Assessing therapeutic effectiveness of scalp treatments for dandruff and seborrheic dermatitis, part 2: the impact of gender and ethnicity on efficacy

The Sequelae and Moderators of Influence of Dandruff on Mental Health Among Mainland Chinese Adults

Introduction

The psychological impact of dandruff has been largely understudied.

Methods

In this cross-sectional study (N = 2116), we examined the consequences of self-perception of dandruff severity on mental health, quality of life, and sleep quality among Chinese adults. Additionally, we examined the moderating factors that influence these associations.

Results

Bivariate analyses revealed that greater self-perceived dandruff severity was associated with poorer mental health, lower quality of life, and reduced sleep quality. Furthermore, dandruff severity was positively correlated with appearance anxiety, feelings of helplessness, and perceived stigma. Individuals with more severe dandruff experienced increased teasing and ostracism and, subsequently, heightened psychological distress. Moderation analyses demonstrated that females were more adversely affected by dandruff than males, and those with comorbid skin conditions or a history of being teased and ostracized during adolescence due to dandruff experienced exacerbated negative outcomes.

Discussion

This study highlights the need for further research on the psychological consequences of self-perceived severity of dandruff and potential interventions to mitigate its impact.

Seborrheic dermatitis: topical therapeutics and formulation design

Seborrheic dermatitis (SD) is a common dermatological disorder with symptoms that include skin flaking, erythema and pruritus. This review discusses the topical products available for treating SD, which target several aspects of disease pathobiology, including cutaneous microbial dysbiosis (driven by Malassezia yeast), inflammation, sebum production and skin barrier disruption. Among the various treatments available, zinc pyrithione (ZnPT) based products that exhibit anti-fungal action are the market leaders. A skin compartment approach is presented here for combining ZnPT exposure information with threshold levels for anti-fungal efficacy and toxicity, overall providing a comprehensive picture of ZnPT therapeutics and safety. While Malassezia yeast on the surface are effectively targeted, yeast residing beyond the superficial follicle may not receive adequate ZnPT for anti-fungal effect forming the basis for skin re-colonisation. Levels entering systemic circulation from topical delivery are well below toxic thresholds, however the elevated zinc levels within the viable epidermis warrants further investigation. Strategies to improve formulation design can be broadly classified as influencing 1) topical delivery, 2) therapeutic bioactivity, 3) skin mildness, and 4) sensory attributes. Successful SD treatment ultimately requires formulations that can balance efficacy, safety, and consumer appeal.

Evaluation of a new-formula shampoo containing 6% glycyrrhetinic acid complex for scalp seborrheic dermatitis: A pilot study

Background

Scalp seborrheic dermatitis (SD) is a chronic inflammatory dermatosis associated with sebum imbalance and proliferation of Malassezia species. Various antifungal shampoos are commonly used for scalp SD.

Aims

Glycyrrhetinic acid is known to have antioxidative, anti‐inflammatory, and anti‐allergic effects. This study was designed to evaluate the effectiveness of a new‐formula shampoo that contains glycyrrhetinic acid for the treatment of scalp SD.

Patients/Methods

Thirty‐four patients were enrolled and treated with the 6% glycyrrhetinic acid complex shampoo. Efficacy was assessed clinically with Dermatology Life Quality Index (DLQI) and Adherent Scalp Flaking Score (ASFS) by the same dermatologist at baseline, week 2, and week 5. Among the 24 subjects with the most significant clinical improvement, four common microorganisms from scalp samples were analyzed by quantitative polymerase chain reaction (qPCR) at baseline, and week 5.

Results

The DLQI and ASFS at week 2 and week 5 improved significantly relative to baseline. The bacteria profiles showed a significant increase of Cutibacterium acnes and a decrease of Staphylococcus epidermidis at week 5. The fungi profiles showed significant decreases of both Malassezia restricta and Malassezia globosa. The ratio of C. acne to S. epidermidis increased significantly from 0.93 at baseline to 1.55 at week 5. The ratio of M. restricta to M. globosa decreased from 5.02 at baseline to 1.00 at week 5.

