Walking associated with reduced risk of dementia, cardiovascular disease and cancer

Walking associated with reduced risk of dementia, cardiovascular disease and cancer

Professeur titulaire au Département de Médecine de l’Université de Montréal. Directeur du Centre ÉPIC de l’Institut de cardiologie de Montréal.7 October 2022

OVERVIEW

  • Participants in a prospective study who walked more had a significantly reduced risk of dementia, premature mortality (all causes), mortality from cardiovascular disease, and cancer incidence.
  • The optimal beneficial effect of walking is obtained at almost 10,000 steps/day for the risks of dementia, premature death and cancer.
  • As little as 3,800 steps/day is associated with a 25% reduced risk of dementia, half the maximum effect (50%) obtained at 9,800 steps/day.
  • Higher intensity (steps/minute) of walking was associated with favourable effects on premature death and the incidence of cardiovascular disease and cancer.

Several studies published to date suggest that increasing the number of daily steps is important to prevent the development of chronic diseases and premature death. We often hear in the news or on social media that 10,000 steps/day is the target to reach to enjoy the maximum health benefits. However, some studies indicate that at 6,000 to 8,000 steps/day, the maximum protective effect is achieved and that taking more steps does not significantly reduce the risk of death from all causes, for example. However, there is relatively little data on the subject, and the studies published to date do not distinguish between the different types of walking (daily life vs. exercise) and have paid little attention to the relative importance of walking intensity or cadence.

A prospective study recently examined the dose-response association between the amount (number of steps/day) and intensity (cadence) of walking and the incidence of dementia. The study, which lasted an average of 6.9 years, was carried out among 78,430 people aged 40 to 79 who were part of the UK Biobank cohort. Participants wore an accelerometer around their dominant wrist 24 hours a day, 7 days a week for at least 3 consecutive days and had no diagnosed cardiovascular disease, cancer or dementia at the start of the study. From the data collected by the accelerometer, it was possible to determine:

  • the total number of steps/day;
  • the number of steps related to activities of daily living (e.g., walking from one room to another), defined as less than 40 steps/minute;
  • the number of steps taken during intentional physical activity, defined as 40 or more steps per minute (e.g., walking for exercise);
  • the maximum 30-minute cadence (i.e., the average number of steps per minute recorded for the 30 minutes, not necessarily consecutive, when the cadence was maximal).

By the end of the study, 6.9 years after its start, 866 participants had developed dementia. The results show a nonlinear association between the number of total steps/day and the risk of dementia. The risk of dementia decreases with the number of total steps/day up to a 51% decrease at 9,826 steps/day. A number of steps/day of 3,826 is associated with a reduction in the risk of dementia by 25%, or half of the maximum effect.

Figure 1. Dose-response association between total daily steps taken and incidence of dementia. Adapted from del Pozo Cruz et al., 2022.

For the number of steps related to daily life, the optimal dose was 3,677 steps/day, with a 42% reduction in the risk of dementia. Regarding the number of purposeful steps, the optimal dose was 6,315 steps, with a decrease in the risk of dementia by 57%. For the maximum cadence over 30 minutes, the optimal dose was 112 steps/minute, with a reduction in the risk of dementia of 62%.

Associations with risk of mortality, cardiovascular disease and cancer
In a second publication by the same researchers and with the same UK Biobank cohort mentioned above, the dose-effect association between the amount and intensity of walking and premature mortality, mortality due to cardiovascular diseases, and cancer incidence was examined. During the seven years of the study, 1,325 participants died from cancer and 664 participants died from cardiovascular disease.

The risk of premature mortality decreases with increasing number of total steps/day, up to approximately 10,000 steps/day. For every additional 2,000 steps, the risk of premature death decreases by 8%, 10% and 11%

Figure 2. Dose-response association between total steps walked/day and all-cause mortality (panel A), cardiovascular disease mortality (panel B), and incidence of 13 cancers known to be associated with a low level of physical activity (panel C). Adapted from del Pozo Cruz et al., 2022.

The strengths of this study are the very large cohort size and the use of accelerometry and algorithms that helped distinguish walking steps from other ambulatory activities (a problem in some previous studies). Among the limitations, there is firstly that this type of study, of an observational nature, does not make it possible to establish a causal link. Second, the accelerometry data at the start of the study was collected only once and therefore may not fully reflect participants’ walking habits. However, multiple measurements carried out 4 years after the start of the study indicates that there is little variation between the data obtained during the different measurements. In addition, there remains a risk of reverse causation, i.e. that the disease (dementia, cardiovascular, cancer) could be the cause of a low number of steps, despite certain precautions taken by the researchers to minimize this risk.

