Study details

For the study, researchers from the University of Oxford looked at brain scans of 39,676 adults between the ages of 44 and 82 who participated in the U.K. Biobank.

The researchers then assessed 161 risk factors for dementia and ranked them according to their impacts on regions of the brain that were specifically vulnerable to age-associated degeneration, as well as schizophrenia and Alzheimer's disease.

The risk factors were divided into 15 categories:

• Blood pressure
• Cholesterol
• Diabetes
• Weight
• Alcohol consumption
• Smoking
• Depressive mood
• Inflammation
• Pollution
• Hearing
• Sleep
• Socializing
• Diet
• Physical activity
• Education

The researchers found that a diagnosis of diabetes, the amount of nitrogen dioxide in the air, and how often someone drinks alcohol were the three most detrimental risk factors to the studied regions of the brain, according to Gwenaëlle Douaud, an associate professor at Oxford and co-author of the study.

Douaud noted that diabetes, air pollution, and alcohol consumption each had an effect that is nearly twice as much as the other leading factors. The next biggest risk factors were sleep, weight, smoking, and blood pressure.

The researchers also found seven genetic clusters that affected the vulnerable regions of the brain, including some that are associated with Parkinson's and Alzheimer's disease. However, Douaud noted that the genetic and modifiable risk factors aren't comparable.

Discussion

According to Douaud, the new study shows "that these specific parts of the brain are most vulnerable to diabetes, traffic-related air pollution — increasingly a major player in dementia — and alcohol, of all the common risk factors for dementia."

Gill Livingston, a professor of psychiatry of older people at University College London, said the new study was "very interesting," but added that participants in the U.K. Biobank are a "much healthier" and highly motivated group of people, meaning the findings may not be applicable to a larger population.

That said, the findings still show that people can make decisions to reduce their risk of dementia as they get older, Livingston said.

"There's quite a lot people can do in their everyday life to maintain cognitive health," she said. "This just reinforces it."

Anderson Winkler, a professor and co-author of the study who works with NIH and the University of Texas Rio Grande Valley, said the study's findings are especially interesting because of the study's comprehensive and holistic approach.

"What makes this study special is that we examined the unique contribution of each modifiable risk factor by looking at all of them together to assess the resulting degeneration of this particular brain 'weak spot,'" he said.

How you can reduce your risk of cognitive decline

According to Douaud, if you want to reduce your risk of cognitive decline, you should try to eat a healthy, varied diet to lower your blood sugar, take steps to protect against "traffic-related pollution," and drink alcohol in moderation.

"Of course, some of these should not only be down to individuals, and the burden should also be shared with (local) governments devising helpful policies," Douaud added.

According to Livingston, social and physical activity, like talking with friends and exercising, "make a huge difference." And any stimulating experiences like walking outside, "seeing different things," can be beneficial as well, she added.

Also, "if you smoke, stop," Livingston said. (Amenabar, Washington Post, 3/27; Dewan, Newsweek, 3/27)

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