Estimated to affect more than 936 million people worldwide, obstructive sleep apnea (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 also have higher rates of depression, but it is not well understood how these issues are connected with the development of the disease, according to researchers at RMIT University in Melbourne, Australia.
The new study examined how the condition affected autobiographical memory and found people with untreated OSA had problems recalling specific details about their lives.
According to lead investigator Dr. Melinda Jackson, 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,” she said.
“Our study suggests sleep apnea 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.
“Sleep apnea 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,” she continued.
The study compared 44 adults with untreated OSA to 44 people without OSA, 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 percent compared with 18.9 percent of the control group.
The study also looked at recall of semantic memory (facts and concepts from your personal history, like the names of your school teachers) and episodic memory (events or episodes, like your first day of high school).
While people with OSA struggled with semantic memory, their episodic memory was preserved, according to the study’s findings. This is likely related to their fragmented sleeping patterns, as research has shown that good sleep is essential for the consolidation of semantic autobiographical memory, researchers explain.
Across both groups, being older was associated with having a higher number of over-general autobiographical memories, while higher depression was linked to having worse semantic memory, the study discovered.
According to Jackson, the results show the need for further studies to better understand the role of untreated OSA on memory processing.
“Brain scans of people with sleep apnea show they have a significant loss of grey matter from regions that overlap with the autobiographic memory network,” she said.
“We need to look at whether there’s a shared neurobiological mechanism at work — that is, does the dysfunction of that network lead to both depression and memory problems in people with sleep apnea?”
The study was published in the Journal of the International Neuropsychology Society.
Source: RMIT University