Association of Serum Biomarker Levels and BDNF Gene Polymorphism with Response to Selective Serotonin Reuptake Inhibitors in Indian Patients with Major Depressive Disorder

<b><i>Introduction:</i></b> Depression is a major public health problem. Response to selective serotonin reuptake inhibitor (SSRI) treatment varies considerably between patients. In the context of polygenic diseases like depression, measurement of a panel of biomarkers involved in the pathophysiology of depression might help predict outcome to treatment with SSRIs. <b><i>Objective:</i></b> The objective was to establish the relationship between serum biomarker levels and the brain-derived neurotrophic factor (BDNF) val66met polymorphism and response to SSRIs in patients with major depressive disorder. <b><i>Methods:</i></b> 50 patients with moderate to severe depression were recruited from the Department of Psychiatry, Sri Ra­machandra Institute of Higher Education and Research. Blood samples were collected, and Hamilton Depression Rating Scale scoring was done at baseline and after 8 weeks of treatment with SSRIs. Baseline and post-treatment levels of high-sensitivity C-reactive protein (hsCRP), BDNF and neuregulin 1β1 (NRG1β1) were analysed using commercially available ELISA kits. Genotyping of the BDNF Val66Met polymorphism was performed using a PCR-RFLP method. <b><i>Results:</i></b> Following treatment, there was a significant decrease in the mean hsCRP and NRG1β1 levels and a significant increase in the mean BDNF level. Responders had significantly lower baseline hsCRP and higher baseline BDNF levels when compared to non-responders. Response rates were significantly higher in the Val/Val group when compared to the Val/Met group. <b><i>Conclusions:</i></b> Baseline serum levels of hsCRP and BDNF predicted response to SSRIs in major depressive disorder, and Val/Val patients responded better when compared to patients carrying the Met allele.