ABSTRACT
Major depressive disorder (MDD), as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV; APA, 1994), is a very common disorder as evidenced by the results of two large epidemiological studies, in which more than 10% and 16.2% of the population respectively were found to experience at least 1 MDD episode during their lifetime (Blazer et al., 1994; Kessler et al., 2003). The prevalence is higher in women compared to men, with a ratio approaching 2 to 1. It is a chronic disorder, with a high tendency for relapse in those who have recovered from a depressive episode (Frank et al., 1990). MDD is characterized by a variety of symptoms from different categories. Emotional dysregulation (low mood, instable mood, irritability, anxiety, emotional apathy) and cognitive dysfunction (concentration, memory) are accompanied by severe disturbances in fundamental biological systems such as sleep, appetite regulation, sexual drive and autonomic regulation. The disorder is also associated with an increased risk for a number of somatic disorders, such as osteoporosis and several cardiovascular diseases. This results in markedly increased morbidity and mortality in individuals with major depression, even if factors like smoking, diet and alcohol intake are corrected for (Vaillant, 1998). The Baltimore portion of the national Epidemiological Catchment Area (ECA) study revealed that major depression subsequently leads to a four- to fivefold increase in the risk for myocardial infarction (Pratt et al., 1996).
