[Differential Diagnosis of Schizophrenia: Psychotic Symptoms in Neurodevelopmental Disorders and Psychotic Disorders due to other Medical Conditions].

This review focuses on the differentiation of schizophrenia in the setting of adult psychiatry from neurodevelopmental disorders (NDD's) and psychosis due to other medical conditions (PDMC). Psychotic disorders in early adulthood are most frequently diagnosed with the schizophrenia spectrum or mood disorders. However, they may be the manifestation of neurologic, endocrine or immunologic disease. Individuals with NDD's such as the autism spectrum disorder (ASD) or intellectual developmental disorder (IDD) may also present initially in adulthood. Therefore it is not uncommon that the psychiatrist is the first physician to assess a psychotic patient with underlying medical illness or a NDD. Failure to identify the underlying cause will delay appropriate management. Overdiagnosis of primary psychiatric disorders may be misleading in planning the treatment, as evidence-based treatment algorithms relevant to psychosis are intended for primary psychotic disorders like schizophrenia, and symptomatic treatment may result in unnecessary exposure to antipsychotic drugs. Exclusion of other medical conditions and NDD's is essential before establishing a diagnosis of schizophrenia.