Insomnia increases risk of memory decline, dementia in older adults

MONTREAL, Quebec — Sleep isn’t always easy to come by in today’s fast-paced “always on” culture, but new research shows just how essential a little bit of shut eye is to our minds. Researchers at Concordia University report older adults with insomnia are more likely to experience memory decline as well as even more serious long-term cognitive impairments like dementia.

These findings are based on an analysis of data pertaining to over 26,000 people (ages 45-85) participating in the Canadian Longitudinal Study on Aging. Study authors compared completed self-reported evaluations of sleep, memory, and neuropsychological testing across several cognitive domains on two occasions: once in 2019 and then again in 2022. Sure enough, those who reported worsening sleep quality over that three-year period were at greater risk of reporting subjective memory decline.

“We found that insomnia specifically was related to worse memory performance compared to those who have some insomnia symptoms alone or no sleep problems at all,” says co-lead study author Nathan Cross, a postdoctoral fellow at the Sleep, Cognition and Neuroimaging Lab, in a university release. “This deficit in memory was specific, as we also looked at other cognitive function domains such as attention span multi-tasking. We only found differences in memory.”

Trouble sleeping is an actual psychological disorder

While there have been a number of studies on sleep quality in the past, this project benefits from a particularly large dataset and special attention given to sleep disorders. While many people deal with the occasional sleepless night spent tossing and turning, insomnia is formally classified as a psychological disorder in the Diagnostic and Statistical Manual of Mental Disorders, the primary reference handbook used by physicians all over the world.

“A diagnosis requires symptoms of difficulty falling asleep, staying asleep or waking too early three nights a week over a period of three months. Additionally, those with insomnia must report that this sleep problem causes them difficulty in the daytime,” Cross explains.

Insomnia can also affect mental health

The team split study participants into three categories: those reporting no sleep issues at all in 2019, those who reported some insomnia symptoms, and those who developed a likely case of insomnia. When researchers added in 2022 data into the equation, those reporting worsening sleep quality (either from no symptoms to some or probable insomnia, or from some symptoms to probable insomnia) were more likely to develop memory decline and/or receive a formal diagnosis of memory decline from their doctor.

These participants were also more likely to display a higher rate of other troubling symptoms such as anxiety, depression, daytime sleepiness, breathing interruptions during sleep, other sleep-related issues, smoking, and a higher body mass index (BMI) score. Notably, all of those issues are also risk factors for cognitive decline and dementia.

Regarding gender, men struggling with insomnia tended to score even lower on memory tests than women with insomnia. This suggests, researchers say, that older men may be at greater risk.

“However, there is some good news: sleep disorders like insomnia can be treated,” Cross concludes. “This highlights the importance of properly diagnosing and managing insomnia as early as possible in older adults. Adequately treating insomnia disorder might become an important preventive measure for cognitive decline and mitigate the incidence of dementia in later life.”

The study is published in the journal SLEEP.

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