Gender differences in scalp health

Abstract

Dandruff is a condition that is cosmetically unappealing. It is the result of cellular hyperproliferation of corneocytes and incomplete desquamation on the scalp resulting in the appearance of aesthetically unappealing white flakes on the scalp and hair. Cosmetic remedies exist to alleviate this condition that include the incorporation of ingredients which inhibit the growth of Malassezia species that are associated with the appearance of dandruff. Such ingredients include zinc pyrithione, ketokonazole and Octopirox. To date all such antidandruff shampoos have been formulated in the same manner for both males and females. Any gender based formulation differences have concentrated on fragrance and colour changes and have assumed that male and female scalps are identical and common formulations will be equally effective. We have carried out an investigation into the biological properties of scalp skin with an emphasis on the differences and similarities between the genders. The results of this investigation identified subtle differences in scalp with males shedding more protein than females (considered to be indicative of a greater propensity to develop dandruff) and higher sebum production.

Full text

Gender Differences in Scalp
Health
Bryan Li
1
, Graham A Turner
2
, Amit Jayaswal
1
,
Jane R Matheson
2
, Fiona Baines
2
P2616
1. Unilever R&D Centre, Shanghai, China
2. Unilever R&D Port Sunlight, Wirral, UK
The authors are all employed by Unilever and report no conflicts of interest

The Life Cycle of Dandruff
Scalp problems such as dandruff and itch vary by age and gender
Women
Hormonal
Fluctuations
More sebum
More Prone to Dandruff
More Hair Loss
Men
teens
Dandruff
Starts
Cradle Cap
Infants Environment
More Scalp Problems
in winter

Dandruff appearance
Dandruff manifests as clumps of white or gray scales on the scalp’s
surface and affects up to 50% of the population globally.
Sometimes this may transform into a heavier form - seborrheic
dermatitis. In such cases massive scaling is accompanied with
formation of local plaques on the surface of scalp, skin redness and
increased itching.
Healthy Dandruff
Seborrheic
Dermatitis

Dandruff is a multifactorial problem
Surfactant damage/impaired stratum corneum barrier
Impaired proliferation/ differentiation
Increased sebum production
Malassezia
Inflammatory mediators
Sensitive scalp skin, itch, nerve density
Stress, hormones, diet, genetics & season

Scalp and Gender
• Very little published information of the
differences in scalp skin between genders.
Scalp skin has been examined with surface
measurement techniques:
• Water barrier function (TEWL)
– scalp=forearm>>facial
• Hydration (high-freq conductance)
– Scalp>forearm>facial
• Sebum-derived lipids
– removal leads to decreased hydration
.
• Superficial corneocytes:surface area
– Forearm>scalp>facial
• Corneocyte layers
– Forearm (15-18)>scalp(12)>face (9)

Gender Studies and Scalp
• Numerous Unilever studies established
over 9 year period where scalp gender
differences have been investigated
• Key Outcome measures:
– Dandruff level (visual assessment)
– Sebum
(Sebumeter SM810)
and sebum
icomposition
– Protein

Gender differences:
Protein (µ
µµ
µg) & Sebum levels
Soluble protein from buffer washes of scalp
was found to be higher in males than
females, p=0.025
96 females, 70 males
Females: 22-45 years
Males: 21-43 years
Bangkok, Sept/Oct 2008
Protein Sebum
Sebum meter SM810
Scalp sebum levels were higher in
Males than females, p<0.05.
A longitudinal study carried out in the
UK confirmed higher scalp sebum levels
in males
54 females, 46 males
Females: mean 36 years
Males: mean 35 years
Sweden, March
-
May 2009
Mean sebum
0
50
100
150
200
250
Gender
Female Male
Mean sebum
Total Protein (ug)
0
100
200
300
400
500
600
Total protein (
µ
µ
µ
µ
g)
Female Male

Sebum quality differences have also
been observed
The GC showed a significant difference in the composition of sebum
between males & females for both studies.
Females have a higher % of volatile, lighter materials such as free fatty acids while
males have a higher % heavier materials such as triglycerides and Cholesterol esters
GC1 GC2 GC3 GC4 GC5
0
10
20
30
40
50
60
Sweden, March-May, 2009 China, March-April 2009
Percentage of total
0
10
20
30
40
50
60
70
GC1 GC2 GC3 GC4 GC5
GC fraction
Gender
Female
Male
Percentage of total
GC fraction GC fraction
0
10
20
30
40
50
60
70
1 Free acid 2 Squalene 3 Wax ester 4 CE/ triglyceride
Gender
Female
Male
GC fraction
Percentage of total

