People who have insomnia may be at much higher risk of developing dementia than people who have no trouble sleeping, a new study suggests.
People who had trouble sleeping at least three nights a week for three or more months were at 40% increased risk of developing mild cognitive impairment or dementia than people without insomnia, the study found. The increased risk equaled about 3 1/2 years of additional aging, according to the researchers.
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"Insomnia doesn't just affect how you feel the next day — it may also impact your brain health over time," the study's author, Dr. Diego Carvalho, of the Mayo Clinic, said in a news release. "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."
For the study, researchers followed 2,750 adults with an average age of 70 for more than five years. Throughout the study, researchers administered yearly thinking and memory tests. Some people also had brain scans to track the accumulation of amyloid plaques associated with Alzheimer's disease, the most common type of dementia, and other brain changes associated with cognitive decline.
Among the group with chronic insomnia, 14% developed mild cognitive impairment, compared to 10% of people without insomnia. People with chronic insomnia also showed a faster deterioration on tests of thinking skills.
"If confirmed in future studies, these results could help shape strategies to preserve long-term brain health by considering not just sleep quality, but also how long people sleep," Dr. Santiago Clocchiatti-Tuozzo, a neurology resident at Yale New Haven Hospital who studies sleep and brain health, told The Washington Post.
Clocchiatti-Tuozzo was not involved in the Mayo Clinic study.
The study, published in the journal Neurology, controlled for age, high blood pressure, use of sleep medications and a diagnosis of sleep apnea. While it found a link between insomnia and dementia, the study did not establish that poor sleep causes cognitive decline.