A retrospective medical record review, study published in the August 19, 2020 online issue of Neurology, suggests that, although disturbed sleep patterns do not cause Alzheimer disease (AD), individuals with high genetic risk for developing AD may be more likely to have those patterns.
There was no evidence that sleep-related characteristics caused AD, and no evidence of cause and effect between major depressive disorder and AD. People with twice the genetic risk for AD were 1% more likely to call themselves morning people than those at lower genetic risk, and people with twice the risk of AD had a 1% lower risk of insomnia. The effect of this association is small and shows only a possible link, not cause and effect.
“We know that people with AD often report depression and various sleep problems, like insomnia,” said Abbas Dehghan, PhD, Imperial College London. “We wanted to find out if there are causal relationships between different sleep patterns, depression, and AD.”
The study found that those at high genetic risk may be more likely to rise early, have shorter sleep duration, and be less likely to have insomnia.
Researchers analyzed the results of genetic studies from databases that included 21,982 invidividuals diagnosed with AD and compared these with records of 41,944 people without AD, 9,240 with major depressive disorder (MDD) and 9,519 without MDD, and measurements of the sleep-related characteristics of 446,118 people.
Researchers determined the risk of AD by clinical examination or autopsy and analyzed genetic information using the Mendelian randomization study design to determine cause and effect.