Cognitive fatigue in aging: psychological and neurobiological mechanisms

PI: Jonas Persson, jonas.persson.1@ki.se

Because more people are working past traditional retirement age, it is increasingly important to learn more about changes in cognitive abilities (memory, problem-solving, and more) as we age. One such change is the ease with which we become mentally drained, a state often referred to as cognitive fatigue (CF). CF can affect our work and quality of life. However, there are no reliable subjective or objective measures of it. Moreover, we know little about how healthy people reach CF when doing mentally demanding tasks, how they recover from it, and whether (and if so, how) reaching and recovering from CF changes with age.

We hypothesize that everyone has finite resources for completing cognitive tasks, and that these resources are coupled to specific brain areas. Further, we think that in older people, these resources may be smaller to begin with and may be more quickly depleted and/or more slowly resupplied than in younger people. If true, these hypotheses may explain much of the cognitive decline observed in healthy older adults.

In this project, younger and older adults complete tasks intended to deplete a specific executive function/brain area. They are then given additional tasks that use the same function/area. We measure (i) performance decline over time in the original tasks and (ii) performance on the additional tasks. We then compare both measures of performance in younger and older adults. These measures of performance, along with subjective rating scales and functional brain imaging, are used to investigate (i) the prevalence of CF, (ii) the cognitive mechanisms that underlie CF, and (iii) changes in how the brain works when we exert ourselves mentally (the neurobiological correlates of CF). Our ultimate goal is to help find ways to reduce CF in older and younger people, either via interventions or via environments that provide room for people to recover from CF.

The project is funded by a grant from the Swedish Research Council.