Obstructive sleep apnoea associated with changes to brain structure typical of dementia

5 July, 2018

Obstructive sleep apnoea (OSA) is associated with changes to the structure of the brain that are also seen in the early stages of dementia, according to a study published in the European Respiratory Journal.

The researchers worked with a group of 83 people, aged between 51 and 88 years, who had visited their doctor with concerns over their memory or mood but had no OSA diagnosis. Each participant was assessed for their memory skills and symptoms of depression, and each was given an MRI scan to measure the dimensions of different areas of the brain.

Participants also attended a sleep clinic where they were monitored overnight for signs of OSA using polysomnography.

The researchers found that patients who had low levels of oxygen in their blood while they were sleeping tended to have reduced thickness in the left and right temporal lobes of the brain.

They also found that this alteration in the brain was linked with participant's poorer ability to learn new information. The researchers say this is the first time a direct link of this kind has been shown.

Conversely, patients with signs of OSA were also more likely to have increased thickness in other regions of the brain, which the researchers say could be signs of the brain reacting to lower levels of oxygen with swelling and inflammation.

The study was led by Professor Sharon Naismith from the University of Sydney, Australia. She said: "Our results suggest that we should be screening for OSA in older people. We should also be asking older patients attending sleep clinics about their memory and thinking skills, and carrying out tests where necessary.

"There is no cure for dementia so early intervention is key. On the other hand, we do have an effective treatment for OSA. This research shows that diagnosing and treating OSA could be an opportunity to prevent cognitive decline before it's too late."

Professor Naismith and her team are now working on research to find out whether CPAP treatment can prevent further cognitive decline and improve brain connectivity in patients with mild cognitive impairment.

Andrea Aliverti, Professor of Bioengineering at Politecnico di Milano, Italy, is Head of the European Respiratory Society's Assembly on Clinical Physiology and Sleep and was not involved in the research. He said: "We already know that as well as disrupting sleep, OSA can increase the risk of high blood pressure, type 2 diabetes, heart attack and stroke. This research adds to evidence that OSA is also linked to dementia and suggests a likely mechanism for the link. However, we can treat OSA and measures such as stopping smoking and losing weight can reduce the risk of developing the condition."