairment (MCI) 10 years earlier and a diagnosis 5 years earlier than those who did not suffer from sleep apnea.  Considering the amount of people who suffer from sleep apnea, the results are extremely alarming.  Thankfully, treatment for sleep apnea seemed to lead to drastic improvements.

So why does a sleep disorder contribute to a neurodegenerative disorder?  The researchers postulate that the hypoxia (loss of oxygen) associated with sleep apnea damages hippocampus cells which are particularly responsive to oxygen changes.  My big question about the topic is: do these people already have a genetic predisposition for Alzheimer’s, or is the hypoxia damaging the hippocampus cells so much that Alzheimer’s is induced in people who wouldn’t normally have it?  Also, how does neurogenesis play a role?  Lack of sleep has been shown to decrease neurogenesis in the hippocampus: the brain region where Alzheimer’s is thought to originate.  Does a decrease in neurogenesis make someone more vulnerable to Alzheimer’s?  Alzheimer’s is a hot topic in neuroscience research, so hopefully these questions will be answered so this devastating disease can be better understood.



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