William Cullen and a missing mind-body link in the early history of placebos

Abstract

Until the late 18th century, the term ‘placebo’ was used in a religious rather than a medical context: an early Latin translation of the Hebrew Bible, Psalm 116, verse 9, was rendered as Placebo Domine - ‘I will please the Lord’. In the medieval Catholic Church, ‘placebo’ was the term used to refer to a funereal rite - Vespers for the Dead - which employed Psalm 116.1 By the 13th century, the term had taken on a disparaging, secular meaning: mourners paid to attend a funeral to ‘flatter’ the dead, were said to ‘sing placebos’ of false and easy praise. Indeed, in the 14th century, in the Canterbury Tales, Chaucer named his obsequious, flattering courtier Placebo.2 How did the word ‘placebo’ come to mean a medical treatment intended to please a patient? The term appears to have entered common usage sometime in the late 18th century. The 1775 edition of George Motherby's New Medical Dictionary contains no listing on the subject, while the 1785 edition defines ‘placebo’ as ‘a commonplace method or medicine’.3 Arthur Shapiro, a distinguished historian of the placebo, has expressed puzzlement over the changing meaning of ‘placebo’, suggesting ‘the reasons for the introduction of the word placebo into medicine in 1785 are largely unknown’.1 The transition from religious to medical meanings of the word ‘placebo’ can be enlightened by an analysis of the writings of William Cullen (1710-1790), dubbed by one historian ‘the leading British physician of the 18th century’.4 Cullen was the most prestigious and thus influential medical educator of his day, holding chairs in chemistry, theory of medicine and practice of medicine at the University of Edinburgh. Over his lifetime, his famous lectures were attended by thousands of pupils from throughout the Anglo-American world, including many of the early leading figures in American medicine. Thousands of patients consulted Cullen by post and in person at the Edinburgh clinic, including such luminaries as his friend Adam Smith, the famous economist.5 In his historical account of Scottish medicine, Risse6 noted that Cullen ‘employed regular drugs as placebos, although at lower doses’. We have examined the manuscripts of Cullen's clinical lectures,7 which are held in the Historical Library of the Royal College of Physicians of Edinburgh. They offer a valuable insight on how notions of placebo pertaining to religious ritual and flattery became a term referring to a method for pleasing difficult or incurable patients. The Cullen lectures also reveal the medical and social context of placebo use in actual medical practice in the late 18th Century.