[Autoimmune encephalitis with psychotic symptoms : Diagnostics, warning signs and practical approach]

Despite intensive research, a precise cause of schizophrenic and schizoaffective disorders has not yet been identified. Therefore, psychiatric diagnoses are still made based on clinical ICD-10/DSM‑5 criteria and not on any objective markers; however, various causes or pathophysiological processes may ultimately lead to similar symptoms. An important task for the future of psychiatry is to identify disease subtypes with a distinct pathophysiology to develop more specific and causally acting therapies. A new diagnostic entity has become established in clinical neurology and psychiatry in recent years: autoimmune encephalitis with psychotic symptoms caused by specific antineuronal antibodies has been identified as a rare but potentially treatable cause of psychotic disorders; however, these inflammatory brain diseases are not reliably detected by routine psychiatric diagnostics. Therefore, this qualitative review is intended to provide structured support for clinical practice, which, guided by clinical warning signals, enables a rapid and reliable diagnosis as well as the initiation of immunotherapy. In the case of psychiatric symptoms, the additional onset of focal neurological signs, disturbances of consciousness and orientation, autonomic instability or epileptic seizures and electroencephalograph (EEG) abnormalities should always be followed by a more specific cerebrospinal fluid analysis with determination of antineuronal autoantibodies. Although the scientific evidence indicates that only a small subgroup of patients is affected, the swift and correct diagnosis is of high therapeutic and prognostic relevance for the affected individuals.