The researchers are of the opinion that the right part of the dose-response curves does not reflect a real reduction in the favourable effect of walking after 10,000 steps, but rather reflects the scarcity of walking data or events (diagnoses of dementia, cardiovascular disease, death) for these few great walkers. In addition, some particularly health-conscious participants may have set a target (popularized in the media) of 10,000 steps/day, which could explain why the optimal effect is observed at this amount of walking.

Walking more and walking faster are associated with health and longevity benefits. Although the optimal health effect seems to be achieved around 10,000 steps/day, it is important to note that walking between 5,000 and 8,000 steps/day allows us to greatly benefit from the positive effects associated with walking. Moreover, there is no minimum threshold for the beneficial association between the number of total daily steps walked and mortality and morbidity. For example, as few as 3,800 steps/day are associated with a reduction in the risk of dementia equivalent to half of the maximum effect obtained at approx. 10,000 steps/day. Future recommendations for the prevention of dementia, cardiovascular disease and cancer could take this new evidence into account and encourage the population to walk more and at a faster pace, in order to optimally benefit from the health benefits of walking.

Replacing tobacco with e-cigarettes reduces the risk of cardiovascular events

Replacing tobacco with e-cigarettes reduces the risk of cardiovascular events

Cardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.4 October 2022

Smoking is directly responsible for 8 million deaths worldwide each year, mainly from cancer (30% of all cancers are due to tobacco) and cardiovascular and respiratory diseases. There is therefore clearly nothing worse than cigarettes for health, and quitting smoking remains, by far, the best decision a person can make to reduce their risk of premature death.

In recent years, electronic cigarettes have emerged as a valid alternative to tobacco cigarettes to reduce the harmful effects of smoking on health. This approach is based on a relatively simple concept: while tobacco addiction is due to nicotine, it is rather the tobacco combustion products present in cigarette smoke that are responsible for smoking-related health problems. If we can satisfy smokers’ nicotine needs while eliminating exposure to cigarette smoke, we can therefore substantially reduce the damage to their health. This is exactly what e-cigarettes do, as these devices allow nicotine to be inhaled, but without the approximately 7,000 chemical compounds found in cigarette smoke, and therefore expose users to much lower amounts of toxins. This marked decrease in toxic molecules in e-cigarette aerosols has been confirmed by several independent bodies (Public Health England, National Academies of Sciences, Engineering, and Medicine and the Committee on Toxicity of Chemicals in Food, Consumer Products, and the Environment), and it is for this reason that organizations such as Public Health England and the Académie nationale de médecine in France strongly recommend that smokers make the transition to vaping.

Cardiovascular benefits
A study recently published in Circulation, the flagship journal of the American Heart Association, is a good illustration of the positive impact of this harm reduction approach. In this longitudinal study, approximately 32,000 American adults were followed for a period of 6 years (2013–2019) to assess the risk of cardiovascular diseases (heart attack, stroke, heart failure) in smokers compared to non-smokers, exclusive e-cigarette users, and dual users (tobacco and e-cigarette).

The researchers first observed, unsurprisingly, that smokers had a much higher risk of heart disease (almost 2 times) than non-smokers (see Figure 1).

Figure 1. Increased risk of cardiovascular disease in smokers, but not in e-cigarette users (vapers). Adapted from Berlowitz et al. (2022).

However, this increase is not observed for exclusive e-cigarette users (15% increase, statistically insignificant), consistent with two recent studies (here and here). In other words, the very strong and well-documented link between smoking and cardiovascular disease is simply not observed for vaping, confirming the much lower toxicity of these devices compared to cigarette smoke. It should, however, be mentioned that dual users (who smoke and vape) have a risk of cardiovascular disease of the same order as that of smokers, which indicates that the residual exposure to tobacco toxins, even if it is slightly reduced in these people, remains harmful and sufficient to damage the heart and blood vessels.

The superiority of e-cigarette use is also highlighted when directly comparing the risk of cardiovascular events between smokers and vapers, with a reduction of about 34% in the risk observed among exclusive vapers (Figure 2). Here again, the benefits provided by e-cigarettes are completely cancelled out in dual users, and it therefore seems clear that to be truly effective in terms of harm reduction, electronic cigarettes must be a substitute for tobacco and not simply a complement, for example to obtain a dose of nicotine when it is not possible to smoke a cigarette.

Figure 2. Decreased risk of cardiovascular disease in vapers, but not in dual users. Adapted from Berlowitz et al. (2022).

These results are extremely important, because even though we already knew that e-cigarettes were safer than tobacco cigarettes, this is the first time that we have been able to quantify the reduction in risk associated with the transition from tobacco to exclusive vaping. It goes without saying that a one-third reduction in the risk of cardiovascular events has major implications in terms of public health and should prompt governments to encourage smokers to adopt vaping to reduce their risk of chronic diseases and premature mortality.