A LONGITUDINAL INVESTIGATION OF CHANGE IN MENTAL HEALTH ACROSS THE TRANSITION TO ADOLESCENCE: THE ROLES OF PUBERTY, WORKING MEMORY, AND FUNCTIONAL BRAIN NETWORK ORGANIZATION

The developmental period spanning the transition from childhood to adolescence is marked by physical, socioemotional, cognitive, and brain changes. Vulnerability for mental health problems increases during this period, and poor mental health in adolescence has been linked to impaired working memory, early and fast pubertal development, and aberrant communication across large-scale brain networks. The work in this dissertation probes the relationships between working memory, pubertal development, and resting state brain network organization that relate to changes in mental health during the transition to adolescence. Chapter 1 tests how working memory and pubertal development relate to change in mental health across 9-14 years. We observed that early pubertal timing predicted faster increases in internalizing problems, and while working memory was related to concurrent mental health, it was not predictive of rate of change in future mental health. Chapter 2 probes how resting state brain network organization relates to change in mental health problems and working memory across 9-12 years, and tested for modulations with pubertal status and tempo. We calculated functional integration, or strong connections across the brain, and segregation, or strong connections within coherent networks relative to across networks. We focused on segregation of two cognitive control-related large-scale brain networks (fronto-parietal and cingulo-opercular) that are integral to working memory and have aberrant function with mental health problems. We identified unique predictors of mental health and working memory, as well as a common set of brain network features that relate to both slower increases in mental health and faster improvement in working memory, including global network integration and fronto-parietal segregation from the default mode and visual networks. Almost all relationships were modulated by either pubertal status or pubertal tempo. We observed a pattern such that for individuals earlier in pubertal development less segregated cognitive control networks was advantageous for slower increases in mental health problems and faster improvements in working memory, but the opposite was true for more advanced pubertal development. Together these projects provide insight to the complex interactions between cognitive, brain, and pubertal development that relate to the emergence of mental health problems during the transition to adolescence.