A Complex Network Perspective on Clinical Science

Abstract

Contemporary classification systems for mental disorders assume that abnormal behaviors are expressions of latent disease entities. An alternative to the latent disease model is the complex network approach. Instead of assuming that symptoms arise from an underlying disease entity, the complex network approach holds that disorders exist as systems of interrelated elements of a network. This approach also provides a framework for the understanding of therapeutic change. Depending on the structure of the network, change can occur abruptly once the network reaches a critical threshold (the tipping point). Homogeneous and highly connected networks often recover more slowly from local perturbations when the network approaches the tipping point, potentially making it possible to predict treatment change, relapse, and recovery. In this article, we discuss the complex network approach as an alternative to the latent disease model and its implications for classification, therapy, relapse, and recovery.

Keywords: complex networks; nosology; psychopathology; psychotherapy.

Figure 1

Hypothetical examples of individual complex networks for two people (Bob and Alice). The red circles show the nodes of the network that are part of the “depression” network (suic: suicidality; inte: loss of interest; depr: depressed mood; repr: self-reproach; moto: psychomotor disturbances; weig: weight problems); the blue circles are the nodes that are part of the “generalized anxiety disorder” (GAD) network (anxi: chronic anxiety/worry; edge: feeling on edge; even: anxiety about more than one even; ctrl: no control over anxiety; musc: muscle tension) and the green circles are part of both networks, bridging the depression and GAD networks (slee: sleep problems; fati: fatigue; conc: concentration problems). The arrows depict hypothetical causal links and the thickness depicts the hypothetical strength of the causal relations. From: Borsboom & Cramer, 2013, Annual Review of Clinical Psychology, 9, 91–121.

Figure 2

Critical slowing down as an indicator that the system has lost resilience and may therefore be tipped more easily into an alternative state (for explanation, see text). From: Scheffer et al., 2012, Science, 338, 344–348. Reprinted with permission.