Thomas A. Ban
Neuropsychopharmacology in Historical Perspective
Education in the Field in the Post-Neuropsychopharmacology Era

Bayle’s discovery and the re-evaluation of the concept of dementia
(Educational Series 2. Bulletin 12, Chapter 5)

          In the third edition of Stedman’s Medical Dictionary, published in 1990, the term “dementia” was defined as “a generalized mental deterioration due to organic or psychological factors; characterized by disorientation, impaired memory, judgement and intellect, and a shallow labile affect” (Stedman 1990). In the current (2017) Merrion-Webster on-line dictionary it is defined “a usually progressive condition (such as Alzheimer’s disease) marked by the development of multiple cognitive deficits (such as memory impairment, aphasia) and the inability to plan and initiate complex behavior.”

          Personality changes are frequently the first warning signals of a dementing process. Yet, the term “dementia” should be used only for personality changes when intellectual deterioration is present or can be confidently predicted at a later stage (Ban 1980; Slater and Roth 1969).

            The origin of the term, “dementia,” is in the Latin word “demens,” i.e., out of one’s mind.  It first appeared in the Third Book of De Medicina of Aurelius Cornelius Celsus (c. 25 BC – c. 50 AC). He used the term to describe the disorder which may follow fever-induced transient “delirium” (Ban 1991; Berrios 1981). 

            Celsus’ recognition that not all cases of “delirium” were followed by “insanity,” but only those in which a continuous “dementia” begins, set the stage for a development which culminated in the distinction between “chronic organic (neuropsychiatric) diseases,” dominated by “dementia,” and “acute organic (exogenous) psychiatric states, “dominated by “delirium” (Ban 1991).

            The term “dementia” was dormant for centuries. It reappeared, at the turn of the 19th century, as the fourth class (“species”) of “mental derangement” in Philippe Pinel’s classification of “insanity” (See Bulletin 7).   Pinel defined “dementia” as an “abolition of the thinking faculty” and characterized it by mental disorganization “where the ideas and internal emotions appear to have no connection with the impressions of sense, and to succeed each other without order and to vanish without leaving any traces of their existence.”   He also distinguished “dementia” from “idiotism,” an “obliteration of intellectual faculties,” characterized by “privation more or less absolute of all ideas and emotions” (Pinel 1798, 1801). 

            Pinel’s concept of “dementia” was adopted virtually unchanged as the fourth class of “general form of insanity” in Jean-Étienne Dominique Esquirol’s (1772–1840), classification. Esquirol emphasized that patients with dementia “utter folly because their organs of thought have lost their energy and the strength requisite to fulfill their function” and noted that most patients classified as having “dementia” were afflicted with “paralysis.” He perceived the “paralysis” as a “complication” of “dementia” (Ban and Ucha Udabe 1995; Esquirol 1838; Pichot 1883; Pierce 2012; Shorter 2005; Szapiro 1975).

          Instrumental to the development of our current concept of “dementia” was the discovery of Antoine Laurent Jessé Bayle (1799–1858) that “insanity sometimes was the symptom of chronic inflammation of the arachnoid.” Bayle, a French physician, became involved in research for preparing his dissertation in which he correlated clinical manifestations with autopsy findings. In his defence of his inaugural thesis (Recherches sur les Maladies Mentales) on November 21, 1822, after presenting on six cases from which two had a history of syphilis, he concluded: “The symptoms of chronic arachnitis can all be reduced to a general and incomplete paralysis and to the derangement of the intellectual faculties. These two orders of phenomena proceed at an equal and proportionate pace that   allow the disease to be divided into three periods (stages)” from which the first is characterized by “mild paralysis, particularly affecting speech, and a monomania (partial insanity) with grandiose ideas,” the second by “generalized mania (universal insanity) and a worsening spastic paralysis” and the third by “dementia with severe paralysis.”

          Between the years of 1822 and 1826, Bayle presented the results of his research in detail in three monographs. In the first, entitled “Recherches sur L’Arachnitis Chronique Considerees Comme Cause d’Alienation,” published in 1822, he discussed his findings of chronic arachnitis in relevance to insanity. In the second, “Nouvelle Doctrine des Maladies Mentales,” published in 1825, he focused on the grandiose delusions encountered in patients at an early stage in the development of their illness. In the third, “Traite des Maladies du Cerveau et de ses Membranes,” published in 1826, he presented a collection of detailed case histories of 60 of his own patients. In all his publications, Bayle maintained that paralysis was only one facet of a complex but distinct disorder that was secondary to a chronic inflammation of the arachnoid and included both mental and physical symptoms (Bayle 1822, 1825, 1826; Pichot 1983).    

