Locker Kathryn C S, Bacon Robert A, Caterino Tamara L, Breyfogle Laurie, Alperet Derrick Johnston, Sarkar Pradipta, Piliang Melissa, Davis Michael G
The Procter & Gamble Company, Mason, Ohio, USA.
The Procter & Gamble Company, Singapore.
Int J Cosmet Sci. 2025 Aug;47(4):703-717. doi: 10.1111/ics.13067. Epub 2025 Mar 31.
Clinical studies assessing the dandruff condition typically focus on the therapeutic resolution of the signs and symptoms of dandruff, starting with a symptomatic scalp as a baseline. The reverse, the progression of events leading to a scalp flare-up after stopping the use of an anti-dandruff (AD) shampoo, is poorly understood. This study explored onset time and progression of the signs and symptoms of dandruff in individuals who stop using an AD shampoo.
This randomized, double-blind, parallel design study recruited self-identified, scalp-concerned adults. After a 2-week run-in with an AD shampoo, participants were randomized into two groups: The first continued using the AD shampoo and the second switched to a cosmetic (non-AD) shampoo. At baseline and defined intervals over the 28-day study period, objective measures of scalp condition were investigated: expert-assessed flaking, scalp impedance, and biomarkers. These were combined with self-assessments of scalp condition. A Stochastic Mixed-Effect Random Forest (SMERF) machine-learning algorithm was explored to model time-varying technical measurements and daily self-assessment responses from participants.
Switching from an AD shampoo to a non-AD shampoo resulted in increased scalp Malassezia load, degree of flaking, barrier disruption, and inflammatory and oxidative stress biomarkers compared to those maintaining AD shampoo usage. Signs of declining scalp condition (histamine, complement component C3) were observed as early as 3 days after ceasing AD shampoo usage despite no statistical increase in flaking (ASFS) until around 3 weeks of using a non-AD shampoo. These changes were accompanied by self-perceived itching and flaking, reported to be significantly worse in those using the non-AD shampoo compared to the AD shampoo at the end of the study. No statistically significant increase from baseline was observed for any objective measure in the AD shampoo group. In the SMERF model, markers of inflammation, oxidative stress, and Malassezia load were predictive of self-perceived scalp attributes.
For the first time, a comprehensive understanding of changes that occur as scalp condition goes from asymptomatic to dandruff-affected has been established. For scalp-concerned individuals, regular, sustained use of an AD treatment promotes optimal scalp health. When switching to a non-AD shampoo, scalp health deteriorates rapidly, even before visible flakes appear.
评估头皮屑状况的临床研究通常从有症状的头皮作为基线开始，重点关注头皮屑体征和症状的治疗缓解情况。而对于停用去屑（AD）洗发水后导致头皮突然发作的事件进展情况，人们了解甚少。本研究探讨了停用AD洗发水的个体中头皮屑体征和症状的发作时间及进展情况。
本随机、双盲、平行设计研究招募了自我认定关注头皮问题的成年人。在使用AD洗发水进行2周的导入期后，参与者被随机分为两组：第一组继续使用AD洗发水，第二组改用化妆品（非AD）洗发水。在28天研究期的基线和规定间隔时间，对头皮状况进行客观测量：专家评估的脱屑情况、头皮阻抗和生物标志物。这些测量结果与头皮状况的自我评估相结合。探索了一种随机混合效应随机森林（SMERF）机器学习算法，以对参与者随时间变化的技术测量结果和每日自我评估反应进行建模。
与继续使用AD洗发水的人相比，从AD洗发水改用非AD洗发水会导致头皮马拉色菌负荷增加、脱屑程度增加、屏障破坏以及炎症和氧化应激生物标志物增加。尽管在使用非AD洗发水约3周之前脱屑（ASFS）没有统计学上的增加，但在停止使用AD洗发水后3天就观察到了头皮状况下降的迹象（组胺、补体成分C3）。这些变化伴随着自我感觉的瘙痒和脱屑，据报告，在研究结束时，使用非AD洗发水的人比使用AD洗发水的人情况明显更糟。AD洗发水组的任何客观测量指标与基线相比均未观察到统计学上的显著增加。在SMERF模型中，炎症、氧化应激和马拉色菌负荷标志物可预测自我感觉的头皮属性。
首次全面了解了头皮状况从无症状到受头皮屑影响时发生的变化。对于关注头皮问题的个体，定期、持续使用AD治疗可促进头皮健康达到最佳状态。当改用非AD洗发水时，即使在可见头皮屑出现之前，头皮健康也会迅速恶化。
