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Chronic insomnia linked to faster cognitive decline

A study found the condition added 3.5 years to brain aging

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Mark Huffman
Reporter

Mark Huffman has covered consumer issues since 2004, with a special focus on protecting and empowering older adults. A former news correspondent for the Associated Press Radio Network, Westwood One, and ConsumerAffairs, Mark brings decades of journalistic experience to RetirementLiving.com. He is passionate about giving consumers a voice and helping them make informed decisions. Mark has also created educational content, including Senior Scam Alert, a video resource designed to help seniors recognize and avoid fraud. He holds a B.A. from the University of Kentucky and lives with his family in Richmond, Virginia.
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Key Insights

  • People with chronic insomnia face a 40% higher risk of developing mild cognitive impairment or dementia.
  • Brain scans reveal that insomnia is linked to white matter damage and amyloid plaques tied to Alzheimer’s disease.
  • Researchers say treating insomnia could help protect brain health as people age.

People struggling with chronic insomnia may be at higher risk for memory loss, thinking problems, and visible brain changes as they age, according to new research.

A study published in the journal Neurology, the medical journal of the American Academy of Neurology, found that older adults with chronic insomnia, defined as difficulty sleeping at least three nights a week for three months or more, were 40% more likely to develop mild cognitive impairment or dementia compared to those who sleep normally. That risk level was comparable to adding 3.5 years of brain aging.

“Insomnia doesn’t just affect how you feel the next day; it may also impact your brain health over time,” said Dr. Diego Z. Carvalho of the Mayo Clinic. “We saw faster decline in thinking skills and changes in the brain that suggest chronic insomnia could be an early warning sign or even a contributor to future cognitive problems.”

Detailed findings

Researchers tracked 2,750 cognitively healthy adults with an average age of 70, over 5.6 years. Sixteen percent reported chronic insomnia. Participants underwent annual memory and thinking tests, and some received brain scans to check for signs of small vessel disease and amyloid plaques, both of which are associated with dementia.

By the study’s end, 14% of participants with insomnia developed mild cognitive impairment or dementia, compared to 10% of those without insomnia. The results held up, even after adjusting for age, high blood pressure, sleep apnea, and use of sleep medications.

People reporting less sleep than usual in the prior two weeks scored lower on cognitive tests at the start of the study, equivalent to being four years older. They also showed more brain damage markers: white matter hyperintensities and amyloid buildup, a protein linked to Alzheimer’s disease. For amyloid deposits, the effect was comparable to having the APOE ε4 gene, a well-known Alzheimer’s risk factor.

By contrast, those reporting more sleep than usual had fewer white matter hyperintensities, suggesting sleep changes may affect the brain differently depending on direction.

Genetic risk and vulnerability

The effects of insomnia were especially pronounced in people carrying the APOE ε4 gene. These participants experienced steeper declines in memory and thinking, underscoring how sleep disturbances may interact with genetic vulnerabilities to accelerate brain decline.

“Our results suggest that insomnia may affect the brain in different ways, involving not only amyloid plaques, but also small vessels supplying blood to the brain,” Carvalho said. “This reinforces the importance of treating chronic insomnia—not just to improve sleep quality but potentially to protect brain health as we age.”

Researchers caution that the findings show an association, not proof that insomnia directly causes dementia. Insomnia diagnoses were based on medical records, meaning undiagnosed or varying severity levels may not have been fully captured.