• Users Online: 231
  • Print this page
  • Email this page


 
 
Table of Contents
ORIGINAL ARTICLE
Year : 2022  |  Volume : 5  |  Issue : 4  |  Page : 328-332

Migraine and Psychiatric Comorbidity among Arabs Living in Different Societal Environments: A Cross-sectional Study


1 Division of Neurology, College of Medicine, Aleppo University, Aleppo, Syria
2 Division of Neurology, Department of Medicine, College of Medicine, King Saud University and King Saud University Medical City, Riyadh, Saudi Arabia

Date of Submission28-Aug-2021
Date of Decision19-Apr-2022
Date of Acceptance03-Sep-2022
Date of Web Publication12-Oct-2022

Correspondence Address:
Mohammed Saleh Alnafisah
PO Box 7805 (38), Neurology Division, King Saud University College of Medicine Riyadh, 11472
Saudi Arabia
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jnsm.jnsm_112_21

Rights and Permissions
  Abstract 


Background: The prevalence of migraine and psychiatric comorbidities has been found to differ on a global scale according to country development. We aimed to determine this prevalence in three samples of Arabs living in different countries at different levels of development and political stability. Methods: The study included Saudi and Syrian participants ≥16 years of age. The cohort was subdivided into three groups: Saudi Arabian residents (SARs), Syrian residents (SRs), and Syrian expatriates (SEs). Information regarding age, sex, education, and marital status was also collected. Migraine was determined by the International Classification of Headache Disorders-3 criteria; depression and bipolar disorder were determined by the Patient Health Questionnaire-9 and the Mini-International Neuropsychiatric Interview, respectively. Odds ratios were estimated for associations. Results: Of 620 participants, 102 (16.5%) met migraine criteria, and 81 (79.4%) were female. Migraine was found in 66 (20.6%) SARs, 25 (19%) SEs, and 11 (6.5%) SRs. Being married was significantly associated with migraine (P = 0.01). Depression had a significant association with migraine within the entire cohort (odds ratio [OR] =2, confidence interval [CI] =1.2–3.1, P = 0.004) and the subgroups of SEs (OR =3, CI =1.14–7.8, P = 0.02) and SARs (OR =2.1, CI =1.14–7.8, P = 0.02); depression was significantly associated in the SE and SAR migraine groups (both P = 0.02). Conclusion: Migraine and comorbid depression occur at a rate similar to international reports in Middle Eastern Arabs and more prominently in SEs and SARs. The migraine frequency was lower in SRs in comparison to SEs and SARs residing in more developed countries. Future research that explores these conditions under different environmental and sociopolitical circumstances will improve the understanding of causal relationships.

Keywords: Bipolar disorder, depression, migraine, Saudi Arabia, Syria


How to cite this article:
Ras YA, Alnafisah MS, Farfouti MT, Alsukhni RA, Alanazy MH, Muayqil TA. Migraine and Psychiatric Comorbidity among Arabs Living in Different Societal Environments: A Cross-sectional Study. J Nat Sci Med 2022;5:328-32

How to cite this URL:
Ras YA, Alnafisah MS, Farfouti MT, Alsukhni RA, Alanazy MH, Muayqil TA. Migraine and Psychiatric Comorbidity among Arabs Living in Different Societal Environments: A Cross-sectional Study. J Nat Sci Med [serial online] 2022 [cited 2022 Nov 30];5:328-32. Available from: https://www.jnsmonline.org/text.asp?2022/5/4/328/358405




  Introduction Top


The World Health Organization (WHO) has identified primary headaches including migraines as a major public health problem due to its high prevalence and widespread occurrence. With a global prevalence of 11.6%,[1] it is an important condition to identify its potential to become chronic and associate with comorbidities.[2],[3],[4] The prevalence of migraine has increased over the years; Woldeamanuel and Cowan found notable increases in some regions such as Europe, Asia, and Africa. This was linked to the possibility that urbanization of many societies in the recent century has contributed to the global increase in migraine's prevalence since residents of rural areas had lower rates of migraine in comparison.[1]

