Dementia during the seventeenth and eighteenth centuries: a conceptual history.

An historical analysis is made of the word and of the concept of 'dementia' before the nineteenth century. With regard to the word, it is shown that it had legal and medical meanings and that, while the former developed during the seventeenth century, the latter did so only during the eighteenth century (earlier than psychiatric historians have suggested). As evidence for the latter point, rare historical material on 'Démence' from the first edition of the Encyclopédie Française is presented for the first time in English. It is also shown that the legal meaning was finally enshrined in the 'Code Napoléon'. With regards to the concept of dementia, it is shown that it took final shape in the work of Willis, Hartley and Cullen in whose view it was made to include terminal states of behavioural incompetence due to severe failure of almost any mental function. During this period, dementia was not yet associated with a particular age group nor was specifically defined in terms of cognitive deficit. The origins of the 'cognitive' paradigm of dementia and of the clinical boundaries of the future concept of dementia are briefly outlined.