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Woman with a cap covered in electrodes for a CPAP test

Sleep trial tests preventable risk factors for dementia

Uncovering the links between sleep, healthy brain ageing and dementia risk
There are currently no known cures for many neurodegenerative diseases including Alzheimer’s. However, a large body of research has demonstrated that some risk factors of cognitive decline can be controlled. One begins with sleep.

When Joan Suter forgot to attend the doctor’s appointment she had made to discuss her forgetfulness, she knew something wasn’t right. Her doctor referred her to the Brain and Mind Centre’s Healthy Brain Ageing Clinic for cognitive testing.

She was told she had mild cognitive impairment, a high risk stage in which around 45% of people progress to dementia within five years - but a time when modifiable risks for dementia should be addressed.

“I was quite devastated and almost shameful. I was very reluctant to tell anybody except some close family members. But since then, I've sort of undergone a transition of acceptance, and I'm not ashamed of it. I'm trying to do the best I can with what I've got”, Joan said.

She volunteered for a clinical trial being led by the Healthy Brain Ageing Clinic in partnership with the Woolcock Institute of Medical Research, investigating the link between obstructive sleep apnoea and cognitive decline.

Until Joan undertook a sleep test at the Woolcock Institute to see if she qualified, she had never suspected that she suffered from OSA, a potentially serious sleep disorder that occurs in a staggering 50-70% of older adults.

Participating in research - The CPAP study

Building on observational evidence suggesting that treating sleep apnea may alleviate the effect of mild cognitive impairment, CPAP participants were compared with no-treatment participants in a randomised blind trial. Eligible participants were aged between 50 and 80 years, with both mild cognitive impairment (MDI) and moderate obstructive sleep apnoea (OSA).

They were primarily assessed for any changes in executive functioning as well as changes in memory, subjective sleep and depressive symptoms.

The findings concluded that compred to no treatment, CPAP did not change processing speed or executive functionin, but clinically significant improvements were observed in verbal learning and memory retention.

“I was shocked to find out I was waking something like 49 times an hour. I wasn't aware that it was a problem. But I was constantly tired and thinking what can I put off today? So there were signs. I just didn’t see them”, Joan explained.

The discovery changed Joan’ life. Given a CPAP machine to treat her OSA, she noticed major improvements to her mood and energy levels. Now four years on, she describes the experience as ‘life transformational’.

“I don’t know how to describe it, other than to say it was totally transformative. Most days I wake up feeling so refreshed, like I could I jump over the moon. And I have more stamina.”

“I used to constantly be thinking ‘what time can I put my head down?’. I’d plan my whole day around it, or not go somewhere if I wouldn’t be home till the mid-afternoon. It’s so freeing to me to have that stamina.”

The Science of sleep

Professor Sharon Naismith, director of the Brain and Mind Centre's Healthy Brain Ageing Clinic, said Joan’s experience mirrors the emerging evidence.

"A common cause of cognitive problems in older people is sleep disturbance, yet this is not yet examined routinely in memory clinics," Prof. Naismith said.

"For OSA, there is a 26% increased risk of dementia when compared to people who don’t have OSA, and given there are many treatment options, we should be assessing this more often. We are now conducting a national trial in this area to determine if we can screen more people like Joan, in the memory clinic setting Australia-wide. We are testing new devices that can be set-up in the clinic and taken home by our patients, and we are looking at more pragmatic and personalised ways to treat sleep apnea.

"Besides sleep, it is important to examine all risk factors that can be modified when we assess an older person for early cognitive impairment. Between 40 and 48% of dementia risk is due to modifiable risk factors that begin to accumulate in the brain from midlife. By the time a person has mild cognitive impairment, around 60% of people already have clinically significant levels of beta-amyloid in their brain, the harmful protein that is characteristic of Alzheimer’s disease. It is in these critical periods that we must try to address those harmful risks to slow progression and keep people engaged and living well in the community for as long as possible."

 

As well as sleep, the HBA clinic's research team collaborates with researchers from disciplines across the University of Sydney to examine many interventions such as those targeting depression, blood pressure, heart disease, cognitive training and is even examining the power of music to promote neuroplasticity and build brain resilience.

For Joan, staying in touch with the Healthy Brain Ageing Clinic and taking part in research and programs that empower her to take a proactive approach to her health is helping her to accept her cognitive decline and to tackle those lifestyle risk factors that she can control.

“I did this really wonderful 10 week course called COG Max. It covered nutrition and habits and a lot of psychology and art and it was just wonderful. When I say life changing, it sounds like I’m exaggerating, but it’s true.”

“I just feel so differently now to when I did four years ago, when I first received the assessment. I feel very privileged to be part of the Healthy Brain Ageing Clinic. I truly do.”