The WHO estimates that major depressive disorders (MDDs) will come second to heart disease as a leading cause of disease burden.[5] Researchers at the turn of the last century have noted strong relationships between psychiatric disorders such as depressive, bipolar, and anxiety disorders with migraine. Many population-based studies revealed that migraineurs are two to four times more likely to suffer from MDD than those without migraine.[6],[7],[8],[9],[10] The comorbidity of depression alone significantly complicates the quality of life among migraineurs;[11],[12] it may also associate with overuse of medication,[13],[14] increase in treatment expense,[15] or even be responsible for disability.[8]

In the Middle East, Syria has been thrown into an armed conflict since 2011 resulting in a humanitarian crisis in which over 5.4 million people have fled from Syria to neighboring countries.[16] It is a less developed nation in comparison to the oil-wealthy Arabian Gulf countries, such as the Kingdom of Saudi Arabia (KSA). While several studies over the past decades have explored migraine in KSA suggesting an increase in migraine prevalence over time,[4],[17],[18] data are lacking for Syria. The impact a geopolitical situation has on migraine and its comorbidities require further exploration considering that emergence of mood disorders has been described in Syrian refugees.[19] In this study, we aimed to determine the frequency of migraine and its association with the comorbidities of depression and bipolar disorder among Middle Eastern individuals between KSA residents, Syrian residents (SRs), and Syrian expatriates (SEs).


  Methods Top


Participants

This study was carried out at Aleppo University Hospital, Aleppo, Syria, and King Saud University Medical City, Riyadh, Saudi Arabia. Participants had to be 16 years of age or older to be included and residing either in Saudi Arabia, Syria, or in a Western developed country for at least 1 year for SEs. We excluded participants who had psychiatric disorders or required psychiatric medications for conditions other than mood disorders. Also excluded were those with chronic medical disorders such as liver or kidney disease, heart disease, stroke, epilepsy, neurodegenerative, and autoimmune disorders. Demographic variables collected were sex, age, marital status, and location of residence.

Materials

Validated Arabic versions of the Patient Health Questionnaire-9 (PHQ-9)[20] and the Mini-International Neuropsychiatric Interview (MINI)[21] were used to assess the presence of depression and bipolar disorders, respectively. The PHQ-9 has a score range from 0 to 27; we considered those with scores in the moderate depression range or higher (≥10) to have depression, whereas those with lower scores in the mild or no symptoms range were considered not depressed. The Arabic M.I.N.I. version 6.0.0 was used to determine the presence of current or previous symptoms that would suggest bipolar disorder. Patients were considered positive if at least four of the symptom-screening questions were answered “yes” with manifestations that lasted for 3 or more days and led to occupational or social impairments or hospitalization, not explained by any other etiology. Migraine was determined present or absent if a patient had suffered from headaches during the past 12 months and was diagnosed according to the International Classification of Headache Disorders-3 criteria.[22] Participants were asked in Arabic to answer questions for each of the migraine features (headaches that lasted between 4 and 72 h, moderate to severe in intensity, pulsatile, tendency to lateralize, worsened with exertion, and were associated with nausea/vomiting or photophobia/sonophobia), and a neurologist then determined if the criteria were fulfilled. Questionnaires were administered either in paper or electronically. Electronic questionnaires were provided to the SE group who were not accessible and lived in various Western nations. Paper and electronic results were reviewed by the investigators to correctly classify the patient according to their score.

Design

Participants were divided based on their areas of residence: SRs, SEs, and Saudi Arabian residents (SARs). Both groups (SRs and SARs) were selected through convenience sampling method recruited from outpatient clinics, inpatient companions, visitors, waiting areas, health-care workers, and students. The entire SE group was recruited through convenience and snowball collecting methods. The study enrollment was completed in 2018. Consent was taken from each participant prior to his or her enrollment in the study. Ethical approval was obtained from the Internal Review Board at the College of Medicine, King Saud University.

Analysis

The cohort was categorized based on the presence or absence of migraine, and the variables were categorized according to age (15–25, 26–40, or >40), sex (male or female), marital status (single or married), education level (≤high school or >high school), depression (none to mild or moderate to severe), and bipolar disorder (present or absent). We used Chi-square tests to compare the proportions of demographic variables, depression, and bipolar disorder between migraineurs and nonmigraineurs. Logistic regression was used to determine the odds ratios (ORs) for the association of the variables with migraineurs in each of the three population subgroups. Estimation of the appropriate sample size was based on preexisting literature of a population study[13] that found bipolar disorder to be less frequent than anxiety and depression in patients with migraine (4.5%), but still occurred more frequently than in patients without migraine (2.2%). To yield a statistically significant finding with a 95% confidence interval with 80% power, a conservative estimate was a minimum of 71 participants in each arm.


