It is important to differentiate between adult autism and schizophrenia. In this presentation, the distinction between autism and schizophrenia will be discussed in the light of two cases.

At the time that they applied to our clinic, we investigated autistic and psychotic symptoms and firstly diagnosed them as schizophrenia.With the more detailed history of illness and investigation the diagnose change as adult autism. In the conclusion the cases will be discussed generally.

The most important clinical differences between adult autism and schizophrenia are stereotypic behaviour and speech. Schizophrenic stereotype has anxiolytic character and autistic one has hedonistic structure. Autistic patients are always aware of their environment and they seem to be mute because of their inner speech, but schizophrenic patients are not. On the other hand, schizophrenic stereotype is aimless and spontaneous, while the autistic stereotype has an aim such as an assurance of being same, and is relatively voluntary. All stereotypic behaviours and speech of the autistic patients are target-locked and cannot be blocked or broken. It seems that, as if autistic patients are addicted to stereotypical behaviours. In such cases, the patient's sentences can be lack of certain grammatical elements or can be incomprehensible. The prosody of this speech can follow certain rules. When he is joined in a conversation, it is rather like a monologue. Patients of schizophrenia generally respond positively to a neuroleptic drug, while autistic patients need a combined therapy of neuroleptic and anti-depressive drugs.