1.1 Introduction: Depression is commonly understood as an individual's feeling of sadness or a general impairment of the individual's normal functioning which has a direct effect on the individual and also about his family and friends. A man named Hippocrates, described as the father of Western medicine, initially described an individual's low mood as “Melancholia”. Hippocrates described melancholia as characterized by specific mental and also physical symptoms. In its 2,400 year history, the term melancholia has changed meaning numerous times. The term melancholia was often used in Greco-Roman antiquity in a very broad sense to describe individual states that today can be defined as "schizophrenic". The term melancholia derives from the Latin transliteration of the Greek term melancholia. In Greece the term described a mental disorder involving a continuous lowering of mood and even feelings of fear which sometimes meant "biliousness" and in medical language this term described "nervous" or "crazy" behavior. The term was taken from the words melaina chole, translated into Latin as astra bilis and into English as black bile (Medicalnewstoday.com, 2009). The affect, mood or emotions caused by depression or melancholy have been well known to humans for thousands of years. It was once believed that clinical depression did not have as wide a range of symptoms as melancholy. Symptoms of melancholy include despondency, despondency, general sadness, fear, anger, obsessions and even disappointments. Abraham Lincoln is believed to have suffered from melancholia, now known more commonly as clinical depression (Medicalnewstoday, 2009). The number of individuals suffering from depression is not exact. anxiety (Fava et al., 1997; Flint & Rifat, 1997; Davidson et al., 2002). A recent large-scale multicenter study on potential TRD-related predictive factors took place in Europe and showed 5 major clinical predictors in order of their strength (1) current suicidal risk (2) comorbid anxiety disorder (3) gender (4) seasonal trend (5) failure to respond to the first antidepressant during life (Oswald et al., 2005). Non-psychiatric comorbidities have been found to be predictors of TRD (Iosifescu et al., 2004). It has been found that patients with elevated serum cholesterol levels do not respond as well to fluoxetine treatment as patients with normal cholesterol levels (Sonawalla et al., 2002). Late-life depression has been linked to comorbid somatic disorders such as circulatory problems, arthritis or skin problems (Oslin et al.., 2002).