A novel perspective on psychopathology [is called the] network perspective, pioneered by the Dutch psychometrician Denny Borsboom and his colleagues.
Borsboom was inspired by contemporary theorising about intelligence – specifically, how it might emerge from the interactions of multiple cognitive subsystems.
According to the network perspective he and others have developed, a psychiatric disorder, such as major depression, is itself an emergent phenomenon. It arises from a network of interactions among its constituent elements (eg, sleep, mood and energy).
For an example of how this could work, consider someone who has experienced a stressor at work, and now has difficulty falling asleep.
Fatigue will likely occur the following day. Fatigue, in turn, can impair attention to tasks at work and increase irritability.
Subsequent conflicts with coworkers can lower mood, exacerbate other symptoms and activate additional ones (such as hopelessness).
Causal interactions among these symptomatic elements can reinforce one another, establishing the state we call depression.
Hence, unlike a bacterial infection or malignant tumour, depression is not the underlying cause of symptoms.
Rather, depression designates the system that emerges from these causal interactions.