Alzheimer’s disease (AD) may have a causal effect on sleep patterns, but disturbed sleep does not appear to cause AD, new research suggests.

The causal association between disturbed sleep and AD that has been observed in previous studies may have resulted from reverse causation, the investigators note.

The current Mendelian randomization analysis also failed to find a causal relationship between AD and major depressive disorder (MDD). Future studies should examine the genetic heterogeneity of depression syndromes to test for causal relationships between subtypes of depression with distinct causes and AD, the researchers write.

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