  Results Top


In total, 620 individuals were recruited; 449 (72.5%) were female and 170 (27.5%) were male (one participant did not disclose gender); 169 (27.3%) were SRs, 131 (21.2%) were SEs, and 320 (51.5%) were SARs [Table 1]. Ninety-one percent of the participants were 40 years of age or younger. The majority of our data were collected by a paper questionnaire (n = 490), whereas the remaining was by an electronic format (n = 130). SRs who lived in the city of Aleppo and SARs who were living in Saudi Arabia completed the survey on paper, whereas SEs completed the survey electronically. Among the SARs, all were Saudi nationals apart from eight who were ethnically non-Syrian Arabs, and were long-time working residents in the country.
Table 1: Demographic features of the entire cohort

Click here to view


Of the total 620 participants, 102 (16.5%) met migraine criteria. Migraine was present in 81 (13.1%) women and 21 (3.4%) men. There was no statistically significant difference, however, with regard to gender when comparing migraineurs and nonmigraineurs in univariate analysis, nor was there statistical significance for any of the age categories [Table 1]. There was no statistical difference in bipolar disorder and education level between migraineurs and nonmigraineurs. Both being married and having moderate-to-severe depression were significantly associated with migraine (P = 0.01 and P = 0.002, respectively).

In the analysis of the subgroups by residence, only 11 (6.5%) SRs living in Aleppo met migraine criteria. Migraine was more prevalent in SEs (19.8%) and SARs (20.69%) than it was in SRs (P = 0.0008 and P < 0.0001, respectively) [Table 2].
Table 2: Multivariate logistic regression of variables influencing the odds of having migraine

Click here to view


Multivariate logistic regression was conducted for the whole cohort and within each subgroup; the results are shown in [Table 2]. Depression had a significant association with migraine within the entire cohort (OR =2, confidence interval [CI] = 1.2–3.1, P = 0.004) and within the subgroups of SEs (OR = 3, CI = 1.14–7.8, P = 0.02) and SARs (OR = 2.1, CI = 1.1–3.7, P = 0.02). Being married was significantly associated with migraine at the entire cohort level (OR = 1.9, CI = 1–3.4, P = 0.043), but not at the level of individual subgroups.


  Discussion Top


In this study, we assessed for migraine and mood disorders in individuals of different Middle Eastern origins and found that migraine was present in about 16.5% of the entire cohort with two times the odds of having comorbid depression. This study also offered a first look at migraine prevalence in Syrians and how it compared to SARs, with a lower rate of both migraine and depression among SRs compared to SARs and SEs.

The overall prevalence of migraine was comparable to other international studies, which found a prevalence ranging from 10% to 16.6%,[1],[23] considering that the reported prevalence on migraine can vary according to the method used to collect data; telephone interviews or filling surveys have had somewhat higher prevalence than when a patient answers based on a previous diagnosis made by their physician.[4],[13],[24]

Migraine was much lower in the SR subgroup compared to the other subgroups in this study. Some previously described factors that have led to varying reports of headache prevalence in Western literature include the frequent underdiagnosis of migraine, or the attribution of headaches to sinus disorders.[1],[25],[26] The self-awareness of migraine, in general, has also been described to be limited regardless of one's education level.[27] However, considering whether the political situation in Syria has played a role in detecting less migraine sufferers is important in explaining the results. One possibility is the lack of modern urban living conditions, given that migraine tends to be more prevalent in urbanized areas.[1] It is also possible that those able to answer our survey were relatively privileged either socially or financially among the rest of Syrians; these social classes tend to have lower migraine prevalence rates in comparison to those with higher financial and social burdens.[4],[28],[29] Wartime environments tend to lead to poverty, which in turn has been associated with increasing migraine prevalence.[28],[29] Yet, in a study that examined refugees from the Middle East of which a quarter were Syrian, headaches, in general, were the third most prevalent chronic problem among asylum seekers found in 8.9% of their patients.[30] This is consistent with our finding of the relatively low prevalence of migraine in socially disadvantaged SRs. Little is known on the prewar prevalence of headaches in Syrians, and there is limited research in the region in general. Gleaning from a large study conducted in bordering Jordan, a country more likely to share similar ethnic roots and environmental influencers with Syrians in comparison to Arab Gulf nations, migraine was described in a similarly low proportion in about 7.7% of its population.[1],[31]

