The idea behind a complex systems perspective in psychiatry is that what we study, the brain and psychiatric disorders, are too complex to accurately capture in a statistical model. There are dependencies, competitions, and other interactions between the parts. This is in some ways a response to our typically Reductionism view in science, and particularly in psychiatry where the Germ theory of disease still prevails.

Complex systems can be presented as networks, for example Network theory of psychopathology, with Network nodes being a specific symptom and Network edges describing the relationships between nodes. Another example is the Internet, where network nodes are computers and links between computers are network edges. Social networks can be described in the same way.

Key concepts



Both the brain, cells, and the immune system can be seen as complex adaptive systems. We have evolved ways to re-arrange the connectivity of our brains, and in some cases neurogenesis occurs in adult brains (in the hippocampus for example).

Feedback loops


Response diversity