Age associated thin hair displays molecular, structural and mechanical characteristic changes

F. Baltenneck, G. Genty, E. BouSamra, M. Richena, D.P. Harland, S. Clerens, E. Leccia, M. LeBalch, R. Betts, J. Doucet, J.F. Michelet, S. Commo

INTRODUCTION

The thinning of individual hairs occurs during normal chronological aging in women and in men, leading to a changing level of thinner hair shafts alongside original thicker shafts Progression occurs as an overall hair density decrease in the elderly affecting almost all the individuals and being frequently a source of dissatisfaction for women and men. Hair shaft forms progressively within a hair follicle during the anagen growing phase of the hair This process relies on complex molecular interplays between dermal papilla fibroblasts and hair keratinocytes that largely govern both the shape and the diameter of the hair fiber in a given genetic background So far, the characteristics of age associated thin hairs remain largely unknown. The aim of our study was to investigate what is different about the thin hairs that become increasingly prevalent in later life We therefore compared at multiscale thin and thick hairs from Caucasian women older than 50 years of age We observed modifications at various levels, namely molecular composition, hair shape, hair fiber organization and mechanical properties.