Conclusions

The effectiveness of this new regimen was objectively demonstrated at the clinical and microbiological levels. This new formula may alleviate the bacterial and fungal dysbiosis in scalp SD.

Comparison of whole-head and split-head design for the clinical evaluation of anti-dandruff shampoo efficacy

OBJECTIVE

Dandruff is a common scalp condition that can be improved by regular use of shampoos containing anti-fungal actives. The efficacy of anti-dandruff shampoos can be assessed by measuring scalp flaking, one of the important dandruff symptoms. A randomized, double-blind trial is often used with one of two clinical designs: whole-head parallel design and split-head paired design. We aimed to explore the difference in product differentiation between these two designs using the same two test shampoos and the same scalp flaking assessment method (Total Weighted Head Score Adhered Flakes-TWHS AF).

METHODS

A clinical study was conducted with a 2- to 3-week wash-out phase and a 4-week test phase, consisting of 2 cells: 120 subjects with whole-head parallel design, divided into 2 subgroups (1:1) using on-site controlled washing method (either wash their own hair at a study site, under the instruction of a study supervisor or wash their own hair at home, as per instructions, but without supervision) and 35 subjects with split-head paired design using salon-staff washing method. Both cells employed hair washing at frequency of three times a week and TWHS AF measurement once a week from the baseline assessment.

RESULTS

Both designs gave similar differences in TWHS AF between products: 5.6 units (95% CI: 4.1-7.0 units) in whole-head design and 5.9 units (95% CI: 4.9-6.9 units) in split-head design.

CONCLUSION

Split-head paired design shows a similar ability of detecting product difference as whole-head parallel design, whereas it is a choice of more efficient and more cost-effective, as only a quarter of the subjects are required to demonstrate the efficacy between anti-dandruff shampoos.

Sex-related differences in response to zinc pyrithione shampoo vs. non-anti-dandruff shampoo

OBJECTIVE

Sex-related differences in skin properties may be expected to impact dandruff formation and treatment. A meta-analysis approach was undertaken to investigate potential differences between males and females in response to zinc pyrithione (ZnPT) treatment vs. non-anti-dandruff (AD) shampoo. A separate pooled statistical analysis of ceramide and total protein loss endpoints was also undertaken to assess potential sex-related differences in stratum corneum properties that might influence response to ZnPT vs. non-AD shampoo in subjects with dandruff.

METHODS

The meta-analysis approach included data from 17 half-head, double-blind, randomized studies (N = 2088) undertaken in Asia to assess the effectiveness of 1% ZnPT shampoo and/or non-AD shampoo in reducing dandruff severity, as assessed by Total Weighted Head Score Adherent Flake (TWHS-AF) methodology. Treatment duration was 4 weeks, with TWHS-AF measured at weekly intervals. Data from an additional three studies (N = 143) conducted in Asia were included in the pooled analysis of ceramide levels and protein loss from scalp skin of subjects with dandruff.

RESULTS

Response to 1% ZnPT vs. non-AD shampoo was greater in males than in females at all time points; after 4 weeks, the between-treatment difference in TWHS-AF was -17.5 (95% confidence interval [CI] -19.5, -15.5) in males and -11.1 (-13.2, -8.9) in females. Sex-related differences were observed between males and females in response to both 1% ZnPT and non-AD shampoos. Males had a stronger response than females to treatment with 1% ZnPT shampoo, while dandruff decreased to a greater extent in females than in males when using non-AD shampoo. Statistically significant sex-related differences in ceramide levels and total protein loss were observed (both P < 0.01). Ceramide levels were 0.76 times lower (95% CI 0.60, 0.97) in males than in females, while total protein loss was 1.4 times greater (95% CI 1.1, 1.9) in males than in females.

CONCLUSION

Males show a greater response than females to 1% ZnPT shampoo, while females show a greater response than males to non-AD shampoo. These findings may in part be explained by the sex-related differences observed in stratum corneum properties, which may make males more prone to dandruff than females.