The Kraepelin Model

Since antiquity, the mental disorders of melancholia, mania, and hereditary insanity had been recognised, but not dementia praecox (now schizophrenia) or manic-depressive illness (now bipolar disorder). Development of a convincing nosology for this and other mental illnesses was then created by Emil Kraepelin towards the end of this nineteenth century, bringing coherence to the field founded on principles and methods largely in use to this day. One of these principles was that ‘the scientific concept of the disease demands knowledge not only of the present state, but also of the entire course of the disease’. He was able to show that over 60% of cases of dementia praecox occurred before the age of 25, with the younger showing progressive deterioration that gradually developed into catatonic symptoms leading to delusions. In the case of manic-depressive illness, he showed over 70% of cases were hereditary. Kraepelin’s nosology, his classification of mental diseases, has had a very significant impact on contemporary classifications as reflected in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-V) originating in the USA and the International Classification of Mental and Behavioural Disorders (ICD10), originating in Europe.