Homotypic and heterotypic continuity of symptoms of psychiatric disorders from age 4 to 10 years: a dynamic panel model

Abstract

Background: Childhood psychiatric disorders and their symptoms evince both within-disorder (homotypic) and between-disorder (heterotypic) continuities. These continuities may be due to earlier symptoms causing later symptoms or, alternatively, that the same (unknown) causes (e.g., genetics) are operating across time. Applying a novel data analytic approach, we disentangle these two explanations. Methods: Participants in a Norwegian community study were assessed biennially from 4 to 10 years of age with clinical interviews (n = 1,042). Prospective reciprocal relations between symptoms of disorders were analyzed with a dynamic panel model within a structural equation framework, adjusting for all unmeasured time-invariant confounders and time-varying negative life-events. Results: Homotypic continuities in symptoms characterized all disorders; strongest for attention-deficit/hyperactivity disorder (ADHD) (r = .32-.62), moderate for behavioral disorders (r = .31-.48) and for anxiety and depression (r = .15-.40), and stronger between 8 and 10 than between 4 and 6 years. Heterotypic continuity also characterized all disorders. A dynamic panel model showed that most continuities were due to unmeasured time-invariant factors rather than effects of earlier symptoms on later symptoms, although symptoms of behavioral disorders, which evinced two-year homotypic continuity (B = .14, 95% CI: .04, .25), did influence later symptoms of ADHD (B = .13, CI: .03, .23), and earlier ADHD symptoms influenced later anxiety disorder symptoms (B = .07, CI: .01, .12). Conclusions: Homotypic and heterotypic continuities of symptoms of childhood psychiatric disorders are mostly due to unobserved time-invariant factors. Nonetheless, symptoms of earlier behavioral disorders may affect later symptoms of such disorders and of ADHD, and ADHD may increase the risk of later anxiety. Thus, even if interventions do not alter basic etiological factors, symptom reduction may itself cause later symptom reduction.

Patterns of Homotypic and Heterotypic Continuity Between ADHD Symptoms, Externalising and Internalising Problems from Age 7 to 15

“…The majority of the available studies have focused on these links in young children. Partly consistent with our results, one such recent study (Wichstrøm et al 2017) based on a community sample of children in Norway assessed biennially from age 4 to 10 found that ADHD predicted anxiety two years later but not vice versa. In our study anxiety/depression were predictors of lower levels of ADHD symptoms at two time points during adolescence.…”

Developmental stability of general and specific factors of psychopathology from early childhood to adolescence: dynamic mutualism or p‐differentiation?

“…Widespread comorbidity (Kessler et al, 2005) coupled with shared genetic and environmental risk (Waldman, Poore, van Hulle, Rathouz, & Lahey, 2016;Wichstrøm, Belsky, & Steinsbekk, 2017) has led to a surge in models that conceptualize psychopathology as a number of broad transdiagnostic dimensions. Currently the most widely discussed model includes a general psychopathological factor, labeled p, that is purported to account for the moderate correlations between psychopathological dimensions (Caspi et al, 2014;Lahey, Krueger, Rathouz, Waldman, & Zald, 2016).…”

Commentary: The dynamic panel model: a promising approach to clarify sources of influence in developmental psychopathology – a commentary on Wichstrøm et al. (2017)

“…As such, the study offers an elegant demonstration of the potential of the DPM approach for disentangling self-perpetuating (or even self-aggravating) factors from common etiology as a cause for continuity and/or comorbidity of mental health problems. The study by Wichstrøm et al (2017) undoubtedly will inspire other research. Potentially, it may hold true in other research that most continuity in symptoms is due to time-invariant factors.…”

“…The study by Wichstrøm et al. () undoubtedly will inspire other research. Potentially, it may hold true in other research that most continuity in symptoms is due to time‐invariant factors.…”

“…Second – as is the case with most types of data analyses – the DPM merely affords a simplified representation of the complexity of the real world. The authors acknowledge this point when explicating the difficulties of conceptually categorizing a variable as time variant or invariant [see supplement of Wichstrøm et al ()]. For example, time‐varying factors may also possess time‐invariant properties (trait) in addition to their time‐varying properties (state), such as stable parenting styles versus time‐varying fluctuations in parenting behavior.…”