Schizophrenia and cardiometabolic abnormalities: A Mendelian randomization study.

Area of Science:

• Psychiatry
• Genetics
• Cardiology

Background:

• Individuals with schizophrenia face higher mortality risk due to physical health issues, particularly cardiovascular disease, diabetes, and obesity.
• Complex factors contribute to these health disparities, including antipsychotic drug side effects, lifestyle, and potentially schizophrenia itself.

Purpose of the Study:

• To investigate the potential causal relationship between schizophrenia and cardiometabolic traits using bi-directional Mendelian randomization (MR).
• To determine if schizophrenia causally influences blood lipids, anthropometric traits, glycaemic traits, and blood pressure, and vice versa.

Main Methods:

• Employed bi-directional two-sample Mendelian randomization (MR) analysis.
• Utilized 185 genetic variants for schizophrenia (n=130,644) and relevant cardiometabolic trait genetic variants from large consortia.
• Applied inverse-variance weighted MR as the primary method, supported by MR-Egger and median/mode-based methods.

Main Results:

• Forward analysis suggested a weak association between schizophrenia and slightly higher low-density lipoprotein (LDL) and total cholesterol levels, but these did not withstand multiple testing correction.
• Reverse analysis found no evidence of a causal effect of cardiometabolic traits on schizophrenia.

Conclusions:

• Schizophrenia itself is unlikely to be the primary driver of dyslipidemia and obesity in affected individuals.
• Lifestyle factors, antipsychotic side effects, and shared mechanisms like low-grade systemic inflammation may contribute to metabolic dysfunction in schizophrenia.
• Further research is warranted to explore potential shared immune mechanisms linking schizophrenia and metabolic disease.