Healthy lifestyle prolongs life, may prevent dementia onset

A healthy lifestyle among older men and women leads to a longer life expectancy, with freedom from Alzheimer’s dementia (AD) in their remaining years, a study has shown.

“The life expectancy estimates might help health professionals, policy makers, and stakeholders to plan future healthcare services, costs, and needs,” the researchers said.

A total of 2,449 older adults (aged ≥65 years) in the US participated in this prospective cohort study. The researchers developed a healthy lifestyle score based on five modifiable factors: a diet for brain health (Mediterranean-DASH Diet Intervention for Neurodegenerative Delay—MIND diet score in upper 40 percent of cohort distribution), late life cognitive activities (composite score in upper 40 percent), moderate or vigorous physical activity (≥150 min/week), no smoking, and light to moderate alcohol consumption (women 1–15 g/day; men 1–30 g/day).

Sixty-five-year-old women with four or five healthy factors had a life expectancy of 24.2 years (95 percent confidence interval [CI], 22.8‒25.5) and lived 3.1 years longer than those with zero or one healthy factors (life expectancy, 21.1 years, 95 percent CI, 19.5‒22.4). [BMJ 2022;377:e068390]

Of the total life expectancy at 65 years of age, women with four or five healthy factors spent 10.8 percent (2.6 years, 95 percent CI, 2.0‒3.3) of their remaining years with AD, while those with zero or one healthy factor spent 19.3 percent (4.1 years, 95 percent CI, 3.2‒5.1) with AD. Life expectancy was 21.5 years (95 percent CI, 20.0‒22.7) for women without AD and four or five healthy factors and only 17.0 years (95 percent CI, 15.5‒18.3) for those with zero or one healthy factor.

In men, total life expectancy was 23.1 years (95 percent CI, 21.4‒25.6) for those with four or five healthy factors, 5.7 years longer than men with zero or one healthy factors (life expectancy, 17.4 years, 95 percent CI, 15.8‒20.1).

Of the total life expectancy at 65 years of age, men with four or five healthy factors spent 6.1 percent (1.4 years, 95 percent CI, 0.3‒2.0) of their remaining years with AD, while those with zero or one healthy factors spent 12.0 percent (2.1 years, 95 percent CI, 0.2‒3.0) with AD. Life expectancy was 21.7 years (95 percent CI, 19.7‒24.9) for men without AD and four or five healthy factors and 15.3 years (95 percent CI, 13.4‒19.1) for those with zero or one healthy factor.

Sex difference

These findings were consistent with those from a previous study, which found that women had a higher life expectancy than men and a higher percentage of life expectancy lived with dementia. [Am J Public Health 2015;105:408-413]

Of note, the research community recognized sex differences in the prevalence and incidence of AD. For instance, a recent study focusing on sex differences in dementia risk found that while vascular, lifestyle, and psychosocial risk factors could have a similar effect on men and women, the latter had a much higher risk upon reaching 80 years. [Am J Public Health 2015;105:408-413; Alzheimers Dement 2015;11:310-320; Alzheimers Dement 2021;17:1166-1178]

“Therefore, our study supports the hypothesis that a higher life expectancy in women could be a potential explanation for seeing more women than men living with dementia,” the researchers said. “However, further research is required to better understand sex differences in AD risk.”

Cognitive decline

Previous studies had also reported the association of adherence to a healthy lifestyle with a slower cognitive decline and a lower risk of AD. In addition, lifestyle factors predicted longevity. The adoption of a healthy lifestyle could thus prolong life expectancy. [Neurology 2020;95:e374-383; Am J Epidemiol 2021;190:1225-1233; Alzheimers Dement 2021;doi:10.1002/alz.12435; Alzheimers Dement 2021;doi:10.1002/alz.12435; Circulation 2018;138:345-355]

“With increasing life expectancy, more people will reach older ages when cognitive impairment and Alzheimer’s dementia become increasingly common, questioning the long-term consequence of lifestyle interventions on AD,” the researchers said.

“We observed that a healthy lifestyle is associated with a lower risk of AD and mortality, suggesting that the event of dementia could be postponed in older ages and people will live longer, which ultimately will contribute to increased years lived free from AD,” they added.