RESEARCH ARTICLE The association between d t

Full list of author information is available at the end of the articleIntroduction The major depressive disorder (MDD), also known as unipolar depression, is one of the most common mood disorders experienced during life. The condition is char-acterized by any changes in appetite, weight, sleeping pattern and routine activities, lack of energy, guilt feel-ing, difficulty in decision making, lack of motivation and pleasure [1,2]. According to the 2000 WHO report, 121 million people worldwide suffer from depression and MDD is considered as the fourth cause of burden and the most cause of disability worldwide. The report also predicts that MDD will become the second leading cause of burden disease on 2020. It is also mentioned that 15 % of patients with MDD eventually commit suicide [3]. In Iran, studies have shown that depression with a prevalence of 3.8 % is on the top of the mental disorders and 21 % of population suffers from this disease [4]. Hadavi et al. [5] reported that the mild, moderate an