Study confirms that keeping the heart healthy also reduces dementia risk

Posted by Olderiswiser Editorial

"Adopting 4 healthy lifestyle habits might cut your chances of developing dementia, new research suggests," the Sun reports.

heart health reduces chance of dementia?

NHS Choices' Behind the Headlines news analysis service examines the science behind recent newspaper claims that a healthy heart and ditching unhealthy lifestyle choices reduces the risk of developing dementia.

The 4 lifestyle habits, or lifestyle changes, are:

The headline was prompted by a new study that assessed whether 6,000 older adults in France had 7 "healthy heart" characteristics, and then followed them for up to 16 years.

As well as the 4 lifestyle habits already listed, these characteristics included not having high blood pressure, high blood sugar or high cholesterol.

Researchers found the more of these healthy characteristics people had, the less likely they were to develop dementia.

These findings aren't particularly surprising. These factors have long been known to impact dementia risk, particularly the form of dementia known as vascular dementia.

Find out how to reduce your risk of dementia

Where did the story come from?

The study was carried out by researchers from the University of Bordeaux and other research centres in France.

It was carried out under a partnership agreement between INSERM, the University of Bordeaux and Sanofi-Aventis. It was also supported by various foundations and agencies in France.

The study was published in the peer-reviewed Journal of the American Medical Association.

Both the Sun and Mail Online provided a broadly accurate report of the study, but with a difference in focus.

The Sun focused on positive changes that people can make, while the Mail focused on potential risk factors people should avoid.

Doing both would seem to be the best option to reduce your risk of dementia.

What kind of research was this?

This was a prospective cohort study called the 3C Study. The study followed older adults aged 65 and over in 3 cities in France to determine the link between cardiovascular health and the development of dementia.

There are different types of dementia. One type is called vascular dementia, which is known to have the same sort of risk factors as those for heart disease.

The causes of other forms of dementia, such as Alzheimer's, are generally less clear cut, but can also include these heart disease risk factors.

This is the best study design for assessing this question. The main limitation with this type of study is that factors other than the ones the researchers are interested in may affect the results.

Researchers can take steps to reduce the impact of these potential confounders on their analyses, as they did in this study, but it's difficult to be certain that this has removed their impact completely.

What did the research involve?

The researchers recruited older adults from 1999 to 2000 and assessed whether they had 7 "healthy heart" characteristics.

They then followed the participants for 12 years, assessing how well their brains were functioning and whether they developed dementia.

Based on their findings, the researchers assessed to what extent having these 7 characteristics reduced the risk of developing dementia.

The 7 characteristics assessed were the American Heart Association's "Life's Simple 7" recommended optimal behaviours and characteristics for a healthy heart:

  • not smoking

  • a BMI below 25

  • regular physical activity

  • eating fruits and vegetables at least 3 times a day and fish twice a week or more

  • having low levels of cholesterol (less than 5.2mmol/L)

  • having low blood sugar levels (fasting blood glucose less than 5.5mmol/L without any diabetes treatments)

  • having a healthy blood pressure (less than 120/80mmHg without any high blood pressure treatments)

Participants were assessed for these characteristics through in-depth face-to-face interviews, as well as clinical assessments that included blood pressure measurement, blood tests, and assessments of their brain and psychological function.

They were given 1 point for each of the healthy heart characteristics they had.

The researchers then followed the participants for up to 16 years (average 8.5 years), assessing them again every 2 to 3 years.

People with dementia were identified through a 3-step procedure. Those whose brain and psychological function tests suggested possible dementia were examined by a neurologist, who gave their diagnosis.

All of those with possible dementia had their test results reviewed by a panel of independent neurologists, who knew nothing about the individual's healthy heart characteristics or other risk factors for dementia.

The panel gave their consensus on the person's diagnosis based on standard diagnostic criteria.

The researchers had enough data to include 6,626 older adults (average age 73.7 years) who didn't have heart disease or dementia at the beginning of the study.

They looked at whether the number of healthy heart characteristics at baseline was linked to the participants' risk of developing dementia during the study.

They took into account other characteristics that could affect results, such as a person's sex, education level, and whether they had a particular genetic risk factor for dementia.

What were the basic results?

The researchers found that at the start of the study about:

  • 7% of the participants had 5 to 7 of the healthy heart characteristics

  • 57% had 3 to 4 of the characteristics

  • 36% had 0 to 2 of the characteristics

During the study, 745 of the participants (11%) developed dementia. The more healthy heart characteristics a person had at the start of the study, the less likely they were to develop dementia.

For every year of follow-up, the number who developed dementia was about 18 in every 1,000 participants who had 0 or 1 healthy heart characteristics, and about 8 in every 1,000 who had 6 or 7 of the healthy heart characteristics.

After taking into account other potential confounders, every additional healthy heart characteristic a person had reduced their risk of developing dementia by 10% (hazard ratio [HR] 0.90, 95% confidence interval [CI] 0.84 to 0.97).

How did the researchers interpret the results?

The researchers concluded that their findings might support the promotion of heart health to prevent risk factors associated with dementia.

Conclusion

This was a well-designed study that supports what's already known: risk factors for heart disease are also risk factors for dementia.

What's interesting is that the people in this study were aged 65 and older, suggesting that even at this age adopting healthy behaviours could have beneficial effects.

The study's strengths include that it followed people for a long time, thoroughly assessed the participants, and used a panel of neurologists who didn't know about the participants' heart health at the start of the study to diagnose dementia.

As with all studies, there are some limitations. For example, people may not have accurately reported their diet or physical activity habits.

Also, some participants were lost to follow-up, and these people tended to have worse health.

This may mean the results are more representative of the effects in a healthier population.

The participants in this study were all aged over 65, and it's likely that to some extent the healthy heart characteristics reflect behaviours they had over a period of time.

But it's likely that adopting the healthy heart behaviours described will bring some benefit at any age, and hopefully the findings will encourage people to do so.

Analysis by Bazian
Edited by NHS Website

Links to the headlines

The four things you need to do to stave off dementia in old age

The Sun, August 21 2018

The 7 health tests that can tell if you are at risk of dementia: Smokers and people who are overweight or have unhealthy diets are most at risk

Mail Online, August 21 2018

Links to the science

Samieri C, Perier M, Gaye B, et al. Association of Cardiovascular Health Level in Older Age With Cognitive Decline and Incident DementiaJAMA. Published online August 21 2018

This content is reproduced courtesy of NHS Choices, for more stories like this visit Behind the Headlines.

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