Sensitive scalp is associated with excessive sebum and perturbed microbiome

In brief

Sensitive scalpis an abnormal and unpleasant sensory reaction to environmental stimulus. Sensitive scalp has different biophysical and microbiotal characteristics than non-sensitive scalp, with impaired barrier function, elevated pH, skin irritation, excess sebum production and disrupted microbiome.

Introduction

Sensitive scalp is an abnormal and unpleasant sensory reaction of the scalp such as itching, prickling, tightness, pain, and burning to environmental stimulus. Impaired skin barrier function, elevated pH, alteration of the quantity and quality of sebum, and disturbed microbiota are believed to play a role in the etiology of sensitive scalp.

Biophysical properties of sensitive scalp

In a study conducted on 30 women with sensitive scalp and on 32 women without sensitive scalp (aged 19-60), biophysical investigations revealed that, in both groups, occiput regions had lower trans‐epidermal water loss and higher hydration level compared with crown regions (Figure 1 A,B).
In women with sensitive scalp, the pH values of the crown and occiput regions were higher than in women without sensitive scalp. (Figure 1C).
There was more irritation (redness) in women with sensitive scalp than controls, in the crown region. There was no difference on the average dandruff scores between the two groups, suggesting that sensitive scalp might have different mechanisms from dandruff.

Figure 1 . Biophysical parameters of sensitive scalp. Trans‐epithelial water loss (TEWL) (A), Hydration (B), and pH (C) values of nonsensitive scalp (NS) and sensitive scalp (SS) groups at both crown and occiput regions. The percentage of sebum covered surface (D), the area of sebum on the tape (E), and the count of sebum dots (F) were measured at both crown and occiput regions. *Represents significant difference (P < 0.05) vs NS, #represents significant difference (P < 0.05) vs Crown

Sebum properties of sensitive scalp.

In both groups, sebum levels were lower in the occiput region than in the crown region. However, in the occiput region, women with sensitive scalp had higher levels of sebum than controls (Figure 1D-F).
At the occiput region of women with sensitive scalp, the amounts of free fatty acids (palmitic acid stearic acid, oleic acid, linoleic acid) were higher than in the control group.

Microbiome composition of sensitive scalp

In the two groups, the most abundant bacterial components on scalp are Propionibacterium and Staphylococcus.
Women with sensitive scalp had a reduced bacterial diversity with a higher proportion of Propionibacterium in both crown and occiput regions.

Conclusion

Sensitive scalp has different biophysical and microbiological characteristics than nonsensitive scalp, with elevated pH, increased redness, excess sebum production and disrupted microbiome. Regulating these physiological conditions of scalp might be a target to treat sensitive scalp.

Reference

Ma L et al. Sensitive Scalp Is Associated With Excessive Sebum and Perturbed Microbiome. J Cosmet Dermatol. 2019 Jun;18(3):922-928.