This study finds that adolescent neurocognitive maturity mediates paths to altered social norms and vulnerability in early adulthood.
This dissertation examines cognitive skills and neural development in relation to social and environmental co-factors to identify paths leading to adverse outcomes in emerging adulthood. Paths to violence perpetration were found to begin with risk accrual in adolescence, followed by elevated environmental strain leading to social exclusion and heightened experiences of violence that resulted in an alteration of normative social and civic beliefs in adulthood. Adult males who experienced greater violence were more likely to report positive attitudes toward delinquency and the use of violence, and in consequence, perpetrate fighting and bullying behavior. Advanced cognitive maturity was common in females further along in puberty, as indicated by elevated inhibitory control of reflexive motor actions, less risk-taking, lower time preference for immediate rewards, and sensitivity to negative emotional faces. Delayed adolescent neurocognitive maturation was more common in physically developed males and directly drove the risk for future experiences of violence through desensitization to negative affect and greater reward responsivity and impulsivity. Age-related changes in cognitive skills and violence risk were explained by changes in brain volume, wiring, and activity measured with Magnetic Resonance Imaging (MRI). Prefrontal cortical and striatal volume, fractional anisotropy, and functional connectivity were revealed to mediate the development of inhibitory control and interact with risk and reward appraisal and facial affect processing to predict maturity. The synthesis of neuropsychological task performance with biophysical measures of the developing brain and sociodemographic factors demonstrate adolescence is a period of cognitive and social malleability susceptible to social influences in determination of lifespan outcomes in emerging adulthood. The rate of risk accrual was measured longitudinally during adolescence and found to predict future violent outcomes independently of the Behavioral Inhibition and Approach Systems, a self-report behavioral instrument for measuring motivational cognitive systems.