Insomnia May Up the Risk of Memory Decline in Middle-Aged and Older Adults

Middle-aged and older adults with insomnia disorder may face increased odds of developing subjective memory decline compared with their peers who have only a few or no insomnia symptoms, an analysis of the Canadian Longitudinal Study on Aging suggests.

“Since sleep is important for memory consolidation and other cognitive functions, disrupted sleep is likely to make cognition more vulnerable,” Thanh Dang-Vu, MD, PhD, professor and Concordia University research chair in sleep, neuroimaging and cognitive health in Montreal, Quebec, Canada, told theheart.org | Medscape Cardiology.

Dr Thien Thanh Dang-Vu

Previous studies have shown that subjective memory complaints are associated with a greater risk of progression to mild cognitive impairment or dementia.

The current analysis, published online July 25 in Sleep, showed that for individuals with no insomnia symptoms (NIS) who develop probable insomnia disorder (PID) within 3 years, the odds of self-reported memory worsening were more than one-and-a-half times greater than for those who developed insomnia symptoms only (ISO) or remained NIS.

Worsening Sleep, Worsening Memory

Dang-Vu and colleagues analyzed 2019 data from 26,363 individuals (mean age 65.5; about half women; 96% White). Participants were categorized as having PID, ISO, or NIS based on sleep questionnaires. Follow-up was 3 years (2022).

Only those who experienced difficulties with sleep onset or maintenance three times or more per week for longer than 3 months, and who said that this significantly interfered with their daily functioning and was not satisfactory, were classified as having PID.

At follow-up, subjective measures of memory were obtained through self-report questions; objective measures of cognitive performance were obtained by neuropsychological testing.

Across the sample, 66.45% of participants with NIS at baseline remained like that at follow-up; 30.92% transitioned to ISO, and 2.63% to PID.

Among those with ISO at baseline, 30.31% remained ISO, 67.22% converted to NIS, and 2.46% to PID.

Of those with PID at baseline, 2.88% had persisting PID, 33.12% reverted to ISO, and 64% to NIS.

NIS participants who developed PID at follow-up had increased odds of self-reported memory worsening compared with those who developed ISO or remained NIS (odds ratio [OR], 1.70).

Furthermore, those whose sleep worsened from baseline to follow-up — ie, transitioned from NIS to ISO, NIS to PID, or ISO to PID — had increased odds (OR, 1.22) of subjective memory worsening at follow-up compared with those who stayed insomnia-free or improved their sleep.

There were no significant associations between the development of PID or worsening sleep and neuropsychological test performance. However, objective memory deficits were found in men who developed PID, indicating a potential sex effect that the authors say needs to be investigated further.

Screen and Treat

“Sleep disorder screening should be part of the routine evaluation for patients with cognitive complaints,” Dang-Vu said. “Besides insomnia, obstructive sleep apnea, for instance, is associated with increased risk of cognitive decline, and worse performance in multiple domains such as memory, attention, and executive functions.”

Alon Y. Avidan, MD, MPH, professor of neurology at the University of California, Los Angeles, and director of the UCLA Sleep Disorders Center, agrees that “being able to screen patients and know their sleep quality is critical.”

“A large proportion of the population suffers from chronic insomnia, and it is often seen in older adults with much higher prevalence, particularly around the time of the pandemic,” he told Medscape Medical News.

Although the study is observational, he said, “this is important new information to help us understand and have additional insights into the impact of chronic insomnia disorder on neurologic and neurocognitive function.”

Dr Alon Avidan

“Can you say that if you're having chronic insomnia, you're going to get dementia? Probably not. We don't have that smoking gun yet,” he said. “But the trend is, it's not healthy for [the] brain to not have adequate sleep duration.

“If I had a patient who asked what they should do after hearing these findings, I would first tell them to always report their sleep quality to me because if they have insomnia, I want to know about it.

“Second, we need to figure out what’s contributing to the correlates or signs of insomnia,” he said. “Is it blue light before bedtime? Is their mind racing? Do they have other conditions like restless legs syndrome or obstructive sleep apnea, which need validation with a sleep study?

“Third is working on solutions,” he said. “Most people will go to their drugstore and start picking up drugs. And those drugs, unfortunately, won’t be the solution, and many will have more side effects than benefit. Decide whether the patient is really a candidate for a drug, or would they be an even better candidate for cognitive behavioral therapy (CBT), which is the way we should be treating insomnia in every patient.”

Dang-Vu reached a similar conclusion about treatment, and his team is currently studying whether CBT for insomnia or other nonpharmacological interventions might benefit cognitive functioning in older adults.

Dang-Vu and Avidan reported no relevant disclosures.

Sleep. Published July 25, 2022. Abstract.

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