We thank Laura Garcia Diaz for our February research blog, focused on the impact of physical activity and brain health.
Let's talk about brain health: Physical activity
By Laura Garcia Diaz
There is strong evidence that people can reduce their risk of cognitive decline by making key lifestyle changes (Livingston et al., 2020), including being physically active.
Over the past decade, there has been an increased interest in understanding the impact of physical activity on cognition. In this blog, I will provide a high-level summary of recent research that has been conducted to help us understand the possible impact of physical activity on reducing the risk of cognitive decline (i.e., prevention) and on supporting people with dementia to live well (i.e., intervention).
Before reviewing some of the literature, it is important to define what I mean by “physical activity”. Physical activity refers to any type of body movement, including recreational or leisure-time physical activity, transportation (such as cycling or walking), occupational (such as lifting things at work), household chores (for example, vacuuming and folding the laundry), play, sports or planned exercise (World Health Organization, 2015). Thus, exercise is one type of physical activity, but it is not the only way in which we can be active throughout the day.
Across all age groups, the World Health Organization recommends participating in 150 minutes of moderate-intensity aerobic physical activity per week (or 75 minutes of vigorous-intensity aerobic physical activity) (World Health Organization, 2015).
Although in this blog I will focus on the impact of physical activity on cognition, it is important to remember that physical activity can improve balance and mental health and reduce the risk of falls, thus it is recommended to participate in regular physical activity for overall well-being (Alty et al., 2020).
In 2020, Whitty and colleagues (2020) conducted a systematic review of lifestyle and psychosocial interventions that aimed to reduce cognitive decline in people at risk of dementia. In this study, a person was considered at risk of dementia if they were 50+ years old, or if they have been diagnosed with mild cognitive impairment, or experienced subjective cognitive decline (i.e., the person reports experiencing cognitive decline, but has not been diagnosed with mild cognitive impairment or another condition). For exercise interventions, the authors found:
- Very good evidence (known as “Grade A”) that participating in aerobic exercise at least twice a week, for 16 weeks or more, may have a positive effect on global cognition in people with and without mild cognitive impairment.
- Very good evidence that participating in 1-3 weekly activities that include cognitive and motor components(for example, dancing or dumb bell training) may improve memory or global cognition in people with mild cognitive impairment.
- Very good evidence that participating in resistance training for four months or less may not improve cognitive outcomes in people with or without mild cognitive impairment.
- Good evidence (known as “Grade B”) that Tai Chi sessions (initially taught by an instructor, and then continued at home for 15 weeks) may improve global cognition, memory and executive functioning in people with mild cognitive impairment. These findings were compared to stretching, toning group and education interventions which were not found to be as effective as Tai Chi.
- Good evidence that participating in resistance training for 6 months or more may improve global functioning in people with mild cognitive impairment.
Based on these findings, to reduce cognitive decline in people at risk of dementia, the authors recommend participating in regular (at least weekly) physical activity involving aerobic or resistance exercise, with a cognitively demanding and/or creative component for at least four months. Please note that I have underline “may improve/not improve” as each person has a unique health background and even when there is very good evidence for an intervention, it will not always work for everyone. Because individual variability (for example, genetics, environment, biomarkers, etc) can influence how a person responds to physical activity, the idea of physical exercise as personalized medicine is gaining attention in dementia research (Müllers et al., 2019).
Personalized medicine is an intervention approach based on individual variability. Müllers and colleagues (2019) recently commented on the potential benefits that personalized preventive exercise strategies could have, recommending future research to focus on identifying individual factors that may postively or negatively interact with different exercise strategies. This would enhance our ability to recommend personalized exercise programs, overcoming the typically used “one-size-fits all” approach.
In 2019, the World Health Organization published guidelines on the risk reduction of cognitive decline and dementia (World Health Organization, 2019). Two recommendations reggarding physical activity are included in the guidelines:
- Physical activity is recommended for adults with normal cognition to reduce the risk of cogntive decline. The quality of evidence for this recommendation is moderate.
- Physical activity may be recommended for adults with mild cognitive impairment to reduce their risk of cognitive decline. The quality of evidence for this recommendation is low.
The authors of the guidelines concluded that, based on current evidence, physical activity has a small, but beneficial effect on cognition, mostly due to aerobic exercise (e.g., swimming, cycling, walking).
Despite increased research around physical activity and cognition, we still don’t know the minimum duration, frequency, type, and intensity of exercise required to improve cognition. Similarly, although there is very good evidence that physical activity may reduce the risk of cognitive decline, there is mixed evidence about the positive impact of physical activity on cognition in people already diagnosed with mild cognitive impairment or dementia.
From personal experience, engaging in physical activity (even a short 10 minute walk) tends to put me in a better mood which is why I am a proponent for trying to incorporate different forms of physical activity throughout the day. My favourite types of physical activities include yoga, walking, dancing, and swimming. I also thoroughly enjoy hula hooping! I know that it isn’t always easy to find the time or energy to engage in physical activity (especially during a cold winter day!) but I encourage you to think about ways in which you could incorporate physical activity in your daily routine.
I hope the information in this blog has been helpful, but most importantly, I hope it has inspired you to think about how you could incorporate physical activity into your daily routine. Your heart, mind and brain will thank you for it!
References
Alty, J., Farrow, M., & Lawler, K. (2020). Exercise and dementia prevention. Practical Neurology, 20, 234–240. https://doi.org/10.1136/practneurol-2019-002335
Livingston, G., Huntley, J., Sommerlad, A., Ames, D., Ballard, C., Banerjee, S., Brayne, C., Burns, A., Cohen-Mansfield, J., Cooper, C., Costafreda, S. G., Dias, A., Fox, N., Gitlin, L. N., Howard, R., Kales, H. C., Kivimäki, M., Larson, E. B., Ogunniyi, A., … Mukadam, N. (2020). Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. The Lancet, 396(10248), 413–446. https://doi.org/10.1016/S0140-6736(20)30367-6
Müllers, P., Taubert, M., & Müller, N. G. (2019). Physical exercise as personalized medicine for dementia prevention? Frontiers in Physiology, 10(MAY), 672. https://doi.org/10.3389/FPHYS.2019.00672/BIBTEX
Whitty, E., Mansour, H., Aguirre, E., Palomo, M., Charlesworth, G., Ramjee, S., Poppe, M., Brodaty, H., Kales, H. C., Morgan-Trimmer, S., Nyman, S., Lang, I., Walters, K., Petersen, I., Wenborn, J., Minihane, A. M., Ritchie, K., Huntley, J., Walker, Z., & Cooper, C. (2020). Efficacy of lifestyle and psychosocial interventions in reducing cognitive decline in older people: Systematic review. Ageing Research Reviews, 62, 101113. https://doi.org/10.1016/J.ARR.2020.101113
World Health Organization. (2015). Global recommendations on physical activity for health. https://www.who.int/publications/i/item/9789241599979
World Health Organization. (2019). Risk reduction of cognitive decline and dementia. https://www.who.int/publications/i/item/risk-reduction-of-cognitive-decline-and-dementia