Article

Gender differences in scalp hair growth rates are maintained but reduced in pattern hair loss compared to controls

Wiley
Skin Research and Technology
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Abstract

Background: Hair loss is related to follicular density, programmed regrowth and hair productivity. Objective: The dissatisfaction with hair growth in patients experiencing hair loss might be due to slower linear hair growth rate (LHGR). Methods: LHGR and hair diameter was evaluated in Caucasian controls and patients with patterned hair loss employing the validated non-invasive, contrast-enhanced-phototrichogram with exogen collection. Results: We evaluated 59,765 anagen hairs (controls 24,609, patients 35,156) and found thinner hairs grew slower than thicker hairs. LHGR in normal women was generally higher than in normal men. LHGR correlates with hair diameter (P < 0.006) and global thinning is associated with slower growth rates. Compared with hair of equal thickness in controls, subjects affected with patterned hair loss showed reduced hair growth rates, an observation found in both male and female patients. Males with pattern hair loss showed further reduction in growth rates as clinical severity worsened. However, sample size limitations prevented statistical evaluation of LHGR in severely affected females. Limitations: Caucasian ethnicity. Conclusion: In pattern hair loss, LHGR significantly contributes to the apparent decrease in hair volume in affected areas. In early onset, LHRG might have a prognostic value in females but not in males.

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... Previous research suggests that thicker hair strands are associated with an increased linear hair growth rate. 23 It has also been noted that reduced hair growth rates observed in both male and female patterned hair loss are also tightly correlated to a reduction in hair diameter. 23 Thus, an increase in the number of terminal hairs seen in this study and a decrease in thin, vellus hairs could be improving hair growth by promoting the presence of thicker hair strands and providing more visible coverage. ...
... 23 It has also been noted that reduced hair growth rates observed in both male and female patterned hair loss are also tightly correlated to a reduction in hair diameter. 23 Thus, an increase in the number of terminal hairs seen in this study and a decrease in thin, vellus hairs could be improving hair growth by promoting the presence of thicker hair strands and providing more visible coverage. ...
Article
Hair thinning affects upwards of 50% of women by age 50, impacting their social-emotional wellbeing. It is a condition now thought to be driven by a multi-factorial etiology, including diet and nutrition. Women following vegan, vegetarian, or other plant-based diets have specific needs for nutrients traditionally sourced from animals, which could affect hair health. To support hair growth and quality in women following a plant-based diet, a novel vegan nutraceutical (Nutrafol Women's Vegan Capsules, Nutraceutical Wellness, Inc., New York, NY) was evaluated for its ability to support hair health. The objectives of this 6-month, multi-site, single-blind prospective clinical study was to evaluate the safety and efficacy of the nutraceutical to improve hair growth and quality in women consuming a plant-based diet. The primary endpoint in this study was an increase in terminal hair count at day 180 compared with baseline, as assessed through phototrichogram analysis. Ninety-five subjects completed the study. Daily intake of the nutraceutical resulted in a significant increase in the number of terminal hairs at day 90 (P<0.01) and day 180 (P<0.01). There was also an increase in total hair counts (P<0.01), the terminal-to-vellus ratio (P<0.01), and a decrease in shedding (P<0.01). Global Investigator Ratings revealed improved hair growth (P<0.00001) and overall quality (P<0.00001). In-person hair strength and brittleness assessments significantly improved as well (P<0.01 for both). A significant proportion of subjects reported improved hair quality, appearance, texture, and volume. Hair problems affecting the quality of life of the subjects were also reported as improved. This study demonstrated significant improvements in hair growth and quality in a plant-based population with a vegan nutraceutical. ClinicalTrials.gov Identifier: NCT05332743. J Drugs Dermatol. 2024;23(8):661-668. doi:10.36849/JDD.8421.
... In 2016, Van Nestand Rushton evaluated total of 59,765 anagen hairs in Caucasian controls (24,609) and patients with pattern hair loss (35,156) employing the validated, non-invasive, contrast-enhanced-phototrichogram with exogen collection and computer assisted image analysis (CE-PTG-EC) [20]. The results revealed that the mean growth rate of the thinner fibres was lower than thicker fibres (P < 0.0001). ...
... The results revealed that the mean growth rate of the thinner fibres was lower than thicker fibres (P < 0.0001). However, for the thicker hair (≥60 μm), there was a slightly faster mean growth rate in females as compared to males [20]. ...
