WORKING MEMORY RELATED BRAIN CONNECTIVITY DISTINGUISHES BIOLOGICAL FROM CHRONOLOGICAL AGE IN MIDDLE-AGED ADULTS

Cognitive aging is a heterogeneous process, often diverging from chronological age. It remains unclear when early signs of decline emerge and which neurophysiological markers distinguish age-related cognitive alteration from preserved performances.
Aim: This work aimed at identifying a brain functional connectivity explanation to the working memory performance variability that can be highlighted as early as the mid-fifties in healthy subjects.
Methods: 84 participants were included in this experiment. A group of young-adults (n=24; mean age ± SEM=22.7±0.5) and a group of 60 middle-aged adults (mean age±SEM=54.3±0.4). All of them performed a computerized visuo-spatial working memory (WM) task. In the middle-aged adults, we identified a group of high-performers (MA_HP) and a group of low-performers (MA_LP), based on their WM performances. Electroencephalography was recorded during a resting state period proposed before the WM task and during the WM task itself. Brain connectivity was analyzed using (S-LORETA) to compare connectivity between groups at rest and during the retention period of the task, i.e., the real “working memory” period of the task.
Results: The main result of this study is that brain connectivity at rest is similar in MA_HP and MA_LP whereas it is increased in MA_HP during “working memory”.
Conclusions: These results show that as early as midlife, independently of age, working memory abilities can be altered or maintained and this variability of performance is independant of the resting state brain connectivity but rather related to brain connectivity when the brain is actively involved in a cognitively demanding task.