While data shows that women make up two-thirds of dementia cases globally, with research showing the loss of estrogen at menopause can increase risk, a 44-year study published in the journal Neurology has revealed cardiovascular fitness when cycling is a powerful tool for long-term brain protection.
The study was conducted on a sample of 1462 women aged 38 to 60. Of this sample, 191 women completed a maximal cycling test on a stationary bike to evaluate cardiovascular fitness at the start of the study, between 1968-1970. Similar to what you’ve probably done in spin classes, the participants performed various cycling intervals – starting at low intensity and increasing in stages every few minutes until they reached voluntary exhaustion. Their peak workload (measured in watts) achieved at exhaustion was recorded, and this was used as a proxy for their maximal cardiovascular fitness.
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Cardiovascular fitness was determined by power output from cycling intervals
Every woman was then examined for dementia incidence in 1974, 1980, 2000, 2005 and 2009, based on neuropsychiatric examinations, informant interviews, and hospital records. The researchers also accounted for factors like income, education, smoking, diet and existing illnesses, in order to isolate the effect of exercise on dementia risk.
The results showed that only 5% of the highly fit women (based on their scores in the maximal cycling tests performed at the start of the study) developed dementia, compared to 32% in the moderate group. High fitness also delayed age at dementia onset by 9.5 years, and time to dementia onset by 5 years compared to medium fitness. The women who demonstrated high cardio fitness also had an 88% lower risk of developing dementia over the 44 years that they were examined compared to those with medium fitness levels.
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Cardiovascular fitness is proven to reduce dementia risk
How? ‘Several mechanisms might be involved in how fitness reduces dementia risk,’ the authors of the study write. ‘These include both indirect effects such as influence on hypertension, hypercholesterolemia, obesity, and diabetes mellitus and direct effects on the brain, like the enhancement of neuronal structures, neurotransmitter synthesis and growth factors.’ However, the study is one of just four longitudinal studies on fitness and dementia, and all show that the direct effects on the brain need to be investigated further (for example, a recent study found that lower cardio fitness was associated with smaller brain volume two decades later – something which this study didn’t investigate).
There are some further limitations to this specific study. For one, the study only watched and recorded what happened; without controlling or changing anything, it can’t prove that being fit actually causes a lower risk of dementia. It just shows they’re linked. For example, those who are classed as ‘highly fit’ may eat healthier or have other habits that lower dementia risk, so fitness might not be the direct cause. The study also included Swedish women only, so the results may not be applicable to other populations. Lastly, the cycling test measured how much power or effort the participants could produce, but it didn’t directly measure how efficiently their body used oxygen, with a VO2 max test – this is often considered the gold standard for measuring cardiovascular fitness since it’s entirely objective and measurable.
All that said, the 44 years of follow-up and the fact that the baseline cycling tests were all performed in midlife (aged 38 to 60) are major strengths of the study, and you can confidently take away that ‘high cardiovascular fitness in midlife is associated with decreased risk of dementia’, according to the researchers. As for the impact of cycling intervals in particular, there are of course other ways to improve your cardiovascular fitness, but another study involving 480k participants aged 40 to 69 found that those who cycled regularly had a 19% lower risk of developing dementia, while performing high-intensity intervals as is common in spin classes has been proven to improve vascular function and markers of blood vessel health (both of which are precursors to dementia, as healthy blood flow is required for blood supply to the brain) compared to moderate intensity workouts. BRB, off to spin.
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As Women’s Health UK’s fitness director (and a qualified yoga teacher), Bridie Wilkins has been passionately reporting on exercise, health and nutrition since the start of her decade-long career in journalism. She secured her first role at Look Magazine, where her obsession with fitness began and she launched the magazine’s health and fitness column, Look Fit, before going on to become Health and Fitness writer at HELLO!. Since, she has written for Stylist, Glamour, Cosmopolitan, Marie Claire, Elle, The Metro, Runner’s World and Red.
Now, she oversees all fitness content across womenshealthmag.com.uk and the print magazine, spearheading leading cross-platform franchises, such as ‘Fit At Any Age’, where we showcase the women proving that age is no barrier to exercise. She has also represented the brand on BBC Radio London, plus various podcasts and Substacks – all with the aim to encourage more women to exercise and show them how.
Outside of work, find her trying the latest Pilates studio, testing her VO2 max for fun (TY, Oura), or posting workouts on Instagram.Â