Education, intelligence and Alzheimer's disease: evidence from a multivariable two-sample Mendelian randomization
Emma L Anderson1,2, Laura D Howe1,2, Kaitlin H Wade1,2
1Medical Research Council Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.
International Journal of Epidemiology
|February 1, 2020
Summary
Intelligence causally reduces Alzheimer's disease (AD) risk, independent of education. Educational attainment's protective effect on AD is likely mediated through intelligence, highlighting cognitive function's role in brain health.
Area of Science:
- Neuroscience
- Genetics
- Epidemiology
Background:
- Alzheimer's disease (AD) poses a significant public health challenge.
- The interplay between educational attainment, intelligence, and AD risk is complex and requires investigation.
- Understanding these relationships can inform preventative strategies for cognitive decline.
Purpose of the Study:
- To investigate the independent causal effects of educational attainment and intelligence on Alzheimer's disease (AD) risk.
- To determine if the relationship between education and AD is mediated by intelligence.
Main Methods:
- Utilized two-sample Mendelian randomization (MR) analysis.
- Examined univariable and multivariable MR to assess causal pathways.
- Employed data from the International Genomics of Alzheimer's Project (IGAP) consortium, including 17,008 AD cases and 37,154 controls.
Main Results:
- Found strong bidirectional causal relationships between intelligence and educational attainment.
- Both higher educational attainment and intelligence were associated with reduced AD risk in univariable analyses (ORs 0.63 and 0.65, respectively).
- Multivariable MR indicated that intelligence independently lowers AD risk (OR 0.69), while education's effect appears mediated by intelligence (OR 1.15).
Conclusions:
- Confirmed a robust, independent causal effect of intelligence in reducing Alzheimer's disease risk.
- The protective association of educational attainment against AD is likely mediated by intelligence.
- Cognitive ability is a key factor in mitigating AD risk.
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