Pubertal development and adolescent risk-taking : understanding individual differences
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This set of projects focused on individual differences—specifically, how variation in the timing, context, and perception of this universal milestone might contribute to individual differences in risky behavior. Study 1 looked at testosterone as a potential endophenotype for substance use in adolescence. Combining self-report, hormonal, and behavioral measures, this study used a twin design to test the hypothesis that testosterone mediated genetic risk for substance use via its effect on reward seeking. The primary hypothesis was not supported, as there were no phenotypic associations between testosterone, reward seeking, and initiation of substance use. Study 2 focused on girls’ perceived pubertal timing in the context of their peer group, testing whether peer delinquency moderated the association between pubertal timing and delinquency. A twin comparison design was used to control for unmeasured between-family differences (family-level genetic and environmental selection effects) that would affect both peer and individual delinquency. Pubertal timing moderated the quasi-causal association between peer and individual delinquency: girls with earlier perceived pubertal timing were more similar to their nominated friends in delinquency. This interaction was only found for relative pubertal timing (asking girls to compare their development to their peers) and not for age-standardized ratings of body changes or for age at menarche. Study 3 examined whether pubertal timing reported by one’s friends and schoolmates related to perceived pubertal timing. Results showed gender differences: boys appeared similar to their peers in perceived body changes and girls appeared similar to peers in perceived relative pubertal timing. Collectively, these 3 studies highlight complexity inherent in studying sources of individual differences at a stage when numerous changes—biological, psychological, social—are underway. Understanding the extent to which these concurrent changes may or may not interact is an important step toward identifying factors that make some children prone to risk behavior.