New Research Explores Sleep Disturbances and Dementia Risk

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By Tiarra Mukherjee

A novel study, reported in the American Journal of Preventive Medicine, uncovered compelling evidence linking three indicators of sleep disruption with the likelihood of developing dementia.

Contributing to a growing body of evidence linking sleep to cognition, these findings reveal that sleep-initiation insomnia (trouble falling asleep in 30 minutes) and the use of sleep medications are correlated with an increased risk of developing dementia. Moreover, the study suggests that people who experience sleep-maintenance insomnia (difficulty falling back to sleep in the middle of the night) have a reduced risk of developing dementia within the same time period.

“We expected sleep-initiation insomnia and sleep medication usage to increase dementia risk, but we were surprised to find sleep-maintenance insomnia decreased dementia risk,” said lead investigator Roger Wong, PhD, MPH, MSW, in a statement.

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The Assistant Professor of SUNY Upstate Medical University in Syracuse, NY, said he was motivated to conduct the study for personal reasons when his father experienced chronic sleep disturbances when the COVID-19 pandemic began. “I was concerned how this would affect his cognition in the future,” said Wong. “After reading the existing literature, I was surprised to see mixed findings on the sleep-dementia relationship, so I decided to investigate this topic.”

Wong’s study is innovative since it is the first to look at the relationship between long-term sleep disturbance indicators and the risk of developing dementia, using a representative sample of older adults from the United States. Prior research has connected cognitive decline to rapid eye movement (REM) sleep behavior, sleep deprivation (less than five hours of sleep), and the usage of short-acting benzodiazepines. This new study’s findings for sleep-maintenance insomnia align with recent research that employed smaller data sets.

The study analyzed data from the National Health and Aging Trends Study (NHATS), a longitudinal panel study of Medicare beneficiaries aged 65 years and older in the United States, over a period of 10 years (2011-2020). Only those who did not have dementia at the start of the study in 2011 were included in the analysis.

 “By focusing on the variations in sleep disturbances, our findings can help to inform lifestyle changes that can reduce dementia risk,” said co-investigator Margaret Anne Lovier, MPH.

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Although more studies are needed to determine how sleep-maintenance insomnia leads to a decreased risk of dementia, the researchers suggest that engaging in activities that help preserve or increase cognitive reserve may be a contributing factor.

“Older adults are losing sleep over a wide variety of concerns,” said Wong. “Our findings highlight the importance of considering sleep disturbance history when assessing the dementia risk profile for older adults. Future research is needed to examine other sleep disturbance measures using a national longitudinal sample, whether these sleep-dementia findings hold true for specific dementia subtypes, and how certain sociodemographic characteristics may interact with sleep disturbances to influence dementia risk.”