Understanding the dandruff scalp before and after treatment: an in vivo Raman spectroscopic study.

ABSTRACT

OBJECTIVES: To study and characterize the stratum corneum (SC) of dandruff scalp using in vivo Raman spectroscopy, to study how it compares with the non-dandruff scalp and to see the effect of treatment with a zinc pyrithione (ZnPTO)-based anti-dandruff shampoo. METHODS: The scalp skin was measured using a recently developed in vivo Raman probe. This method allows the inherent molecular components of the SC to be measured in vivo and confocally with depth, in particular the levels of natural moisturizing factors (NMF), lipids, lactic acid, urea and water. RESULTS: Depth-profile data for the skin components in dandruff SC in vivo are shown for the first time. The dandruff SC has lower NMF than the non-dandruff SC (0.16 compared with 0.39 a.u.), lower hydration, elevated levels of urea and lower levels of lactic acid. Treatment with an anti-dandruff shampoo containing 1% ZnPTO substantially restores the levels of each of these components close to the non-dandruff levels. Further to this, it is shown that sebum penetrates deeper into dandruff SC and at higher levels compared with non-dandruff SC. The levels of sebum localized within the SC are also brought closer to those of the non-dandruff condition after ZnPTO treatment. CONCLUSION: The in vivo Raman probe has allowed the direct measurement of dandruff-affected skin in situ for the first time. It has been shown that the dandruff SC is different from that of the non-dandruff scalp and that it is changed by treatment with shampoo containing ZnPTO and brought towards the characteristics of non-dandruff scalp. It offers novel insights into how the nature of a healthy scalp should be defined.