         On the basis of Bayle’s findings Esquirol’s view that paralysis was a complication of insanity was rejected. Bayle’s findings also upset traditional classifications of insanity by perceiving several diseases in these classifications as different stages in the development of the same disease manifest in a dementing process.

          In a historical perspective, Bayle was first to separate “essential (sui generis) insanity,” a distinct population. from “insanity,” which fulfilled Giovanni Battista Morgagni’s (1682 -  1771) criteria of disease, i.e., detectable changes by pathological anatomy corresponding with clinical manifestations (Morgagni 1769).

          Bayle’s recognition that chronic inflammation of the arachnoid lead to “dementia” stimulated research to study clinical neuropathological correlations in “insanity.” In the course of this research, by the turn of the 20th century, several diseases which culminated in “dementia” with distinctive neuropathological changes were identified. Included among them are Huntington’s chorea, discovered in 1872; Pick’s disease identified in 1889; Binswanger’s disease separated in 1894; Alzheimer’s disease, described in 1907; and Creutzfeldt and Jakob’s disease, recognized in 1920.    



Alzheimer O. Ueber eine Eigenartige Erkrankung der Hirnrinde. Allg Z Psychiat 1907; 64: 146-8.  

Ban TA. Psychopharmacology for the Aged. Basel: Karger; 1980.

Ban TA. Declino Cognitivo Nell'Anziano Demenza e Sindromi Demenziali Epidemiologia, Diagnosie Terapia. Milan: UTET; 1991

Ban TA, Ucha Udabe R. Clasificacion de los Psicosis. BuenosAires: Editorial Salerno; 1995.

Bayle ALJ.  Recherhes sur les Maladies Mentales. Thesis Paris, 1822.

Bayle ALJ. Recherches sur L’Arachnitis Chronique Considerees Comme Cause d’Alienation. Paris: Gabon 1822.

Bayle ALJ. Nouvelle Doctrine des Maladies Mentales. Paris: Gabon; 1825.

Bayle ALJ. Traite des Maladies du Cerveau et de ses Membranes. Paris: Gabon; 1826.

Berrios GE. Delirium and confusion during the nineteenth century: A conceptual history. Brit J Psychiatry 1981; 139: 439-49.

Binswanger O. Die Abgrenzung der allgemeinen progressiven Paralyse (Referat, erstattet auf der Jahresversammlung des Vereins Deutscher Irrenärzte zu Dresden am 20. 09. 1894). Verl Klin Wochenschr 1894; 31:1103–5, 1137–9, 1180–6.

Creutzfeldt HG. Ueber eine eigenartige herdformide Einkrankung das Zentralnervensystm. Z ges Neurol Psychiat 1920; 57: 1-18.

Esquirol JÉD.  Des maladies mentales considérées sous les rapports médical, hygiénique et médico-légal. Paris: Baillière; 1838

Huntigton G. On chorea. Med Surg Reporter 1872; 26: 317-71.

Jakob A. Ueber eigenartige Erkrangungen des Zntralnervensystems mit bemerkensuerten antatomischen Befunde. Spastische pseudoklerose Enephalomyopathy mit disseminierte Degenerationsherden. Z ges Neurol Pychiat 1921; 64: 147-229.

Mortgagni GB. The Seats and Causes of Disease Investigated by Anatomy. London: A. Millar and, T. Cadell; 1769.

Pichot P. A Century of Psychiatry. Paris: Roger Dacosta; 1983.

Pick A. Ueber die Beziehungen der senilen Hirnatrophie zur Aphasie. Prag med Wochenschrift 1892; 17: 165-7. 

Pierce JMS. Brain disease leading to mental illness Eur Neurol 2012; 67: 272–8. 

Pinel P. Nosographie Philosophique ou la Methode de l’Analyse Appliquée a la Medicine. Paris: Brosson; 1798.

Pinel P. Traité Médico-Philosophique sur l’ Aliénation Mentale ou la Manie. Paris: Brosson; 1801.

Shorter E. A Historical Dictionary of Psychiatry. Oxford: Oxford University Press; 2015.

Slater E, Roth M. Clinical Psychiatry. London: Tyndale and Cassell; 1969.

Stedman TL. Stedman’s Medical Dictionary. 25th edition. Bangore/Hong Kong/London/Sydney: Williams & Wilkins; 1990.

Szapiro E. Pinel and Esquirol: some comments on the beginning of a friendship. Annales médico-psychologiques 1975; 2: 59–61. 


April 5, 2018