The Arab Countries’ Contribution to the Research of Neurodegenerative Disorders

Background: Neurodegenerative diseases are disorders in which nerve cells start to lose function due to different causes. Like many other illnesses, they are considered to be highly prevalent in the 22 Arabic-speaking countries known to constitute the Arab world. The two most prevalent neurodegenerative disorders are Alzheimer's disease and Parkinson's disease. Aim: The aim of this paper is to assess the amount of research dedicated to neurodegenerative diseases by the Arab countries during a 15-year period, between 2005 and 2019. Methods: The number of publications by each Arab country as well as some non-Arab speaking countries was retrieved from PubMed. Publications in top 10 neuroscience journals were also tracked using the same method with each journal’s name included. The numbers were then normalized with respect to the average population and average gross domestic product (GDP) in each country to eliminate bias. Results: Arab countries were shown to contribute only 1,311 (0.774%) of the 169,330 articles published worldwide on neurodegenerative disorders. These 1,311 also constitute only 0.660% of the 198,869 Arab publications during the indicated period. Saudi Arabia had the highest contribution to these numbers with more than one-quarter the number of publications on neurodegenerative disorders. Approximately one-third of all neurodegenerative disease-related articles were associated with Alzheimer's disease, whereas one-fifth were related to Parkinson's disease. For the top 10 neuroscience journals, only a minimal contribution by Arab countries was noted. Conclusion: Although an increase in the number of articles by the Arab world was noted from 2013 onward, the contribution of the Arab countries on the subject to the number of publications still seems to be insufficient.


Introduction
The Arab world consists of 22 Arabic-speaking countries, concentrated mainly in the Middle East and North Africa. As in any part of the world, the various Arab countries differ significantly with respect to incomes, where some are considered high-income countries and others low-income. Although the amount of research conducted by the Arab world has increased remarkably during the last few years, Arab countries still seem to provide a deficient contribution to the total research conducted worldwide [1]. Moreover, the fact that this contribution is concentrated in a few of all 22 Arab countries intensifies the problem. Thus, in a study by El Rassi et al., only four countries (Qatar, Tunisia, Lebanon, and Kuwait) contributed more papers per million people than the world average [1].
Neurodegenerative disorders are diseases where nerve cells start to lose function and consequently die, and proteins accumulate in the brain and other peripheral organs [2]. They are mainly classified according to the deposited protein and the better-known tauopathies, alpha-synucleinopathies, prion diseases, trinucleotide repeat diseases, neuroserpinopathy, ferritinopathy, and cerebral amyloidoses [2]. Neurodegenerative disorders are an emerging cause of mortality worldwide, many of which affect the elderly [3]. Globally, Alzheimer's disease is considered to be the most prevalent neurodegenerative disorder constituting 60-80% of all dementia cases, with approximately 24 million people affected with the disease worldwide [4]. Parkinson's disease ranks second after Alzheimer's disease as to prevalence, affecting an estimated 0.3% of the total human population [4]. Arab countries proved neurodegenerative diseases to be prevalent regionally, ranging between   1  1  2  1  1  3, 4, 5 1.1-2.3% in the ≥ 50 years population and 13.5-18.5% in the ≥ 80 years population [5]. Many factors have been proven to contribute to the incidence of neurodegenerative diseases, including age, education, gender, genetic factors, and health conditions [5]. It is noteworthy that studies have shown that hypertension and type-2 diabetes mellitus facilitate the onset of neurodegenerative disorders through neuroinflammation [6], which explains one cause of the high prevalence in Arab countries. For instance, Arab countries have a high prevalence of hypertension (29.5%), which is higher than in many other regions [7]. Similarly, type-2 diabetes was shown to be highly prevalent in several of the 22 Arabic-speaking countries [8].

Studies on
Keeping in mind the high incidence of neurodegenerative disorders and their risk factors, in addition to the low quantity of research on these disorders in the Arab world, we performed a bibliometric analysis of these countries' contribution to such research. Therefore, this paper aims to assess the number of publications concerning neurodegenerative diseases between 2005 and 2019 from the 22 Arab countries, focusing mainly on the two most prevalent disorders: Alzheimer's disease and Parkinson's disease. Countries with the highest research productivity related to neuroscience were also searched, including the US, the United Kingdom (UK), Germany, Japan, Canada, Italy, France, China, Netherlands, and Australia [9].

Database and search strategy
The same methods were used to track publications in the top 10 neuroscience journals, searching for the journal's name in addition to the procedures stated above.

Inclusion and exclusion criteria
All types of articles were included, as long as they had an author from the targeted country, and the article was published between 2005 and 2019.

Interpretation and comparison
The average population and gross domestic product (GDP) were acquired for each country between 2005 and 2019 using data from the 2019 World Population Prospects and the 2019 World Bank report on GDP respectively [10][11]. For each country, the number of publications per 1,000,000 persons was calculated, as well as per GDP. Similar approaches have been used in other bibliometric analyses [12][13][14].
Data were analyzed using IBM SPSS Statistics for Windows, version 22.0, released 2013 (IBM Corp, Armonk, NY) where linear regression was used to relate the number of publications to both the average population and the average GDP.

