The first psychiatric pandemic: Encephalitis lethargica, 1917-27

Finding a link between COVID-19 and subsequent psychiatric symptoms has resulted in renewed interest in the psychiatric sequelae of pandemics. The first such instance was apparently the encephalitis lethargica pandemic which arose around the time of the First World War, moving in the shadow of a repiratory virus pandemic. The epidemic of encephalitis lethargica (EL), or Von Economo's Disease, in the years 1917-27 was the first pandemic involving the central nervous system. It moved in some places in parallel with the Great Flu Pandemic but does not seem to have been caused by it. Unlike the coronavirus, pandemic EL affected children heavily, leading often to bizarre changes in character and personality. It often left sequelae lasting for decades in the form of postencephalitic Parkinsonism (PEP). Unlike the coronavirus, it had a high mortality of around 20 percent. Although encephalitis lethargica involved a number of systems, psychiatric morbidity was most prominent and entailed severe depression, mania, catatonia and psychosis. It ended without therapeutic or public-health measures; today, sporadic cases of EL continue to be reported. The hypothesis is that we can derive from the EL psychiatric pandemic certain lessons that might be useful in studying tardive COVID symptoms today.