The Effect of Age on the Architecture of Psychological and Cognitive Dimensions: A Network Perspective

Ageing refers to a series of changes occurring throughout the lifespan in cognitive abilities, physical and mental health, and personality traits. While these dimensions have traditionally been studied as separate compartments, recent findings highlight their interdependence and dynamic interplay over time. To investigate their relationships, we analysed data from the Human Connectome Project using a psychometric network approach. Participants were grouped into three age categories: Young (22–35), Middle-aged (36–59), and Older (60–100) adults. We examined the interrelationships among 31 cognitive, psychological, and personality variables using Exploratory Graph Analysis (EGA) to estimate one network per age group and explore how these variables cluster into communities across the lifespan. Networks were then compared using the Network Comparison Test (NCT) to identify age-related differences in both global and local network properties. We observed substantial age-related changes: variables clustered into six communities in the Young Adults group but only into four in both the Middle-aged and Older Adults, suggesting dedifferentiation and reduced domain specificity in the older age groups. The NCT revealed distinct network architectures for each age group, with the most pronounced differences between Young Adults and the two older groups. Additionally, global strength—a measure of overall network connectivity—was significantly lower in Older Adults, indicating that associations among variables were on average weaker. Overall, 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 and highlighting the reorganization of behavioural functioning with age.