Certain variations found in genes that correlate with intelligence and may affect “cognitive reserve” are evident in people with higher levels of education and appear to work to protect against Alzheimer’s disease (AD), new research shows.
Better educating young adults may help to reduce the expected rise in AD incidence as people worldwide live longer, its researchers said.
In the study “Modifiable pathways in Alzheimer’s disease: Mendelian randomisation analysis,” researchers examined 24 modifiable risk factors, or factors that can be changed — such as lifestyle and diet — using “genetic variants as proxies” for these factors.
Specifically, they compared variations in genes — called genetic variants — among 17,000 Alzheimer’s patients and 37,000 healthy controls using a technique called Mendelian randomization. This technique makes it possible to identify a cause for a given disease by first establishing an association between certain genes or genetic variants and a disease risk factor.
Variants that predict a potential for higher levels of education, they reported, were associated with a reduced risk for AD. “We … found suggestive evidence for an inverse association between genetically predicted intelligence and [Alzheimer’s] risk,” the team wrote.
Study results also suggested that higher coffee consumption, but not alcohol consumption, may be associated with Alzheimer’s development. Other modifiable risk factors are socioeconomic, cardiometabolic (risk of cardiovascular disease and diabetes) or inflammatory in nature.
The exact reason why higher education protects against AD is not known, but the researchers consider that “cognitive reserve” may be it. Cognitive reserve is the ability to compensate for aging by using brain structures or networks that are not normally used, instead of relying on those that no longer function or work less well.
“Evidence suggests that education helps improve brain networks and thus could increase this reserve,” Susanna Larsson, a lead study investigator and an associate professor at the Institute of Environmental Medicine at Karolinska Institutet in Sweden, said in a press release.
Obesity and cardiometabolic risk factors are not associated with AD, the study reported.
“Our findings corroborate the results from previous Mendelian randomisation analyses showing no associations of genetically predicted BMI … diabetes, fasting glucose and insulin … cholesterol (with exclusion of genetic variants near APOE), or triglycerides with Alzheimer’s disease,” the researches wrote. The APOE gene known to affect a person’s AD risk.
“Our results provide the strongest evidence so far that higher educational attainment is associated with a lower risk of Alzheimer’s disease. Therefore, improving education may substantially decrease the number of people developing this devastating disease,” Larsson said.
The European Union’s Horizon 2020 research and innovation program and the Swedish Brain Foundation funded the study, published in the British Medical Journal.