Symptomological vs. Physiological based classification of psychiatric disorders: half baked thoughts

Introduction & Definitions

will add later

What has prevented translational psychiatric research from making meaningful advances in treatments the past 50 years?

Or: a very brief essay I wrote in response to an exam prompt when I was 18. My ideas have developed since then but this is still roughly accurate and a good placeholder until I get some more polished writing done.

Currently, psychiatric disorders are defined as groups of commonly co-occurring symptoms which cause sustained functional impairment in a patient. There are several issues with this standardised, symptomology-based approach to these disorders. First, psychiatric diagnosis is strongly influenced by the time period’s dominant cultural norms. At one point in American history, slaves who tried to escape were considered mentally ill, as were homosexual people. Even though the bias underlying these “illnesses” is now recognized, cultural norms are sure to change as time progresses, and the diagnostic criteria are sure to change with it. The definition of a psychiatric illness can also be highly variable across countries and cultures, despite the existence of an international diagnostic guide (the ICD from the WHO). Second, psychiatric disorders exist on a spectrum. Many psychiatric symptoms are experienced by people who would not be diagnosed with a disorder—rather, there are thresholds of symptom duration and functional impairment, set by a diagnostic handbook, which separate those with mental illnesses from the general population. However, the biggest issue at hand—and the primary cause of disconnect between neuroscience and psychiatry-- is that diagnostic criteria are symptom-based, rather than biology-based. Medical fields aside from psychiatry understand that a symptom (or collection of symptoms) can be caused by a myriad of biological factors: therefore, most diseases and syndromes are defined by their underlying causes. Yet for some reason, the field of psychiatry remains rooted in symptomology. As a result, there is often a great amount of biological variation between two patients with the same disorder—indeed, sometimes patients can be more neurologically similar to neurotypical/control subjects than they are to other patients. Focusing on symptoms instead of biology hinders any potential insight from translational neuroscience research, since neuroscience and psychiatry are operating on two different frames of reference. Perhaps the reason it is so difficult to uncover a neurological basis for some disorders is because there does not exist a single neurological basis--- instead, patients with entirely different medical conditions are being grouped together by their shared symptoms. A shift to a neural biomarker- or activity-based diagnostic system will undoubtedly result in meaningful improvements from translational neuroscience research. Using biological factors as diagnostic criteria reduces possible cultural or moral bias; allows for more objective, scientific definitions of illness; and facilitates connections between basic/translational research and the clinical environment. Using a neuroscientific approach to psychiatry would allow the purposeful development of more effective pharmaceuticals, more accurate prediction models, and improved, personalized treatment plans. Overall, using a biology-based approach to psychiatric disorders would not only provide a better understanding of these disorders, but would also result in improved treatment and therefore better quality-of-life for patients with such disorders.