Greater Physical Fitness Correlates with Lower Risk of Dementia

It is well established that exercise and physical fitness correlate well with reduced incidence of all of the common age-related diseases, and reduced mortality risk. It is hard to establish causation from the contents of human epidemiological databases, but the analogous animal studies convincingly demonstrate that exercise improves health. There is no reason to expect humans to be all that different in this matter. Here, researchers show that, much as expected, greater fitness correlates with reduced risk of dementia. Of note, patients that improved their fitness over the years of later life exhibited reduced disease risk and improved life expectancy.

Cardiorespiratory fitness is associated with risk of dementia, but whether temporal changes in cardiorespiratory fitness influence the risk of dementia incidence and mortality is still unknown. We aimed to study whether change in estimated cardiorespiratory fitness over time is associated with change in risk of incident dementia, dementia-related mortality, time of onset dementia, and longevity after diagnosis in healthy men and women at baseline. We linked data from the prospective Nord-Trøndelag Health Study (HUNT) with dementia data from the Health and Memory Study and cause of death registries (n=30,375). Included participants were apparently healthy individuals for whom data were available on estimated cardiorespiratory fitness and important confounding factors.

Cardiorespiratory fitness was estimated on two occasions 10 years apart, during HUNT1 (1984-86) and HUNT2 (1995-97). HUNT2 was used as the baseline for follow-up. Participants were classified into two sex-specific estimated cardiorespiratory fitness groups according to their age (10-year categories): unfit (least fit 20% of participants) and fit (most fit 80% of participants). To assess the association between change in estimated cardiorespiratory fitness and dementia, we used four categories of change: unfit at both HUNT1 and HUNT2, unfit at HUNT1 and fit at HUNT2, fit at HUNT1 and unfit at HUNT2, fit at both HUNT1 and HUNT2. Using Cox proportional hazard analyses, we estimated adjusted hazard ratios (AHR) for dementia incidence and mortality related to temporal changes in estimated cardiorespiratory fitness.

During a median follow-up of 19.6 years for mortality, and 7.6 years for incidence, there were 814 dementia-related deaths, and 320 incident dementia cases. Compared with participants who were unfit at both assessments, participants who sustained high estimated cardiorespiratory fitness had a reduced risk of incident dementia (AHR 0.60) and a reduced risk of dementia mortality (AHR 0.56). Participants who had an increased estimated cardiorespiratory fitness over time had a reduced risk of incident dementia (adjusted hazard ratio 0.52) and dementia mortality (adjusted hazard ratio 0.72) when compared with those who remained unfit at both assessments. Each metabolic equivalent of task increase in estimated cardiorespiratory fitness was associated with a risk reduction of incident dementia (AHR 0.84) and dementia mortality (AHR 0.90). Participants who increased their estimated cardiorespiratory fitness over time gained 2.2 dementia-free years, and 2.7 years of life when compared with those who remained unfit at both assessments.

Link: https://doi.org/10.1016/S2468-2667(19)30183-5

Comments

"It is well established that exercise and physical fitness correlate well with reduced incidence of all of the common age-related diseases"

Actually the correllation between fitness and health benefits is pretty weak. If you'd draw a graph with amount of daily exercise on one axis and various health benefits on the other axis you'd see that there is only a correlation from zero exercise up to about 1hr/day. Beyond that it flattens out or in other words the correlation is gone.

So if you exercise for 3 hours per day (being fitter) compared to someone who exercises 30-60min per day you won't get additional health benifits. There is probably also a point where too much exercise is detrimental to your health as elite athletes suffer 4.5 times more often from upper respiratory illness than recreational athletes.

Posted by: Christian at November 20th, 2019 9:18 AM

@Christian,

So you mean to tell me there is still no concrete evidence for longevity? Because last time I checked the more you work out, the better physique you have, the stronger you are, more endurance. So, a football team that goes to the gym for an hour per day verse one that puts in 3 hours per day should be equally as fit? I don't think so..

Posted by: Person1234 at November 20th, 2019 9:54 AM

My true hero is not Arnold Schwarzenegger nor Dwyane Johnson, but Jack Lalane. He exercised all his life(heck, I remember him on a black/white TV doing exercise with makeshift stuff around the house during the 70's) and died in his early 90's I think due to an infection.

So, yea, we're meant to move our asses often otherwise our bodies will penalize us with sickness and a shorter life.

My home gym is almost finished, yea.

Posted by: Robert Church at November 20th, 2019 10:12 AM

@Person1234

"So, a football team that goes to the gym for an hour per day verse one that puts in 3 hours per day should be equally as fit?"

That's not what I meant at all. Of course the more you train the more endurance you get. But endurance or fitness is not the driving factor of the health benefits of exercise. Because then if you'd run a marathon every day you'd become 150 ;)

If you look at what amount of exercise you get the most health benefits then the sweet spot is 30-60 minutes. Do more, good for your fitness, looks etc. But you won't see additional health benefits.

Btw...supercentenarians are rarely athletes. They all lead an active life though. So once again: Exercise is important. but yeah, you don't need to spend all day in the gym. And btw2: exercising at night is probably as healthy as working night shifts ;)

Posted by: Christian at November 20th, 2019 10:24 AM

> Actually the correllation between fitness and health benefits is pretty weak.

I think the causation is mostly the other way around. People that are young biologically tend to be fitter than the really old ones and healthier, too.

> Because then if you'd run a marathon every day you'd become 150 ;)

You do, but you have to keep on running every day until you reach 150 ;-).

Posted by: Matthias F at November 20th, 2019 10:03 PM

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