Chapter
By evoking hair variations related to gender, the first elements which come to mind are hair length, hair beauty, hair style or androgenic alopecia. However, sex steroids have a much more tremendous impact on skin and hair by modulating epidermal and dermal thickness as well as immune system function, skin surface pH, quality of wound healing, sebaceous gland excretions, hair growth and response to treatment, among so many others. In dermatology there has been increasing interest in studying gender differences in skin and hair to learn more about the physiology, the environment, diseases pathogenesis and to discover more effective and adapted treatments.
... Our observations will require external validation in another cohort and must be extended to larger cohorts for the investigation of potential patient-related and other confounding factors, as well as to establish clinical applicability. Firstly, the skewed sex ratio prevented us from assessing the effect of sex; the short hair length non-inclusion criteria meant that few men participated in the study, and the hair growth rate is reportedly around 8% faster in females than in males (Van Neste and Rushton, 2016). The availability of hair of sufficient length is one of the limiting factors of the technique. ...
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Background: Although adherence to inhaled medication is critically important for treatment efficiency, around half of patients taking these drugs are non-adherent or make critical errors when using their delivery device. Segmental hair analysis might be a valuable tool for therapeutic monitoring because hair concentrations reflect exposure from month to month. The objective of the present proof-of-concept study was to establish the feasibility of segmental hair analysis of inhaled budesonide and formoterol in asthma patients. Methods: We conducted a prospective, open-label, interventional study of adult patients being treated with budesonide/formoterol for controlled, moderate-to-severe asthma (CorticHair, NCT03691961). Asthma control, lung function, and medication adherence were recorded. Hair samples were taken 4 months after enrolment and cut into four 1 cm segments. Results: Samples were available from 21 patients (20 women; median age: 53; median budesonide dose: 600 μg/d). Budesonide and formoterol were detected in samples from 18 to 13 patients, respectively. The median hair concentrations were 6.25 pg/mg for budesonide and 0.9 pg/mg for formoterol. The intrapatient coefficient of variation between hair segments was 21% for budesonide and 40% for formoterol. Pearson’s coefficients for the correlations between the hair concentration and the self-reported drug dose and the prescribed drug dose were respectively 0.42 (p = 0.08) and 0.29 (p = 0.25) for budesonide and 0.24 (p = 0.44) and 0.17 (p = 0.57) for formoterol. Conclusion: Segmental hair analysis of inhaled medications was feasible, with low intrapatient variability. This innovative, non-invasive means of assessing monthly drug exposure might help physicians to personalize drug regimens for patients with difficult-to-treat asthma.
... The insights have helped differentiate hair loss issues in male versus female with respect to: incidence frequency, [1] pattern, [7,8] and inception age (teens to early 20s for males and the late to mid-20s for females). [9] One of the various approaches is to look at the distinctions from the gender construct and arrive at specific targets for male and female hair loss. Another approach is to understand hair loss from traditional medicine perspectives and utilize modern science validation steps to screen solutions in terms of herbs, recipes, and regimes. ...
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Modern scientific research has distinguished between the male and female hair loss while Ayurveda does not explicitly make that demarcation. The present work describes the male and female hair loss distinctions from Ayurveda perspective.
... Gender, hair diameter and health status are significant factors influencing hair growth rates and there is a slightly faster mean growth rate in females as compared to males 24 . In the present study, gender difference in the speed of hair growth was also found in C57BL/6Mlac mice (with a slightly faster in females) as evaluated in the control groups either by the initial hair growth (the first hair growth being visualized) as well as complete hair growth (the whole depilated area being occupied with hair) in Table 1, or percent area of hair growth in Table 2. ...
... Other candidates have been considered for longterm exposure to metal(loid)s, such as hair and nails (Butler et al., 2019;Fernández-Olmo et al., 2021;Nakaona et al., 2020;Parhizkar et al., 2021), because of their slow growth: between 1 and 1.2 cm/ month of hair (Van Neste & Rushton, 2016) and about 3.47 mm/month of fingernails (Yaemsiri et al., 2010). They are easy to sample, transport, handle and store (Haynes et al., 2015;Menezes-Filho et al., 2009;Sukumar & Subramanian, 2007), although it is not possible to discriminate between the specific exposure route to them, providing us with a final concentration resulting from inhalation, oral and dermal routes. ...
