Method for assessing the risk of wrinkle formation in the neck

Abstract

To provide a measuring method for assessing a risk of wrinkle formation in the future at the neck.SOLUTION: The measuring method for assessing a risk of wrinkle formation measures a horny layer moisture content of the skin surrounding the collarbones of a subject, in the assessing a risk of the wrinkle formation at the neck. In the assessing, in a case where the horny layer moisture content is less than a determination threshold, the risk of wrinkle formation is determined to be higher than that in a case where the horny layer moisture content is the determination threshold or more, and furthermore, the determination threshold is varied in accordance with the measurement time of the horny layer moisture content.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a measurement method for assessing the risk of wrinkle formation in the neck of a subject. [Background technology]

[0002] With the advent of a super-aging society, the number of women who wish to look younger is increasing. For example, wrinkles, which are a typical sign of skin aging, are a major factor that determines a person's apparent age. Many women are particularly concerned about wrinkles on the neck, and it has been reported that the shape of neck wrinkles changes significantly from the age of 30 to 50 (see Non-Patent Document 1).

[0003] Skin care cosmetics designed to care for the area below the collarbone, from the neck to the décolleté, have been on the market for some time. Many of these products focus on neck wrinkles caused by aging and UV rays, and various research findings have been obtained. However, evaluations limited to the neck have not revealed the definitive causes directly linked to wrinkle formation. Furthermore, there is currently little knowledge regarding the relationship between neck wrinkles and changes in skin physiology in nearby areas.

[0004] For example, cosmetics retailers offer services such as proposing skin care cosmetics and skin care methods based on the customer's skin condition. However, these services are limited to the current skin condition and do not provide services based on the results of, for example, assessing the risk of future wrinkle formation. Furthermore, little is currently known about predicting the formation of wrinkles in the neck. [Prior art documents] [Patent documents]

[0005] [Non-Patent Document 1] Journal of the Japan Cosmetics Society, 2013, Vol37, p.81-89 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to provide a measurement method for assessing the risk of future wrinkle formation in the cervical area. [Means for solving the problem]

[0007] The measurement method for assessing wrinkle risk of the present invention is characterized in that it measures the moisture content of the stratum corneum of the skin around the clavicle of a subject in assessing the wrinkle risk in the neck. In the present invention, the wrinkle risk refers to the possibility of wrinkle formation in the future, and a high risk indicates a high possibility of wrinkle formation.

[0008] When the stratum corneum moisture content is less than the judgment threshold, the risk of wrinkle formation is evaluated as being higher than when the stratum corneum moisture content is equal to or greater than the judgment threshold.

[0009] The determination threshold is changed depending on the timing of measurement of the stratum corneum moisture content. [Effects of the Invention]

[0010] The present invention is based on the finding that neck wrinkles are closely related to the moisture-retaining ability of the clavicle area, and the above-described measurement method allows a non-invasive and simple method to evaluate a subject's risk of developing neck wrinkles. Furthermore, the evaluation results can be used to propose skin care cosmetics and skin care methods.

[0011] In addition, if the stratum corneum moisture content is below the judgment threshold, the risk of wrinkle formation is assessed as high, and the judgment threshold is changed depending on the time of measurement of the stratum corneum moisture content, so the risk of wrinkle formation can be accurately assessed regardless of the measurement time, which affects the stratum corneum moisture content. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an example of the relationship between wrinkle formation risk and stratum corneum moisture content, etc. [Figure 2] FIG. 2 is a diagram showing measurement sites of skin physiological parameters in an example. [Figure 3] 1 is a graph showing the correlation between wrinkle formation score in the neck and age. [Figure 4] 1 is a graph showing the correlation between skin viscoelasticity (R2, R7) and age. [Figure 5] 1 is a graph showing a comparison of skin viscoelasticity (R2, R7) between sites. [Figure 6] 1 is a graph showing the correlation between stratum corneum moisture content and age. [Figure 7] 1 is a graph showing a comparison of stratum corneum moisture content between sites. [Figure 8] 1 is a graph showing the correlation between the moisture content of the stratum corneum under the clavicle and skin viscoelasticity (R7) at each site. [Figure 9] 1 is a graph showing the effect of seasonal variation in the moisture content of the subclavian stratum corneum. DETAILED DESCRIPTION OF THE INVENTION

