Peter Liddle has carried out a considerable number of brain imaging studies, particularly in schizophrenia, and this book hinges on his concept that there are five principal dimensions of psychopathology. These are reality distortion, disorganization, psychomotor symptoms, abnormalities of mood, and anxiety. Each of these dimensions is associated with a characteristic syndrome and symptom cluster, and the symptom clusters are noted in differing psychiatric illnesses. Classically, the disorganization syndrome is most commonly seen in schizophrenia and the depression syndrome is characteristic of major depressive illness.