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The environmental exposure to trace metal(loid)s (As, Cd, Cu, Fe, Mn, Pb, and Zn) was assessed near a ferromanganese alloy plant using filters from personal particulate matter (PM) samplers (bioaccessible and non-bioaccessible fine and coarse fractions) and whole blood as short-term exposure markers, and scalp hair and fingernails as long-term biomarkers, collected from volunteers (n = 130) living in Santander Bay (northern Spain). Bioaccessible and non-bioaccessible metal(loid) concentrations in coarse and fine PM from personal samplers were determined by ICP-MS after extraction/digestion. Metal(loid) concentration in biomarkers was measured after alkaline dilution (whole blood) and acid digestion (fingernails and scalp hair) by ICP-MS as well. Results were discussed in terms of exposure, considering the distance to the main Mn source, and sex. In terms of exposure, significant differences were found for Mn in all the studied fractions of PM, As in whole blood, Mn and Cu in scalp hair and Mn and Pb in fingernails, with all concentrations being higher for those living closer to the Mn source, with the exception of Cu in scalp hair. Furthermore, the analysis of the correlation between Mn levels in the studied biomarkers and the wind-weighted distance to the main source of Mn allows us to conclude that scalp hair and mainly fingernails are appropriate biomarkers of long-term airborne Mn exposure. This was also confirmed by the significant positive correlations between scalp hair Mn and bioaccessible Mn in coarse and fine fractions, and between fingernails Mn and all PM fractions. This implies that people living closer to a ferromanganese alloy plant are exposed to higher levels of airborne metal(loid)s, mainly Mn, leading to higher levels of this metal in scalp hair and fingernails, which according to the literature, might affect some neurological outcomes. According to sex, significant differences were observed for Fe, Cu and Pb in whole blood, with higher concentrations of Fe and Pb in males, and higher levels of Cu in females; and for Mn, Cu, Zn, Cd and Pb in scalp hair, with higher concentrations in males for all metal(loid)s except Cu.
... In balding, this initially includes a shortened cycle length with slowing down of daily growth rates without any significant change in hair diameter followed by a progressive regression through an 'intermediate' stage, that ultimately leads to a stable miniaturized or transformed vellus-like follicle 4,18 even before the clinician can perceive reduced scalp coverage, terminal hair (diameters >60µm) decrease ( Figure 1s). The earliest measurements in affected follicles involve a shortening of the anagen phase, an increase in telogen (shed) hairs and, in particular those telogen club hairs ≤30mm in length, a reduced rate of hair growth, followed by a reduction in hair diameter [19][20][21] . From the clinical point of view, a substantial amount of individual hair follicle regression is required before noticeable hair loss is perceived by clinicians (>15% 19 ). ...
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Pattern Hair Loss (PHL) is a chronic regressive condition of the scalp, where follicular miniaturisation and decreased scalp hair coverage occurs in affected areas. In all PHL cases there is a measurable progressive shortening of the terminal hair growth duration, along with reduced linear growth rates. In both genders, PHL initially shows an increase in short telogen hairs ≤30mm in length, reflecting a cycle completion of under six months in affected terminal hair follicles. To understand the miniaturisation process, we re-examine the dynamics of miniaturisation and ask the question, ‘why do miniaturised hair follicles resist treatment?’ In the light of recent developments in relation to hair regeneration, we looked back in the older literature for helpful clues ‘lost to time’ and reprise a 1978 Hermann Pinkus observation of an array of elastin deposits beneath the dermal papilla following subsequent anagen/telogen transitions in male balding, originally described by Arao and Perkins who concluded that these changes provide a “morphologic marker of the entire biologic process in the balding scalp”. Thus, we have reviewed the role of the elastin-like bodies in hair pathology and we propose that alterations in elastin architecture may contribute to the failure of vellus-like hair reverting back to their terminal status and may indicate a new area for therapeutic intervention.
... However, the older a person gets, the shorter the anagen phase becomes [5]. In addition to age and genetic predisposition, sex also plays a role-male hair does not tend to grow as long, but it usually grows faster than female hair [6,7]. ...
