Sleep apnea tied to gaps in life memories, depression

February 25, 2019

A study conducted at Australia’s RMIT University has found that people with sleep apnea struggle to retrieve memories of their own lives—possibly increasing their vulnerability to depression, PsychCentral reports.

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 slumber.

The new study examined how the condition affects autobiographical memory — and concluded that people with untreated OSA had problems recalling specific details about their lives.

Lead investigator Dr. Melinda Jackson told PsychCentral that the study was 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,” Dr. Jackson noted, adding, “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 childhoods, early adult lives, and recent lives.

The results established that people with OSA had significantly more loss of general memories—52.3% compared with 18.9% of the control group.

The study also looked at recall of semantic memory (facts and concepts from your personal history, such as the names of your elementary 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.

Research contact: @RMIT

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