Trajectories of children's internalizing symptoms: the role of maternal internalizing symptoms, respiratory sinus arrhythmia and child sex.

Results from epidemiological studies illustrate rates of internalizing disorders increase dramatically during adolescence (Kessler et al., 2005) and show predictive validity for the development of subsequent depressive and anxiety disorders (Kovacs & Devlin, 1998). Comorbidity rates for depression and anxiety are typically reported to be 50% (Angold, Colstello, &Erkanli, 1999). Individuals diagnosed with internalizing disorders tend to show impairment across multiple domains and are at increased risk for suicide attempts (Bolton et al., 2008). Thus, it is important to identify risk and protective factors during childhood that influence the development of internalizing disorders. One promising approach is the study of how biological and environmental factors interact to predict individual differences in risk and resilience to psychopathology (Steinberg &Avenevoli, 2000). Environmental factors such as parental depression (particularly maternal depression) and individual differences in physiological activity, including those pertaining to parasympathetic nervous system (PNS) activity, contribute to risks for internalizing disorders among children and adolescents (Shannon, Beauchaine, Brenner, Neuhas, &Gatzke-Kopp, 2007). As noted by developmental psychopathologists (Cicchetti & Rogosch, 2002), it is critical to consider individual differences in abnormal and normal development and how complex interactions of biological and environmental processes contribute to risk and protective factors for psychopathology. The current study is consistent with this perspective and aims to identify individual differences in physiological regulation that can exacerbate or ameliorate risk for child internalizing symptoms otherwise associated with maternal internalizing symptoms. The goals of this study were twofold. First, we examined individual growth trajectories of children's internalizing symptoms from mean ages 8-10 and investigated the predictive role of maternal internalizing symptoms and children's basal respiratory sinus arrhythmia (RSA; an index of PNS functioning) in accounting for changes in children's internalizing symptoms over time. For children in this age group the 3-month prevalence rates for internalizing disorders range from 0.3 - 7.5% (Costello, Mustillo, Erkanli, Keeler, & Angold, 2003), highlighting the need to study individual differences in these disorders over time and to understand better trajectories of internalizing disorders prior to the dramatic increase observed in adolescence.Second, we examined interactions among maternal internalizing symptoms and children's RSA to identify trajectories of increased risk and/or resilience in the development of children's internalizing symptoms. Because sex has been associated with risk for internalizing symptoms (Hankin, Wetter, & Cheely, 2008), we also investigated child sex as a moderator of effects. We build on the current literature by using a longitudinal design, multiple reporters, and advanced statistical techniques to investigate if RSA moderates the link between maternal internalizing symptoms and the development of children's internalizing symptoms; to our knowledge, this is the first such examination in the literature.