Probably the most striking case of the former is anti-NMDA-receptor encephalitis, which causes schizophenia-like symptoms in its early stages (delusions, halluc

Probably the most striking case of the former is anti-NMDA-receptor encephalitis, which causes schizophenia-like symptoms in its early stages (delusions, hallucinations, disorganized thinking, depersonalization/derealization) [1]. It doesn't even seem to be especially rare, but it wasn't identified until 2007. The latter is tricky because modern psychiatry doesn't really give us the notion of confirming that a condition is psychogenic. Almost all modern psychiatric diagnoses are diagnoses of exclusion (more or less) and do not carry any particular assertions about etiology. We can be reasonably certain that cases of psychogenic disorders do exist, but I don't think they tend to explain any preexisting diagnosis because the signs and symptoms vary so much. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3983958/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3983958/