One of the leading psychoanalytical theories concerning depression was first proposed by Sigmund Freud. Freud argued that at some point in early childhood, the depressed patient suffered the loss, real or imagined, of someone with whom they were very close. Moreover, the individual depended on that other person to maintain his/her self-esteem. Unable to cope with the loss, the person then creates an internal representation of the lost individual so that they can maintain the close relationship. Anger begins to develop to develop towards the lost individual, but since this anger is not recognized and dealt with on a conscious level and since the object is internalized, the person directs the feelings toward him- or herself.

Depression, then, is essentially an instance of anger turned inwards. This theory, since it deals with the unconscious, is hard to support, but it does manifest itself in some of the social and psychological explanations for depression. One support comes from the discovery that depressed individuals were more likely to have experienced stressful life events than non-depressed individuals--and, more significantly, many of these stressful or negative events involved the loss of an important person or role.

One of the most influential proponents of a cognitive view of depression has been Aaron Beck. Beck proposed that the depressed individual's tendency to express more negativity than non-depressed individuals is derived from his or her cognitive distortions, or erroneous ways, of thinking about the self. Negative and derogatory views of the self, the world, and of the future are core features of the depressed individual. More specifically, a depressed individual tends to attribute global, personalized reasons for failure, form overarching principles of the self based on negative experiences, to exaggerate negative events and dismiss positive events, and to selectively recall more negative events. One could then say that these self-defeating biases lead to the development of a cognitive schema that affects the way the individual interprets, perceives, and interacts with the environment. This negative schema in turn increases the probability of the individual being more negatively affected by stressful life events.

A behavioralist would more likely identify with the Theory of learned helplessness originally proposed by Marty Seligman to explain major depression. Seligman suggested that depression was similar to the passive behavior shown by animals that had been exposed to shock. Depressed individuals, then, like the animals in the lab experiments, begin to believe that they are helpless--that they do not have the power to control the events in their lives. They therefore fail to realize the contingency between their actions and the outcome of events. Learned-helplessness theory, in an attempt to answer some of the criticisms raised against it, such as the fact that most people do not become depressed after experiencing a negative life event, was later revised and described instead in terms of "hopelessness." L. Y. Abramson and his colleagues proposed that individuals who are vulnerable to depression possess an attributional style consisting of negative expectations concerning future events, regardless of their own actions. After the occurrence of a negative life event, the causal attributions (explanations and importance) that the person ascribes to the event is correlated with the probability of then becoming depressed. This attributional style also consists of the tendency to explain negative events as internal, stable, and global factors. This means that unlike non-depressed individuals, a depressed person is more likely to think of negative events as proof of their own inadequacies (internal), as having existed in the past and continuing to persist in the future (stable), and responsible for his or her failure in other areas of life (global).

Similar to Beck's cognitive schema, this theory points to an influential factor that may predispose an individual to developing depression. Taken together, people with this attributional style--logically, it may seem--tend to perpetuate the levels of stress that they may experience in the environment, again demonstrating the reciprocal relationship between stressful life events and the individual's cognitive response to failure. Thus, depression may be self- perpetuating, in that through this erroneous cognitive schema, negative life events enhance the intensity of the depression, which in turn leads to more stimuli being interpreted as negative. This results in an increased memory for negative events, regardless of whether or not the perception of these events is accurate.