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Brain Connectivity for Executive Control over Action in Ageing

Periodic Reporting for period 1 - ConnectExAct-Age (Brain Connectivity for Executive Control over Action in Ageing)

Reporting period: 2018-05-01 to 2020-04-30

Over the past years, the European Commission has been pursuing the goal to promote an active and healthy lifestyle of the group of older adults in our ever-ageing society. One hallmark of ageing is a decline in motor functioning that represents a crucial impediment for an active living and functional independence. Hence, this core issue must be addressed in order to promote mental and physical health throughout the lifespan. Age-related motor functioning decline can include movement slowing, postural instability, and coordination deficits, all of which may severely hinder older adults’ active participation in society and impairing their quality of life. The present project was designed to pave the way for effective, cost-efficient interventions to mitigate motor decline in older adults by targeting more generic brain functions that guide and control goal-directed actions—the executive functions.

Complex motor tasks, such as coordinating simultaneous actions of both hands, require precisely controlled movements. Therefore, complex motor coordination relies on an individual’s capacity to plan and control their actions. Such high-level mental processes that control low-level processes are termed “executive functions”. These executive abilities thus represent a conjunction between motor and cognitive functions. Previous research has demonstrated older adults to rely increasingly on executive functions to maintain successful motor performance. At the same time, executive functions decline during ageing, which potentially further compromises motor control in ageing. If better executive functions facilitate movement control, ameliorating executive abilities will represent a promising approach for enhancing motor abilities in older adults.

Executive functions is an umbrella term for multiple functions. One well-established framework distinguishes between three key aspects of executive functioning: inhibition (suppressing unwanted actions), updating (monitoring and processing of working memory content), and shifting (flexibly switching between dissimilar tasks). Interestingly, all these executive functions likely contribute to successful motor functioning, but it has remained unclear so far whether some facets of executive functioning are particularly crucial for motor control. Hence, this project aims at revealing which aspects of executive functioning are most relevant for movement decline in older adults. Executive functions that are closely linked to motor performance constitute potential intervention targets. To investigate the relations between executive functions and motor performance, a battery of computerized executive and motor tasks is administered to a large number of older adults (60 years and older). For comparison, a group of young individuals (18-40 years) completes the same test battery.

To gain a comprehensive understanding of age-related changes in motor function, this project studies behavior in conjunction with its neural correlates. The healthy brain is organized in networks, where clusters of different brain areas are specialized for performance of distinct tasks. Profound network re-organization occurs during ageing, with aberrant coupling between usually distinct areas. Previous research has indicated that abnormal connectivity between brain networks is related to decreased motor performance. In this study, networks are investigated using multimodal neuroimaging techniques. Specifically, resting-state functional magnetic resonance imaging is applied to study functional networks (i.e. networks of brain areas showing similar activity over time), whereas diffusion-weighted neuroimaging is applied to study structural networks (i.e. networks of brain areas that are anatomically linked).

This work combines motor and neuropsychological assessments with multimodal neuroimaging to pave the way for cognitive training interventions to improve motor functions in older adults. It will unravel how brain network alterations are linked to motor and executive performance, allowing for a better understanding of age-related performance declines in both domains.
In the preparatory phase, approval was obtained from the appropriate ethical committee. A computerized behavioral testing battery was setup. This battery comprises nine neuropsychological tasks as well as a series of complex motor coordination tasks. The neuropsychological tests were designed to tax the three executive functions referring to inhibition, shifting, and updating with three tasks, each. The motor coordination tasks were designed to be complex enough to tax executive functions during task completion. A neuroimaging protocol was setup. This protocol contained anatomical, functional and diffusion magnetic resonance imaging scan sequences and hence allowed for a comprehensive analysis of functional and structural brain networks.

Data collection involved three sessions per individual. The neuropsychological and motor tasks as well as a number of background questionnaires were administered in two separate sessions. Neuroimaging was performed during a third session. Data were collected from 140 participants (107 individuals 60 years or older during testing, 33 individuals between 18 and 40 years). Due to the COVID-19 pandemic, data collection has been discontinued in March 2020 and will potentially continue in the future until data of 114 older adults and 33 young adults have been collected. Initially, it was planned to collect data of 109 older adults. This represents an exceptionally large sample size. This ensures that the relations between executive functions and motor performance are highly likely to be detected in the collected dataset, provided that such a relation exists. The planned sample size has been increased by five in order to ensure the inclusion of 109 complete datasets in the analyses. In addition, a group of young participants has been added in order to validate the postulated association between age and behavioral performance as well as age-related changes in brain networks.

Data pre-processing and data analysis is currently ongoing, with first results expected during the coming months. The results will be disseminated in form of scientific articles in international peer-reviewed journals. In addition, it is planned to communicate the results to a general audience in the form of a seminar.
This project lays a basis for a thorough understanding of the relation between motor and executive abilities and age-associated changes in brain networks. The results will inspire a cognitive training tool for enhancing motor abilities in older adults. Motor and executive control have been studied mostly in isolation, and only few studies have assessed the relation between executive and motor abilities in older adults. Hence, the idea to improve motor abilities by enhancing executive functions is unconventional. This is surprising given a) the evidence that older adults increasingly rely on cognitive resources during complex movements, and b) the theoretical link between executive and motor abilities. This project will contribute to the understanding of aberrant brain network organization in ageing by studying its interactions with motor and executive performance. This dataset will consist of an exceptionally large sample, which implies that the study will potentially deliver highly reliable and meaningful outcomes.
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