Untreated obstructive sleep apnea (OSA) is a known risk factor for depression. A 2019 study in the Journal of the International Neuropsychological Society suggests that OSA may increase the risk for depression by clouding people’s memories of their past.
An earlier study suggested that people with OSA struggle with semantic autobiographical memory, or the ability to recall specific events from the past, such as a birthday party or vacation. However, researchers compared the OSA patients to significantly younger healthy people, which may have distorted the severity of the memory problems.
In the new study, researchers asked 44 people with moderate to severe OSA to recall memories from childhood, early adulthood, and their recent lives. The interviewers asked them to provide details such as classmates’ and teachers’ names. A group of 44 healthy control subjects received the same questions; the average age in both groups was about 50.
People with OSA had a harder time recalling their younger days—52.3 percent of them had “overgeneral” memories (lacking in specific details), compared to 18.9 percent of control subjects. Past research has shown that people with overgeneral autobiographical memories are at higher risk for persistent depression.
It’s unclear why people with OSA develop problems with recollection, but brain scans of people with the disorder have detected a loss of nerve cells in regions that play a role in autobiographical memory.