We know that physical activity is beneficial for health, including that of the brain. Cognitive exercises are also recommended to delay the onset of dementia. This time, a pan-Canadian study published in the Journal of the American Medical Association (JAMA) shows that combining these two types of training is even more beneficial, because it not only wards off dementia, it improves cognitive functions.
A clinical study on this subject was carried out by five Canadian universities, including the University of Montreal. In total, 175 people aged 60 to 75 years old and presenting mild cognitive impairment took part in a program combining physical training — resistance and aerobic training — and progressive cognitive exercises (i.e. whose intensity increased as participants reached a plateau), program which was compared to various control situations.
Usually, we test a combination of everything, and compare it to a group that does nothing. The group that does everything is getting better, no wonder! We wanted to see if there was really added value [de la combinaison].
“We wanted to test the synergistic effect of physical exercise and cognitive training – in fact the clinical trial is called SYNERGIC – and we compared it to control groups for each condition, which is quite unique, explains neuropsychologist Louis Bherer, professor in the Department of Medicine at the University of Montreal, who led the study with Manuel Montero-Odasso, of the University of Western Ontario. Usually, we test a combination of everything, and compare it to a group that does nothing. The group that does everything is getting better, no wonder! We wanted to see if there was really added value [de la combinaison]. »
The almost six-month (20-week) program consisted of three workouts per week, each lasting an hour and a half. Each session consisted of 30 minutes of active cognitive training consisting of small computer games. These games aimed to improve two cognitive mechanisms that decline in older people: the capacity for inhibition and the ability to perform two tasks simultaneously.
This period of cognitive stimulation was followed by an hour of physical resistance training (20 to 30 minutes) aimed at increasing muscular strength (exercises consisting of lifting weights, pushing with the legs) and endurance, i.e. aerobic (like running or stationary cycling).
The cognitive performances of subjects who followed this program were compared to those of subjects from three other cohorts; one whose program included the same cognitive training, but physical training limited to stretching (stretching), the other whose program included physical training in resistance and endurance, following a cognitive activity limited to receiving instructions on the use of the Internet, and finally a group having been assigned to a program entirely placebo.
Neurons in shape
The program combining resistance and aerobic physical training plus progressive cognitive exercises not only slowed participants’ cognitive decline, but it significantly improved their cognitive functions such as memory, attention control, speed information processing (the person’s ability to make decisions quickly), and executive functions (planning, inhibition of impulsivity, regulation of emotions).
Louis Bherer was very surprised by the magnitude of the effect of the combination of the two trainings. “Knowing that physical exercise already has a major impact, I didn’t expect to see such a big effect with the addition of cognitive training. And another reason to be surprised to see such an improvement is the fact that the participants had mild cognitive impairment, which had been diagnosed clinically and who, therefore, were at high risk of developing Alzheimer’s disease. , he said.
Will this training program prevent these people from developing dementia? “We don’t know,” he replies, despite the fact that the participants’ cognitive performance measured six months after the end of the program had declined very slightly and had not returned to the starting point.
“If the diet was maintained beyond six months, I would be more inclined to say yes,” continues the researcher, who is director of the EPIC Center at the Montreal Heart Institute.
“It’s not the little Sunday walk that works,” he emphasizes, moreover. It’s more of a consistent training program. We’re not just maintaining, we want to see progression. When we see that individuals have improved physically and cognitively, we push them even more. We aim to improve their cardiorespiratory health and their muscular strength. »
How do we explain the spectacular effect of this type of training? “When we exercise, we improve our metabolism, our blood flow and the distribution of oxygen in the body, so it cannot help but improve the brain, which is a large consumer of oxygen and glucose,” says the specialist.
In addition, it has been shown in animal models that exercise leads to the release of molecules, called exerkines, notably from the muscles (myokines) and the heart (cardiokines). These exerkines which are found in the blood circulation, also that of humans, are said to have “a neurotrophic effect” in the brain. “When we exercise, we create these molecules which would be factors of neurogenesis, angiogenesis and synaptogenesis,” says Mr. Bherer.
The production of these exerkines would perhaps explain the better connectivity between frontal and temporal regions that was observed in the brains of elderly people after a training program like that proposed in the SYNERGIC study. “Better connectivity means in particular that there is better use of mental resources,” explains the researcher.
What’s more, two studies, one published in PNAS and the other in Frontiers in Aging Neuroscience, also showed that a year of aerobic exercise training increased the volume of the hippocampus, a brain structure that plays a central role in memory. This increase in the hippocampus made it possible to counteract the shrinkage of 1.5 to 2% per year which occurs in people aged 65 and over.
“A lot of people think they can’t exercise because they have high blood pressure, or they’ve had heart surgery or knee surgery. It’s the opposite, it’s those who will benefit the most. You simply have to choose physical activities that will be adapted to the condition of each person. There are a multitude of them that work,” underlines Mr. Bherer.