Abstract
BACKGROUND:
Stress and food habits seem to be associated with acne, but no study has been reported from in Taif, Saudi Arabia. The aim of this study was to determine the association between the severity of acne, stress, and food habits of undergraduate medical students.
MATERIALS AND METHODS:
A cross-sectional study was conducted among 585 undergraduate medical students. Data was collected on students’ demographics, academic year, and level. The Global Acne Grading System (GAGS) was utilized for a clinical evaluation of acne severity and an assessment of the presence and location of acne lesions. To assess respondents’ stress, the Perceived Stress Scale (PSS) was employed, and adolescent food habits checklist (AFHC) assessed the food habits. To test for statistical significance, Chi-squared test was used for qualitative data, whereas Mann-Whitney U test and, Kruskal–Wallis tests were performed for quantitative variables.
RESULTS:
The mean age of students was 21.16 ± 1.81 years, 53.5% were female and 53.8% were in the preclerkship academic level. Of these, 9.7%, 78.5%, and 11.8% had low, moderate, and high stress levels. The overall prevalence of acne was 88.2%; Mild, moderate, severe and very severe acne were present among 59%, 23.9%, 3.9% and 1.4% of students respectively. Female students had a significant higher percent of severe acne and students in preclerk ship years had significant higher mean AFHC scores. Students with severe stress had a significant higher mean GAGS score and lower mean AFHC scores. A significant positive correlation was found between GAGS scores and PSS.
CONCLUSION:
The high rates of stress and acne of the study’s participants demand that medical students be given greater attention with regard to dermatology and psychiatric diseases.
Keywords: Acne, food, medical, stress, students
Introduction
Acne is a chronic inflammatory condition of the pilosebaceous unit that affects hair follicles on the face, neck, chest, and back.[1] Contrary to popular belief, acne can affect people of all ages and is not restricted to teenagers and young people.[2-4] Eating high glycemic index foods may contribute to the development of acne while drinking milk or eating chocolate could aggravate it. Omega-3 fatty acid-rich diets are beneficial because they reduce the production of inflammatory cytokines.[5,6]
The interaction between the nervous system and the skin is complicated,[7] and although it has long been assumed that stress causes or worsens acne, its impact on the severity of the condition has been overlooked.
A multicenter study by 17 Korean hospitals discovered that 82% of individuals had acne as a result of psychological stress.[8] Furthermore, a study of final-year medical students at the University of Melbourne in Australia discovered that 67% of students identified stress as an exacerbating factor for acne.[9] Previous Saudi research found that medical students had significant stress. In this region, 63% and 53% of medical students attend King Saud University and King Faisal University, respectively.[10,11]
There was a correlation between an increase in stress intensity and an increase in acne severity.[12,13] Research has also related dietary habits with the consumption of fast food, sugar, and fat all of which are favorably linked to the development of acne.[14-16] However, no study has as yet been conducted to address this issue in undergraduate medical students at Taif University, Saudi Arabia. The aim of this study was, therefore, to determine the association between the severity of acne, stress, and the food habits of undergraduate medical students.
Materials and Methods
A cross-sectional study was conducted from June to September 2022. Ethical approval was obtained from the Institutional Review Board vide Letter No. HAO-02-T-105 dated 05/12/2021 and informed written consent was taken from all participants in the study.
The inclusion criteria were undergraduate medical students of 1st to 6th year at Taif University, who agreed to participate in the study by signing an informed consent form at the beginning of the questionnaire. The exclusion criteria were postgraduate or undergraduate students who refused to participate in the study. The total number of undergraduate medical students was 1100, and our sample size was calculated using a sample size calculator from the University of California, San Francisco. Using a margin of error of 5% and a 95% confidence interval, we assumed the optimum sample size as 285 medical students. However, owing to the nature of the investigation, and also to boost the power of the study, all 585 responses were included in the statistical analysis.
