Dementia Risk: Genetics, Metabolome & Mediterranean Diet

Here’s a breakdown of the facts provided, focusing on the GWAS data sources and study methodology:

Study Overview:

The study aims to understand the causal relationships between plasma metabolites (and their ratios) and cognitive outcomes.
It uses a method called Mendelian Randomization (MR), which leverages genetic data to infer causality.

GWAS data Sources:

Exposures (Plasma Metabolites & Ratios): GWAS summary statistics were obtained from Chen et al. (2023)¹¹, which provides a “genomic atlas of the plasma metabolome.” This study analyzed 1,091 metabolites and 309 metabolite ratios.
Outcomes (Cognitive Traits): GWAS summary statistics were obtained from several sources:
Overall Dementia: kurki et al. (2023)⁶⁶
Alzheimer’s Disease (AD): Wightman et al. (2021)⁸
Vascular Dementia: Kurki et al. (2023)⁶⁶
Cognitive Performance: lee et al. (2018)⁶⁷

Crucial Considerations:

No Participant Overlap: The individuals included in the GWAS for the metabolites (exposures) were not the same individuals as those in the GWAS for the cognitive outcomes. This is crucial for MR analysis to avoid confounding.
European Ancestry: All GWAS populations used in the study were of European ancestry.This limits the generalizability of the findings to other populations.
Variant Selection: The study included all variant-metabolite pairs selected in the original Chen et al. (2023) study,plus additional pairs based on criteria described in the Supplementary Text. Total Variants: A total of 1,431 variant-metabolite/ratio pairs were used.

In essence, this study is a secondary analysis that re-purposes existing, large-scale genetic data (GWAS) to investigate potential causal links between what’s happening in your blood (metabolites) and how your brain functions (cognitive outcomes).