The effectiveness of listening to the Holy Quran to improve mental disorders and psychological wellbeing: Systematic review and meta-analysis

Background: Listening to the Quran is one of spiritual therapies that have been used for treating mental disorders. Many studies have been conducted to assess the effect of listening to the Quran on mental health and psychological wellbeing. Several reviews were conducted to summarise results of such evidence. However, they either focused on studies published in a certain country (Iran), focused on certain setting (intensive care unit), or were written by Persian language. Moreover, none of them synthesised results of studies statistically. Objective: The study aimed to assess the effectiveness of listening to the Quran to improve mental disorders and psychological well-being by summarizing and pooling the ndings of previous literature. Methods: A systematic review was conducted to accomplish this objective. The search sources included 6 bibliographic databases (e.g., MEDLINE, PsycINFO, CINHAL), the search engine “Google Scholar”, and backward and forward reference list checking of the included studies and relevant reviews. Two reviewers independently carried out the study selection, data extraction, risk of bias assessment, and quality of evidence evaluation. Results of the included studies were synthesized narratively and statistically, as appropriate. Results: Of 1724 citations retrieved, 11 studies met the eligibility criteria. Of these studies, 7 were included in meta-analysis. The evidence showed that listening to the Quran is signicantly effective in improving state anxiety, trait anxiety, general anxiety, depression, stress and mental health. However, the evidence quality ranged from very low to low due to the high risk of bias, heterogeneity, and impression. Conclusion: Listening to the Quran has the potential to improve mental disorders and psychological wellbeing. Until high-quality studies approve its effect, health professionals and individuals should consider listening to the Quran as a complementary therapy to already available interventions. Researchers should conduct further studies to compare the effectiveness of reciting and listening to the Quran and Al-Ruqya Al-Shariya with active interventions on mental disorders and psychological well-being among Muslims and non-Muslims from different countries.

Mental disorders are a growing public health concern worldwide [1]. One-quarter of adults and 10% of children may be affected by mental disorders yearly [2]. Mental disorders have a substantial impact on the lives of millions of people and on community and economy [3]. Globally, mental disorders are deemed as one of the most common causes of disability [4]. In 2010, about 10% of global Disability-Adjusted Life Years (DALYs) and 28.5% of global Years Lived with Disability (YLDs) were caused by mental, neurological and substance use disorders [5].
Pharmacological treatments are usually used for treating mental disorders [6]. However, non-pharmacological interventions may be preferred by patients due to the risk of adverse events that pharmacological treatments may cause [7]. According to a systematic review conducted by Gartlehner et al. [8], adverse events were experienced by about 63% of patients who had second-generation antidepressants, and this led to discontinuing treatment in 7% and 15% of patients.
There is a large number of non-pharmacological interventions reported by the Cochrane Depression and Neurosis Group [9] and Australian patient advocacy group [10], such as cognitive behavioural therapy, meditation, music, massage, relaxation, yoga, aromatherapy, and spiritual therapies. Listening to the Quran is one of spiritual therapies that have been used for treating mental disorders [11].
Quran is a holy book for Muslims, who believe that it was revealed by God to the nal prophet, Mohammad. Quran consists of 114 chapters (Surah), which are composed of different numbers of verses (Ayah). Several verses in the Quran indicate directly or indirectly to its ability in healing and achieving tranquility. For example, God says in Surah al-Isra' verse 82: "And We send down of the Qur'an that which is healing and mercy for the believers". God also says in Surah Yunus verse 57: "O people! There has come to you advice from your Lord, and healing for what is in the hearts, and guidance and mercy for the believers".

Research problem and aim
Numerous studies have been conducted to assess the effect of listening to the Quran on mental health and psychological wellbeing [12][13][14][15][16][17][18]. Three systematic reviews were conducted to summarise such studies [11,19,20]. The rst review focused on the effect of listening to the Quran on anxiety in Iranians [19]. The second review assessed the physiological and psychological effects of listening to the Quran in the intensive care unit patients [11]. The last review was written in the Persian language and examined the effect of listening to Quran on hygiene, mental health, and physiological functions. None of these reviews statistically synthesized results of the included studies. There is a pressing need to address the aforementioned shortcomings of the previous reviews by conducting a systematic review, including metaanalysis, to assess the effectiveness of listening to the Quran on mental health and psychological wellbeing in any setting in any country. To ll this gap, this study aimed to assess the effectiveness of listening to the Quran on mental disorders and psychological well-being by summarizing and pooling the ndings of previous literature.