A predesigned online questionnaire in a Google form was administered to all medical students who satisfied the inclusion criteria. The questionnaire, in English, had four sections. The first section had items to collect data on the participants’ demographics, academic year, and level. The second section included the Global Acne Grading System (GAGS), which is used to clinically classify the severity of acne. Acne lesions (comedones, papules, pustules, and nodules) were observed and documented. Each type of lesion was given a value depending on severity: no lesions = 0, comedones = 1, papules = 2, pustules = 3, and nodules = 4. The local score (local score) was calculated as follows: local score = factor × grade (0–4). The global score is the sum of the local scores, and the global score was used to grade acne severity. A score of 1–18 is considered mild; a score of 19–30 is moderate; a score of 31–38 is severe; and a score of >39 is very severe.[17]
The third section included the Perceived Stress Scale (PSS), the most commonly used psychological test to assess stress perception was used to measure the degree to which the respondents’ external situation was perceived as being under stress. The scale also includes numerous direct questions about current stress levels.[18] The Arabic version of the PSS scale showed adequate reliability and validity.[19] The scale consists of ten questions, with scoring done using a 5-point Likert scale (0 = never, 1 = rarely, 2 = sometimes, 3 = fairly frequently, and 4 = always). The scores for the four positively stated items 4, 5, 7, and 8 were reversed (e.g., 0 = 4, 1 = 3, 2 = 2, 3 = 1, and 4 = 0), and the total was calculated by adding the scores for each item. Individual PSS scores range from 0 to 40, with higher scores indicating greater perceived stress.
The fourth section had the adolescent food habits checklist (AFHC). The AFHC is a widely used effective tool for determining the eating habits of adolescents and adults. To complete the AFHC questionnaire, a positive/negative (yes/no) response format was chosen. Each “healthy” response earned participants one point. Attaining a high score demonstrated healthy eating habits on the part of the individual.[15,20,21] Both the GAGS and the AFHC were tested for validity and reliability. A pilot study was conducted on 30 students for each scale and for the introduction of any modifications to the questionnaire. The preliminary sample was not included in the final sample.
Data were analyzed using the Statistical Package for the Social Sciences Software (SPSS) program version 26 (IBM Corp.: Armonk, NY, USA). To assess the relationship between variables, qualitative data were expressed as numbers and percentages, and the Chi-squared test (χ2) was used. Quantitative data were expressed as mean and standard deviation, and nonparametric variables were tested using the Mann–Whitney and Kruskal–Wallis tests. The correlation analysis was performed using Spearman’s test. The odds ratio was calculated with a 95% confidence interval and a P < 0.05 was considered statistically significant.
Results
Table 1 shows that the mean age of the participants was 21.16 ± 1.81 years, 53.5% were females, 53.8% were in the preclerkship academic level, and 18.5% were in the 3rd academic year.
Table 1.
Sociodemographic characteristics of medical students at Taif University, Saudi Arabia, 2022 (n=585)
| Characteristics | N (%) |
|---|---|
| Age | |
| ≤21 | 327 (55.9) |
| >21 | 258 (44.1) |
| Age (years) | 21.16±1.81 |
| Gender | |
| Male | 272 (48.5) |
| Female | 313 (53.5) |
| Academic year | |
| 1st | 100 (17.1) |
| 2nd | 107 (18.3) |
| 3rd | 108 (18.5) |
| 4th | 107 (17.1) |
| 5th | 100 (17.1) |
| 6th | 63 (10.8) |
| Academic level | |
| Preclerkship | 315 (53.8) |
| Clerkship | 270 (46.2) |
| Stress level | |
| Low stress | 57 (9.7) |
| Moderate stress | 459 (78.5) |
| High stress | 69 (11.8) |
| Acne prevalence | |
| No acne | 69 (11.8) |
| Mild | 345 (59) |
| Moderate | 140 (23.9) |
| Severe | 23 (3.9) |
| Very severe acne | 8 (1.4) |
The mean PSS was 20.22 ± 5.51 and the mean total GAGS was 13.13 ± 10.05. The mean AFHC was 10.33 ± 4.72. Of the participants, 9.7%, 78.5%, and 11.8% had low, moderate, and high stress levels, respectively, based on the PSS scale scores classification. The prevalence of any type of acne was 88.2%, with a prevalence of mild, moderate, severe, and very severe acne at 59%, 23.9%, 3.9%, and 1,4%, respectively.
Female participants had a significant higher percent of severe acne compared to males (39.1% vs. 60.9%) (P < 0.05). However, a nonsignificant relationship was found between the severity of acne and participants’ demographics other than gender, academic year, stress level, or AFHC scores (P > 0.05) [Table 2].
Table 2.
