Risk Factors in Depression Keith S. Dobson and David J.A. Dozois

The variable symptoms of Major Depressive Disorder (MDD), or ClinicalDepression, indicate that depression is a heterogeneous disorder. Individuals who experience depression may suffer from a number of possible symptoms, and the duration of these symptoms may range from a few weeks to years. Increasingly, the chronic and recurrent nature of depression has been recognized, and efforts at treatment and prevention have been emphasized.
MDD is a highly debilitating condition, as it affects multiple domains of psychosocial functioning, including interpersonal relationships, occupational and academic functioning, and long-term psychological well-being. MDD is one of the most common presenting complaints encountered by mental health professionals and is among the most financially costly of disorders. Depression also exacts a heavy toll on society; the direct and indirect annual costs associated with MDD in Canada) and the United States have been estimated at $14.4 billion and $33 billion, respectively. Researchers have predicted that by the year 2020 depression will be second only to ischemic heart disease in terms of cost to society). Surprisingly, the economic impact of depression may actually be underestimated, due to the fact that sometimes depression co-occurs with medical problems and so is downplayed ormissedas a problem, and due to the fact that many depressed people do not seek treatment.
Given the profound and continuing social importance of depression, it is notsurprising that it has been examined from a number of theoretical approaches, and has been the subject of a considerable body of literature. There have been significant advances related to neurotransmitter models, stress-generation models of depression, models of relapse prevention, enhancements in the study of information processing problems in depression, and of interpersonal processes such as interpersonal reassurance seeking and rejection. Unfortunately, models in this area have developed in relative isolation from each other, as there is a pronounced tendency for theorists and researchers to highlight a particular model, to the relative diminishment of other constructs and models.
Depression is a human experience that has various forms. In its more subtle form, depression is a momentary feeling of sadness or despondency, most often related to a perceived loss or sense of helplessness about a particular event.
Moderately intense experiences of depression often involve biological, psychological and social elements. For example, the affected person may have a strongblueor down feeling, coupled with a reduced desire to engage in the world and decreased appetite or an increased desire to withdraw from usual activities.
Such a conceptualization of depression can be assessed by a dimensional measure, such as a questionnaire or a rating scale.
In its clinical state, major depressionrepresents a debilitating syndrome which lasts for a minimum of 2 weeks, although in many instances the length of depression is unfortunately much longer. The symptoms of major depression have been more or less set in the psychiatric literature since the early1970s, when the Research Diagnostic Criteria were originally developed. Although the required pattern of symptoms was modified slightly in the version III-revision of the Diagnostic and Statistical Manual (DSM), the symptoms list itself was not. These symptoms are also very similar to those presented in the International Classification of Diseases-10 (World Health Organization, 1992 ).

Indeed, the description of major depression that is used today is not markedly different from descriptions of Melancholia seen in the Enlightenment period.
Diagnostic Criteria for major depression in the DSM-IV.
A period of at least 2 weeks, in which at least five of the following symptoms are present most of the day, nearly every day, and of which at least one is the first or second listed symptoms: