HIGH FITNESS LEVEL: PROTECTION FROM DEMENTIA. The USA TODAY headline, “’Highly fit’ middle age women nearly 90% less likely to develop dementia decades later, study finds” grabbed my attention. The accompanying short article briefly summarized the findings of the official research study, “Midlife Cardiovascular Fitness and Dementia,” which was published online ahead of print in the medical journal Neurology March 14, 2018.
Earned Runs was interested in the details, especially the methods for determining fitness level.
Scientists from the University of Gothenberg, Sweden felt that although aerobic cardiovascular fitness programs have been aimed at improving cognitive function in older persons there were few very long-term prospective studies, and no randomized controlled trials, able to subjectively “relate fitness to dementia.”
A US study followed participants for roughly 24 years and a Finnish study had followed men for 25 years. The former had shown high fitness was associated with lower dementia risk, and the latter that poor self-described fitness was associated with higher risk. A previous study in Swedish men had shown that low cardiovascular fitness at age 18, assessed by a bicycle ergometer test, was associated with increased early onset dementia (< age 60). It has been suggested, the scientists indicated, that “midlife was a ‘sensitive period’ for the effect of cardiovascular risk factors on dementia.”
Dr. Helena Horder and colleagues decided to track dementia incidence over 44 years in a group of women who had been tested for fitness at the beginning of that time span.
In 1968, researchers looked in depth at a ‘systematic subsample’ of 191 Swedish women, out of a larger population-based sample group of 1,492 women aged 38 to 60 years. The smaller group had “completed a step-wise maximal ergometer cycling test that year to evaluate cardiovascular fitness”. In subsequent years, on 6 different occasions (1974, 1980, 1992, 2000, 2005, and 2009), the women were evaluated for dementia.
The results revealed that, after 44 years, the women whose test indicated a high level of fitness were much less likely to develop dementia than women with medium fitness; risk was reduced by 88%. Age of onset was found to be delayed by about a decade (9.5 years older) in the highly fit women, and time to dementia onset was delayed by about 5 years compared with medium fit women.
Specifically, the study reported that the “adjusted hazard ratio for all-cause dementia” when compared with medium fitness, was 0.12 “among those with high fitness”, and 1.41 “among those with low fitness” (the medium fitness women were at 1.0). There was a very high incidence of dementia in women who were physically unable to even complete the test (45%).
The fitness testing description is rather complicated. Each woman was given a workload, measured as power, kilopond m/minute, converted to W on the cycling ergometer according to the results of a pretest. The pretest determined how high the workload needed to be set to bring her to “maximal subjective exhaustion” at the end of 6 minutes of effort.
Peak workload was used to categorized participants into 3 fitness groups: low (80W or interrupted test) that included 59 women, medium (88-112W) with 92 women, and high (equal to or greater than120W) with 40 women.
“During the period of maximal work, heart rate and ECG were registered every minute, blood pressure was registered after 1 and 2 minutes, and respiratory frequency and perceived exertion by the Borg scale.” Taken together, 93% of the group perceived their effort as “strenuous” (at or about scale point 15) and half as “very, very strenuous” (at scale points 19-20).
[The original Borg scale rated perceived exertion from 1 to 21 (maximal) and a later revised score from 6-20. The publication describing the original scale was released in 1962 and mostly likely used in 1968, since the revision was issued in 1970].
The results reported in their study, the scientists indicated, were in line with other studies on all-causes of death in that the reduction of risk data related to fitness level were “stronger” than that which took weight (obesity) into consideration. The authors felt this information “highlights the need for fitness-driven rather than weight loss approaches” to reducing risk for dementia.
Additional discussion in the publication pointed out that fitness and physical activity are NOT equal. In terms of the protection each provides against dementia, their study showed the hazard ratio was “stronger” for high fitness than that reported for physical activity. This was the same as reported with cardiovascular disease protection. They emphasized that fitness has a significant genetic component.
In discussing the potential mechanisms by which fitness may diminish dementia risk, the researchers believed their study was similar to the findings of others. Fitness is thought to indirectly influence other illnesses (hypertension, obesity, diabetes mellitus, high blood levels of cholesterol for example) that may affect cognitive function. But the evidence also showed that fitness level may have a direct effect on the brain, “for example enhancement of neuronal structures, neurotransmitter synthesis, and growth factors.”
They cited recent research which showed that lower cardiovascular fitness was associated
with lower brain volume (size) 20 years later. And explained that “brain regions that seem most influenced by physical activity are those that are also vulnerable to age–related changes and early pathologic changes in Alzheimer disease such as the hippocampus.`” The Swedish scientists believe that more research into the effects of fitness on brain structures is needed to “improve strategies for dementia prevention”
To accept and act on these findings, as with all research, we must wade through the science and take into consideration the shortcomings of such a project. These were Swedish women; there were no males or persons of other ethnicities included, so results are generalizable to all populations. The sample was small. There was no way to study cause and effect. Genetic markers for risk were not examined. Lifestyles and environmental conditions before 1970 are not reflective of current life. The influence of childhood fitness was not investigated.
However, we may not have the luxury of time to wait for comprehensive data from the next, possibly perfect, future study before devising a personal action plan to lessen risk. The methods portion of this research reveals that women born in 1908, 1914, 1918, 1922, and 1930 were “systematically sampled* from the Swedish Population Register” for the study! If sampled today, would we accept the risk of burning another 44 years for findings to be revealed in 2062?
What to take from these results? The FITNESS level that matters for improved brain health:
What actions does Earned Runs recommend taking?
In 1968, it is unlikely that Swedish women were into performing formal HIIT sessions. The research participant characteristics table doesn’t include information on fitness activities prior to the study, so we don’t know for sure exactly how they became highly fit by middle age. To follow their example, it is possible to occasionally increase exercise intensity while performing activities we already enjoy. Simple change-ups may do the trick. Massive re-working of exercise habits is likely not necessary.
The American College of Sports Medicine offers some guidance on interval training. An excellent article posted by Paige Waehner for verywellfit.com discusses aerobic and anaerobic high intensity interval training with suggested workouts.
If new to training, very strenuous exercise should be undertaken with caution. Best to find a certified trainer at a gym to help develop a plan to gradually build to interval work. Ask for an in-home routine which doesn’t require a gym membership if desirable. That’s my goal and plan. I’m not an exercise novice but know enough to recognize that qualified coaching is the safest option and fastest route to achieving goals.
RUN &MOVE HAPPY!
*Born on the sixth day of uneven month in those years (January, March 6, May 6, and so on)
BRIDGE TO PHYSICAL SELF
Running, walking, and fitness activities enable us to experience our physical selves in a world mostly accessed through use of fingers on a mobile device.
EARNED RUNS is edited and authored by me, runner and founder. I began participating in road races before 5Ks were common. I've been a dietitian, practiced and taught clinical pathology, and been involved with research that utilized pathology. I am fascinated with understanding the origins of disease as well as health.
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