Genetic instrumental variable analysis reveals multivariate dietary patterns beneficial to patients with Alzheimer's disease.

Background: Dietary patterns (DPs) are important in the modulation of the pathogenesis of Alzheimer's disease (AD) and progression of neurodegeneration. However, literature reports are inconsistent in studies examining how DPs benefit AD patients. Objective: To assess potential causal links between diets and AD risk occurrence. Methods: Based on comprehensive genome-wide association studies data, potential links between diets and AD risk were assessed by conventional and advanced Mendelian randomization and sensitivity analyses using single nucleotide polymorphisms as genetic instruments. Results: Protein (95% CI: -0.280 to -0.250), fat (95% CI: -0.091 to -0.042), and carbohydrates (95% CI: -0.048 to -0.021) displayed protective roles in AD. The role of sugar, one component of carbohydrates, was ambiguous in development of AD. 24 DPs derived from daily diet habits were negative in the association with AD and 24 DPs of daily diet habits positively associated with AD. Many single diet factors such as beer, decaffeinated coffee, non-oily fish, lamb/mutton, and biscuit cereal were found to display harmful or protective roles in AD development and progress. However, their roles were varied in DPs of individual diet habits and showed significant positive or negative loadings to AD risks dependent on DPs, not dependent on single diet factors themselves. Conclusions: Significantly detrimental or protective loadings to AD risks are dependent on DPs of individuals, not dependent on the single diet factor itself. Data here suggests that, for principles, daily DPs should balance protein, fat, including saturated fatty acids and unsaturated fatty acids, and carbohydrates to prevent AD development and progress.