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Hair plays a major role in perception within a society. It provides information about gender, age, health, and social status. It is therefore not surprising that those affected are exposed to great suffering due to the widespread occurrence of hair loss. As a result, the demand for new products to remedy this problem is not diminishing. Hair grows in cycles, and a hair follicle goes through several phases called the hair cycle. The active growth phase (anagen phase) lasts 2–6 years. In this state a hair follicle shows a growth of about 1 cm per month. In order to improve the existing hair status, hair should be kept in the active anagen phase as long as possible, or the transition to anagen should be stimulated. A number of reviews already describe the influence of individual active ingredients on hair growth. However, the following review describes existing studies of complex dietary supplements with their experimental weaknesses and strengths and their influence on hair loss. Also, for the determination of hair loss, it is important to use a valid method with high acceptance by the test persons. In this context, the TrichoScale® is a validated and non-invasive tool for quantifying hair loss/hair growth. Thus, it is an ideal measuring instrument to objectively quantify the effectiveness of a hair loss treatment.
... Yet, if m P; ab ¼ m P; ox is true then, in general, all absorbed dietary protein is only utilized for EE; and thus, over time, total body protein persistently decreases because the EE-independent protein loss is not being compensated by dietary intake. EE-independent protein loss occurs in feces (e.g., excretion of mucin, an indigestible protein secreted by the intestinal mucosa [27]), in sweat (e.g., amino acids may be excreted during physical exertion [28]), in urine (e.g., urinary excretion of glycine in creatinine [29] and C-peptide [30], a 31 amino acid polypeptide generated from insulin secretion) and during renewal of skin, hair and nails (e.g., shedding of dead cells filled with keratin [31,32,33]). As a consequence, we run into a contradiction since body weight is simultaneously stable (true absorbed-oxidation identities imply mass balance) and decreasing (body protein is continuously diminishing). ...
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Energy metabolism theory affirms that body weight stability is achieved as over time the average energy intake equals the average energy expenditure, a state known as energy balance. Here it is demonstrated, however, that weight stability coexists with a persistent energy imbalance. Such unexpected result emerges as a consequence of the answers to three fundamental problems: 1. Is it possible to model body weight fluctuations without the energy balance theory? And if so, what are the benefits over the energy balance strategy? 2. During energy balance, how the oxidized macronutrient distribution that underlies the average energy expenditure is related to the macronutrient distribution of the average energy intake? 3. Is energy balance possible under a low-fat diet that simultaneously satisfies the following conditions? (a) The fat fraction of the absorbed energy intake is always less than the oxidized fat fraction of the energy expenditure. (b) The carbohydrate fraction of the absorbed energy intake is always greater or equal to the oxidized carbohydrate fraction of the energy expenditure. The first of these issues is addressed with the axiomatic method while the rest are managed through analythical arguments. On the whole, this analysis identifies inconsistencies in the principle of energy balance. The axiomatic approach results also in a simple mass balance model that fits experimental data and explains body composition alterations. This model gives rise to a convincing argument that appears to elucidate the advantage of low-carbohydrate diets over isocaloric low-fat diets. It is concluded, according to the aforementioned model, that weight fluctuations are ultimately dependent on the difference between daily food mass intake and daily mass loss (e.g., excretion of macronutrient oxidation products) and not on energy imbalance. In effect, it is shown that assuming otherwise may caused unintended weight gain.
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Background and aims Retrospective analysis of hair testing data provides insights in drugs abuse patterns and improves results interpretation. Cases from subjects undergoing driving fitness assessment (2010-2020) were examined to evidence patterns in methamphetamine (MA) abuse. Materials and Methods: All cases with positive MA (≥0.025 ng/mg) were included (n=585). Data available were gender, age, MA and A (amphetamine) in hair (h), hair color/treatment, length of proximal hair. Cases with Ah/MAh≤0.35 (n=469) were arbitrarily selected to remove as many combined A, MA users. ANOVA was performed to detect Ah/MAh predictors. Results: No predictors affected Ah/MAh. A bimodal frequency distribution was observed. We clustered cases in two groups (1, Ah/MAh 0.025-0.070; 2, Ah/MAh 0.071-0.120) and performed logistic regression. Only gender exhibited significant difference across groups (p=0.0080). Odds ratio for females falling into group 2 was 2.86 times higher (CI97.5 1.34-6.44). Conclusion: Literature data support the hypothesis that the two Ah/MAh groups represent different phenotypes of the CYP2D6-mediated MA N-demethylation. Whether gender plays a role in such difference could not be confirmed. However, these results provide further suggestion of an association of gender and pharmacogenomics with MA disposition, requiring these factors to be considered in future research.
