Motor variability as a marker of the aging effects on the neuro-musculo-skeletal system

« Old age is a ship wreck », said Charles de Gaulle. Evens as cognitive and physical capabilities keep on declining with the passage of time, life expectancy in countries like Sweden, Japan or Italy has now reached 83 years old. Consequently, Benoît Rey-Robert's work will be significant to get a better understanding of age-related changes of behavioral performance. Traditional research approaches focus on domain and/or task specificities linked with ageing, such as the cardiovascular system, neurodegenerative diseases, locomotion or grip force control. In keeping with this tradition, each process is considered individually as it generates specific dynamics that have consequences on behavior.
The methods and findings of this type of research have led Rey-Robert to consider things from another angle. What if degeneration processes could be integrated in a complex network that operates on multiple scales in space and time? All the changes that take place in this system, however subtle, could impact the whole functional organisation.
Rey-Robert has set up different types of measures that could give information about the effects of ageing on the brain. He tested healthy elderly people andthey were asked to perform two complete different tasks, an aiming tasks evaluating the sensorimotor domain and a reaction time tasks for the cognitive domain.
By doing this, they managed to deduce the rate of mental processing speed. Coupling the data, revealed an increased coupling between the cognitive and sensorimotor domain suggesting an increased in shared ressources linked with ageing. This phenomenon, the general slowing of information, representing alterations in the neurobiological system, is visible through behavior in the slowing of movement.
This theory still needs to be strengthened, but it already has a high potential of application: indeed some preliminary results suggest that training one domain (let's say cognitive) improves the other. So by training your mind you can improve your sensorimotor abilities and reciprocally.
By designing well thought and purposeful training, like walking while doing arithmetics for example, that could help prevent the early deleterious effects of the passage of time on the neuro-musculo-skeletal system. Instead of being more and more fragile, elderly people could adapt to the exigencies of everyday life.

Understanding how cognitive and motor processes interact is a major challenge for aging research. Numerous studies have shown that elderly people are slower and more variable than young adults in a wide range of cognitive and motor tasks. However, whether slowing and increased variability express common cause factors that affect both cognitive and motor domains is still unclear. Our research program aims at determining whether slowing and variability are markers of correlated changes in motor and mental functioning. Then, these markers could be used as a predictive assessment tool.

The intricate process of ageing

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Université de la Méditerranée