Discussion
In this bibliometric analysis, we assessed the neurodegenerative disease research productivity in all 22 Arab countries over a 15-year period, ranging from 2005 till 2019. As our results indicated, Saudi Arabia followed by Egypt published the greatest number of neurodegenerative diseases-related articles during this timeframe. In similar analytic studies, Saudi Arabia and Egypt have also ranked the highest in the number of Arab world publications on tobacco use [15] and biomedical topics [16]. Saudi Arabia also published the most among all Arab countries on mental health research topics [17] and substance use disorders [18].
Nevertheless, it was essential to normalize this by using some parameters like population size and GDP. Among the two indicators used, we found GDP to be more representative in comparing the Arab countries' neurodegeneration research activity, with a strongly positive correlation. Egypt was ranked first among the 22 Arab countries in number of publications per GDP. Population size, however, which showed that Qatar had the highest number of neurodegenerative diseases publications per million persons, had a weaker correlation.
We can therefore say that GDP, or the number of publications per billion dollars, is the most reliable marker for neurodegenerative diseases publications in the Arab world. Similarly, GDP has been found to be the most reliable indicator for stroke publications [19] and for biomedical research in Arab countries [16]. In contrast, for psoriasis-related publishing activity in the Arab world, population size was considered the most accurate marker [20].
Our results revealed that the number of neurodegeneration-related publications in Arab countries has been on the rise in the past seven years. One cannot, however, overlook the fact that the total number of neurodegenerative publications in the Arab world account for only 0.77% of the research done worldwide on this subject in the past 15 years. In fact, several studies have addressed the problem of shortage of medical research in Arab countries, proving that they are still lagging behind in biomedical publications, average citation frequency, and top journal publishing activity [21,1]. A bibliometric analysis, done between the years 1996 and 2012, indicated that the Arab world publications represented only 4% of those published by the USA [1].
This inadequacy of medical publications in Arab countries can be traced to various factors including limited research facilities, inadequate academic advancements, and the absence of interest in research programs and funding opportunities [1]. The lack of political and economic stability also plays a major role in hindering research programs [22]. Arab countries are chronically suffering from corruption, lack of proper democracy, wars and internal conflicts, which are all quite unfavorable for proper economic growth [23]. This can actually be illustrated by the fact that most Arabian countries belong to low-income economic groups, aside from six Arabian Gulf countries: Saudi Arabia, Bahrain, Kuwait, Qatar, United Arab Emirates, and Oman [24]. The poor economic resources might also help explain our results that proved GDP to be the most crucial factor in assessing neurodegenerative diseases research in Arab countries.
Furthermore, in our analysis, it was evident that Alzheimer's disease-related publications made up onethird of the total neurodegenerative disease studies in the Arab world. This might be justified by the importance of this inevitably progressive disease that has a major negative impact on the life of the patient's family [25]. Another important aspect is the important prevalence of this neurocognitive disease. A systematic review done in 2019 to evaluate the epidemiology of dementia and Alzheimer's disease in Arab countries revealed that the prevalence is indeed high, ranging between 13.5% and 18.5% among elderly patients > 80 years of age. Of those 50 years and older, the prevalence ranged between 1.1% and 2.3% [5]. Moreover, the WHO has reported dementia as a public healthcare priority, estimating its worldwide prevalence at 35.6 million [26]. Despite all this, research done in the Arab world on this subject remains scarce. It is encouraging to note that publications on this topic have been increasing in the last few years.
When comparing the number of neurodegenerative-related publications in countries with the highest research activity in this field to the combined Arab countries, a huge difference is present between the 10th country Netherland, which is around four times the sum of Arab publications. This difference becomes surprisingly enormous when compared to the 1st country USA, which is around 40 times the sum of Arab publications.
Regarding the quality of Arab papers in the field of neurodegenerative diseases, they were shown to be of low quality, since only 21 papers were published in top-ranked neuroscience journals, comprising no more than 2% of published neurodegenerative-related studies.

Limitations
The major limitation of this study was that only the PubMed database was searched, as the tracked number of publications might not be accurate. Furthermore, this study lacks publications written in languages other than English, such as French, which is widely used in some Arab regions, including Algeria, Comoros, Djibouti, Mauritania, Morocco, and Tunisia. Moreover, inaccuracy of data tracking may have occurred due to searching for the indexed and not the published date.

Conclusions
To our knowledge, this is the first bibliometric analysis to assess research activity related to neurodegenerative diseases in the Arab world. Despite showing an increase in research productivity in the last few years, numbers remain far behind top-ranked countries in neuroscience research productivity. The low quality of research and strong correlation to GDP highlight the importance of collaboration between high-and low-income countries to establish new institutions that can come up with high-quality research.

Additional Information Disclosures
Human subjects: All authors have confirmed that this study did not involve human participants or tissue. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue.

Conflicts of interest:
In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.