Shampoo selection
• New dual active formulation
– Surfactant
– Active system: 1% zinc pyrithione + 0.5%
climbazole
– Formulation screened for deposition and
Malassezia inhibition prior to clinical testing
Zinc pyrithione Climbazole

Dual active shampoo: active
deposition
Zinc deposition
0
2
4
6
8
10
12
14
16
18
1% ZnPTO Dual Active
ppm
Climbazole deposition
0
0.5
1
1.5
2
2.5
3
3.5
4
1% ZnPTO Dual Active
ppm
•Dual active formulation
results in significantly
higher deposition of
zinc onto VitroSkin
(p<0.05)
•Dual active formulation
successfully deposits
the second active
(climbazole) onto
VitroSkin

Dual active shampoo: Malassezia
inhibition
Malassezia inhibition on VitroSkin
-3
-2.5
-2
-1.5
-1
-0.5
0
1% ZnPTO Dual Active
Log Malassezia Number
Reduction
•Dual active formulation results in significantly greater
reduction in Malassezia growth on VitroSkin

Antindandruff shampoo evaluation
•Primary Objective:
To show that in males the anti-dandruff efficacy of shampoo
containing 1% & 0.5%Climbazole (“1.5%dual active”) is superior to a
leading marketed 1% ZnPTO shampoo over a 4 week period of
regular product use and/ or over 2 weeks following withdrawal of test
product.
4 week run-in phase
(standard shampoo)
4 week test phase 2 week
Regression
(standard
shampoo)
Visual scalp assessment
Using Unilever Total Weighted Head Score (TWHS)
Wash frequency: 3 x per week. Salon wash.
Double-blind, randomised, half-head study

Antidandruff clinical test
selection criteria and shampoo
• Selection criteria:
Males and females: 20-60 years of age
Self perceived dandruff sufferers
Wash frequency: 3-4 times per week
TWHS (dandruff)
≥
32
n= 69 on test phase
• Formulations
Test (Dual active): 1% Zinc Pyrithione and 0.5%
Climbazole
Control: Market leading antidandruff shampoo
Active ingredient: 1% zinc pyrithione

Antidandruff test results: Male
• Dual active shampoo showed superior antidandruff efficacy
compared to 1% zinc pyrithione control shampoo over the 4
week test period
(95% CI 0.8-3.2, p<0.002)
• Superiority of the dual active system was maintained during
the two week regression phase
(95% CI 4.1-7.4, p<0.001)
Active Phase – Using AD shampoo
Regression phase – Non-AD shampoo
99%
99%
95%
N=69
Active phase Regression phase
0
10
20
30
40
50
Day 0 Wk 1 Wk 2 Wk 3 Wk 4 Wk 5 Wk 6
TWHS Dryness
Dual Active Test Control
P<0.012 P<0.004
N=69 N=60 N=58
P<0.001

Males & Females respond differently to AD actives
Treatment significant (p<0.0001). Also treatment*gender interaction
significant (p<0.001) indicating that the treatment effect (the difference
between placebo and DA) is greater in males than in females.
23.2-28.3* 25.8-30.8*
0
5
10
15
20
25
30
35
40
45
Average treat
LSM TWHS dryness
Male Placebo
Male DA
Female Placebo
Female DA
(n=36)
(n=35)
Males Females

Conclusions
• Scalp gender differences have been found to
exist. These are primarily in the area of
extractable protein, sebum and sebum
composition
• A novel antidandruff shampoo has been
formulated with a dual active system (zinc
pyrithione and climbazole) which:
– Deposits higher levels of zinc to the scalp
– Enhances anti-malassezial activity
– Has a greater dandruff reduction on males than
females than a standard ZnPTO shampoo

Acknowledgments
•Sahlgrenska University Hospital
Prof Jan Faergemann
•Unilever R&D Port Sunlight
Karen Darling
Iain Fairweather
Clare Jones
•Unilever R&D Shanghai
Vicki Li
•Unilever R&D Thailand
Nittaya Srisuwankul