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Ηardy described the hair follicle as “a treasure waiting to be discovered by even more molecular biologists” [1]. And there is nothing more intriguing about hair follicle physiology than its life cycle.
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The words "hair growth" frequently encompass many aspects other than just growth. Report on a validation method for precise non-invasive measurement of thickness together with linear hair growth rates of individual hair fibres. To verify the possible correlation between thickness and linear growth rate of scalp hair in male pattern hair loss as compared with healthy male controls. To document the process of validation of hair growth measurement from in vivo image capturing and manual processing, followed by computer assisted image analysis. We analysed 179 paired images obtained with the contrast-enhanced-phototrichogram method with exogen collection (CE-PTG-EC) in 13 healthy male controls and in 87 men with male pattern hair loss (MPHL). There was a global positive correlation between thickness and growth rate (ANOVA; p<0.0001) and a statistically significantly (ANOVA; p<0.0005) slower growth rate in MPHL as compared with equally thick hairs from controls. Finally, the growth rate recorded in the more severe patterns was significantly (ANOVA; P≤0.001) reduced compared with equally thick hair from less severely affected MPHL or controls subjects. Reduced growth rate, together with thinning and shortening of the anagen phase duration in MPHL might contribute together to the global impression of decreased hair volume on the top of the head. Amongst other structural and functional parameters characterizing hair follicle regression, linear hair growth rate warrants further investigation, as it may be relevant in terms of self-perception of hair coverage, quantitative diagnosis and prognostic factor of the therapeutic response.
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At a population level female scalp hair growth shows features of regression with chronological ageing, although there is wide interindividual variation in timing and degree. The subjective assessment of hair loss is classically determined by hair density but it is apparent that other factors contribute to the clinical picture. Changes can occur in hair cycling, hair density, hair diameter and pigmentation, and possibly in structural qualities of the hair fibre. These changes are most pronounced in female pattern hair loss. Although conventionally considered as the female counterpart of male androgenetic alopecia the evidence that female pattern hair loss is androgen dependent is less clear cut than in men and it probably has a multifactorial basis. The emerging evidence implicating environmental factors is of particular interest as, unlike genes, such factors may be amenable to intervention. The clinical signs in women complaining of hair loss may be variable. In evaluating the patient complaining of hair loss, while true pathology must always be considered, the clinician needs to be aware of how age affects hair growth. These changes form the focus of this article.
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We have developed a quantitative method for measuring hair growth using optical microscopy and image analysis, and have used this to investigate the rate of growth in subjects with and without alopecia. The hairs were cut from an area 7-8 mm in diameter and 24 h and 72 h later, images of the areas were obtained using an optical microscope and were recorded on a video disc. Measurements of the regrowing hairs, placed parallel to the scalp using a glass slide attached to the front of the microscope, were made using the image analyser. In subjects with little or no baldness there was a clear difference between fast-growing hairs and resting or slow-growing hairs. However, in subjects with alopecia there was no such difference and the growth rate of all the hairs showed a continuous distribution. Using this method other parameters such as the number of hairs per unit area and hair diameter as well as grouping of the hairs could be measured.
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Global changes of scalp hair represent the cumulative end result of discrete changes of individual hair follicle structure and/or function. Monitoring of such changes requires an accurate non-invasive method. The phototrichogram (PTG) appears to be an appropriate choice to do so. However, a known weakness of the method is the lack of detection of less pigmented or thinning hair. Balding scalp of male subjects with androgenetic alopecia (AGA) was analysed with our previously published PTG method and with contrast enhanced (CE-)PTG followed by biopsy and transverse section examination with the light microscope. As compared with PTG, the CE-PTG method significantly improved detection not only of thin but also of thick hair. Equal numbers of thick (diameter > 40 mm) hair were detected with CE-PTG and with histology. CE-PTG was also able to detect the severely miniaturised hair fiber (down to 8 mm diameter) and was comparable to scalp biopsy analysis. The latter could identify hair fibres, which did not reach the scalp surface, a measure that is considered as not clinically significant. All growth stages - anagen, catagen and telogen - as well as the empty follicle stage could clearly be observed with CE-PTG. Staging of the more severely affected hair follicles was not always possible neither with CE-PTG nor histology - even with serial sectioning. The finding of such technological advantages makes the CE-PTG a first choice method for detailed analysis of hair cycling in androgenetic alopecia - a scalp disorder characterised by extreme hair follicle miniaturisation, decreased hair pigmentation and hair thinning.
