Krista Power, who is an associate professor at the School of Nutrition Sciences of the Faculty of Health Sciences, recently received a grant from the Alzheimer’s Society of Canada/Brain Canada Foundation to conduct a sub-study within a Canadian Institutes of Health Research (CIHR) research project. This large CIHR project, conducted across four Canadian provinces (Quebec, Ontario, Manitoba, and Saskatchewan), looks at how lifestyle changes could help prevent cognitive decline and delay the onset of dementia.
An ambitious project
Professor Power explains that this project involves 140 study participants, all adults aged 65 to 80 experiencing subjective cognitive decline, who commit to one of four interventions, which are delivered fully online in a group setting. The four intervention groups focus on either physical activity (aerobic and resistance exercises); diet counseling based on the Canada Brain health food guide; a combination of diet and exercise; or stretching and brain health education as the control group. These groups hold online meetings with a clinical exercise physiologist or dietician three times a week over a six-month period. The first cohort began in October 2023.
Krista Power adds that the study participants are still in the very early stages of cognitive decline, and they have not yet been diagnosed or characterized as cognitively impaired. Therefore, the goal is to test them to see if their cognitive function improves over the six-month intervention period, but also to check whether such interventions can be delivered online, since “not everyone lives close to big centres where they can access this type of health care.”
Power states that one of the problems with this type of intervention is the need to provide long-term support to maintain these lifestyle changes. “People will do it for the short time that they are in a study, but then will fall back into their old routines and old dietary patterns.” As such, the researchers will continue to follow the participants for up to 12 months after the interventions to see whether the changes are sustainable, namely whether the participants have been able to maintain the change without being guided by professionals.
This ambitious research project involves many people and partners, including researchers from the University of Waterloo (Dr. Laura Middleton, co-PI), Baycrest’s Rotman Research Institute (Dr. Nicole Anderson, co-PI), and the University of Montreal, to name a few. “Everyone is playing different roles on the team,” explains Krista Power, with some partners focusing on the nutritional aspects and others on exercise. Dr. Power and her team (graduate student Sarah Grenville and undergraduate students Jiaqian Xie and Sandra Markos) are analyzing biomarkers in fecal and blood samples, collected at zero, three, and six months, to determine the role that gut microbiota plays in mediating the effects of exercise and/or diet on cognitive function.
What is the gut microbiota?
Indeed, the aim of Power’s study is to evaluate how gut microbiota contributes to the effects of diet and exercise on cognition in people experiencing subjective cognitive decline.
To illustrate what the gut microbiota is, Krista Power explains that “within your gut, there are trillions of microbial cells. There are different families of bacteria, and some of them can produce adverse or potentially harmful metabolites.” Put simply, the interventions aim “to increase the function and numbers of the good bacteria so that they can make the bad bacterial population smaller and less effective.”
Krista Power asserts that the gut microbiota plays a significant role in mental health, as it communicates with the brain through the different metabolites it produces. “Diet itself is known to change the microbiota,” adds Professor Power, “so if you typically consume a highly processed diet, your microbiota may look different from someone who is eating more healthy food.” For example, having a diet rich in fibre and polyphenols is known to promote the growth of good bacteria and create metabolites that are beneficial for us.
Researchers anticipate that diet and exercise, and more so their combination, will beneficially improve the microbiome, resulting in increased production of the anti-inflammatory factors that improve cognition. “We will be looking at which microbes change and what their functions may be, as well as measuring some of those metabolites that may be beneficial or inducing beneficial effects across the gut-brain axis.”
Reducing risks of dementia
If alterations to the microbiota explain the cognitive effects of these interventions, this discovery could inform tailored treatments to prevent disease.
Given that the study participants are subjectively experiencing cognitive decline, i.e., they feel that their memory or other thinking abilities are declining, “the goal is to delay further cognitive decline, given that about 6.5% of people with subjective cognitive decline will convert to mild cognitive impairment or dementia each year,” says the professor.
Because people with subjective cognitive decline do not generally have notable deficits and therefore are not managed within the health-care system, lifestyle interventions may be an ideal strategy to reduce risk. This project aligns with a key objective of the National Dementia Strategy for dementia prevention: it involves research to deepen evidence on the beneficial effects of a healthy lifestyle in maintaining brain health.