Methods
A systematic review was conducted to achieve the objective of this study. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement were followed in this review [21] (Appendix 1). The protocol for this review is registered at PROSPERO with the number CRD150963.

Search terms
Terms used to search the bibliographic debases were related to the intervention (e.g., the Quran, ruqyah, spiritual healing) and study design (e.g., trial and experiment). Appendix 2 shows the search strings used for searching each bibliographic database.

Study eligibility criteria
The population of interest was individuals with or without health problems regardless of their age, gender, ethnicity, and religion. Eligible interventions were reciting or listening to the Quran or Al-Ruqya Al-Shariya regardless of the used chapter (Surah), reciter, duration, and frequency. Al-Ruqya Al-Shariya is an Islamic therapy where a patient listens or recites verses of the Quran and prayers taken from the Quran and Prophet Mohammed [22]. However, the following non-quranic interventions were excluded: Hazrat Zahra's praises (saying the word Allah 100 times), Sahifeh Sajadiyeh, supplications, prayers, mustahab praises (e.g., Subhan Allah, Alhamdullah, Allah Akber). The outcomes of interest were any symptoms of mental disorders or issues (depression, anxiety, stress, phobia) and psychological well-being. Outcomes related to physiological disorders and physical health were excluded in this review. Only randomized controlled trials (RCTs) were included in the current review. The following types of publication were included: peerreviewed articles, dissertations, conference proceedings. We excluded reviews, conference abstracts, proposals and editorials. This review included only studies written in the English language. No restrictions were applied related to the comparator, country of publication, and year of publication.

Study selection
The studies were selected based on two steps. In the rst step, two reviewers (AAM & AHM) independently sifted titles and abstracts of all retrieved citations. In the second step, both reviewers independently read full texts of studies included from the previous step. A third reviewer (AA) resolved any disagreements between both reviewers. Interrater agreement between reviewers was examined using Cohen's kappa [23], and it was 0.70 and 0.79 in the rst and second step of the selection process respectively; indicating a good level of agreement according to Altman [24].

Data extraction
To conduct a systematic and accurate extraction of data, we developed a data extraction form and piloted it using 4 included studies (Appendix 3). Data were extracted from the included studies by two reviewers (AAM & AHM). A third reviewer (AA) resolved disagreements between both reviewers. Interrater agreement between reviewers was very good (Cohen's kappa = 0.86) [24].

Assessment of risk of bias
Risk of bias in the included studies was assessed using the Risk-of-Bias 2 (RoB 2) tool, which was developed and recommended by Cochrane Collaboration [25]. RoB assesses the risk of bias in RCTs in terms of 5 domains: the randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result [25]. According to risk of bias judgments in these domains, overall risk of bias will be determined for each study [25]. Risk of bias results were summarized using a graph showing reviewers' judgments about each "risk of bias" domain for all included studies. They were also presented as a gure showing reviewers' judgments about each "risk of bias" domain for each included study. Risk of bias was assessed by two reviewers (AAM & AHM), and the third reviewer (AA) resolved disagreements between both reviewers. There was a good interrater agreement between the reviewers (Cohen's kappa = 0.66) [24].

Data Synthesis
Findings of the included studies were grouped according to the measured outcome (e.g., anxiety and depression). When there was more than one RCT examining the same comparison for a given outcome, ndings were synthesized statistically using meta-analysis. Otherwise, a narrative approach was used to synthesize the ndings.
Review Manager (RevMan 5.3) was utilized to conduct a meta-analysis. Given that all extracted data were continuous, the effect of each trial and the overall effect were measured using either the mean difference (MD) or the standardized mean difference (SMD). Speci cally, the MD was used to meta-analyze data of an outcome assessed using the same tool in the studies. The SMD was selected when, between studies, the outcome was measured using different tools. Given the clinical heterogeneity between studies in terms of population (hemodialysis patients, pregnant women, depressed women, and healthy athletes) and intervention (listening to different chapters of the Quran for different period), random-effects was used as an analysis model.
When results showed a statistically signi cant difference between two groups, we examined whether this difference was clinically important. Minimal clinically important difference is de ned as the smallest change in a measured outcome that a patient would deem as worthy and signi cant and which mandate a change in a patient's treatment [26].
Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess the overall quality of the evidence that was synthesized statistically [28]. The quality of the evidence was assessed by two reviewers (AAM & AHM), disagreements were resolved by the third reviewer (AA). Cohen's kappa was 0.78 indicating good interrater agreement between the reviewers according to Altman [24].

