AGING AND HAIR CYCLES

The phototrichogram is a non-invasive technique by which, on the same precise area of the scalp, each individual hair may be identified, and its current growth phase established. This technique was used to stud y the duration of hair cycles in 10 male subjects, balding and non-bal ding, by observations at monthly intervals over a period of 8-14 years . The accumulated data served to characterize the effects of ageing in these subjects: a reduction in the duration of hair growth and in the diameter of hair shafts, most evident in the thickest; hairs, and a p rolongation of the interval separating the loss of a hair in telogen a nd the emergence of a replacement hair in anagen. These various aspect s of ageing of scalp hair contribute to its progressive overall impove rishment. They resemble those observed in the course of male-pattern b alding, although their development is less marked.