Alzheimer's: a healthy lifestyle can delay the onset of the disease up to 6 years

More than 55 million people worldwide have a disease linked to dementia, according to data from the World Health Organization (WHO). This number will almost double every 20 years, reaching 78 million in 2030 and 139 million in 2050. Much of the increase will occur in developing countries.

Faced with the advancement of this mental illness, scientists are investigating how to prevent or delay its onset. Now, a new analysis showed that a healthy lifestyle could delay the onset of Alzheimer's disease by up to six years and shorten the length of time spent living with dementia, according to a new prospective study conducted by the University of Michigan School of Medicine and its pair of the University of Chicago, which has just been published in The British Medical Journal.

Although it was already known that a good diet, physical exercise, and reducing tobacco and alcohol consumption helped people live longer, it was unknown whether those extra years would be ruined by aging diseases, such as Alzheimer's.

The new study found that people with four or five healthy lifestyle factors (including a good diet, stimulating cognitive activity, regular physical exercise, a smoke-free life, and moderate alcohol consumption) at age 65 lived longer than their peers on zero or one of the factors said Klodian Dhana, a specialist at Rush University Medical Center in Chicago. Women, as scientists found in their research, added 3.1 years of life, while men 5.7 years.

Of their total life expectancy at age 65, women with four or five health factors spent 10.8% of the remaining years with Alzheimer's dementia, while women with zero or one factor passed 19.3%, they reported. Men with four or five health factors spent 6.1% of the rest of their lives with dementia, while those with zero or one spent 12%. “At age 85, these differences were even more noticeable,” said Dhana.

Healthy lifestyles have been linked to a lower risk of Alzheimer's dementia and longer life, “but with increased life expectancy, more people reach ages when cognitive decline and dementia become increasingly common. Older age is strongly associated with an increased risk of dementia, so while a healthier lifestyle could delay the onset of the disease, it could also increase the number of years spent with dementia,” said HwaJung Choi, co-author of the study and professional at the University of Michigan.

“A better understanding of this nuance (years lived with dementia versus without it) is important to assess the overall implications of interventions that promote a healthy lifestyle for individuals, families and society. Clearly, reducing the incidence and prevalence of dementia is an urgent public health imperative for long-term sustainable care systems, the researcher added. Alzheimer's disease and other dementias are among the most expensive health conditions, both economically and socially, and have a profound impact on the people who suffer from them, their families and society at large.”

It is estimated that 6.5 million adults in the US have dementia. The national cost of caring for people with Alzheimer's and other dementias is estimated at $321 billion in 2022, according to that country's Alzheimer's Association. In addition, family and friends contribute an additional $271 billion in unpaid care.

In their analysis, Dhana and her colleagues evaluated data from 2,449 older adults with an average age of 76 years in the Chicago Health and Aging Project (CHAP) who were recruited between 1993 and 2009. The study population included 2,110 people without Alzheimer's dementia at the start of the study and 339 people with prevalent Alzheimer's dementia. More than half of the participants (57% women and 56% men) were African-American.

Participants completed detailed food frequency and lifestyle questionnaires. And five factors of a healthy lifestyle were evaluated:

1 - A diet rich in whole grains, leafy greens and legumes and low in fast food, fried food and red meat

2 - Stimulating cognitive activities such as reading, doing crosswords, playing games or visiting a museum

3 - Moderate or vigorous physical activity, at least 150 minutes a week of including walking, gardening or swimming

4 - No fumar

5 - Low or 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 slower cognitive decline and a lower risk of incident Alzheimer's dementia.

For each lifestyle factor, participants received a score of 1 if they met the health criteria and 0 if they did not. Scores for five lifestyle factors were added together to obtain a final score of 0 to 5, with a higher score indicating a healthier lifestyle.

The results showed that at age 65, women with a healthy lifestyle could expect to live to 89 and men to 88. On the other hand, the average life expectancy for women with unhealthy habits was 86 years and 82 for men.

For women with a healthy lifestyle, only 2.6 years were lost to Alzheimer's disease and 1.4 for men. But sick women suffered an average of 4.1 years of dementia, while men spent 2.1 years with the disease.

The study suggested that the approximate age of onset of dementia among healthy women would be around 86 years, compared to 81 years for unhealthy women. For healthy men, Alzheimer's can be expected to start around age 86, but unhealthy men can expect a diagnosis 6 years earlier, around age 80.

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