[0013] In order to clarify the actual state of neck wrinkle formation, the present inventors have thoroughly investigated the relationship between the degree of neck wrinkles and skin measurements in the vicinity of the neck. As a result, they have found that the moisture content of the stratum corneum of the skin around the collarbone is closely related to the formation of neck wrinkles, and therefore found that the risk of neck wrinkle formation can be evaluated (determined) using the moisture content of the stratum corneum of the skin around the collarbone as an index.

[0014] In the present invention, the "neck" refers to the part connecting the head and torso, i.e., the neck. The "area surrounding the clavicle" refers to the part of the torso centered on the clavicle, including, for example, the subclavian and supraclavicular areas. In the present invention, the "neck" and the "area surrounding the clavicle" are clearly distinguished as parts of a human body.

[0015] The measurement method of the present invention measures the moisture content of the stratum corneum of the skin around the clavicle in assessing the risk of wrinkle formation in the neck of a subject. The moisture content of the stratum corneum is measured by conductance measurement using a stratum corneum moisture content meter. Conductance measurement is a method of measuring the conductivity (unit: μS) of an alternating current using high frequency. High frequency current flows easily on the surface of an object, and there is a close correlation between conductivity and moisture content, so the moisture content of the stratum corneum in the superficial layer can be measured quickly. Note that conductance measurement allows for measurement of moisture content at a more superficial layer than capacitance (electrostatic capacity) measurement.

[0016] The measurement site around the collarbone is preferably the area below the collarbone. The stratum corneum moisture content is measured in an environment without sweating, specifically, at around 20°C and a humidity of 30% to 50%.

[0017] The risk of wrinkle formation in the neck is assessed using the measured stratum corneum moisture content as an index. As shown in the Examples below, multiple subjects were classified into a group with prominent neck wrinkles (high score) and a group with inconspicuous neck wrinkles (low score), and the skin physiological parameters were compared between the groups. No significant differences were observed between the groups in the stratum corneum moisture content of the cheeks and the neck, whereas a significant difference was observed between the groups in the stratum corneum moisture content of the subclavian region (see Figure 7 below). This result indicates that neck wrinkles are more closely related to the moisture retention capacity of the subclavian region, a different region adjacent to the neck, than to the moisture retention capacity of the neck itself. Furthermore, it is inferred that age is not a major factor in this relationship. Based on these findings, it can be said that the stratum corneum moisture content of the skin around the collarbone can be used as an index for assessing the risk of neck wrinkle formation.

[0018] Furthermore, the results of Figure 7 show that the stratum corneum moisture content in the subclavian region of the group with inconspicuous neck wrinkles was significantly higher than that of the group with noticeable wrinkles, and that the stratum corneum moisture content remained relatively constant. Therefore, in assessing wrinkle risk using the measurement method of the present invention, when the stratum corneum moisture content is below the threshold, it can be determined that the wrinkle risk is higher than when the stratum corneum moisture content is equal to or higher than the threshold. It can also be determined that the lower the stratum corneum moisture content, the higher the wrinkle risk.

[0019] In the example of Figure 1, wrinkle formation risk is evaluated on a four-level scale ("A" to "D") according to the stratum corneum moisture content in the subclavian region. In this case, multiple judgment thresholds are set for the stratum corneum moisture content to separate each evaluation level, and each level is determined according to the measured stratum corneum moisture content. In Figure 1, an "A" rating is considered to represent the lowest risk of wrinkle formation, and a "D" rating is considered to represent the highest risk of wrinkle formation. Note that the method for evaluating wrinkle formation risk is not limited to the example of Figure 1.

[0020] The above-mentioned judgment threshold can be set based on experimental results, etc. For example, as shown in the examples below, in a group with inconspicuous neck wrinkles, the stratum corneum moisture content in the subclavian region was concentrated around 400 μS, whereas in a group with prominent neck wrinkles, the stratum corneum moisture content in the subclavian region was approximately 280 μS on average. From these results, it can be said that when the stratum corneum moisture content is maintained at around 400 μS, neck wrinkles (horizontal wrinkles) are not noticeable. The above-mentioned judgment threshold can be set taking such values ​​into consideration.

