They all attempt to explain the causes and treatments for all psychological illnesses, and all from a different approach.
The biological model of abnormality (the only model not based on psychological principles) is based on the assumptions that if the brain, neuroanatomy and related biochemicals are all physical entities and work together to mediate psychological processes, then treating any mental abnormality must be physical/biological.
Part of this theory stems from much research into the major neurotransmitter, serotonin, which seems to show that major psychological illnesses such as bipolar disorder and anorexia nervosa are caused by abnormally reduced levels of Serotonin in the brain.
[2][3] The main cures for psychological illness under this model: electroconvulsive therapy, drugs, and surgery at times can have excellent results in restoring "normality" as biology has been shown to play some role in psychological illness.
However, they can also have consequences, whether biology is responsible or not, as drugs always have a chance of causing allergic reactions or addiction.
Electrotherapy can cause unnecessary stress, and surgery can dull the personality, as the part of the brain responsible for emotion (hypothalamus) is often altered or even completely removed.
A diagnosis of mental 'illness' implies that a person is in no way responsible for the abnormality of functioning and, as such, is not to blame.
A considerable amount of research has been carried out within the medical model framework, which has dramatically increased our understanding of the possible biological factors underpinning psychological disorders.
[6] The cognitive model of abnormality is one of the dominant forces in academic psychology beginning in the 1970s and its appeal is partly attributed to the way it emphasizes the evaluation of internal mental processes such as perception, attention, memory, and problem-solving.
One key assumption in cognitive therapy is that treatment should include helping people restructure their thoughts so that they think more positively about themselves, their life, and their future.
Although it does not deal with the cause of the problem directly, it does attempt to change the situation more broadly than the behavioural model.
Due to their respective characteristics and similarities, there are instances when psychologists combine cognitive and behavioural models to treat mental disorders.
This model can be successful, especially where the patient feels comfortable to speak freely and about issues that are relevant to a cure.