For best experience please turn on javascript and use a modern browser!
Bekijk de site in het Nederlands

Many psychiatric disorders may not be isolated illnesses. Instead, such disorders are a complex system of symptoms that influence each other. This theory, put forward by researchers from the University of Amsterdam , contradicts the standard model for psychiatric disorders that forms the foundation of a great deal of psychiatric and clinical psychology research.

Many psychiatric disorders may not be isolated illnesses. Instead, such disorders are a complex system of symptoms that influence each other. This theory, put forward by researchers from the University of Amsterdam , contradicts the standard model for psychiatric disorders that forms the foundation of a great deal of psychiatric and clinical psychology research. Their proposition recently appeared in the scientific journal PLoS ONE.

In the standard model, disorders (such as depression) were viewed as illnesses that caused a number of symptoms (such as insomnia, or difficulty concentrating). However, psychologist Denny Borsboom and his colleagues do not consider psychiatric disorders as isolated illnesses. They believe that symptoms, instead of being caused by an underlying illness, actually influence other.

Depression presents a plausible case for this pattern of symptoms influencing each other. According to the researchers, someone suffering from insomnia inevitably becomes exhausted. Once this happens, it becomes more difficult to concentrate. This can lead to feelings of low self-esteem and anxiety which makes sleep even more difficult. In this case, it may be more effective to focus research on the role played by these symptoms as they pertain to the individual rather than on disorders as they are defined by the standard model.

Comorbidity

The model developed by the researchers also explains why comorbidity (the simultaneously appearance of disorders) is more likely the rule than the exception: problems do not remain limited to a single domain because different disorders can trigger each other. Such causal relationships between disorders run contrary to traditional disorders. On this point, the researchers were able to use simulations to demonstrate that their model comes close to representing the actual situation.

Research method

The researchers studied disorders using analysis methods developed for researching complex networks. They derived the network structure of symptoms using the way they were classified in the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV), a standard manual for classifying psychiatric disorders. The structure of the network revealed that almost half of the symptoms found in DSM-IV were directly or indirectly connected to each other.

Publication details

D. Borsboom, A.O.J. Cramer, V.D. Schmittmann, S. Epskamp en L.J. Waldorp: ‘The small world of psychopathology’, in PLoS ONE, 17 November 2011.