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Hair growth parameters have been studied mostly in caucasian hair, whereas few data on African hair have been reported in the literature. To evaluate hair growth characteristics of African volunteers born in Africa. Thirty-eight young adults (19 women, 19 men, mean +/- SD age 27 +/- 10 years), native of central and western Africa, took part in the study. Phototrichograms were performed in order to record three parameters of hair growth: hair density, telogen percentage and rate of growth. For each volunteer, three regions of the scalp, namely vertex, temporal and occipital areas, were assessed. Hair density varied from 90 to 290 hairs cm(-2), with higher counts on the vertex. No significant difference between men and women was recorded. Telogen percentage showed wide variations, from 2 to 46%, with higher levels on the temporal area and in men. The rate of growth fluctuated from 150 to 363 microm day(-1) with no difference related either to gender or to scalp region. These data were compared with those previously obtained in caucasian volunteers of comparable age, and showed significant differences between the two ethnic groups in all three parameters studied. Hair density in African volunteers was lower than that in caucasians (mean +/- SD 190 +/- 40 and 227 +/- 55 hairs cm(-2), respectively). African hair grew at a much slower rate than caucasian hair (mean +/- SD 256 +/- 44 vs. 396 +/- 55 microm day(-1)), and telogen counts were frequently higher in African hair (mean +/- SD 18 +/- 9% vs. 14 +/- 11%). This study demonstrated significant differences between African and caucasian hair growth parameters, which might suggest a trend towards increased hair loss in Africans, even though it contrasts with a lower and slower incidence of the development of alopecia in Africans.
Article
The hair growth cycle is generally recognized to comprise phases of growth (anagen), regression (catagen), and rest (telogen). Whereas, heretofore, the hair shedding function has been assumed to be part of the telogen phase, using a laboratory mouse model and newly developed techniques for quantitative collection and spectroscopic determination of shed hair, we found that shedding actually occurs as a distinct phase. Although some shedding occurs throughout the growth cycle, the largest peak is coupled to anagen. Using hair dye and rhodamine labeling we established that the shafts that shed arise during the previous hair cycle. We found that over the cycle the ratio of shed overfur to shed underfur hair shafts varies with the cycle phase and that the shed shaft base is unique morphologically, having a cylindrical shape with scalloped or "nibbled" edges. By electron microscopy the mooring cells of the exogen root show intercellular separation suggesting a proteolytic process in the final shedding step. This is the first report describing a distinct shedding, or exogen, phase of the hair cycle. This study supports the notion that this phase is uniquely controlled and that the final step in the shedding process involves a specific proteolytic step.
Article
Hair growth patterns of 101 Japanese female subjects with diffuse, chronic hair loss and 58 healthy Japanese female volunteers were categorized into subgroups using noninvasive quantitative methods after determining the key parameters of hair growth. Phototrichogram was performed at 0 and 48 h after clipping hairs in the parietal region of the scalp. Shaft diameters of the excised hairs were then measured. Multiple regression analysis indicated that hair densities, hair diameters, short hair ratios, and hair growth rates, but not anagen hair ratios, were significant, in order of decreasing importance, for grading female diffuse alopecia. Using cluster analysis, hair growth patterns among subjects complaining of diffuse hair loss were divided into six abnormal groups (n=60), two borderline groups (n=21), and one normal group (n=20). The control subjects judged to be normal by macroscopic observation, actually included two subjects with borderline hair growth patterns and one abnormal subject. Most of the abnormal groups shared features of female androgenetic alopecia. Hair patterns showing a decrease in hair density but without vellus hair change, however, emerged as the most prevalent and distinct pattern of chronic diffuse hair loss among the Japanese female subjects. The phototrichogram, combined with the measurement of hair diameters, is an accurate tool for assessing hair growth patterns, especially in detecting the slight changes indicative of the early phase of diffuse alopecia.
