Quantitative trichoscopic analysis of hair density in people attending tertiary care hospital – A cross-sectional study

INTRODUCTION

Mechanical properties of the hair are attributed to the cortex, which forms the bulk of the fiber. Hair is important to trace evidence commonly encountered in almost all criminal cases. Forensic anthropologists routinely compare the morphological characteristics of the hair samples to determine a transfer.¹ However, many questions such as how populations can be analyzed and possibly distinguished based on the morphology and appearance of their hair remain unanswered. Assessment of parameters such as hair density, hair diameter, follicular units, and empty hair follicle/yellow dots is useful for the diagnosis of various hair disorders, monitoring treatment outcomes, and research purposes.² The hair parameters can be assessed using a trichoscopy. Trichoscopy is a videodermoscopy of hair and scalp.³ It is a new method that has been developed for hair image analysis which is a non-invasive, easy-to-use, and less time-consuming method, and provides accurate results. It provides ×20–70 magnification of the images.⁴

However, there is a dearth of data on the Asian population using the same evaluation procedure. The purpose of this study was to analyze hair density concerning age groups, as well as to identify the effect of sex and aging on these values.

MATERIAL AND METHODS

The present cross-sectional observational study was carried out under the Department of Dermatology at a tertiary care center. All the subjects attending the Dermatology Outpatient Department (OPD) of Tertiary Rural Health Care Center fulfilling inclusion criteria were studied. Data were collected after the approval from the Institutional Ethical Committee. The procedure was explained and a written consent was taken and signed by each patient participating in the study in the language best understood by the patient.

RESULTS

In the present study, the majority of the study subjects belonged to the age group 26–35 years (38%), followed by 18–25 years (34.7%), 36–45 years (20.7%), and least in the age group of 46–55 years (6.7%). The average age is 30.4 ± 8.4 with a minimum of 18 years and a maximum of 54 years [Table 1].

It was observed that the majority of study subjects were female (53.3%) and male (46.7%).

The mean hair count terminal on males was 40.03 ± 5.22 and that of females was 40.12 ± 4.66. There is no significant difference in hair count terminal between males and females (P = 0.89). In turn, the hair count terminal is almost the same in both males and females [Table 2].

There is a significant negative correlation between age with hair density terminal (r = −0.144, P = 0.01), whereas there is a significant positive correlation between age with hair density vellus (r = 0.183, P = 0.001) [Table 3].

Trichoscopic image shows the follicular unit with 2–3 hairs, terminal hair, vellus hair, honeycomb pigment network, and white dots [Figure 1].

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Figure 1:

Hair follicle.

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DISCUSSION

In the present study, the majority of the study subjects belonged to the age group 26–35 years (38%), followed by 18–25 years (34.7%), 36–45 years (20.7%), and least in the age group of 46–55 years (6.7%). Leerunyakul and Suchonwanit,⁵ in 2020, conducted a study whose hair examination findings were normally evaluated. Two hundred and thirty-nine subjects participated in this study, of whom 79 were male and 160 were female with an average age of 37.9 years. Our findings are not consistent with the above study since the mean age was higher and may be due to ethnic differences.

In the present study, the mean ± standard deviation (SD) of hair parameters were as follows: hair density terminal was 168.62 ± 20.80, hair density vellus 26.08 ± 10.65 and mean thickness 0.06 ± 0.007. Hu et al.⁶ reported that the hair density, mean hair per follicle unit, and vellus hair ratio from 4-mm punch biopsy were 214.97 ± 48.73/cm², 2.24 ± 0.30, and 10.48 ± 6.43%, higher than those from quantitative trichoscopy analysis (163.07 ± 28.17/cm², 1.87 ± 0.25 and 6.60 ± 3.95%). The hair shaft diameter and terminal hair shaft diameter of the biopsy were 68.65 ± 8.00 µm and 73.77 ± 6.74 µm, less than those of trichoscopy (74.52 ± 8.02 µm and 77.87 ± 7.53 µm). The differences were statistically significant (P < 0.05). Our findings are not consistent with the above study which may be due to ethnic differences. Leerunyakul and Suchonwanit⁵ reported comparisons of hair diameter as follows: Frontal 81.3 ± 4.4 and 81.2 ± 5.1, vertex-81.1 ± 6.5 and 80.7 ± 6.3, temporoparietal −80.2 ± 5.8 and 80.3 ± 4.7, and occipital −80.1 ± 3.6 and 80.1 ± 6.9.

In the present study, the mean unit density in males was 104.78 ± 14.33 and that of females was 108.36 ± 17.60. Chen et al.⁷ reported that the average occipital hair shaft diameter and single hair follicle unit ratio of 35 normal Chinese females from quantitative trichoscopic analysis were 68.34 ± 7.70 µm and 13.47 ± 8.74%, which were slightly lower than this study (74.52 ± 8.02 µm and 33.77 ± 12.78%). However, the occipital vellus hair ratio reported by Chen was 8.88 ± 4.23%, higher than 6.60 ± 3.95% in this study. The distinction may be caused by different magnification and count modes.

The previous research in Asians utilizing computer-assisted phototrichogram found a reduction in hair density in normal Japanese females beyond the age of 40.⁸ In Korean studies, a similar observation was made.⁹ When hair diameter was compared between age groups, Japanese girls in their 20s had a different hair diameter than those in their 40s. However, while Kim et al. observed a decrease in hair diameter beginning in the 40s, this was not statistically significant.⁹ Our study found that hair density declined with age, but the reduction was not great enough to be statistically significant until participants were in their 60s. Our findings also revealed that aging causes hair follicular stem cells to senescence and lose their function.

It is common knowledge that the frequency of hair loss rises with age. Several earlier research demonstrated that age variations affect hair density in the absence of hair loss.

Because our study was conducted at a single tertiary care center, it may not be representative of the overall community. To overcome this problem, another nationwide cross-sectional study with stratification could be conducted. As a result, a large-scale study with a diverse sample size should be conducted in the future to assess the pattern of hair density and different age groups among different ethnicities.

CONCLUSION

In the present study, mean hair density varies concerning age group in the study population. A deeper awareness of hair density differences on the scalp can also be relevant for evaluating and selecting hair transplantation treatments for individuals. Furthermore, these disparities are significant because being aware of ethnic differences in hair density can affect the capacity to effectively diagnose hair diseases, evaluate response to therapy, and undertake hair-related research in these patients.