Search results
As shown in Figure 1, 1724 citations were retrieved by searching the electronic databases. Of those, 566 duplicates were excluded. By screening titles and abstracts of the remaining 1158 citations, we excluded 1130 citations for several reasons detailed in Figure 1. Of the remaining 28 studies, we included 8 studies after reading the full texts. By backword reference list checking, three additional studies were found and added to this review. Overall, 11 studies were included in a narrative synthesis [29][30][31][32][33][34][35][36][37][38][39], and 7 of those studies were included in a meta-analysis [29-31, 34, 35, 37, 38].

Characteristics of included studies
As detailed in Table 1, all included studies were published in the last nine years (2011-2019). Most studies (8/11) were conducted in Iran. The study design used in all studies was the randomised controlled trial (RCT). The sample size ranged between 12 and 168 with a mean of 65 participants. The mean age, reported in only 9 studies, ranged from 21 to 65 with a mean of 41 years. Of the 10 studies that reported sex, the mean percentage of males was 30% with a value of zero in 5 studies. In the included studies, the target population was: pregnant women (n=3 studies), haemodialysis patients (n=3 studies), patients waiting for surgery (n= 2 studies), medical staff (n=1 study), athletes (n=1 study), and depressed women (n=1 study). Participants were Muslims in 6 studies while the rest of the studies did not report the religion of participants. Most studies (9 of 11) recruited participants from clinical settings (hospital or healthcare centre). In most studies (8 of 11), the intervention was listening to one whole chapter (Surah) of the Quran, such as Ya-Sin, Ar-Rahman, Maryam, Yusuf, and Al-Waqi'ah ( Table 2). The intervention was listening to all chapters of the Quran in one study. The frequency of the intervention varied between studies: once, three times a week for one month, three times a week for 6 months, one time a day for three months, and two times a day for one month. The listening duration was ranged from 3 to 45 minutes with a mean of 21 minutes. Different reciters of the Quran were selected in the study, such as Al-Afasy, Al-Shateri, Al-Dosari, and Abdul Basit. MP3 players were used for delivering the intervention in most studies (8 of 11). As shown in Table 3, the control group received no intervention in 7 studies while music and physical training were delivered to the control group in 2 and 1 study, respectively. The frequency and duration of the active comparators varied between studies. Overall studies assessed the effect of the intervention on at least one of four outcomes: anxiety, depression, stress, and mental health. Different tools were used to measure study outcomes, Spielberger State-Trait Anxiety Inventory (STAI) was the most common (n=5). The follow-up period ranged between 0 and 24 weeks.

Risk of bias in the included studies
As shown in Figure 2, the domain of randomisation process was judged as 'some concerns' in most studies (10 of 11). This was due to lack of information about allocation sequence and concealment. In all studies, participants, carers, and individuals delivering the interventions were aware of assigned intervention during the trial. No information was reported regarding deviation arose due to the experimental contexts. Thus, the domain of deviations from the intended interventions was rated as 'some concerns' in all studies. Given that outcome data were available for all, or almost all, participants in most studies (10 of 11), the domain missing outcome data was judged as 'low risk' in these studies. In all studies, risk of bias in the measurement of the outcome was high because assessors of the outcome were aware of the intervention received by participants; this knowledge could affect the outcome assessment. The domain of selection of the reported result was judged as some concerns in all studies due to either unavailability of study protocols or insu cient details in published protocols regarding outcome measurements and analyses. As there was a 'high risk' of bias in at least one domain in all studies, the domain of overall bias was rated as 'high risk' in these studies. Reviewers' judgements about each 'risk of bias' domain for each included study are shown in Appendix 4.

