Psychoses following influenza, as precipitated by the epidemic of 1890-1892 and reprecipitated by the epidemic of 1918-1919, make a particularly interesting study. Among the nearly 200 cases of postinfluenzal psychoses studied at the Boston Psychopathic Hospital during the past year, only two such cases were observed. A third case, in which a psychosis had followed the earlier epidemic, was received at the hospital during this period, but without the history of recent influenza. These three cases are reported below.
These cases are interesting because of the question of specificity which Kraepelin1 raised. He maintained that each acute infectious disease was probably capable of producing mental symptoms of a peculiar sort, a virtual “influenza psychosis,” “typhoid psychosis,” etc. This view has never been well supported, and as yet we know only that the psychoses following influenza are numerous and of great variety.2 This might connote a quantitative specificity