Background: The diagnosis of the disease, major depressive disorder (MDD), entirely depends on the presence of some symptoms without any biochemical parameter to support it. Depletion of dopamine though is an established feature, is not the sole causative factor of MDD. Moreover, it has very little diagnostic value due to a short half-life. Other chemical messengers like hormones have also been found to get altered due to significant over activity of hypothalamo-pituitary axis. Literature review suggests that cortisol, thyroid-stimulating hormone (TSH), and prolactin (PRL) are mostly altered in MDD, which can be utilized to diagnose the condition.
Materials and methods: A total of 101 patients suffering from MDD along with 106 age- and sex-matched controls were included in this study. Cortisol, TSH, and PRL were assayed in all the study participants by enzyme immunoassay. Student's t-test and linear discriminant analysis were used for statistical analysis.
Results: All the three hormones were found to be significantly high in cases with MDD. When applied for classification purpose, the errors in training group were found to be 15% and 15.74% from test set. None of the normal population was wrongly diagnosed as a patient of depression.
Conclusion: To the best of our knowledge, this is the first attempt to evaluate multiple biochemical parameters as diagnostic marker of MDD. The study is in progress to find out a cutoff value of the responsible parameter so that they can be optimally used to diagnose a case of MDD.
Keywords: Cortisol; major depressive disorder; prolactin; thyroid-stimulating hormone.