Sleep apnoea causes early cognitive decline

Snoring man with irritated partner

It seems an inevitability that eventually we will all suffer at least cognitive decline, if not full-on dementia. Of course there are ways to slow this decline (don’t drink and don’t think too much. But exercise!) but it’s always there as a risk.

And now to add another issue, a small study has shown that obstructive sleep apnoea (OSA), which leads to headaches, disrupted sleep, loud snoring and other health issues, may come with cognitive decline at an earlier age.

In people with OSA, the throat muscles relax and prevent the lungs from getting air, resulting in the sleeper not breathing for a moment. It’s the most common sleep-related breathing disorder. While it can be treated with certain devices and surgery, it’s considered a serious medical condition that comes with an increased risk of health complications such as heart disease.

OSA has long been linked with cognitive problems, psychiatric issues including depression, and neurodegenerative diseases such as Alzheimer’s. However, what hasn’t been clear is whether these are caused by OSA or by some of the medical issues related to OSA.

The study

The latest study involved 27 men aged between 35 and 70, with a new diagnosis of mild to severe OSA and no comorbidities – that is, other health issues or diseases that may or may not be linked to OSA. Another 7 men matched for age, BMI, and education but not OSA were used as a control group.

In cognitive tests, the men with OSA scored lower for sustained attention, executive functioning, short-term visual recognition memory, and social and emotion recognition than the control group. The more severe the OSA, the worse the scores compared to the control group.

That these study participants had no other health issues – which is ‘rare’ in people with OSA, according to researchers – suggests that the cognitive decline observed in the tests is due to OSA and not something else. Previously, this mental deterioration had been attributed to other conditions such as systemic hypertension or type 2 diabetes.

What this research doesn’t address in detail is what the root cause of this link might be, but the team has some ideas: the way OSA interferes with the oxygen and carbon dioxide levels in the blood might be one explanation.

OSA is also linked to changes in the blood flow to the brain, inflammation in the brain, and, of course, fragmented sleep. Issues with quality and quantity of sleep have long been associated with a higher risk of developing cognitive problems.

As well as studying larger and more diverse groups with OSA, the researchers are keen to look more closely at how it affects the brain’s circuitry and how related comorbidities might impact the onset of cognitive decline.

I talked about this with Danny Hoyland on West Bremer Radio on 15 April 2023. Listen live each week: Saturday 7.40 am, West Bremer Radio.

Source: The First Draft of The Human Pangenome Has Arrived. Here’s Why It’s So Important.

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