Longevity Without Alzheimer's Tied to Lifestyle

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A healthy lifestyle was tied to a longer life but the extra years did not mean more time living with Alzheimer's dementia, a prospective study showed.

People who had four or five healthy lifestyle factors -- spanning diet, cognitive activity, physical exercise, smoking, and alcohol patterns -- at age 65 lived longer than their counterparts with zero or one healthy factors, according to Klodian Dhana, MD, PhD, of Rush University Medical Center in Chicago, and colleagues. Women added 3.1 years of life, while men added 5.7 years.

Of their total life expectancy at age 65, women with four or five healthy factors spent 10.8% of their remaining years with Alzheimer's dementia, while women with zero or one factors spent 19.3%, they reported. Men with four or five healthy factors spent 6.1% of their remaining life with dementia, while those with zero or one spent 12%.

"At age 85, these differences were even more notable," Dhana and colleagues wrote inBMJ.

Healthy lifestyles have been linked with a lower risk of Alzheimer's dementia and longer life. But with increasing life expectancy, more people reach ages when cognitive impairment and dementia become increasingly common, noted HwaJung Choi, PhD, of the University of Michigan in Ann Arbor, in an accompanying editorial.

"Older age is strongly associated with a higher risk of dementia, so although a healthier lifestyle may delay the onset of dementia, it might also increase the number of years spent with dementia," Choi wrote. "A better understanding of this nuance -- years spent with versus without dementia -- is important for assessing the overall implications of interventions promoting a healthy lifestyle for individuals, families, and society."

"Plainly, reducing the incidence and prevalence of dementia is an urgent public health imperative for sustainable long term care systems," she added. "Alzheimer's disease and other dementias are among the most expensive health conditions both economically and socially, having a profound impact on those with dementia, their families, and wider society."

An estimated 6.5 million adults in the U.S. have dementia. The national cost of caring for people with Alzheimer's and other dementias is an estimated $321 billion in 2022, according to the Alzheimer's Association. In addition, family members and friends contribute $271 billion more in unpaid care.

In their analysis, Dhana and colleagues evaluated data from 2,449 older adults with a mean age of 76 in the Chicago Health and Aging Project (CHAP) who were recruited from 1993 to 2009. The study population included 2,110 people free of Alzheimer's dementia at baseline and 339 people with prevalent Alzheimer's dementia. More than half of participants (57% of women and 56% of men) were Black or African American.

Participants completed detailed food frequency and lifestyle questionnaires. A healthy lifestyle score was based on five factors: a diet rich in whole grains, green leafy vegetables and berries and low in fast food, fried food, and red meats; late-life cognitive activities like reading, playing games, or visiting a museum; at least 150 minutes a week of moderate or physical activity including walking for exercise, gardening, or swimming; not smoking; and low-to-moderate alcohol consumption.

Diet quality was determined using the Mediterranean-DASH Diet Intervention for Neurodegenerative Delay (MIND) diet score, which has been significantly associated with a slower cognitive decline and lower risk of incident Alzheimer'sdementia.

For each lifestyle factor, participants received a score of 1 if they met criteria for healthy and 0 if they did not. Scores from five lifestyle factors were summed to yield a final score ranging 0 to 5, with a higher score indicating a healthier lifestyle.

At age 65, after adjusting for age, sex, ethnicity, and education, total life expectancy for women and men with the healthiest lifestyle was 24.2 and 23.1 years, respectively. For 65-year-olds with the least healthy lifestyle, life expectancy was 21.1 years for women and 17.4 years for men.

The research had limitations, Dhana and colleagues acknowledged. Adherence to lifestyle factors was self-reported at baseline and not updated during follow-up. In addition, people with unhealthy lifestyles may have been less likely to participate in the study.

"The life expectancy estimates provided in this study should not be generalized to other populations without additional research and validation," the researchers noted.