Psychosocial adversity and adolescents’ mental health problems:Moderating influences of basal cortisol, resting heart rate and Dopamine Receptor D4

Exposure to stressors is a well-established risk factor for psychopathology, both externalizing (aggressive and rule-breaking) and internalizing (mood and anxiety) problems, but affects some individuals more than others. Central to this dissertation are three biological factors that may increase or decrease the risk of psychopathology after exposure to stressors (thus reflecting susceptibility or resilience): basal cortisol level upon waking, resting heart rate, and the Dopamine D4 Receptor 7-repeat allele (DRD4-7R). The results showed that all three biological factors significantly changed the risk of psychopathology after exposure to stressors, although findings on basal cortisol were not consistent. The results also showed that the influence of basal cortisol and resting heart rate on the relationship between stressors and psychopathology was dependent on the degree of general vulnerability, measured as parental psychiatric history. However, effects were small and not always in the expected direction. Therefore, it seems unlikely that a single biological measure such as basal cortisol, resting heart rate, or a genetic polymorphism will someday be useful to the clinical practice in terms of risk assessment or in determining treatment course. Future research may focus on combinations of established risk or resilience factors.The studies described in this dissertation are based on data from TRAILS (TRacking Adolescents’ Individual Lives Survey, www.trails.nl), both the population-based birth cohort (n = 2230) and the parallel clinic-referred cohort (n = 543) and the first three measurement waves when participants were on average 11, 13.5, and 16 years old