Behavioural Science Blog

In medicine, diseases are classified according to the physiological problem that is presumed to have caused the disease. Classification is guided by advanced biological and chemical theories that have proven to have explanatory value. For mental illnesses that is a different story, because the working mechanism is mostly unknown and there is no unified scientific framework that can explain the abnormal processes. Mental health professionals for different schools might explain any given symptom according to a different theory. In that light the DSM was created to be purely atheoretical and give a minimal framework on which everyone involved could agree upon. The resulting manual has helped communication about mental illnesses and has fostered comparable research in the field of mental health. However it is questionable if the structure of the DSM is compatible with the reality of humans, who (for the most) are driven by the unstoppable urge to make sense of their environment. Indeed it was found in many studies that therapists often classify without adhering to the specific rules laid out by the DSM. They are guided by internal rules, that work in a different way than the DSM checklist. For example therapists regard some symptoms as more important for a specific diagnose than others (concept of centrality). The DSM on the other hand usually assigns equal weights to all factors. Because the concept of centrality has profound influence on memory and other cognitive processes the therapist’s personal theory plays an important role in the classification. I believe that the DSM should be regarded as a tool supporting communication that allows discussion about the different theories at hand. It can and will not replace the theories people have. If a theory based classification system is available (for a specific disease) it should be used next to or instead of the DSM.