December 18, 2017
While the search for a drug to treat Alzheimer’s disease trudges on, emerging prevention evidence is the most encouraging news for those who have seen loved ones in the grips of the disease. In a new study from the University of Cambridge, scientists have concluded that education is likely a key factor in prevention, a theory that is supported by many researchers and other studies.
A genetic study of 17,000 Alzheimer’s patients and a control group of 37,000 healthy people showed that genetic variants that predict higher education—yes, there are genes associated with the likelihood of higher education—were the strongest factors in preventing Alzheimer’s disease. Researchers also looked at genes associated with smoking, vitamin D, coffee and alcohol consumption, but did not find conclusive results.
“Many studies have shown that certain risk factors are more common in people with Alzheimer’s disease, but determining whether these factors actually cause Alzheimer’s is more difficult,” said Hugh Markus, a professor from the Department of Clinical Neurosciences at the University of Cambridge.
It’s always tricky to tease out the role lifestyle factors play in preventing or causing Alzheimer’s. Often studies can show that certain factors are correlated with increased or decreased risk, but proving that they causation is almost impossible without a randomized control trial like the FINGER study, which showed that diet and cognitive training made a difference in dementia risk.
“Many studies have shown that the more years spent in full time education, the lower the risk of Alzheimer’s,” said Markus. “But it is difficult to unravel whether this is an effect of education improving brain function, or whether it’s the case that people who are more educated tend to come from more wealthy backgrounds and therefore have a reduction in other risk factors that cause Alzheimer’s disease,” he added.
In order to do so, Markus used a technique called Mendelian randomization. This analyzes an individual’s DNA and compares genes associated with certain risk factors—like education or smoking—and looks at what genes are also associated with Alzheimer’s disease. If a gene is associated with both, Mendelian theory says that it’s likely the risk factor is a cause of the disease.
While education proved to be the strongest association with Alzheimer’s prevention in this study, it’s not clear how education protects against Alzheimer’s. One theory is that it increases a person’s cognitive reserve, or the amount of brain power in other areas they can use to compensate for areas Alzheimer’s destroys.
The good news, though, is the addition of more evidence for prevention tactics. “This provides further strong evidence that education is associated with a reduced risk of Alzheimer’s disease,” says first author Dr. Susanna Larsson. “It suggests that improving education could have a significant effect on reducing the number of people who suffer from this devastating disease.”