THURSDAY, Aug. 20, 2020 (HealthDay News) -- Alzheimer disease (AD) may causally influence sleep patterns, but these patterns do not have a causal role in AD, according to a study published online Aug. 19 in Neurology.
Jian Huang, Ph.D., from Imperial College London in the United Kingdom, and colleagues conducted bidirectional two-sample Mendelian randomization analyses to examine the causal relationships between sleep, major depressive disorder (MDD), and AD. Data were included from genome-wide association studies in the U.K. Biobank (446,118 individuals), the Psychiatric Genomics Consortium (18,759 individuals), and the International Genomics of Alzheimer's Project (63,926 individuals).
The researchers found that after adjustment for multiple comparisons, the risk for AD was significantly associated with being a morning person (odds ratio, 1.01), shorter sleep duration, being less likely to report long sleep, earlier timing of the least active five hours, and a smaller number of sleep episodes. There was an association for higher risk for AD with a lower risk for insomnia (odds ratio, 0.99). No evidence was found for a causal relationship for either of these abnormal sleep patterns with AD or for a significant causal relationship between MDD and the risk for AD.
"We found evidence supporting a potential causal influence of AD on sleep disturbances," the authors write. "However, we did not find evidence supporting a causal role of disturbed sleep patterns on AD, suggesting that observed associations between sleep disorders and AD may be due to reverse causation."
One author disclosed financial ties to the biopharmaceutical industry.