Article
The biological importance and/or significance of human hair colour is unknown even though greying is obviously associated with ageing. In order to further characterise hair pigmentation in relation with hair growth variables we evaluated 3 scalp sites (top of the head (T): left and right and occipital(O)) in 12 untreated menopausal women (age range: 49-66 years: average 59.63 +/- 5.66) who presented complaining of hair loss and/or diffuse alopecia. Controls were 12 non menopausal sexually mature woman (7 age range 15-21 and 5 age range 38-48) not complaining of hair loss. One hair sample (whenever possible n = 60) was taken one month after clipping from T and O on each person; menopausal women were sampled twice. The following measures were performed with a light microscope: diameter (average min-max., microm), medulla (0% = absent to 100% = fully developed) and linear hair growth rate (mm/day). The hairs were categorised as pigmented (P) or non-pigmented (white, W) as compared with a black and white reference card. A total of 3343 hairs were analysed with 2-factor analysis of variance (ANOVA). A global comparison (all hairs) showed that the average diameter of W hair (67.68 microm) exceeded that of P hair (57.41 microm) (p = 0.0001) and this was maintained on all 3 scalp sites. In addition, the medulla of W hair (23.91%) appeared more developed than the medulla of P hair (12.21%) (p = 0.0001) and was more expressed in W T hairs as compared with W O hairs (p = 0.0325). There was also a significant interaction between site and pigmentation (p = 0.0074). Growth rate of W hairs (0.38 mm/d) was higher than that of P hairs (0.35 mm/d) (p = 0.0001) and there was a significant variation according to scalp sites (p = 0.0001). There was also a significant interaction between site and pigmentation (p = 0.0062) with the following rank order: O W (0.40 mm/d), T W (0.37 mm/d), O P (0.37 mm/d) and T P (0.34 mm/d). Subgroups of W and P of paired thickness in the range of 50 to 80 pm consistently showed a 10% faster growth rate of W. Previous studies have shown that growth rate and diameter declines in age and alopecia i.e. in hair thinning. Our data shows that the reduced growth rate of terminal hairs is in fact limited to the pigmented hairs. The mechanisms by which white hairs are spared these ageing changes are not yet understood. Less pigmented hairs are usually undetected by photo- graphic techniques used for drug trials. The potential role of drug induced modifications of hair pigmentation should be taken into account during the interpretation of efficacy except if contrast-enhancement has been applied.
Article
The tight coupling of hair follicle melanogenesis to the hair growth cycle dramatically distinguishes follicular melanogenesis from the continuous melanogenesis of the epidermis. Cyclic re-construction of an intact hair follicle pigmentary unit occurs optimally in all scalp hair follicles during only the first 10 hair cycles, i.e. by approximately 40 years of age. Thereafter there appears to be a genetically regulated exhaustion of the pigmentary potential of each individual hair follicle leading to the formation of true gray and white hair. Pigment dilution results primarily from a reduction in tyrosinase activity within hair bulbar melanocytes. Thereafter, sub-optimal melanocyte–cortical keratinocyte interactions, and defective migration of melanocytes from a reservoir in the upper outer root sheath to the pigment-permitting microenvironment close to the follicular papilla of the hair bulb, will all disrupt normal function of the pigmentary unit.
Article
The complaint of chronic hair loss frequently affects female subjects and there is little or no objective technology available in the general dermatology or even in the hair clinics to guide the observer in the management of the patient. The purpose of this report is to share the results of refined hair growth measurements that were collected in 92 female subjects complaining about hair loss. Clinically they were classified as having a patterned hair loss according to Ludwig (L; n=50), diffuse hair loss (D; n=13) or no visible hair loss but complaining of hair shedding (N; n=29). Two scalp sites on the top of the head and one occipital site were investigated after clipping by close-up photography before and after a hair dye (contrast enhancement, CE). Forty-eight hours later a new photograph was taken after CE in view of phototrichogram analysis (CE-PTG). Finally a last hair clip was performed 30 days later and hair thickness and length determined for linear growth measurements (LHGR). Herein we confirm that the top of the head shows usually a higher hair density than occipital sites, a physiological observation that applies both to men and women. From the technological perspective, we also document that CE improves hair detection in all sites. Interestingly, in affected patients (L and D) the relative increase of hair counts after CE was much higher (range +22.4% to +28.3%) compared with apparently unaffected females (N; range +8.2% to +9.7%). This increase in hair counts was only due in part to the presence of less pigmented thinning hair (thickness less than 40 microm). Such thin hairs were found in statistically significantly higher proportions in younger patients with mildly severe (grade I) patterned alopecia (Ludwig: L). In other patients with hair loss and in more severe forms of patterned alopecia - especially in older patients - the thin hair is not detected in abnormal proportions. In all sites slower growth rates and decreased anagen percentages indicate a defective hair replacement programme distinguishing L patterns from diffuse hair loss and from apparently unaffected patients complaining of chronic hair loss. Globally, we also noted that increasing age is associated with significant regression of scalp hair (decreased hair counts, thinner hair and slower LHGR). On the basis of the present data together with female data from the literature and our own studies in male subjects, we suggest a three-step mechanism leading to hair loss 1. Shortening of growth phase the hair cycle with maintained thick hair, i.e. more frequent hair cycling that leads to more hair shedding. 2. Intermittent production of short thin hair, i.e. morphological evidence of miniaturisation. 3. Very occasional or almost no hair production, i.e. dormant follicles or irreversible follicular atrophy. Depending on the genetic background, hormonal microenvironment in the scalp and conditioning of individual hair follicle bio-responses, female and male patterned hair loss may end up into different phenotypes.
