Despite their close connection to concepts from ancient and Islamic medicine (concepts that would continue to be regarded as valid far into the eighteenth century), early modern notions of old age do not constitute a monolithic block. Rather, from the late middle ages on they are characterized by a competition between Islamic-Galenic elderly physiology and gerocomy, on the one hand, and ideas about extending life, on the other. These latter ideas are predominantly, although not exclusively, connected to alchemists, and later they are related to iatrochemists. Differences from traditional authorities can already be found in the above-mentioned authors Roger Bacon and Arnald of Villanova, although initially only concerning the question of old age's inevitability and certain options for therapy. Mutual influence between Galenism and alchemical ideas can still regularly be seen in the sixteenth century. Nevertheless, it is the Galenic conception of old age that dominated in learned Western medicine down to the latter half of the seventeenth century. It is largely developed outside of the immediate realm of the university, mainly in monographs devoted specifically to elderly care (gerocomies). Then it is relatively quickly replaced by iatrochemical and especially iatromechanical conceptions of old age, which on the whole find their expression in university writings. In the tradition of elderly dietetics, however, Galen's influence continues to be felt for a long time.

One could attempt to distil discrete systematic accounts of the two concepts of old age (the Galenic and the alchemical/iatrochemical) that coexisted in the sixteenth and seventeenth centuries.