Relationship between acne severity and participant’s demographics, academic year, stress level, and adolescent food habits checklist scores (n=585)
| Variables | Acne prevalence | χ 2 | P-value | ||||
|---|---|---|---|---|---|---|---|
|
| |||||||
| No acne N (%) | Mild acne N (%) | Moderate acne N (%) | Severe acne N (%) | Very severe acne N (%) | |||
| Age | |||||||
| ≤21 | 45 (65.2) | 190 (55.1) | 76 (54.3) | 11 (47.8) | 5 (62.5) | 3.42 | 0.49 |
| >21 | 24 (34.8) | 155 (44.9) | 64 (45.7) | 12 (52.2) | 3 (37.5) | ||
| Age (years) | 21±1.98 | 21.21±1.85 | 21.08±1.75 | 21.3±1.18 | 21±1.6 | 4* | 0.695 |
| Gender | |||||||
| Male | 45 (65.2) | 148 (42.9) | 66 (47.1) | 9 (39.1) | 4 (50) | 12.08 | 0.017 |
| Female | 24 (34.8) | 197 (57.1) | 74 (52.9) | 14 (60.4) | 4 (50) | ||
| Academic year | |||||||
| 1st | 9 (13) | 54 (15.7) | 30 (21.4) | 4 (17.4) | 3 (37.5) | 25.7 | 0.135 |
| 2nd | 20 (29) | 57 (16.5) | 27 (19.3) | 2 (8.7) | 1 (12.5) | ||
| 3rd | 16 (23.2) | 67 (19.4) | 19 (13.6) | 4 (17.4) | 2 (25) | ||
| 4th | 9 (13) | 61 (17.7) | 27 (19.3) | 8 (34.8) | 2 (25) | ||
| 5th | 8 (11.6) | 62 (18) | 26 (18.6) | 4 (17.4) | 0 | ||
| 6th | 7 (10.1) | 44 (12.8) | 11 (7.9) | 1 (4.32) | 0 | ||
| Stress level | |||||||
| Low stress | 10 (14.5) | 33 (9.6) | 12 (8.6) | 2 (8.7) | 0 | 10.18 | 0.252 |
| Moderate stress | 52 (75.4) | 275 (79.7) | 111 (79.3) | 16 (69.6) | 5 (62.5) | ||
| High stress | 7 (10.1) | 37 (10.7) | 17 (12.1) | 5 (21.7) | 3 (37.5) | ||
| AFHC, mean ± SD | 10.7±4.56 | 10.23±4.74 | 10.14±4.67 | 11.38±5.38 | 10.65±4.8 | 4* | 0.722 |
*Kruskal–Wallis test. AFHC=Adolescent food habits checklist, SD=Standard deviation
With regard to academic level, participants in the preclerk ship years had significant higher mean AFHC scores healthy eating habits compared to participants of the clerkship years (P < 0.05). However, there was a nonsignificant relationship between academic level and acne severity or stress level (P > 0.05) [Table 3].
Table 3.
Relationship between academic level and acne severity, stress level, and adolescent food habits checklist scores (n=585)
| Variables | Academic level | χ 2 | P-value | |
|---|---|---|---|---|
|
| ||||
| Preclerkship. N (%) | Clerkship N (%) | |||
| Acne prevalence | ||||
| No acne | 45 (14.3) | 24 (8.9) | 6.74 | 0.15 |
| Mild acne | 178 (56.5) | 167 (61.9) | ||
| Moderate acne | 76 (24.1) | 64 (23.7) | ||
| Severe acne | 10 (3.2) | 13 (4.8) | ||
| Very severe acne | 6 (1.9) | 2 (0.7) | ||
| Stress level | ||||
| Low stress | 29 (9.2) | 28 (10.4) | 1.5 | 0.47 |
| Moderate stress | 253 (80.3) | 206 (76.3) | ||
| High stress | 33 (10.5) | 36 (13.3) | ||
| AFHC (mean±SD) | 11.09±4.38 | 9.43±4.96 | 4.31* | <0.001 |
*Mann–Whitney test. AFHC=Adolescent food habits checklist, SD=Standard deviation
Participants who had a severe stress level had a significant higher mean GAGS score and a significant lower mean AFHC scores (P < 0.05) [Table 4].
Table 4.