3.4
Results of studies
For state anxiety, 4 studies reported enough data to conduct meta-analysis [29,30,35,37]. As shown in Figure 2, the overall effect is statistically signi cant (P<0.001) indicating that listening to the Quran is more effective than no intervention in decreasing state anxiety in haemodialysis patients, pregnant women, and patients waiting for a surgery: mean difference (MD) -14.75 (95% con dence interval (CI) -19.88 to -9.63). This difference was also clinically important as the overall effect and its CI were outside minimal clinically important difference (MCID) boundaries (-3.8 to 3.8); MCID boundaries for this outcome were calculated as ± 0.5 times the median standard deviation (SD) of the control arms of studies at baseline. Heterogeneity of the evidence was considerable in this analysis (P<0.001; I 2 =96%).
The quality of the evidence was very low due to high risk of bias and heterogeneity (Appendix 5). One study assessed the effect of the Quran on state anxiety compared to music [36]. That study found a statistically signi cant difference (P=0.02) favoring the Quran over music on state anxiety in primiparous women (i.e. pregnant for the rst time).
In relation to trait anxiety, the above-meta-analysed studies were also reported su cient data to perform a meta-analysis. Figure 3 shows that there is a statistically signi cant difference (P<0.001) favoring listening to the Quran over no intervention on trait anxiety in haemodialysis patients, pregnant women, and patients waiting for surgery; MD -12.38 (95% CI -16.64 to -8.11). This difference was also clinically important because that overall effect and its CI were outside MCID boundaries (-3.125 to 3.125); MCID boundaries for this outcome were calculated as ± 0.5 times the median SD of the control arms of studies at baseline. There was considerable heterogeneity among the studies (P<0.001; I 2 =96%). The quality of the evidence was very low due to high risk of bias and heterogeneity (Appendix 5). Kadkhodaei et al. demonstrated that listening to the Quran is more effective than listening to music in reliving trait anxiety in primiparous women (P=0.04) [36].
With regards to general anxiety, 4 studies reported adequate data to carry out a meta-analysis [29,30,34,38]. As presented in Figure 4, there is a statistically signi cant difference (P<0.001) favoring listening to the Quran over no intervention on anxiety in haemodialysis patients, pregnant women, patients waiting for a surgery, and athletes; standardised mean difference (SMD) -2.06 (95% CI -2.57 to -1.54). This difference was also clinically important as the overall effect and its CI were outside MCID boundaries (-1.03 to 1.03); MCID boundaries for this outcome were calculated as ± 0.5 times the SMD value (-2.06).
There was moderate heterogeneity of the evidence (I 2 = 59%), but it was not a concern as P-value was higher than 0.05 (P=.06). The quality of the evidence was low due to high risk of bias (Appendix 5). A study conducted by Frih et al. [33] showed that listening to the Quran and physical training is more effective than only physical training in reducing general anxiety in hemodialysis patients (P<0.05).
As shown in Figure 5, the overall effect was statistically signi cant (P=0.01) indicating that listening to the Quran is more effective than no intervention in decreasing depression in haemodialysis patients and pregnant women: SMD -3.77 (95% CI -6.68 to -0.87). This difference was also clinically important as the overall effect were outside MCID boundaries (-1.89 to 1.89) and its CI did not cross 'no effect' line (Zero effect). MCID boundaries for this outcome were calculated as ± 0.5 times the SMD value (-3.77). There was considerable heterogeneity among studies (P<0.001; I 2 =97%). The quality of the evidence was very low due to high risk of bias, heterogeneity, and impression (Appendix 5). According to Frih et al. [33], listening to the Quran and physical training is more effective than physical training alone in reducing depression in hemodialysis patients (P<0.05). Further, Ra que et al. found that there is a statistically signi cant difference (P=0.005) favoring listening to the Quran over listening to music on depression in depressed women.

Mental health
One Iranian study assessed the effect of listening to the Quran on overall mental health [32]. The study showed that there is a statistically signi cant difference (P=0.001) favoring listening to the Quran over no intervention on overall mental health in medical staff [32]. Further, the study demonstrated that the effect of listening to the Quran on overall mental health was higher for females between the ages of 40-50 than males younger than 40 and older than 50 [32].

Stress
An Iranian study examined the effect of listening to the Quran with or without Persian translation on stress in pregnant women [35]. The study found that there was a statistically signi cant difference (P=0.001) favoring listening to the Quran with or without translation over no intervention on stress as measured at the 4th and 8th week since the beginning of the intervention [35].

