The effect of age on the architecture of psychological and cognitive dimensions: a network perspective

Ageing involves changes across the life span in cognitive abilities, mental health, and personality traits. Although these domains are often studied separately, recent findings highlight their interdependence and dynamic interplay. To examine these relationships, we analysed data from the Human Connectome Project (HCP-Young and HCP-Aging datasets) divided into three age groups: Young (22-39; n = 230), Middle-aged (40-59; n = 242), and Older adults (60-79; n = 209). The interrelationships among 19 cognitive, psychological, and personality variables were investigated using a psychometric network approach, estimating one network per age group and examining how variables clustered into communities (exploratory graph analysis) and comparing the emerging networks using the network comparison test (NCT). We observed substantial differences across age groups. In younger adults, cognitive variables were split into two communities, separating lower from higher cognitive functions, whereas middle-aged and older adults did not present this separation. Two variables-delay discounting and emotion recognition -associated with cognition in younger populations clustered with personality traits and psychological factors in the Older Adults' network, suggesting an increased relevance of their affective significance. The NCT confirmed that the architectures of the Young Adults and the two older groups' networks were significantly different. Compared to the Young Adults, the Older Adults network also showed reduced overall association strength. Altogether, these findings support the view that ageing is associated with structural transformations in the relationships among cognitive, psychological, and personality domains, following a dedifferentiation trajectory across cognitive variables and a general reorganization of psychometric factors.