Relationship between stress level and participant’s age, global acne grading system, and adolescent food habits checklist scores (n=585)
| Variables | Stress level | Kruskal–Wallis test | P-value | ||
|---|---|---|---|---|---|
|
| |||||
| Low Mean±SD | Moderate Mean±SD | Severe Mean±SD | |||
| Age | 21.12±1.72 | 21.15±1.86 | 21.19±1.63 | 2 | 0.899 |
| GAGS | 10.86±10.13 | 12.86±9.27 | 16.77±11.31 | 2 | 0.005 |
| AFHC | 10.76±4.6 | 10.63±4.6 | 7.91±4.99 | 2 | <0.001 |
GAGS=Global acne grading system, AFHC=Adolescent food habits checklist, SD=Standard deviation
Table 5 shows that a nonsignificant relationship was found between acne severity and PSS or AFHC scores (P > 0.05).
Table 5.
Relationship between acne severity and Perceived Stress Scale and adolescent food habits checklist scores (n=585)
| Variables | Acne severity | Kruskal–Wallis test | P-value | ||
|---|---|---|---|---|---|
|
| |||||
| No or mild acne Mean±SD | Moderate acne Mean±SD | Severe or very severe acne Mean±SD | |||
| PSS score | 2±0.45 | 2.03±0.45 | 2.19±0.54 | 2 | 0.079 |
| AFHC | 10.31±4.71 | 10.19±4.67 | 11.19±5.16 | 2 | 0.425 |
PSS=Perceived Stress Scale, AFHC=Adolescent food habits checklist, SD: Standard deviation
A significant positive correlation was found between GAGS scores and PSS (r = 0.16, P < 0.001) [Figure 1].
Figure 1.
Spearman’s correlation analysis between GAGS scores and PSS scores. r = 0.16, P = <0.001). GAGS = Global Acne Grading System, PSS = Perceived Stress Scale
Multivariate logistic regression analysis was done to assess the risk factors (independent predictors) of acne severity in the studied patients. It was found that being a female or being under a high level of stress were risk factors (independent predictors) of acne severity in the studied students [Table 6].
Table 6.
Multivariate logistic regression analysis of risk factors of acne severity like age, gender, academic year, stress level, and adolescent food habits checklist scores
| Variables | β | P-value | AOR (95% CI) |
|---|---|---|---|
| Age ≤21 | 0.12 | 0.076 | 0.12 (0.91-1.07) |
| Females | 3.07 | 0.031 | 1.8 (0.61-2.01) |
| 1st academic year | 0.5 | 0.817 | 0.13 (0.8-1.06) |
| Severe stress | 3.19 | 0.004 | 2.05 (1.6-3.14) |
| AFHC score >10 | 1.34 | 0.063 | 0.89 (0.19-1.45) |
AOR=Adjusted odds ratio, CI=Confidence interval, AFHC=Adolescent food habits checklist
Discussion
The aim of this study was to assess the association between acne severity, stress, and the food habits of medical students. According to the study, 9.7% of participants had low stress, 78.5% had moderate stress, and 11.8% had high stress.
According to the study, 9.7% of participants experienced low stress, 78.5% had moderate stress, and 11.8% had high stress. A survey of 400 undergraduate students in Riyadh found that 29.8% had little stress and 29.5 had high stress levels.[22] Furthermore, a study of 98 Portuguese medical students showed that 62.2% them had acne.[23]
We discovered that female participants had a significantly higher percentage of severe acne than male participants, with a significant P = 0.05. This can be explained by another study conducted in Riyadh, which found that females under stress ate more than usual, 82% of whom chose to eat sweets and snacks when under stress, and 68% reported that they were losing control.[15] A systematic review of 35 articles discovered that high glycemic index/glycemic load foods, dairy products, fat-containing foods, and chocolate are acne-promoting variables. Acne-protective factors include fatty acids and fruit and vegetables.[14] Therefore, we believe that changes in the levels of stress do alter food habits leading either directly or indirectly to an increase in the prevalence of and severity of acne.