Principal ndings
The current systematic review assessed the effectiveness of listening to the Quran on mental disorders and psychological well-being. The 11 included studies assessed its effectiveness on at least one of the four outcomes: anxiety, depression, stress, and overall mental health.
The current review showed a statistically and clinically important difference favoring listening to the Quran over no intervention on state anxiety, trait anxiety, and general anxiety in haemodialysis patients, pregnant women, patients waiting for a surgery, and athletes. Further, the evidence demonstrated that listening to the Quran is more effective than music and physical training in reducing state and trait anxiety and general anxiety in primiparous women and hemodialysis patients, respectively. However, all above-mentioned ndings resulted from low or very low quality of evidence that had high risk of bias. In a systematic review conducted by Ghiasi & Keramat [19], the effect of listening to the Quran on anxiety were examined in 28 studies. Of these studies, only 4 were included in the current review. The remaining 24 studies were not included in the current review because either they were written in Persian language, or their full text was not available [19]. Although Ghiasi and Keramat's review did not meta-analyse results of the included studies, its conclusion was in line with our conclusion [19]. To be more precise, Ghiasi and Keramat revealed that listening to the Quran is more effective than no intervention, music, and muscle relaxation in reducing anxiety in various settings [19]. This nding supports our conclusion regarding the effect of listening to the Quran on anxiety.
Our review found a statistically and clinically important difference favoring listening to the Quran over no intervention on depression in haemodialysis patients and pregnant women. Listening to the Quran was also more effective than music and physical training in reducing depression in depressed women and hemodialysis patients, respectively. However, all aforementioned conclusion resulted from very low quality of evidence that had a high risk of bias. The effect of listening to the Quran on depression was not examined by any systematic review before the current review. However, a study excluded from the current review due to language (Persian) supported our ndings [16]. Speci cally, Jaberi and colleagues revealed that listening to the Quran signi cantly reduced depression in depressed patients in comparison with no intervention [16]. Similarly, an RCT found that spiritually integrated psychotherapy is more In the current review, evidence from a single RCT showed a statistically signi cant difference favouring listening to the Quran over no intervention on mental health in medical staff. However, the risk of bias was rated as high in the RCT. Our ndings are consistent with those of other studies excluded from the current review due to study design (quasi-experiment) [42], and language (Persian) [43]. The former study demonstrated that listening to the Quran without its musical tone (Tartil) had a positive in uence on mental health in Iranian personnel in a university [42]. The latter study found that listening to the Quran signi cantly improved mental health in Iranian nursing students in comparison with no intervention [43].
Only one of the included studies revealed that listening to the Quran is more effective than no intervention in relieving stress in pregnant women. Yet, that evidence had a high risk of bias. Our ndings are in line with what has been found by three studies excluded from the current review due to language (Persian) [44,45] and study design (a cross-sectional survey) [18]. The former two studies found a statistically signi cant difference favouring listening to the Quran over no intervention on stress in Iranian young people & adolescents [44] Iranian personnel in a university [45]. The third study revealed that Iranian students who recite Quran have less stress than those how do not recite it [18].
The effect of listening to the Quran on mental disorders and psychological well-being may be attributed to the fact that listening to the Quran may increase religiosity and spirituality, which were found to have a positive effect on several mental disorders, such as depressive symptoms [46][47][48][49][50] and anxiety [51][52][53][54].
From a psychological perspective, the effect of the Quran can be explained by its ability to relax, reinforce and generate positive and pleasant thoughts, divert the mind from unpleasant irritations and ruminations, and restore harmony between the body and soul [31,33]. The relaxing abilities of listening to the Quran may also result from its sound, meaning of its words, its miraculous combination of words within verses, and its rhythmic agreeable intonation [16,33]. From a physiological perspective, Babamohamadi and colleagues believe that listening to the Quran may result in release of endorphins in the brain, which were found to affect mood and memory positively [31].

Strengths
The current study is the rst systematic review that focused on effectiveness of listening to Quran on mental disorders and psychological well-being, meta-analysed results of studies, followed the PRISMA statement. Therefore, it is a more comprehensive, robust, transparent review than the previous reviews [11,19,20].
The review minimized the risk of publication bias through searching the most popular databases in healthcare eld, searching the largest grey literature databases, conducting backward and forward reference list checking, using a comprehensive list of search terms, and not restricting the search to a certain year of publication, country of publication, and comparator.
To minimize the selection bias, two reviewers independently carried out the study selection, data extraction, risk of bias assessment, and quality of evidence evaluation. Interrater agreement was good for all processes, except for data extraction (which was very good). When possible, results of the included studies were meta-analyzed, and this improved the power of studies and increased the estimates of the likely size of effect of listening to the Quran on different outcomes.

