Researchers find link between sleep apnoea and dementia diagnosis

Sleep apnoea is thought to affect 100 million people around the world and new research has found that it could also be linked to brain changes associated with dementia.

Sleep apnoea is the term given when the airway becomes blocked when muscles in the throat relax. During this process, a person can stop breathing and blood oxygen levels can be reduced. Researchers from the University of Sydney’s Brain and Mind Centre believe obstructive sleep apnoea, the most common form of the condition, may be linked to the shrinkage of the brain’s temporal lobes, thus causing a decline in memory.

The condition is more common in the older population and has previously been linked to an array of other serious health conditions including heart disease, stroke and even cancer. In many cases, patients can be cured with a breathing device which they wear when sleeping to prevent the airways from closing.

Between 30 and 50 per cent of dementia risk is caused by modifiable factors such as depression, high blood pressure, obesity and smoking, although new research has also found sleep disturbances can increase the risk of dementia.

“We wanted to look specifically at obstructive sleep apnoea and its effects on the brain and cognitive abilities,” study leader Professor Sharon Naismith said in a statement.

Researchers worked with 83 people aged between 51 and 88 who had raised concerns over their memory with a doctor, but had no formal obstructive sleep apnoea diagnosis. Each participant had their memory skills and depression symptoms analysed, while MRI scans measures different areas of their brains.

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Next, each person attended a sleep clinic where they were monitored for signs of obstructive sleep apnoea. Researchers used polysomnography to record brain activity, oxygen levels in the blood, heart rate, breathing and movements. It was discovered that patients who had lower levels of oxygen in their blood while sleeping also had thickness in regions of the brain known to affect people with a dementia diagnosis. Increased thickness was also detected in other parts of the brain, although researchers believe this was the body’s way of reacting to lower levels of oxygen.

The changes in these areas of the brain also caused patients to struggle when it comes to learning new information – the first time such a link has been shown in research. Researchers specifically analysed older people in the study because they are at greater risk of dementia.

“We chose to study this group because they are older and considered at risk of dementia,” Naismith said. “Our results suggest that we should be screening for OSA in older people. We should be asking older patients attending sleep clinics about their memory and thinking skills – and carrying out tests where necessary.”

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At present, there is no cure for dementia, however, early intervention can help when it comes to treating the cognitive condition. Obstructive sleep apnoea can be treated and treating it could delay symptoms associated with dementia.

As explained in The European Respiratory Journal, researchers are now looking at ways sleep apnoea treatment can assist patients with mild cognitive impairment.

What do you think? Do you think sleep could be linked to dementia?