Autoantibody-associated schizophreniform psychoses: pathophysiology, diagnostics, and treatment

In the context of secondary, possibly organic schizophreniform psychoses, autoantibody(AB)-associated autoimmune encephalitis (AE) plays an increasingly important role. If this is suspected, clinical investigations, including laboratory, magnetic resonance imaging, electroencephalography and cerebrospinal fluid (CSF) analyses are recommended. The AB screening should include the most frequent ABs against neuronal cell surface antigens (NMDA receptor [R], CASPR2, LGI1, AMPA-R, GABAB-R), intracellular antigens (Hu, Ri, Yo, CV2/CRMP5, Ma2[Ta], amphiphysin, GAD65), thyroid tissue (TG, TPO, TRAK), and antinuclear antigens (ANAs). The ABs against cell surface antigens and GAD65 should be examined directly in serum and CSF. Less frequent ABs can be looked for in a second step. Furthermore, immunofluorescence tests on brain slices of rodents may identify previously unknown ABs. The detection of ABs in combination with further findings can lead to the diagnosis of AE which implies new therapeutic opportunities with immunomodulators.