Diagnosis of psychiatric disorders in Asia, Europe differs: Study

Hyderabad: In a recent study published in the journal 'Psychiatry and Clinical Neurosciences', researchers from Japan investigated whether genetic correlations between major psychiatric disorders differed among European and East Asian populations. They found differences in how bipolar disorders are diagnosed by psychiatrists in the East and the West, which might affect the results of clinical trials.

Psychiatrists diagnose psychiatric disorders by observing a patient's symptoms and applying diagnostic criteria. However, the diagnostics tests available for psychiatric disorders do not rely on purely objective data. As a consequence, the results of a diagnostic test for a psychiatric disorder may be influenced by how the psychiatrist interprets the patient's symptoms.

While this problem is still prevalent, genomic studies can be used to identify genes associated with increased risk of certain disorders. Genetic correlation analyses have shown that different psychiatric disorders have certain degrees of shared genetic risk. Such were the findings of a recent analysis of the Psychiatric Genomics Consortium datasets, for which scientists calculated the genetic correlations between major psychiatric disorders, including schizophrenia, bipolar disorder, and major depressive disorder. This analysis was based mainly on samples from European countries.

This motivated a research team led by Professor Masahi Ikeda of the department of psychiatry at Fujita Health University School of Medicine, Japan, to compare these genetic correlations with those obtained from an East Asian population. This study was co-authored by Takeo Saito and Nakao Iwata, also from the same university.

What did the study find?

The researchers focused mainly on bipolar disorders (BDs), which can be classified based on the degree of 'extreme moods' as BD subtype I (manic and depressive states) and BD subtype II (hypomanic, which is a milder form of manic and depressive states). The results of the genomic analysis revealed that in the East Asian population, the genes of patients with BD subtype I were more correlated with those for major depression. This was in stark contrast with the results for the European population, for which BD subtype I was more genetically correlated with schizophrenia.

As per the research team, this difference stems from how Japanese psychiatrists diagnose bipolar disorders. Another plausible explanation was that Japanese psychiatrists tend to enroll patients with mood-driven problems more than patients with psychotic features in research on BD.

"The bottom line is that these differences in diagnostic (or 'enrollment') tendencies should be noted by psychiatrists when analyzing data, especially the results of clinical trials so that evaluation of drug responsiveness is not adversely affected," noted Professor Ikeda.

In Indian context

In the Indian context, genetic testing may not be feasible beyond the research arena. Dr. Vidit Singh, senior resident of psychiatry at Manipal Tata Medical College, said, "In India where patient load is heavy, especially in government hospitals, it is difficult and too expensive to perform genetic testing for supporting the diagnosis.

Also, rarely confusion occurs between diagnoses because there are numerous structured and validated scales to help with the diagnostic procedure. Even if some confusions creep in, (most likely due to comorbid psychiatric disorders), it wouldn't affect the treatment much because we have a wide variety of drugs with specific properties and drugs with multiple properties. However, this doesn't mean genetic testing isn't a welcome approach. It will definitely help with diagnosing patients and in tailoring the treatment better."