International studies have demonstrated a lower prevalence of migraine, close to 10%, in populations from African and Asian nations.[1] Earlier studies at the start of this century in Oman and Qatar demonstrate prevalence rates of 8%–10%.[32],[33] Consistent with the finding in SRs, international studies have similarly found a lower prevalence of migraine in rural areas of around 8.4%[1] The estimates obtained in the current study are similar to prevalence reports of migraine in Saudi Arabia which has ranged from 5% to 26.97%[4],[28] with higher prevalence occurring in the recent decade. Of recent development, a recently published study on migraine in Syrian university students suggested a prevalence of 11.7%–18.7%,[34 ] indicating that specific populations within Syria will demonstrate different prevalence rates. In addition, students in universities are likely to represent individuals with higher social status and income.

Females are generally at a higher risk of developing migraine; many studies have consistently shown that migraines can be up to four times more common in women than men.[1],[4],[6],[7],[8],[9],[13] However, while we observed here higher frequencies of migraine in women, it did not reach a statistically significant level. One possibility is from the overrepresentation of women which reached 80.6% of respondents. The large female composition of our cohort is even higher than previous studies that also demonstrated a high response rate for women.[4],[35] Interestingly, in neighboring Jordan, migraine had a higher prevalence in men compared to women, at 8.3% and 6.8%, respectively, in a population sample composed of 60% of men,[31] suggesting that other environmental or societal factors also play a role in prevalence among both genders.

Our study found that migraine headaches were more prevalent among married people, different to what has been previously described in a large Western cohort.[1] This could be attributed to the higher number of young individuals in the study and a cultural tendency to marry young among Arab Middle Easterners. This association did not maintain significance in any of the subgroups when analyzed separately. In addition, this predominantly young cohort is also the explanation of why no significant differences were appreciated among age categories, as migraine is more prevalent in younger individuals.[1],[8],[10],[13]

Various associations have come forward at the turn of the last century between psychiatric disorders such as depression, bipolar disorders, and anxiety disorders with migraine. Many Western population-based studies revealed that migraineurs are two to four times more likely to suffer from MDD than those without migraine.[6],[7],[8],[9],[10] Our study coincides with the literature regarding the relationship between migraine and depression among the whole cohort with P = 0.02. This significance was also present in the SE and SAR subgroups. The findings in the SAR group are in line with the recent findings of a large Saudi sample that described a similar association between migraine and a diagnosis of depression.[4] It is likely that a low number of migraineurs in the SR subgroup limited the ability to identify associations. SEs and SARs are likely to live in more urbanized environments and have a better access to health care and better health literacy overall which plays a role in recognizing symptoms. We did not find any relationship between migraine and bipolar disorder, which is still an area of disagreement in the literature.[8] Exploring depression and migraine further in the SR cohort with a larger sample would help clarify associations, mainly if there is a stronger association between depression and migraine, given the current political situation. A recent European study found psychiatric comorbidities to be quite prevalent among refugees from the Middle East, with almost 20% of an entire cohort suffering from depression; this was close to 16% in a Syrian refugee subgroup.[30] The psychological status of refugees might be worse than those who can still live safely in their country, as a higher prevalence of depression was found in 44% of forced Syrian immigrants to Lebanon.[19]

Among our study limitations is a fewer number of participants in both Syrian subgroups, especially the SRs subgroup, which was difficult to access given the geopolitical restrictions. Due to the various locations of participants, some were required to fill the surveys online, whereas those who were accessible filled it in person with an assessor; this may contribute to a measurement bias.

Another limitation related to the SR group is that since the study had to take place in a relatively protected area, it was done in a hospital setting where most of the participants were either companions of patients or health-care staff, which might have led to a selection bias in that subgroup.

