By means of conceptual history and statistical analysis of historical data, this report shows that studies into the psychiatry of multiple sclerosis (MS) underwent a qualitative improvement between the Great War and the publication of A.G. Ombredane's great work. Analysis of his database, collected 60 years ago, shows that some of his conclusions (later to be influential) were unwarranted, but that, on the other hand, it enshrined hidden information showing a relative independence between euphoria (and other affective changes) and chronicity and illness duration. An earlier knowledge of this point might have had a corrective effect on later claims about the neuropsychiatry of MS.