The Value of Psychiatric Diagnoses

Heckers [1] questions whether we are “using the best diagnoses to make progress in psychiatric research” and the suggestion that we may need dimensional rather than categorical diagnoses. Three articles in the same issue also address the question, with reference to a proposed Research Domain Criteria (RDoC) classification.  Diagnosis of mental illness has been a major problem for some two hundred years [2] and psychology was heavily involved before psychiatry became a medical specialty. It has still had a lot to say particularly in my early career time –when models of madness [3] were argued about as well as diagnosis. It is only in the last fifty years that we have started to know enough about the neurobiology of mental disorders to be able to hope for a truly medical diagnostic classification. The current practice of using a wide range of pharmaceuticals across divergent diagnostic categories [4] points to the extreme complexity of the molecular relationships in mental functioning, well and sick.  One of the criticisms of evidence based medicine is the relative departure from preclinical basic sciences [5] in which psychiatry has ever been way behind the rest of medicine.

Thus the time is ripe to have two classifications, as the ICD has tried. The DSM in its turn is fine for clinical use, changing from time to time as our knowledge base increases, or our treatment practices change, sufficiently to warrant a revision. It almost certainly will not be satisfactory until it reflects an understanding of the basic, whole of body, neurobiology. If RDoC is preferred by researchers and especially biologists, so be it. As Hecker says “The proponents of RDoC are correct that we need a much deeper exploration of neuroscience and genetics to advance a mechanistic understanding of mental illness”. Clinicians should welcome and encourage such research into the molecular physiology of all psychiatric disorders, without the misleading distinction between organic and psychological disorders and bearing in mind that important molecular relationships extend beyond the head. Like infection the response to threat and challenge (including of course infection/invasion) is among the oldest life functions and the molecular response is therefore likely to show up in all later more sophisticated responses and functions. With such research we may well come full circle and somatic symptoms might again feature in the diagnostic process [2]. The pursuit of a truly medical diagnostic classification does not mean that psychology is not recognized for the valuable part it has to play in understanding and in the treatment of mental disorders.

 

References
[1] Heckers S. The Value of Psychiatric Diagnoses. Editorial. [published online Nov. 11, 2015]. JAMA Psychiatry. doi: 10.1001/jamapsychiatry.2015.2250.
[2] Berrios GE. The History of Mental Symptoms: descriptive psychopathology since the nineteenth century. 1996. Cambridge University Press. Cambridge.
[3] Siegler M, Osmond H. Models of Madness. British Journal of Psychiatry, 1968; 112;1193-203.
[4] Homberg JR, Kyzar EJ, Stewart AM et al. Improving treatment of neurodevelopmental disorders: Recommendations based on preclinical studies. [published first online Nov 11, 2015] Expert Opinion on Drug Discovery

[5] Greenhalgh T, Howick J, Maskrey N et al. (Evidence Based Medicine Renaissance Group) 

Evidence based medicine: a movement in crisis? British Medical Journal. 2014; 13;348:g3725. 
doi: 10.1136/bmj.g3725.