In summary, migraine occurs at a rate similar to international reports and is associated with depression in Middle Eastern Arabs. The prevalence varied between the three subgroups, being less among current SRs than SEs and Saudi residents who live in more developed regions, suggesting the important role of living conditions on the prevalence of migraine. Future research that addresses changes in the prevalence of migraine and depression according to living conditions in similarly stressed population groups will provide a better understanding of the causal or associative relationship between these conditions and the environmental and sociopolitical circumstances.

Ethics approval and consent to participate

Ethical approval was obtained from the Internal Review Board at the College of Medicine, King Saud University (reference no: 16 / 0316/IRB), and it was approved on May 26th, 2016.

Written or electronic consent was taken from all participants.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Woldeamanuel YW, Cowan RP. Migraine affects 1 in 10 people worldwide featuring recent rise: A systematic review and meta-analysis of community-based studies involving 6 million participants. J Neurol Sci 2017;372:307-15.  Back to cited text no. 1
    
2.
Kurth T, Schürks M, Logroscino G, Gaziano JM, Buring JE. Migraine, vascular risk, and cardiovascular events in women: Prospective cohort study. BMJ 2008;337:a636.  Back to cited text no. 2
    
3.
Wang SJ, Chen PK, Fuh JL. Comorbidities of migraine. Front Neurol 2010;1:16.  Back to cited text no. 3
    
4.
Muayqil T, Al-Jafen BN, Al-Saaran Z, Al-Shammari M, Alkthiry A, Muhammad WS, et al. Migraine and headache prevalence and associated comorbidities in a large Saudi sample. Eur Neurol 2018;79:126-34.  Back to cited text no. 4
    
5.
Simon GE. Social and economic burden of mood disorders. Biol Psychiatry 2003;54:208-15.  Back to cited text no. 5
    
6.
Breslau N. Psychiatric comorbidity in migraine. Cephalalgia 1998;18 Suppl 22:56-8.  Back to cited text no. 6
    
7.
Hamelsky SW, Lipton RB. Psychiatric comorbidity of migraine. Headache 2006;46:1327-33.  Back to cited text no. 7
    
8.
Saunders K, Merikangas K, Low NC, Von Korff M, Kessler RC. Impact of comorbidity on headache-related disability. Neurology 2008;70:538-47.  Back to cited text no. 8
    
9.
Swartz KL, Pratt LA, Armenian HK, Lee LC, Eaton WW. Mental disorders and the incidence of migraine headaches in a community sample: Results from the baltimore epidemiologic catchment area follow-up study. Arch Gen Psychiatry 2000;57:945-50.  Back to cited text no. 9
    
10.
Zwart JA, Dyb G, Hagen K, Ødegård KJ, Dahl AA, Bovim G, et al. Depression and anxiety disorders associated with headache frequency. The Nord-Trøndelag health study. Eur J Neurol 2003;10:147-52.  Back to cited text no. 10
    
11.
Lantéri-Minet M, Radat F, Chautard MH, Lucas C. Anxiety and depression associated with migraine: Influence on migraine subjects' disability and quality of life, and acute migraine management. Pain 2005;118:319-26.  Back to cited text no. 11
    
12.
Pesa J, Lage MJ. The medical costs of migraine and comorbid anxiety and depression. Headache 2004;44:562-70.  Back to cited text no. 12
    
13.
Jette N, Patten S, Williams J, Becker W, Wiebe S. Comorbidity of migraine and psychiatric disorders – A national population-based study. Headache 2008;48:501-16.  Back to cited text no. 13
    
14.
Lake AE 3rd. Medication overuse headache: Biobehavioral issues and solutions. Headache 2006;46 Suppl 3:S88-97.  Back to cited text no. 14
    
15.
Radat F, Swendsen J. Psychiatric comorbidity in migraine: A review. Cephalalgia 2005;25:165-78.  Back to cited text no. 15
    
16.
Available from: http://www.unhcr.org/syria-emergency.html. [Last accessed on 2018 Sep 13].  Back to cited text no. 16
    
17.
Abduljabbar M, Ogunniyi A, al Balla S, Alballaa S, al-Dalaan A. Prevalence of primary headache syndrome in adults in the Qassim region of Saudi Arabia. Headache 1996;36:385-8.  Back to cited text no. 17
    