[0021] Furthermore, the moisture content of the stratum corneum of human skin is affected by seasonal changes. For example, the moisture content of the stratum corneum in autumn (November) and winter (February) tends to be lower than that in spring (May) and summer (August). Therefore, when assessing the risk of wrinkle formation using the measurement method of the present invention, it is preferable to change the judgment threshold depending on the time of measurement of the stratum corneum moisture content. Specifically, the judgment threshold is changed so that it is lower during times when the moisture content of the stratum corneum below the clavicle is low (e.g., autumn and winter) compared to other times (e.g., spring and summer).

[0022] The measurement method of the present invention can be used, for example, in cosmetics stores. Specifically, for women in their 20s to 30s, the moisture content of the stratum corneum of the skin around the collarbone of the subject is measured, and the resulting moisture content of the stratum corneum is used as an index to evaluate the risk of wrinkle formation 10 or 20 years from now. Based on the evaluation results, services for preventing future wrinkle formation can be provided. For example, cosmetics effective in preventing wrinkle formation can be suggested, and beauty counseling can be provided.

[0023] Furthermore, the findings underlying the present invention can be used to screen the development of drugs, cosmetics, etc. that can improve neck wrinkles. For example, the drug or cosmetic to be screened can be applied to the skin around the collarbone, and its effectiveness in improving neck wrinkles can be determined based on the change in the moisture content of the stratum corneum at that site.

[0024] The following describes an emulsion composition as one form of cosmetic product that can improve neck wrinkles.

[0025] The emulsion composition according to the present invention preferably contains at least hydrolyzed conchiolin and hydrolyzed collagen, and further preferably contains succinoyl atelocollagen. Hydrolyzed conchiolin is a hydrolysate of conchiolin, a scleroprotein contained in pearl oysters, and hydrolyzed collagen is a hydrolysate of collagen or gelatin. Succinoyl atelocollagen is succinylated atelocollagen, and the atelocollagen is extracted from, for example, the mantle of pearl oysters.

[0026] Furthermore, from the viewpoint of improving moisturizing properties, the emulsion composition preferably contains additional moisturizing components in addition to the three moisturizing components described above. The additional moisturizing components can be any moisturizing component commonly used in the cosmetics field. Examples include polyhydric alcohols such as glycerin, polyethylene glycol, propylene glycol, 1,3-butylene glycol, dipropylene glycol, and pentylene glycol; sugars such as sorbitol, glycosyltrehalose-hydrogenated starch hydrolyzate mixture, maltitol, trehalose, and raffinose; amino acids such as valine, leucine, alanine, arginine, glutamine, lysine, aspartic acid, and glutamic acid; betaine; and plant extracts such as Sagarame extract and carrot root extract. These moisturizing components may be used alone or in combination.

[0027] Among the above moisturizing ingredients, it is more preferable to include at least one moisturizing ingredient selected from betaine, glycerin, Sagarame extract, and carrot root extract. Betaine is a natural amino acid moisturizing ingredient that prevents moisture from escaping and keeps it in the skin. Sagarame extract is a component derived from seaweed and promotes the production of ceramides and filaggrin, which are the source of moisture. Carrot root extract is rich in carotenoids and exhibits antioxidant effects and skin metabolism-promoting effects.

[0028] The emulsion composition preferably contains a cell membrane component. Examples of the cell membrane component include soybean lecithin extracted from natural soybeans or egg yolk, egg yolk lecithin, and hydrogenated lecithin (hydrogenated lecithin) obtained by hydrogenating these components, which are generally known as phospholipids. By combining the cell membrane component with succinoyl atelocollagen (more preferably, with betaine and glycerin), moisture produced inside the skin can be more easily retained in the stratum corneum, effectively suppressing moisture evaporation.

