Sleep, major depressive disorder, and Alzheimer disease: A Mendelian randomization study.

Objective: To explore the causal relationships between sleep, major depressive disorder (MDD), and Alzheimer disease (AD).

Methods: We conducted bidirectional 2-sample Mendelian randomization analyses. Genetic associations were obtained from the largest genome-wide association studies currently available in UK Biobank (n = 446,118), Psychiatric Genomics Consortium (n = 18,759), and International Genomics of Alzheimer's Project (n = 63,926).