The present study aimed to 1) determine the levels of primary and secondary antioxidants in the serum of schizophrenics, 2) assess homocysteine levels and their relation to thyroid dysfunction, 3) examine serotonin-dopamine-prolactin interactions and hyperprolactinemia mediated depression (HMD), 4) observe the schizophrenics susceptibility to thyroid disorders by measuring their thyroid profile and 5) elucidate vitamin D levels and their effects in rendering the schizophrenics to autoimmune thyroid disorders (AITDs). The gene discussed is PRL; the disease is major depressive disorder.