In chronic cases, the florid symptoms persist over years and it is difficult to distinguish discrete episodes. The onset tends to be later than in the hebephrenic and catatonic forms. Delusions can be of almost any kind of delusions of control, influence, or passivity, and persecutory beliefs of various kinds are the most characteristic. It is important to exclude epileptic and drug-induced psychoses, and to remember that persecutory delusions might carry little diagnostic weight in people from certain countries or cultures. A form of schizophrenia in which affective changes are prominent, delusions and hallucinations fleeting and fragmentary, behaviour irresponsible and unpredictable, and mannerisms common.
Thought is disorganized and speech rambling and incoherent.
There is a tendency to remain solitary, and behaviour seems empty of purpose and feeling. In addition, disturbances of affect and volition, and thought disorder are usually prominent. Hallucinations and delusions may be present but are not usually prominent. Drive and determination are lost and goals abandoned, so that the patient's behaviour becomes characteristically aimless and empty of purpose. A superficial and manneristic preoccupation with religion, philosophy, and other abstract themes may add to the listener's difficulty in following the train of thought.