INDIVIDUAL ARTICLE: A Clinical Evaluation of Scalp Barrier Function, Ceramide Levels, and Microbiome in Diverse Dandruff Patients.

Dandruff is a common chronic scalp condition that affects approximately half the population irrespective of their origin. Dandruff scalps are characterized by flaking skin, pruritus, and minimal visible scalp inflammation. At the biological level, dandruff scalp presents a disruption of the barrier function supported by lower levels of ceramides in the stratum corneum and typically accompanied by altered microbiome diversity, including a higher abundance of Malassezia yeasts and exacerbated sebum peroxidation. This study evaluated the relationship between skin barrier integrity in association with epidermal ceramide profile, microbiome imbalance, and inflammatory markers in pathophysiology of dandruff in an ethnically diverse panel. Our results confirm a significant increase in TEWL and decrease in hydration along with an increase in erythema, dryness, flakiness, and itchiness in patients with dandruff vs normal scalps; and an elevation of IL1RA:IL1α ratio dependent on the severity of the dandruff, supporting the inflammatory association with dandruff. For the first time, a study shows that dandruff scalps have a significantly higher amount of short-chain ceramides and a significantly lower proportion of long-chain ceramides consistent with lower conformational ordering and, thus explaining a higher permeability of the skin contributing to barrier dysfunction. In addition, reduced phytosphingosine and dihydrosphingosine based ceramides (NP, AP, NDS) were also observed, supporting a weakened scalp barrier. In addition to an expected increase in Malassezia, especially Malassezia restricta, in dandruff scalp, an increase in Staphylococcus aureus and decrease in Malassezia globosa was also observed as compared to healthy scalp in the population analyzed. J Drugs Dermatol. 2025;24:3(Suppl 1):s3-14.