Current Diagnosis of Mental Disorders and its Limitations

“A mental disorder is a syndrome characterized by clinically significant disturbance in an individual’s cognition, emotion regulation, or behavior that reflects a dysfunction in the psychological, biological, or developmental processes underlying mental functioning.”1

Well, the above is the classic definition of mental illness according to the American Psychiatric Association following the Diagnostic and Statistical Manual (DSM)2. DSM is the latest and widely-used tool by clinicians to diagnose an individual with a psychiatric illness. To have a little better insight, let’s understand how the DSM works; an individual who suffers from certain symptoms visits their psychotherapist, and the latter would diagnose them after just hearing their complaints and corresponding symptoms.
Mental disorders, however, are complex and heritable (40%-70%), and, therefore, looking only into the observable symptoms would simply be ineffective. Furthermore, the treatment of many mental disorders is successful only for ~50% of the patients. The rationale for this is that there are no general medical tests to run in order to provide better diagnostics for those patients. That is the most concerning issue in the field.

The expectations from current medicine are higher than symptomatology diagnosis.

We cannot imagine a visit to our physician nowadays without providing some minimal medical tests (blood, urine, imaging scans etc), can we? The same should apply to neuropsychiatry. We cannot accomplish better diagnostics for the psychiatric patients without general medical tests. However, current DSM diagnostics and treatments are based solely on symptom severity and classification. Therefore, to have more precise psychological treatments, we need to understand the underlying biology and genetic etiology of these disorders. This could entirely change the way we classify psychiatric disorders.

Currently, to overcome those challenges, researchers study genetic etiology of these complex disorders; i.e. the genes that are in any way associated with the disease psychopathology. This can be carried out by identifying the genetic mutations of the risk genes or even the processes that those risk genes are playing a role in.
For instance, there is enormous work done in schizophrenia research, and as schizophrenia is highly heritable (~70%), the identification of the causative genes will moderate current treatment. Thus, the medications that target gene products which are specifically and precisely associated with schizophrenia are more effective.

Psychiatric genetics is a growing field and work done here is unexchangeable. Transdiagnostic tools need to be created and applied with the ultimate goal of creating precision medicine for psychiatry. After having causative genes for the disorders, an expert in the field will be able to prescribe a medication to target the right gene. The RDoC (research domain criteria) framework is another tool currently used only by researchers (DSM is mainly used by clinicians) that will facilitate the psychiatric diagnostics following the opposite flow.3 According to RDoC framework, other tests such as genetics, neuroimaging, cognitive test should be mandatory for the final outcome. This transdiagnostic tool will integrate available vast amounts of data into knowledge for a better diagnosis in future.

To sum up, future psychiatric treatment should adapt to the precision medicine paradigm. Genomics and neuropsychiatry should be equally considered for the diagnosis. This will bring up a different dimensionality distribution for psychiatric disorders which will help to achieve better therapeutic approaches and more effective treatment for mental illness.

References

  1. F. Edition, Diagnostic and statistical manual of mental diorders. Am Psy- chiatric Assoc, 2013. s
  2. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington VA
  3. Cuthbert, Bruce N. (March 2015). “Research Domain Criteria: toward future psychiatric nosologies”. Dialogues in Clinical Neuroscience. 17 (1): 89–97

Guest post written by Lilit Antonyan.

Lilit is a PhD candidate pursuing her degree in Medical Genetics and Psychiatry in Canada. She has been involved in many research studies in Armenia, Germany and Canada. She started her academic journey by earning her BSc degree in Yerevan State University and National Academy of Sciences, in Armenia. She moved to Germany to obtain her MSc degree at the University of Bonn, Germany. She started to work on psychiatric genetics already in her MSs student job at the Fraunhofer Institute for Algorithms and Scientific Computing (Fraunhofer SCAI), Germany.

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