Comorbidity: A network perspective

Abstract

The pivotal problem of comorbidity research lies in the psychometric foundation it rests on, that is, latent variable theory, in which a mental disorder is viewed as a latent variable that causes a constellation of symptoms. From this perspective, comorbidity is a (bi)directional relationship between multiple latent variables. We argue that such a latent variable perspective encounters serious problems in the study of comorbidity, and offer a radically different conceptualization in terms of a network approach, where comorbidity is hypothesized to arise from direct relations between symptoms of multiple disorders. We propose a method to visualize comorbidity networks and, based on an empirical network for major depression and generalized anxiety, we argue that this approach generates realistic hypotheses about pathways to comorbidity, overlapping symptoms, and diagnostic boundaries, that are not naturally accommodated by latent variable models: Some pathways to comorbidity through the symptom space are more likely than others; those pathways generally have the same direction (i.e., from symptoms of one disorder to symptoms of the other); overlapping symptoms play an important role in comorbidity; and boundaries between diagnostic categories are necessarily fuzzy.

PTSD symptomics: network analyses in the field of psychotraumatology

“…We hope that this special issue encourages researchers to conceptualize and model PTSD data from a network perspective, which arguably has the potential to inform and improve the efficacy of therapeutic interventions (Borsboom, 2017; Cramer et al, 2010; Hayes & Strauss, 1998; McNally, 2016). The methodological field of psychological network psychometrics has moved remarkably quickly from visualizing correlation matrices in 2010 (Cramer et al, 2010) to using sophisticated statistical models in 2014 (Van Borkulo et al, 2014).…”

“…We hope that this special issue encourages researchers to conceptualize and model PTSD data from a network perspective, which arguably has the potential to inform and improve the efficacy of therapeutic interventions (Borsboom, 2017; Cramer et al, 2010; Hayes & Strauss, 1998; McNally, 2016). The methodological field of psychological network psychometrics has moved remarkably quickly from visualizing correlation matrices in 2010 (Cramer et al, 2010) to using sophisticated statistical models in 2014 (Van Borkulo et al, 2014). The gap between clinical sciences and methodology is slowly closing, in part due to several tutorial papers (Costantini et al, 2017; Epskamp, Borsboom, & Fried, 2017; Epskamp & Fried, 2017) that have enabled clinical researchers to apply network models to a large number of disorders (for a review see Fried, van Borkulo et al, 2017).…”

“…A new research framework entitled ‘Symptomics’ was proposed recently that aims to describe such studies under one framework, and complement diagnosis-level research with more detailed research on symptoms (Fried, 2017). Symptomics has three cornerstones:The relationship of individual symptoms with important variables such as risk factors, biomarkers, impairment of functioning, and treatment response (Bentall et al, 2012; Costello, 1993; Fried & Nesse, 2015b; Hieronymus, Emilsson, Nilsson, & Eriksson, 2016; Persons, 1986);The analysis of the potentially causal relations among symptoms in symptom networks (Borsboom, 2017; Cramer, Waldorp, van der Maas, & Borsboom, 2010; Wichers, Wigman, & Myin-Germeys, 2015);Gaining better understanding of psychopathology by investigating personalized processes at the level of individuals instead of heterogeneous groups of patients (Fisher & Boswell, 2016; Molenaar, 2004). …”

“…The analysis of the potentially causal relations among symptoms in symptom networks (Borsboom, 2017; Cramer, Waldorp, van der Maas, & Borsboom, 2010; Wichers, Wigman, & Myin-Germeys, 2015);…”

A Bayesian network analysis of posttraumatic stress disorder symptoms in adults reporting childhood sexual abuse

“…The network perspective on psychopathology, pioneered by Borsboom and his associates (e.g. Borsboom, 2008, 2017; Borsboom & Cramer, 2013; Cramer, Borsboom, Aggen, & Kendler, 2012; Cramer, Waldorp, van der Maas, & Borsboom, 2010), offers a radically different way of understanding PTSD (McNally, 2012) and other mental disorders (for reviews, see Fried et al, 2017; McNally, 2016). According to this perspective, a mental disorder is not an underlying, latent (unobserved) disease entity, whether construed categorically or dimensionally.…”