Psychological theories provide evidence-based explanations for why people think, behave, and feel the way they do. Personality factors, history and early experiences; and interpersonal relationships are seen as important factors in causing depression. Unlike biology, psychology is not truly a unified field. There are still many disagreements within the field as to what subject matter is important to focus on, and what methods are best to use for studying the subject matter. Consequently, different schools of thought within psychology have developed their own theories as to why someone becomes depressed.
Psychodynamic theory was the dominant school of thought within psychiatry and much of clinical psychology during the first part of the 20th century, at least with regard to ideas about how psychotherapy should be conducted. Early psychodynamic approaches focused on the interrelationship of the mind (or psyche) and mental, emotional, or motivational forces within the mind that interact to shape a personality. The famous Dr. Sigmund Freud, who is credited with inventing psychodynamic theory and psychoanalysis, influentially suggested that the unconscious mind is divided into multiple parts, including the irrational and impulsive Id (a representation of primal animal desires), the judgmental Super-ego (a representation of the rules and norms of society inside the mind), and the rational Ego (which serves as an attempt to bridge the other two parts).
According to Freud, the conscious and unconscious parts of the mind can come into conflict with one another, producing a phenomena called repression (a state where you are unaware of having certain troubling motives, wishes or desires but they influence you negatively just the same). In general, psychodynamic theories suggest that a person must successfully resolve early developmental conflicts (e.g., gaining trust, affection, successful interpersonal relationships, mastering body functions, etc.). in order to overcome repression and achieve mental health. Mental illness, on the other hand, is a failure to resolve these conflicts.
There are multiple explanations that fall under the psychodynamic "umbrella" that explain why a person develops depressive symptoms. Psychoanalysts historically believed that depression was caused by anger converted into self-hatred ("anger turned inward"). A typical scenario regarding how this transformation was thought to play out may be helpful is further explaining this theory. Neurotic parents who are inconsistent (both overindulgent and demanding), lacking in warmth, inconsiderate, angry, or driven by their own selfish needs create a unpredictable, hostile world for a child. As a result, the child feels alone, confused, helpless and ultimately, angry. However, the child also knows that the powerful parents are his or her only means of survival. So, out of fear, love, and guilt, the child represses anger toward the parents and turns it inwards so that it becomes an anger directed towards him or herself. A "despised" self-concept starts to form, and the child finds it comfortable to think thoughts along the lines of "I am an unlovable and bad person." At the same time, the child also strives to present a perfect, idealized (and therefore acceptable) facade to the parents as a means of compensating for perceived weaknesses that make him or her "unacceptable". Caught between the belief that he or she is unacceptable, and the imperative to act perfectly to obtain parental love, the child becomes "neurotic" or prone to experiencing exaggerated anxiety and/or depression feelings. The child also feels a perpetual sense that he or she is not good enough, no matter how hard he or she tries.
This neurotic need to please (and perpetual failure to do so) can easily spread beyond the situation in which it first appears, such that the child might start to feel a neurotic need to be loved by everyone, including all peers, all family members, co-workers, etc. The goal of a traditional psychodynamic psychotherapy might be to help the child (now an adult in therapy) to gain insight into the mistaken foundations of his or her belief in his or her badness and inadequacy so that the need to punish himself/herself and to be perfect decreases.
Psychodynamic theory has evolved a fair amount over its long history, and many variations of the original theory are available today. One popular branch of modern psychodynamic theory, known as object relations theory, is concerned with how people understand and mentally represent their relationships with others. The "objects" in object relations theory are representations of people (how other people are experienced, represented and remembered by the person doing the objectification). According to object relations theory, people's moods and emotions (and many other aspects of their personalities) can only be properly understood against the backdrop of the relationships those people have experienced. It is a foundational assumption of object relations theory that early relationships tend to set the tone for later relationships.
According to object relations theory, depression is caused by problems people have in developing representations of healthy relationships. Depression is a consequence of an ongoing struggle that depressed people endure in order to try and maintain emotional contact with desired objects. There are two basic ways that this process can play out: the anaclitic pattern, and the introjective pattern. Even though these terms are not currently used in the DSM, some therapists may still use them to label different types of depression.
Anaclitic depression involves a person who feels dependent upon relationships with others and who essentially grieves over the threatened or actual loss of those relationships. Anaclitic depression is caused by the disruption of a caregiving relationship with a primary object and is characterized by feelings of helplessness and weakness. A person with anaclitic depression experiences intense fears of abandonment and desperately struggles to maintain direct physical contact with the need-gratifying object.
Introjective depression occurs when a person feels that they have failed to meet their own standards or the standards of important others and that therefore they are failures. Introjective depression arises from a harsh, unrelenting, highly critical superego that creates feelings of worthlessness, guilt and a sense of having failure. A person with introjective depression experiences intense fears of losing approval, recognition, and love from a desired object.
Historically, psychodynamic theories were extensively criticized for their lack of empiricism (e.g., their disinterest in subjecting their theories to scientific testing). However, this resistance to putting psychodynamic concepts on a scientific footing has started to change recently. Another modern derivative of psychodynamic theory, Coyne's interpersonal theory of depression has been studied extensively, and forms the basis of a very effective treatment option known as Interpersonal Therapy or IPT. According to interpersonal theory a depressed person's negative interpersonal behaviors cause other people to reject them. In an escalating cycle, depressed people, who desperately want reassurance from others, start to make an increasing number of requests for reassurance, and the other people (to whom those requests are made) start to negatively evaluate, avoid, and reject the depressed people (or become depressed themselves).. Depressed people's symptoms then start to worsen as a result of other people's rejection and avoidance of them. IPT has been designed to help depressed people break out of this negative spiral. We'll have more to say about IPT in the treatment sections of this document.