Mental disorders as networks of problems: a review of recent insights

Abstract

Purpose: The network perspective on psychopathology understands mental disorders as complex networks of interacting symptoms. Despite its recent debut, with conceptual foundations in 2008 and empirical foundations in 2010, the framework has received considerable attention and recognition in the last years.

Methods: This paper provides a review of all empirical network studies published between 2010 and 2016 and discusses them according to three main themes: comorbidity, prediction, and clinical intervention.

Results: Pertaining to comorbidity, the network approach provides a powerful new framework to explain why certain disorders may co-occur more often than others. For prediction, studies have consistently found that symptom networks of people with mental disorders show different characteristics than that of healthy individuals, and preliminary evidence suggests that networks of healthy people show early warning signals before shifting into disordered states. For intervention, centrality-a metric that measures how connected and clinically relevant a symptom is in a network-is the most commonly studied topic, and numerous studies have suggested that targeting the most central symptoms may offer novel therapeutic strategies.

Conclusions: We sketch future directions for the network approach pertaining to both clinical and methodological research, and conclude that network analysis has yielded important insights and may provide an important inroad towards personalized medicine by investigating the network structures of individual patients.

Keywords: Comorbidity; Early warning signals; Mental disorders; Network analysis; Treatment.

Fig. 1

a Pairwise associations among eight symptoms of a hypothetical patient Susan; this network is based on time-series data and thus leads to a directed network. b Pairwise associations among eight symptoms in a hypothetical group of patients; this network is based on cross-sectional data and thus leads to an undirected network

Fig. 2

How comorbidity can arise according to the network approach. Disorder X consists of the eight symptoms X1–X5 and B1–B3, and disorder Y consists of the eight symptoms Y1–Y5 and B1–B3. B1–B3 are bridge symptoms that feature in both diagnoses. In this case, a person first develops X3 in response to an environmental stressor E, then symptoms of disorder X, then bridge symptoms B, and finally symptoms of disorder Y

Fig. 3

Psychopathological network showing the pairwise associations among ten symptoms. Each node depicts a number that is the sum of all connections of the node with all other nodes, called degree centrality. The red node has the highest degree centrality with six connections