[0029] The above-mentioned emulsion composition may further contain, as needed, surfactants, thickeners such as carboxyvinyl polymers, emollients (oily components), vitamins (e.g., vitamin E derivatives), inorganic salts, chelating agents, preservatives, pH adjusters, pigments, water-soluble drugs, and the like.

[0030] The surfactant may be an ionic surfactant or a nonionic surfactant. Examples of nonionic surfactants that can be used include glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, propylene glycol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene hydrogenated castor oil. One or more surfactants may be used.

[0031] Examples of emollients that can be used include hydrocarbon oils such as liquid paraffin and squalane; ester oils such as isopropyl palmitate; vegetable oils such as soybean oil, olive oil, and castor oil; silicone oils such as methylpolysiloxane; higher fatty acids such as oleic acid; higher alcohols such as stearyl alcohol and behenyl alcohol; alkyl glyceryl ethers such as batyl alcohol; petrolatum, lanolin, and shea butter. One or more types of emollients can be used.

[0032] A particularly preferred form of the emulsion composition according to the present invention contains hydrolyzed conchiolin, hydrolyzed collagen, succinoyl atelocollagen, betaine, Sagarame extract, carrot root extract, hydrogenated lecithin, a glycyrrhetinic acid derivative, a vitamin E derivative, an emollient, a surfactant, and water. In fact, by continuously applying a cream made from this emulsion composition to the neck, décolleté (including the area around the collarbone), and hands for four weeks, the moisture content of the stratum corneum in each area increased, improving moisturization.

[0033] The content of water contained in the emulsion composition according to the present invention is, for example, 30% by mass to 80% by mass (preferably 50% by mass to 80% by mass) relative to the total amount of the emulsion composition.

[0034] The method for producing the emulsion composition is not particularly limited, and in addition to conventional emulsification, methods such as multi-stage emulsification, D-phase emulsification, phase inversion emulsification, liquid crystal emulsification, PIT emulsification, gel emulsification, and membrane emulsification can be selected.The emulsification apparatus is also not particularly limited, and in addition to conventional emulsification apparatus such as a stirrer, impeller agitator, and homomixer, high-pressure emulsifiers such as a Manton-Gaulin type high-pressure homogenizer, a water jet reversal type high-pressure emulsifier, a microfluidizer, a nanomizer, and a starburst can also be used, and the required particle size can be obtained by combining one or more of these.

[0035] The emulsion composition can be used in combination with other ingredients to form various dosage forms, such as gel, paste, liquid, cream, and solid. [Example]

[0036] The present invention will be specifically explained below by way of examples, but the present invention is not limited to these examples in any way.

[0037] The following measurements were conducted on 32 healthy women in their 20s to 50s (mean age 41.66 ± 7.29 years). Skin viscoelasticity measurements were conducted on 31 women. After cleansing, the cheeks were washed with a facial cleanser, while the neck and subclavian areas were washed with a wipe-off lotion. The subjects then rested for 20 minutes in a temperature- and humidity-controlled room at 21°C and 45% RH before undergoing the following measurements. As shown in Figure 2, the measurement sites for the cheeks were a point 2 cm vertically down from the outer corner of the eye, with a 2 cm square measurement area. For the neck, the measurement point was midway between the earlobe and the clavicle, and for the subclavian area, the measurement point was the center of the subclavian area. The measurements were conducted in late August.

[0038] <Visual evaluation> Visual evaluation was performed by five expert evaluators, who scored the wrinkle condition grade according to evaluation criteria based on Kim et al.'s classification (Reference: Kim E. et al., IFSCC, Buenos Aires (2010)) (see Table 1), and the average score of the expert evaluators was used as the score. Visual evaluation was performed using photographic images, and photographs were taken from the front, focusing on the neck and covering the area from the mandible to the subclavian region. Furthermore, because a significant inverse correlation was found between the wrinkle assessment score and the stratum corneum moisture content in the subclavian region, subjects were divided into high and low score groups using GP analysis (division by quartiles).