In our study, 59% of the students had mild acne, 23.9% had moderate acne, 3.9% had severe acne, and 1.4% extremely severe acne. Zari and Alrahmani, 2017, discovered that 72%, 22.9%, and 2.8% of 144 6th-year female medical students, respectively, had low, moderate, and severe acne.[12]
We discovered that students with a high stress level had a significantly higher mean GAGS score and a significantly lower mean AFHC score, indicating that they were eating unhealthy foods. We also discovered that stress levels had a significant relationship with GAGS and AFHC scores, with P = 0.005 and P < 0.001, respectively.
We discovered a significant positive correlation between GAGS and PSS with P = 0.001 in our study, implying that students with higher PSS had higher acne grades. These findings are consistent with a Jeddah study that included 104 medical students and discovered that increased level of stress was strongly correlated with increased severity of acne with a P < 0.01.[13] Furthermore, a study conducted by Chiu et al., of 19 participants showed that an increase in perceived stress strongly correlated with exacerbation of the severity of acne with a P < 0.01.[24]
The reason for this is that stress activates the hypothalamic-pituitary-adrenal axis, which raises corticotropin-releasing hormone levels (CRH). CRH aggravates acne by stimulating lipid synthesis and steroidogenesis in the sebaceous gland. CRH also stimulates the production of the cytokines interleukin 6 (IL-6) and IL-11 in keratinocytes, which causes inflammation thought to play a role in the etiology of acne.[12]
One of the limitations to this study was that the questionnaires were distributed online and for only one medical college with a snapshot method. Besides, the use of a self-administered survey to assess the severity of acne without confirmatory assessment by a dermatologist could also present another limitation. Future prospective or case–control studies are recommended to assess the causal relationships between variables.
Conclusion
The high prevalence of acne and stress observed in the studied students need to prompt attention to skin and psychiatric disorders in medical students. As the study revealed a positive correlation between stress and acne severity, a reduction in the stress level of students through psychological support and awareness campaigns is required. Therapeutic approaches can be tailored to needs, with possible behavioral intervention as necessary.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
- 1.Williams HC, Dellavalle RP, Garner S. Acne vulgaris. Lancet. 2012;379:361–72. doi: 10.1016/S0140-6736(11)60321-8. [DOI] [PubMed] [Google Scholar]
- 2.Tom WL, Friedlander SF. Acne through the ages: Case-based observations through childhood and adolescence. Clin Pediatr (Phila) 2008;47:639–51. doi: 10.1177/0009922808315444. [DOI] [PubMed] [Google Scholar]
- 3.Gollnick H, Abanmi AA, Al-Enezi M, Al Hammadi A, Galadari I, Kibbi AG, et al. Managing acne in the middle east: Consensus recommendations. J Eur Acad Dermatol Venereol. 2017;31(Suppl 7):4–35. doi: 10.1111/jdv.14491. [DOI] [PubMed] [Google Scholar]
- 4.Claudel JP, Auffret N, Leccia MT, Poli F, Dréno B. Acne and nutrition: Hypotheses, myths and facts. J Eur Acad Dermatol Venereol. 2018;32:1631–7. doi: 10.1111/jdv.14998. [DOI] [PubMed] [Google Scholar]
- 5.Conforti C, Agozzino M, Emendato G, Fai A, Fichera F, Marangi GF, et al. Acne and diet: A review. Int J Dermatol. 2022;61:930–4. doi: 10.1111/ijd.15862. [DOI] [PubMed] [Google Scholar]
- 6.Baldwin H, Tan J. Effects of diet on acne and its response to treatment. Am J Clin Dermatol. 2021;22:55–65. doi: 10.1007/s40257-020-00542-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Grigore O, Mihailescu AI, Solomon I, Boda D, Caruntu C. Role of stress in modulation of skin neurogenic inflammation. Exp Ther Med. 2019;17:997–1003. doi: 10.3892/etm.2018.7058. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Suh DH, Kim BY, Min SU, Lee DH, Yoon MY, Kim NI, et al. Amulticenter epidemiological study of acne vulgaris in Korea. Int J Dermatol. 2011;50:673–81. doi: 10.1111/j.1365-4632.2010.04726.x. [DOI] [PubMed] [Google Scholar]
