People with untreated sleep apnoea struggle to remember details of memories from their own lives, potentially making them vulnerable to depression, new research has shown.
Estimated to affect more than 936 million people worldwide*, obstructive sleep apnoea (OSA) is a serious condition that occurs when a person's breathing is interrupted during sleep.
People with OSA are known to suffer memory problems and have higher rates of depression, but it is not well understood how these issues relate to the development of the disease.
The new study led by RMIT University examined how the condition affected autobiographical memory and found people with untreated OSA had problems recalling specific details about their lives.
Lead investigator Dr Melinda Jackson said the research built on the known links between depression and memory.
“We know that overly general autobiographical memories – where people don’t remember many specific details of life events – are associated with the development of persistent depression,” Dr Jackson said.
“Our study suggests sleep apnoea may impair the brain’s capacity to either encode or consolidate certain types of life memories, which makes it hard for people to recall details from the past.
“OSA is increasingly common, affecting up to 30% of elderly people and around one in four Australian men aged over 30.
“Sleep apnoea is also a significant risk factor for depression, so if we can better understand the neurobiological mechanisms at work, we have a chance to improve the mental health of millions of people.”
The study compared 44 adults with untreated OSA to 44 healthy controls, assessing their recall of different types of autobiographical memories from their childhood, early adult life and recent life. The results showed people with OSA had significantly more over general memories - 52.3% compared with 18.9% of the control group.
Dr Jackson said the use of CPAP machines to treat OSA had been shown to improve some of the cognitive impairments related to the condition.
“An important next step will be to determine whether successful treatment of sleep apnoea can also help counter some of these memory issues or even restore the memories that have been lost.”
The study is published in the Journal of the International Neuropsychology Society.
About sleep apnoea
- Sleep apnoea occurs when the muscles in the upper airway collapse during sleep, blocking off the airway above the voice box.
- Breathing stops for a period (generally between 10 seconds and up to one minute) until the brain registers the lack of breathing or a drop in oxygen levels and sends a small wake-up call. The sleeper rouses slightly, opens the upper airway, typically snorts and gasps, then drifts back to sleep almost immediately. This pattern can repeat itself hundreds of times a night, causing fragmented sleep.
- It’s estimated that about 5% of Australians suffer from sleep apnoea.
- Active treatment includes nasal CPAP, mouthguards or surgical correction of upper airway obstruction.
- Daytime sleepiness may distinguish simple snorers from people with sleep apnoea.