18.
Rajeh SA, Awada A, Bademosi O, Ogunniyi A. The prevalence of migraine and tension headache in Saudi Arabia: A community-based study. Eur J Neurol 1997;4:502-6.  Back to cited text no. 18
    
19.
Naja WJ, Aoun MP, El Khoury EL, Abdallah FJ, Haddad RS. Prevalence of depression in Syrian refugees and the influence of religiosity. Compr Psychiatry 2016;68:78-85.  Back to cited text no. 19
    
20.
21.
Sheehan DV, Lecrubier Y, Sheehan KH, Amorim P, Janavs J, Weiller E, et al. The Mini-International Neuropsychiatric Interview (M.I.N.I.): The development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10. J Clin Psychiatry 1998;59 Suppl 20:22-33.  Back to cited text no. 21
    
22.
Available from: https://www.ichd-3.org/1-migraine/1-1-migraine-without-aura/. [Last accessed on 2018 Sep 13].  Back to cited text no. 22
    
23.
Smitherman TA, Burch R, Sheikh H, Loder E. The prevalence, impact, and treatment of migraine and severe headaches in the United States: A review of statistics from national surveillance studies. Headache 2013;53:427-36.  Back to cited text no. 23
    
24.
O'Brien B, Goeree R, Streiner D. Prevalence of migraine headache in Canada: A population-based survey. Int J Epidemiol 1994;23:1020-6.  Back to cited text no. 24
    
25.
Eross E, Dodick D, Eross M. The sinus, allergy and migraine study (SAMS). Headache 2007;47:213-24.  Back to cited text no. 25
    
26.
Marmura MJ, Silberstein SD. Headaches caused by nasal and paranasal sinus disease. Neurol Clin 2014;32:507-23.  Back to cited text no. 26
    
27.
Lipton RB, Scher AI, Kolodner K, Liberman J, Steiner TJ, Stewart WF. Migraine in the United States: Epidemiology and patterns of health care use. Neurology 2002;58:885-94.  Back to cited text no. 27
    
28.
Herekar AA, Ahmad A, Uqaili UL, Ahmed B, Effendi J, Alvi SZ, et al. Primary headache disorders in the adult general population of Pakistan – A cross sectional nationwide prevalence survey. J Headache Pain 2017;18:28.  Back to cited text no. 28
    
29.
Stewart WF, Roy J, Lipton RB. Migraine prevalence, socioeconomic status, and social causation. Neurology 2013;81:948-55.  Back to cited text no. 29
    
30.
Pfortmueller CA, Schwetlick M, Mueller T, Lehmann B, Exadaktylos AK. Adult asylum seekers from the middle East including Syria in Central Europe: What are their health care problems? PLoS One 2016;11:e0148196.  Back to cited text no. 30
    
31.
Alzoubi KH, Mhaidat N, Azzam SA, Khader Y, Salem S, Issaifan H, et al. Prevalence of migraine and tension-type headache among adults in Jordan. J Headache Pain 2009;10:265-70.  Back to cited text no. 31
    
32.
Bener A. Frequency of headache and migraine in Qatar. Neuroepidemiology 2006;27:61-6.  Back to cited text no. 32
    
33.
Deleu D, Khan MA, Al Shehab TA. Prevalence and clinical characteristics of headache in a rural community in Oman. Headache 2002;42:963-73.  Back to cited text no. 33
    
34.
Alkarrash MS, Shashaa MN, Kitaz MN, Rhayim R, Alhasan MM, Alassadi M, et al. Migraine and tension-type headache among undergraduate medical, dental and pharmaceutical students of university of Aleppo: A cross-sectional study. BMJ Neurol Open 2021;3:e000211.  Back to cited text no. 34
    
35.
Stewart WF, Wood GC, Razzaghi H, Reed ML, Lipton RB. Work impact of migraine headaches. J Occup Environ Med 2008;50:736-45.  Back to cited text no. 35
    



 
 
    Tables

  [Table 1], [Table 2]



 

Top
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
Abstract
Introduction
Methods
Results
Discussion
References
Article Tables

 Article Access Statistics
    Viewed460    
    Printed16    
    Emailed0    
    PDF Downloaded79    
    Comments [Add]    

Recommend this journal