- 9.Green J, Sinclair RD. Perceptions of acne vulgaris in final year medical student written examination answers. Australas J Dermatol. 2001;42:98–101. doi: 10.1046/j.1440-0960.2001.00489.x. [DOI] [PubMed] [Google Scholar]
- 10.Almojali AI, Almalki SA, Alothman AS, Masuadi EM, Alaqeel MK. The prevalence and association of stress with sleep quality among medical students. J Epidemiol Glob Health. 2017;7:169–74. doi: 10.1016/j.jegh.2017.04.005. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Saeed AA, Bahnassy AA, Al-Hamdan NA, Almudhaibery FS, Alyahya AZ. Perceived stress and associated factors among medical students. J Family Community Med. 2016;23:166–71. doi: 10.4103/2230-8229.189132. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Zari S, Alrahmani D. The association between stress and acne among female medical students in Jeddah, Saudi Arabia. Clin Cosmet Investig Dermatol. 2017;10:503–6. doi: 10.2147/CCID.S148499. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Adebamowo CA, Spiegelman D, Danby FW, Frazier AL, Willett WC, Holmes MD. High school dietary dairy intake and teenage acne. J Am Acad Dermatol. 2005;52:207–14. doi: 10.1016/j.jaad.2004.08.007. [DOI] [PubMed] [Google Scholar]
- 14.Dall’Oglio F, Nasca MR, Fiorentini F, Micali G. Diet and acne: Review of the evidence from 2009 to 2020. Int J Dermatol. 2021;60:672–85. doi: 10.1111/ijd.15390. [DOI] [PubMed] [Google Scholar]
- 15.Aksu AE, Metintas S, Saracoglu ZN, Gurel G, Sabuncu I, Arikan I, et al. Acne: Prevalence and relationship with dietary habits in Eskisehir, Turkey. J Eur Acad Dermatol Venereol. 2012;26:1503–9. doi: 10.1111/j.1468-3083.2011.04329.x. [DOI] [PubMed] [Google Scholar]
- 16.Penso L, Touvier M, Deschasaux M, Szabo de Edelenyi F, Hercberg S, Ezzedine K, et al. Association between adult acne and dietary behaviors: Findings from the NutriNet-Santéprospective cohort study. JAMA Dermatol. 2020;156:854–62. doi: 10.1001/jamadermatol.2020.1602. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Doshi A, Zaheer A, Stiller MJ. A comparison of current acne grading systems and proposal of a novel system. Int J Dermatol. 1997;36:416–8. doi: 10.1046/j.1365-4362.1997.00099.x. [DOI] [PubMed] [Google Scholar]
- 18.Park SY, Colvin KF. Psychometric properties of a Korean version of the Perceived Stress Scale (PSS) in a military sample. BMC Psychol. 2019;7:58–69. doi: 10.1186/s40359-019-0334-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Almadi T, Cathers I, Hamdan Mansour AM, Chow CM. An Arabic version of the perceived stress scale: Translation and validation study. Int J Nurs Stud. 2012;49:84–9. doi: 10.1016/j.ijnurstu.2011.07.012. [DOI] [PubMed] [Google Scholar]
- 20.Skolmowska D, Głąbska D, Guzek D. Differences in adolescents food habits checklist (AFHC) scores before and during pandemic in a population-based sample: Polish adolescents COVID-19 experience (PLACE-19) study. Nutrients. 2021;13:1663. doi: 10.3390/nu13051663. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Mohamed BA, Mahfouz MS, Badr MF. Food selection under stress among undergraduate students in Riyadh, Saudi Arabia. Psychol Res Behav Manag. 2020;13:211–21. doi: 10.2147/PRBM.S236953. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Zahr Allayali A, Nassir Asseri B, AlNodali NI, Nasser M Alhunaki R, Goblan Algoblan SF. Assessment of prevalence, knowledge, attitude, and psychosocial impact of acne vulgaris among medical students in Saudi Arabia. J Clin Exp Dermatol Res. 2017;08:4–11. [Google Scholar]
- 23.Gonçalves G, Amado JM, Matos ME, Massa A. The prevalence of acne among a group of Portuguese medical students. J Eur Acad Dermatol Venereol. 2012;26:514–7. doi: 10.1111/j.1468-3083.2011.04080.x. [DOI] [PubMed] [Google Scholar]
- 24.Chiu A, Chon SY, Kimball AB. The response of skin disease to stress: Changes in the severity of acne vulgaris as affected by examination stress. Arch Dermatol. 2003;139:897–900. doi: 10.1001/archderm.139.7.897. [DOI] [PubMed] [Google Scholar]