Among the most common forms of depression a psychiatrist treats is recurrent Major Depressive Disorder (without psychotic features). In this condition, individuals experience, as the name implies, recurrent episodes of major depression. In a major depressive episode, an individual typically experiences a noticeable decline in mood or loss of pleasure in usually pleasurable activities for a period of two weeks or longer. In addition, he experiences a variety of other symptoms, including changes in sleep pattern, energy level, ability to focus and concentrate, appetite, sex drive, etc. When an individual suffers from a major depressive episode, he may also feel hopeless about the future or feel worthless as an individual. He may have suicidal thoughts or impulses. If enough of these symptoms are met (see Definition of Depression) and the individual has been with depressed mood for two weeks or longer and has a significant decline in his functioning (e.g. making mistakes at work, not showing up to work, not functioning in the home, etc.), the episode is considered to be a major depressive episode. If an individual has experienced more than one episode of major depression in his life and does not meet criteria for a bipolar spectrum mood disorder, he is considered to have recurrent Major Depressive Disorder.

Typically, a psychiatrist first meets an individual with this diagnosis in the midst of the individual's major depressive episode. After he concludes the diagnostic portion of his assessment, he might try to educate the individual about the diagnosis. In my practice, I start by naming the diagnosis, itself. I might say something to the effect of, "I believe that your diagnosis is most consistent with a recurrent form of Major Depressive Disorder." I then explain to the individual what this illness is, what symptoms it comprises, the natural course of the illness, etc.

Every psychiatrist has his own way of conceptualizing Major Depressive Disorder and whether or not he makes it explicit, his conceptualization of the illness will influence how his patients understand their own illness.

Normally, I tell my patients with recurrent Major Depressive Disorder that I tend to view their illness through a "stress-vulnerability model." That for some reason, some individuals, given a certain level of emotional stress, are vulnerable to experiencing a major depressive episode. Because approximately 17% of the U.S. population will, at some point in their lives, experience a major depressive episode, some basic vulnerability to this illness is extremely common.[*] Nevertheless, there are individuals with much more serious forms of major depression (including psychotic major depression) and individuals who experience repeated episodes. These individuals probably have some separate neurological and endocrine vulnerabilities that give their illnesses the specific qualities they have (e.g. increased frequency of depressive episodes, higher severity of depressive episodes, presence of psychotic symptoms, presence of suicidal thoughts, etc.)

Clearly, too, some individuals are under chronic emotional stress - sometimes very severe levels of stress - and they are at increased risk for a major depressive episode.

I tell my patients that the genetic underpinnings for vulnerability to major depressive disorder are being sorted out through ongoing research. I tell them, too, that available evidence also suggests that vulnerability in adulthood for Major Depressive Disorder may also have been modulated by early childhood experiences, particularly negative experiences - not just genetic loading, per se.[*]

While I don't think that it is necessary to inform every individual with recurrent major depressive disorder about all the intricacies of the brain and what happens in the brain of someone with this type of depression, I do try to lay out some basic principles. I usually tell people that functional imaging studies of the brain have found areas of the brain that "behave" differently in individuals with major depressive disorder than those without depression and that treatment with anti-depressants and psychotherapy seems to normalize the functioning of these specific areas. I spend some time educating my patients about the concept of "stress response" in the brain - that the brain, under a certain amount of emotional stress, will produce certain hormones that, in turn, lead to a cascade of physiological events. And the idea that the final common set of events in this cascade likely leads to the "physiology" of major depression.