[0039] [Table 1]

[0040] <Skin viscoelasticity measurement> Measurements were performed using a Cutometer MPA580 (manufactured by Courage+Khazaka (C+K)). The rate of change between the skin elongation (Uf) 2 seconds after applying a negative pressure of 300 mbar and the height of elastic elongation (Ua) when sucked into the probe was calculated as R2 (Ua / Uf), and the rate of change in elongation between just before the load was released (Uf) and 0.1 seconds after the release (Ur) was calculated as R7 (Ur / Uf). The same site was measured three times, and the average was used as the measured value.

[0041] <Stratum corneum moisture content measurement> Measurements were taken at each site using a SKICON-200EX (manufactured by IBS) at a frequency of 3.5 MHz. Seven measurements were taken at each site, and the average of the five measurements, excluding the maximum and minimum values, was used as the measurement value (unit: μS).

[0042] For each measurement, the mean and standard deviation (SD) were calculated for all subjects and for each group at each measurement site. The correlation between age and each item group (wrinkle assessment score, stratum corneum moisture content, skin viscoelasticity) was determined using Spearman's correlation coefficient. To test for site differences, a paired test between the three items was performed using Mauchly's test of sphericity, and only when significant differences were found were multiple comparisons performed using the Bonferroni method. Comparisons between groups at each site were performed using Student's t-test. In all tests, a risk level of 5% or less was considered significant.

[0043] Figure 3 shows the correlation between wrinkle assessment scores on the neck and age. Spearman's correlation coefficient (r) and p-value are displayed in Figure 3 (n=32). As shown in Figure 3, there was a significant inverse correlation between wrinkle assessment scores and age, indicating a tendency for wrinkles to become more noticeable with age. Furthermore, all subjects were divided into a low score group (7 subjects) and a high score group (7 subjects) by GP analysis. The mean wrinkle assessment scores for the low score group and the high score group each differed by 1 or more points compared to the overall mean (see Table 2).

[0044] [Table 2]

[0045] Figure 4 shows the correlation between skin viscoelasticity (R2, R7) and age for each area. Spearman's correlation coefficient (r) and p-value are also displayed in Figure 4 (n=31). As shown in Figure 4, skin viscoelasticity (R2, R7) was significantly inversely correlated with age at all areas: cheek, neck, and subclavian, and decreased with age.

[0046] Figure 5 shows a comparison of skin viscoelasticity (R2, R7) between sites. Figures 5(a) and (c) show the results for all subjects (n = 31), while Figures 5(b) and (d) show the results for different groups (low score group: n = 7, high score group: n = 10). As shown in Figures 5(a) and (c), skin viscoelasticity was significantly higher in the order cheek < neck < subclavian. Similarly, in both the low score group and the high score group, skin viscoelasticity was significantly higher in the order cheek < neck < subclavian (see Figures 5(b) and (d)). This result generally supports previous reports that neck skin has characteristics intermediate between those of the trunk and cheek. Furthermore, in a comparison between groups, R2 in the neck area in the low-score group was significantly higher than in the high-score group (see Figure 5(b)). On the other hand, R7 in the low-score group tended to be significantly higher than in the high-score group, not only in the neck area but also in the subclavian area (see Figure 5(d)). Table 3 shows the ratio of the standard deviation of the low-score group to the standard deviation of all subjects for skin viscoelasticity (R7).

[0047] [Table 3]

[0048] As described above, the results of skin viscoelasticity and the like shown in Figures 3 to 5 showed similar trends to previously reported findings. Next, the moisture content of the stratum corneum was examined.

[0049] Figure 6 shows the correlation between stratum corneum moisture content and age for each area. Figure 6 also displays Spearman's correlation coefficient (r) and p-value (n=32), with low-scoring groups indicated by dark black dots. As shown in Figure 6, no correlation was observed between age and stratum corneum moisture content in the cheeks, neck, or subclavian areas. Furthermore, with regard to subclavian stratum corneum moisture content, the low-scoring group was not limited to younger age groups, but was concentrated in a relatively narrow, fixed area (around 400 μS) (see the right panel of Figure 6).

