Fruit Intake and Alzheimer's Disease: Results from Mendelian Randomization

Area of Science:

• Nutritional Neuroscience
• Genetic Epidemiology

Background:

• Alzheimer's disease (AD) is a leading cause of dementia and a global health concern.
• Dietary factors are increasingly investigated for their role in neurodegenerative disease etiology.
• Understanding the specific impact of fruit intake on AD risk is crucial for public health recommendations.

Purpose of the Study:

• To investigate the potential causal effects of fresh fruit intake and dried fruit intake on Alzheimer's disease (AD) liability.
• To differentiate the impact of various fruit processing methods (fresh vs. dried) on AD risk.

Main Methods:

• Utilized Mendelian randomization (MR) analysis with genome-wide association study (GWAS) data from UK Biobank and FinnGen.
• Employed inverse variance weighted (IVW), MR-Egger, and weighted median approaches for robust causal inference.
• Assessed result stability through visual inspections, heterogeneity, and pleiotropy analyses.

Main Results:

• Found no significant evidence for a causal relationship between fresh fruit intake and AD liability (OR=0.97, P=0.939).
• Demonstrated a significant, robust positive causal association between dried fruit intake and increased AD liability (OR=4.09, P<0.001).
• Stability analyses confirmed no significant heterogeneity or pleiotropy, supporting the credibility of the findings.

Conclusions:

• Strengthened evidence supports a positive causal effect of dried fruit consumption on Alzheimer's disease liability.
• The study did not find evidence to support a causal role for fresh fruit intake in Alzheimer's disease risk.
• Findings highlight the importance of considering food processing in dietary recommendations for neurodegenerative disease prevention.