AAIC19: Lifestyle Interventions and Alzheimer’s Risk

One of the big topics presented at the Alzheimer’s Association International Conference (AAIC) 2019 in Los Angeles was the effect of lifestyle on the risk of Alzheimer’s disease.

One of the studies presented on Sunday evaluated data from 196,383 adults of European ancestry who were 60 years of age or older. The data was pulled from the UK Biobank. The researchers found 1,769 cases of dementia over a median follow-up period of eight years.

The team then sorted the participants into high, intermediate and low genetic risk for dementia, as well as favorable, intermediate and unfavorable lifestyles based on diet, physical activity, smoking and alcohol consumption.

“We included four healthy lifestyle factors in our lifestyle score: no current smoking, regular physical activity, moderate alcohol consumption and healthy diet,” Elzbieta Kuzma, a researcher at the University of Exeter Medical School and a visiting academic at the University of Medical Center Hamburg-Eppendorf and the Albertinen-Haus Centre for Geriatrics and Gerontology, Scientific Department at the University of Hamburg in Hamburg, Germany, told BioSpace.

Kuzma and the research group utilized a polygenic risk score (PRS) based on Alzheimer’s disease genome-wide association studies statistics that have already been published. This PRS included all mutations linked to Alzheimer’s. Then the genetic risk factor was weighted according to how closely associated it was with the disease.

“Genetic risk and lifestyle factors were independently associated with risk of dementia, meaning that living a healthy lifestyle was associated with a reduced dementia risk, regardless of genetic risk,” Kuzma said. “When we investigated dementia risk within genetic risk categories, healthy lifestyle was associated with a 32% reduced risk of dementia in those with high genetic risk.”

The bottom line is that people with a high genetic risk of Alzheimer’s and an “unfavorable lifestyle,” are nearly three times more likely to develop dementia than people with a low genetic risk and a favorable lifestyle. Even if a person has a high genetic risk, a healthy lifestyle, meaning not smoking, regular exercise, limited alcohol intake and a healthy diet, could decrease the risk of dementia by a third.

“Many people are worried about developing dementia,” Kuzma told BioSpace. “Our findings are very exciting as they show that living a healthy lifestyle is associated with a reduced risk of dementia even in those with high genetic risk for dementia. This strengthens the need for healthy lifestyle interventions that may help to prevent or delay dementia.”

This study was led by the University of Exeter Medical School.

At least four other lifestyle-related studies were also presented at the AAIC 2019 meeting on Sunday. Researchers at Rush University Medical Center in Chicago used data from the Chicago Health and Aging Project and the Rush Memory and Aging Project to study healthy lifestyles and Alzheimer’s. This research focused on five low-risk lifestyle factors including a healthy diet, at least 150 minutes per week of moderate to vigorous physical activity, no smoking, light to moderate alcohol intake and cognitively stimulating activities.

In their study, they found that patients who adopted four out of five of the low-risk factors had about 60% lower risk of Alzheimer’s dementia compared to patients who didn’t follow any or only one of the low-risk factors. But patients who adopted one or more low-risk lifestyle factors, regardless of current behaviors, decreased their risk by 22%.

Another presentation, by Diana Younan, a senior research associate at the University of Southern California, looked at women aged 65 to 79 years from the Women’s Health Initiative Memory Study who did not have dementia at the time of enrollment. They evaluated whether exposure to outdoor air pollution changed the risk of Alzheimer’s. Their research confirmed that high air pollution increased the risk for Alzheimer’s and other dementias, and that older women with a higher cognitive reserve had a 21% increased risk compared to 113% for women with lower cognitive reserve. Cognitive reserve refers to the brain’s capacity to deal with the negative impact of brain damage on cognition.

A similar study presented by Amber Bahorik, a postdoctoral researcher at the University of California, San Francisco (UCSF), and the team led by Kristine Yaffe, the principal investigator, evaluated the risk cigarette smoking may have on cognitive function in mid-life. The investigation looked at patients over 25 years to determine the connection between smoking and cognitive function.

They found that compared to non-smokers, “heavy stable” smokers were 1.5 to 2.2 times more likely to have cognitive impairment. People who quit or who were classified as “minimal stable” did not have an increased risk. Cognitive impairment among smokers was observed as early as their 40s.

Bahorik and Yaffe also presented research on alcohol use disorder (AUD) among female military personnel over the age of 55. They studied 2,207 female veterans without AUD over the age of 55 at Veterans Health Administration medical centers from October 2004 to September 2015—all were free of dementia at baseline. They found that an average of 3.6 years of follow up, 4% of female veterans with AUD developed dementia compared to only 1% in the control, non-AUD group. Essentially, women with AUD have a greater than a threefold increased risk of developing dementia.