[0050] Figure 7 shows a comparison of stratum corneum moisture content between sites. Figure 7(a) shows the results for all subjects (n=32), while Figure 7(b) shows the results for different groups (low-score group: n=7, high-score group: n=7). As shown in Figure 7(a), the stratum corneum moisture content of the neck and subclavian regions was significantly higher than that of the cheek region, while no significant difference was observed between the neck and subclavian regions. Regarding the stratum corneum moisture content of the subclavian region, no difference was observed between the low-score group and the neck, while it was significantly lower in the high-score group compared to the neck (see Figure 7(b)). Furthermore, in a comparison between groups, the stratum corneum moisture content of the subclavian region in the low-score group was significantly higher than that of the high-score group (see Figure 7(b)). This unusual phenomenon suggests that age is not a major factor, as no clear correlation was observed between the subclavian stratum corneum moisture content and age across all age groups, as shown in Figure 6.

[0051] The results for the low-scoring group in Figure 7(b) generally supported previous reports that neck skin has characteristics intermediate between those of the trunk and cheek. Surprisingly, the high-scoring group showed different results. These results suggest that changes in the water-retaining capacity of the subclavian area, which is part of the trunk, have a significant impact on the formation of neck wrinkles.

[0052] Furthermore, as shown in Table 4, the ratio of the standard deviation of the low-score group to the standard deviation of all subjects for the subclavian stratum corneum moisture content was smaller than that of other areas. Therefore, it was found that the subclavian stratum corneum moisture content in the low-score group tended to remain relatively constant.

[0053] [Table 4]

[0054] Next, Figure 8 shows the correlation between the stratum corneum moisture content in the subclavian region and R7 for each site. In Figure 8, the low-score group is indicated by dark black dots. The subclavian region of the low-score group maintained a relatively constant stratum corneum moisture content (see Table 4 and Figure 8). In addition, the ratio of the standard deviation of the low-score group to the overall standard deviation was also small compared to other sites for R7 in the subclavian region, and therefore R7 in the low-score group tended to be a relatively constant, high value (see Table 3 and Figure 8).

[0055] These results demonstrate that the moisture content of the stratum corneum in the skin around the collarbone is closely related to the formation of wrinkles in the neck. Therefore, the risk of wrinkle formation in the neck can be assessed by using the moisture content of the stratum corneum in the skin around the collarbone as an index.

[0056] Next, we investigated the effect of seasonal variations in stratum corneum moisture content. We measured the stratum corneum moisture content of 11 healthy women in their twenties, different from the subjects mentioned above. The method for measuring stratum corneum moisture content was the same as the above measurements. This time, measurements were taken for each subject in May, August, and November. The results are shown in Figure 9.

[0057] Figure 9 shows the correlation between the moisture content of the stratum corneum under the clavicle and R7 of the neck. As shown in Figure 9, it can be seen that even people in their twenties have low moisture content of the stratum corneum under the clavicle. However, compared to all age groups, R7 of the neck tended to be generally high. Furthermore, with regard to seasonal variation, there was almost no difference between May and August, while R7 tended to be lower in November compared to May and August. From this, it can be inferred that the moisture content of the stratum corneum under the clavicle varies with the season, being lower in autumn and winter than in spring and summer. Therefore, it is considered preferable to change the judgment threshold used to evaluate the risk of wrinkle formation depending on the time of measurement (season, etc.).

[0058] The measurement method of the present invention allows for a non-invasive and simple method for evaluating the risk of wrinkle formation in the neck, and thus can be widely used in the field of cosmetics, etc. Furthermore, no approach has been made to the area around the collarbone to evaluate neck wrinkles in the past, and the present invention provides a new approach. Furthermore, application to cosmetics development, etc. is expected, and the approach of maintaining a constant, optimal stratum corneum moisture content specific to the area around the collarbone is very simple and is thought to be of great value in the field of cosmetics, etc.

Claims

1. A method for assessing the risk of wrinkle formation in the neck, comprising measuring the moisture content of the stratum corneum of the skin around the collarbone of a subject, and assessing that the risk of wrinkle formation is higher when the moisture content of the stratum corneum is less than a judgment threshold compared to when the moisture content of the stratum corneum is equal to or greater than the judgment threshold.

2. The evaluation method according to claim 1, wherein the determination threshold is changed depending on the timing of measurement of the stratum corneum moisture content.

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