Article
There have been few studies of the features of hair with aging and hair loss in Japanese women. Features of Japanese women's hair with aging and with progressing hair loss were investigated. Japanese women with hair loss (n=46) or with no or less hair loss (n=113), aged 14-68 years, were studied. Severity of hair loss was rated by visual comparison with six standard photographs. Hair density, hair growth rate, and hair diameter were analyzed by phototrichogram. Follicular units were deduced by a non-invasive method using tree-view analysis on scalp imaging. Hair loss in Japanese women is commonly characterized by a diffuse central pattern occurring after approximately 40 years of age. Hair density declines with age after the 40s. The reduction resulted from an increase in the number of one-haired follicular units and a reduction of three- and more-haired follicular units. Both the ratio and the growth rate of anagen hair also declined with age after the 40s. Mean hair diameter and the ratio of thick hairs increased with age from about 10 to 40 years, and decreased with progressing hair loss. There were few vellus-like hairs in women with hair loss, in comparison with male-pattern baldness. In Japanese middle-aged women, hair density declined with age without the appearance of hair loss. Hair loss appeared after approximately 40 years of age. The major causes might be reduction of hair density and the ratio of thick hairs, but not an increase of vellus-like hairs.
Article
Classically, the hair cycle is described as a sequence of three successive phases: a hair-growth phase named anagen, a regression phase or catagen and a resting phase or telogen. In rodents, it appears that the resting hair follicle population contains also a new phase that has been identified recently as the exogen phase of the hair cycle. This phase leads to the release of the telogen club and results in hair shedding. The aim of this paper is to propose a method that is applicable to humans and that is able to discriminate the two components of the resting hair population i.e. the telogen and the exogen hair follicles. We used non-invasive approaches to entrap exogen scalp hair into silicon-based polymers. We also extracted growing and non-growing hair with a calibrated dynamometer. We characterized differences between anagen, catagen, telogen and exogen root ends with histochemical stains and with the scanning electron microscope. Furthermore, we documented all known hair-cycle stages with the contrast-enhanced phototrichogram (CE-PTG) technique. We demonstrated that anagen and telogen hair are firmly anchored to the hair follicle and that cohesion forces are correlated with hair thickness. On the contrary, exogen hair are passively retained within the hair follicle. Among the resting hair population, telogen clubs retain cellular elements of the outer root sheaths that are not found on exogen hair. The specificity of the new exogen collection method was documented with the simultaneous use of the CE-PTG method: indeed anagen, catagen and telogen follicles remain unaffected by the exogen extraction procedure. Exogen hair can be sampled specifically from the human scalp with a new non-invasive method. Our data suggest that the casual levels of exogen hair, in normal individuals and under the present experimental conditions, are usually less than seven hair per cm(2).
Hair research for the next millenium
  • Sivayathorn A
  • Perkins T
  • Pisuttinusart P
A comparison of the hair growth characteristics of thai and caucasian men with male pattern baldness
  • A Sivayathorn
  • T Perkins
  • P Pisuttinusart
Sivayathorn A, Perkins T, Pisuttinusart P et al. A comparison of the hair growth characteristics of thai and caucasian men with male pattern baldness. In: Van Neste DJJ and Randall VA, eds. Hair research for the next millenium. Amsterdam, the Netherlands: Elsevier Science B.V; 1996: 341-344.