Cognitive explanations of depression

Depression is the most common type of affective disorder, characterised by feelings of worthlessness, loss of pleasure in normal activities, and negative thought patterns.

The cognitive approach to psychology works on the basis that it is necessary to refer to internal mental processes such as thought and perception in order to understand behaviour. Thus, in order to explain psychological disorders, it refers to internal mental processes. 

In reference to depression specifically, this approach suggests that it is caused by habitual depressive thought patterns, and often becomes more of a long-term problem when personal problems become inseparable in the mind of the individual. For example, their depression may have been reactive to dropping out of university, but then their depressive mental state and thought patterns lead them to think negatively about themselves, the world and their future and it may become a vicious cycle. Referring back to the university example, someone may begin to think they dropped out because they can't commit to anything, and that they'll never be able to, and that they don't fit in so there's something wrong with them, e.t.c. 

One study which helps to explain depression from a cognitive point of view is Beck et al (1974) which aimed to help psychologists understand the specific cognitive distortions experienced by people with depression. A sample of 50 patients undergoing therapy for depression was compared to a control group of people undergoing psychotherapy for another form of dysfunctional behaviour. Face-to-face clinical interviews were conducted, and patients were often asked to keep diaries of their thoughts and feelings about things that happened to them. The results suggested that depression is characterised by thoughts of self-blame, poor self-esteem, anxiety and inferiority, and that these and other cognitive distortions present in depressed patients were involuntary, automatic and persistent. 

Thus, the cognitive approach explains that depression is caused by distortions in thought and perception, such as catastrophic thinking, persistent pessimism and poor self-esteem.