For many years scientists, including doctors, psychologists, and psychiatrists, have been interested in trying to understand human behaviour, in particular behaviour that is described as being ‘abnormal’. It is difficult to define ‘abnormal’ in terms of behaviour because there are many differing descriptions which have radically changed over the years. ‘Abnormal’ behaviour is widely categorised as being persistent and in a serious degree contrary to the continued wellbeing of the individual and/or the surrounding community. Cultural beliefs and expectations determine which behaviour patterns are deemed as being ‘abnormal’.
In ancient societies it was believed that ‘abnormal’ behaviours were caused by divine intervention or supernatural forces, although by the medieval ages the belief that individuals of who strayed from the accepted ‘norm’ were possessed by an evil spirit became a predominant explanation and exorcisms were carried out regularly to treat such individuals. Other beliefs such as magic, astral influences and physical illness were also thought to be the cause of ‘abnormal’ behaviour. However by the 19th Century a German physician Wilhelm Griesinger (1817-1868) argued that it was disease of the brain that caused ‘abnormal’ behaviour.
Over the years many perspectives have been discussed, researched and explored in order to try and best understand and explain human behaviour, these perspectives are termed models, there are currently six prevalent models which try to explain the ‘abnormal’ functioning of individuals the medical model, the cognitive model, the psychodynamic model, the sociocultural model, the behavioural model and the biopsychosocial model. The various models that are used to try and understand the causes, symptoms, diagnosis and treatment of mental disorders have been used to help group mental disorders which are outlined