Unipolar Depression There are five main perspectives on the causes of unipolar depression. No one theory has been proven entirely correct, and it is believed that depression is in fact caused by a combination of factors from several different models. Below you will find descriptions of the five models and an assessment of their relative levels of validity. Psychodynamic Perspective The psychodynamic model of depression, developed by Sigmund Freud and Karl Abraham, attributes the development of depression to the loss of a loved one or an imagined loss. An imagined loss occurs when a person equates a failure in life, such as the loss of a job, to a loved one’s death. After a loss, it is normal to feel a period of sadness, but if, over the months after the loss, the sadness does not improve or even worsens, a long-term depressed mood may result. Freud and Abraham determined that mourners (either from a real or imagined loss) will regress into the oral stage of development, in which they are completely dependent upon others. The oral stage naturally occurs during the first 18 months of life. Proponents of the psychodynamic model believe that those who have either had their needs met in excess or did not have their needs met adequately during the oral stage of development are more susceptible to depression. Those who were overly gratified during the oral stage retain their dependency because of they are unwilling to leave such a favorable period. Those whose needs were not met are more inclined to display low self-esteem and constantly seek the approval of others. Though Freud and Abraham set solid groundwork for the psychodynamic perspective on depression, the beliefs of modern day psychodynamic therapists have diverged from their initial theories. Today, a popular psychodynamic explanation for depression is the object relations theory, which states that depression is caused by an individual’s insecurity in his interpersonal relationships. These unsafe or insecure feelings about relationships may be explained by the quality of that person’s relationship with his parents; parents who either excessively or inadequately met needs may have contributed to the severity of the problem. There are several scientific studies that support the psychodynamic model of depression, but there are still many unknowns about this model. For instance, though studies have shown that an early separation from a parent may lead to depression, a significant portion of subjects who are separated do not develop depressed symptoms. Other studies have found no correlation between early loss and depression. Imagined loss is a concept too difficult to solidly support because it occurs on the unconscious level and cannot be properly studied in either animal or human models. Behavioral Perspective Advocates of the behavioral perspective believe that depression results from the loss of rewards as individuals age. The theory was developed during the 1970’s and 1980’s by Peter Lewinsohn. Lewinsohn hypothesized that due to decreased rewards, as people age, they develop lower motivation for accomplishing tasks, leading to depression. In his research, Lewinsohn found evidence that depressed subjects feel they are experiencing fewer rewards than non-depressed subjects. He also found that as social rewards increase, so too do the moods of depressed patients. This model has a flaw in the respect that the number of rewards reported by depressed research participants may be underestimated because their depression hinders them from reporting accurately. The research also does not establish that the loss of rewards caused the depression and the depression did not merely cause a decrease in rewards. Cognitive Perspective The two main theories in the cognitive perspective are the theories of negative thinking and of learned helplessness. According to the negative thinking theory, a repetitive cycle of dismal thoughts and maladaptive thinking patterns cause depression. The researcher Aaron Beck invented the cognitive triad, which states that depressed persons are trapped in a cycle of thinking poorly about their life experiences, themselves, and their futures. These maladaptive thoughts hinder the individual’s daily tasks because he focuses so heavily on failures. The thoughts become automatic, meaning that they recur repeatedly. Under this theory, depressed patients also make arbitrary inferences, which are pessimistic conclusions based upon a paltry amount of evidence. For instance, if a college student fails a test, an arbitrary inference she could make would be that she will fail every test she will ever take. Research has shown reasonable support for depressed patients suffering from negative thinking. Learned helplessness is a theory developed by Martin Seligman in 1975. According to the theory, due to past experience in which a person could not control the events in his own life, that person develops the attitude that he cannot control any events which arise, even if that belief is impractical. Seligman believed that these thoughts were internal, global, and stable, meaning these individuals attribute their problems largely to themselves, think the problems affect all aspects of their lives, and that the problems will never go away. The model has recently been revised to state that events will cause learned helplessness only if they cause a sense of hopelessness within the individual. Though the theory has been extensively tested on animal models, it is possible that these animals used in the laboratory do not produce the exact equivalent of human depression. Sociocultural Perspective Those who support the sociocultural perspective believe that outside stressors cause depression. For instance, because depression rates are twice as high in women as they are in men, theorists hypothesize that these increased rates are caused by particular stresses endured by women due to their position in society. Racial stresses may also play a role in the development of depression; research has shown that Native American communities have very high rates of depression, which may be explained by the stressful social and economic situations on reservations. Sociocultural theorists relate an individual’s level of poverty, family stressors, and health problems to the onset of depression. Another sociocultural theory is that an individual’s level of social support may affect depression’s onset. Troubles relationships with parents or a spouse could be leading causes. Research into different social groups has supported the uneven distribution of depression across class, race, and sex. Biological Perspective Research has demonstrated the connection between genetic background and the onset of depression. In family pedigree tests, researchers analyze the family tree of a person suffering from depression in order to examine which other relatives are affected. These tests have shown that a depressed person’s relatives generally have a higher rate of depression than the rest of the population. Twin studies are tests that analyze the development of depression in identical and fraternal twins. One of these tests found evidence that identical twins have a much higher chance (46%) of inheriting depression than fraternal twins, though fraternal twins also have an increased risk (20%). An individual with no family history of depression has less than a 10% chance of developing the disorder. Adoption studies look at the relationship between depressed persons and their biological parents. They have generally found that the biological parents of a severely depressed adopted child have a higher chance of also suffering from severe depression. An abnormality in the 5-HTT gene, a gene responsible for serotonin transport, has been implicated in leading to depression, though more research on the subject is necessary. Low levels of the neurotransmitters serotonin and norepinephrine have been commonly found among depression patients. It is currently thought that abnormal interactions between these neurotransmitters and possibly others are to blame for depression. One theory is that serotonin is a neuromodulator, regulating the activity of other neurotransmitters, so low serotonin levels would disrupt this regulation. Other depression theories from the biological perspective implicate the body’s endocrine system, which produces hormones. Another theory involves abnormal activity of brain-derived neurotropic factor (BDNF), which is a chemical that works inside of neurons. Though there are many theories within the biological perspective, most of the research in this field has been done on animal models, and it is unclear whether their depression-like symptoms are the same as human depression. Though there are limitations, the biological perspective proves to be one of the most promising views in regard to effective treatment options. |