Limitations
The intervention of interest in this review was restricted to reciting or listening to the Quran, but not other Islamic spiritual interventions (e.g., supplications, prayers, mustahab praises). Further, this review focused on mental health-related outcomes and excluded outcomes related to physiological disorders or health.
Accordingly, this review cannot comment on the effectiveness of other Islamic spiritual interventions and on the effect of listening to the Quran on physiological disorders or health.
The review was restricted to RCTs written in the English language, therefore, many studies were excluded because they were quasi experiments and/or written in the Persian language. This restriction was necessary because RCTs have higher internal validity than any other study design [55] and, given the resource available, it was not feasible to translate all non-English studies.
Most included studies recruited Iranian Muslims without mental disorders. This may limit the generalizability of our ndings to non-Muslims with mental disorders in other countries. The overall risk of bias was rated as high in the all included studies, and quality of evidence for all meta-analyzed outcomes ranged from very low to low. Therefore, ndings in this review must be interpreted with caution.

Practical implications
Although this study revealed that listening to the Quran is effective in improving anxiety, depression, stress, and mental health, it is di cult to draw de nitive conclusions due to high risk of bias in the included studies, low quality of evidence, and lack of studies assessing each outcome. For this reason, health professionals and individuals should consider listening to the Quran as a complementary therapy to already available interventions for anxiety, depression, stress, and psychological well-being.
The effect of listening to Quran was smaller in studies that delivered the intervention only once [29,37,38] than those that delivered it more than once [30,35]. Hence, people should consider listening to the Quran more than once to increase the effectiveness. Given that all chapters (Surah) and reciters used as an intervention in the included studies showed improvements in the measured outcomes, people should consider these chapters and reciters to improve anxiety, depression, stress, psychological well-being.
Most included studies used MP3 players delivering the intervention, and none of them used mobile applications (apps), which may be more accessible in the last decade. Thus, we encourage development and evaluation mobile apps that enable users to listen to the Quran and/ or Al-Ruqya Al-Shariya.

Research implications
The current review found relatively few studies assessing the effectiveness of listening to the Quran.
Thus, researchers should conduct further studies to examine the effectiveness of listening to the Quran. They also should recruit non-Muslims with mental disorders from different countries given the lack such evidence.
While listening to the Quran was the intervention in all included studies, no study assessed the effect of reciting Quran by patients themselves. Further, no studies investigated the effectiveness of Al-Ruqya Al-Shariya. Accordingly, there is a need to assess the effectiveness of reciting the Quran by patients and Al-Ruqya Al-Shariya.
In most included studies, comparators were inactive intervention (i.e. no intervention). Future studies should assess the effectiveness of listening to the Quran in compassion with active interventions such as medications, music, yoga, and other spiritual or Islamic therapies.
In all included studies, outcomes were measured subjectively using self-administrated questionnaires. Therefore, participants' answers might be biased to show a positive effect of listening to the Quran given that participants were Muslims in most studies and were aware of their treatment allocation. In addition to subjective outcome measures, researchers should objectively assess outcomes using, for example, electroencephalogram (EEG) to monitor changes in brainwaves.
Given that the overall risk of bias was judged as high in the included studies, we encourage researchers to follow recommended guidelines or tools (e.g., RoB 2 [25] and CONSORT-EHEALTH [56]) when conducting and reporting their studies in order to minimize biases.

Conclusion
Listening to the Quran was signi cantly effective in improving anxiety, depression, stress and mental health. However, this nding resulted from low or very low quality of evidence that had a high risk of bias.
People should not consider listening to the Quran as a replacement for established mental health treatments. Instead, they should use it as an adjunct to already available interventions. There is a pressing need to develop and evaluate mobile applications that provide recitations of the Quran and Al-Ruqya Al-Shariya. Researchers should conduct further studies to compare the effectiveness of reciting and listening to the Quran and Al-Ruqya Al-Shariya with active interventions on mental disorders and psychological well-being among Muslims and non-Muslims from different countries.

Declarations
Author contributions The protocol of this review was developed by AA, TA, MH, and BMB. The search was run by AA. The study selection and data extraction were carried out by AAM and AHM under supervision of AA & MH. AA synthesised the data and drafted the manuscript. The manuscript was revised critically for important intellectual content by all authors. All authors approved the manuscript for publication and agree to be accountable for all aspects of the work. Figure 1 Flow chart of the study selection process Review authors' judgements about each 'Risk of bias' domain. Forest plot of four studies assessing the effect of the Quran on trait anxiety.

Figure 5
Forest plot of four studies assessing the effect of the Quran on general anxiety.

Figure 6
Forest plot of two studies assessing the effect of the Quran on depression.