The protocol, inclusion criteria, exclusion criteria

A study protocol based on Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols (PRISMA) was drafted for an MSc dissertation project at Liverpool Johns Moore University (LJMU), UK, and revised by the faculty board. As of now, the protocol cannot be accessed by the public, but it can be shared upon request.

Inclusion and exclusion criteria were established using the Context-Context-Population Framework (CoCoPop) in order to define prevalence data in accordance with the research question [21].

Articles considered in this review met the following inclusion criteria: (a) investigated the prevalence, predictors, and economic cost of mental illness and/or psychiatric disorders among refugees, migrants, and asylum seekers from African countries (definitions of all terms can be found in the S1 File) (b) were published in the English language, (c) were peer-reviewed and based on official reports from credible institutions and organizations and were published between 1 January 2000 and 31 January 2024.

The exclusion criteria included the lack of peer review or not coming from credible official sources and the inclusion criteria not meeting the study topic and language (English). The review excluded publications in which mixed populations were involved (both from Africa and elsewhere), in addition to research abstracts, reviews, news, commentary on protocol development, case reports, letters, guidelines, and books.

Search strategy

We developed a comprehensive search strategy following the JBI Scoping Review Network guidelines. In order to gather all possible evidence in this field, an initial search was conducted for articles published between January 1, 2000, and January 31, 2024, including Medline (through PubMed), EMBASE, APA PsycINFO, Web of Science, EBSCO, Scopus and ProQuest. Additionally, we searched grey literature, such as the ProQuest theses database, and reviewed the references of eligible articles. We used a combination of Medical Subject Headings/Entree terms as well as free terms according to population, intervention, and outcome frameworks. S2 File provides detail of search terms.

Screening, quality of evidence, and critical appraisal of studies

Following the search of the databases, and removal of duplicate articles, a total of 2475 articles were exported to Excel spreadsheet for further analysis. To screen the data, the first step was to review the abstracts for clear points that addressed the research question, screening full text if the abstract was either unavailable or did not provide sufficient information. Exclusion of the papers was due to the following reasons: ineligible study types or populations, ineligible research questions, review articles, reports, or perspectives, no additional data, or duplication of publications. Additionally, we read references in papers to identify potential articles. We then categorized the searched papers into yes, no, and unclear categories, and included uncertain abstracts until we reviewed the full text articles to prepare the final list of eligible articles that were imported into EndNote (version X9) according to their eligibility. To assess the quality of cross-sectional studies, we used a modified version of the Appraisal Tool for Cross-Sectional Studies (AXIS) [22]. This tool is designed to ensure systematic interpretation and to inform decisions about the quality of cross-sectional studies. This critical appraisal (CA) method is usually used in systematic reviews, but we found it very useful in this scoping review study. The main components of this CA include assessing whether the study is suitable to answer the hypothesized question and whether bias might be introduced. According to AXIS tool, we used the following parameters for CA of studies:

1. The introduction: should include clear objectives.
2. Methods: a suitable study design; a sufficient sample size, usually > 100 except for quantitative studies; a target population (African); a clear definition of the condition to be studied, a validated instrument to assess it, and an appropriate statistical analysis plan for the described data.
3. Results: the basic data were adequately presented; respondents and non-respondents were described along with their reasons for not responding, and the results presented were described in the methods section.
4. Discussion: The authors’ discussion and conclusions were supported by study results, and limitations of the study were addressed clearly.
5. Other: funding source explained appropriately; no conflict of interest; ethics statement available as needed.

For qualitative studies, a ten-point appraisal list consistent with the Critical Appraisal Skills Programme (CASP) tool was used. The CAPS tool covers key aspects such as study design, methodology, data analysis, and interpretation of results.

Data charting

The key information we charted for all publications was the following: the author(s), publication year, origin/country of the study (where it was conducted), category of the population whether it is refugees, immigrants, or asylum seekers, study population and sample size (if applicable), age categories, gender percentages, techniques, approaches, and methods used to assess the MH under study, prevalence of the MH problem(s) under study, predictors and determinants of the prevalence of the MH problems under study, and an overview of key findings related to one or more of the scoping review questions. For the economic burden studies, we extracted data about the approach used for the economic evaluation of the studied MH problem. We also extracted data about study type and design, and the study outcome.

Data quality assurance and appraisal of individual sources

To achieve this goal, we used the condition-context-population-framework (CoCoPop) to determine data eligibility. In addition to the comprehensive search which included searching the grey literature, particularly theses through the ProQuest database, we included only articles which were written in English to avoid misinterpretations and considered both the rationale and limitations of publications. The data charting process included reviewing evidence from all sources and using predefined charting formats. Following the inclusion of studies and the recording of key information relevant to review questions, we developed a proposal to present results in accordance with the objectives or review questions using diagrams, tables, or descriptive formats.

Data analysis & synthesis

The extracted data were compiled using the narrative synthesis of Barnett-Page and Thomas [23], and we followed the guidelines for data synthesis without meta-analysis [24].

Characteristics of the included studies

Fig 1 summarizes the results of the study, which included 38 articles that met the inclusion criteria.

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Fig 1. Flow chart illustrating the search and identification of eligible articles according to the PRISMA chart style.

https://doi.org/10.1371/journal.pone.0305495.g001

Based on the 38 studies included in this review, 35 were quantitative cross-sectional studies, while three were qualitative exploratory studies. A summary of the important findings of the eligible articles is presented in Table 1 and Fig 2 illustrates the country location of each study. As shown in Fig 2, the majority of the studies were conducted within the African continent, with 22 studies being conducted on the continent. Among the studies, seven were from Uganda, followed by four from Italy, and three from the United States. In most of these studies, both males and females are examined, focusing on refugees’ adult populations. A single study focused on women, two on unaccompanied minors, one on children and parents as dyads, and one on young adults. In the select studies, gender representation varies, but most studies include more males than females. According to most studies, participants were less than 40 years old on average. East Africa represented the majority of study participants, followed by West Africa. No study included populations from Northern or Southern Africa. A study of unaccompanied Eritrean minors in Sudan [25], used both research approaches. In this study, after researchers determined the prevalence of anxiety and depression in the group, they used a quantitative approach to develop themes based on the daily stressors associated with these mental health disorders.

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Fig 2. Distribution of the 38 eligible studies across the world.

The world map in the figure was taken from NASA (https://eoimages.gsfc.nasa.gov/images/imagerecords/47000/47427/global_tm5_mangroves_lrg.png).

https://doi.org/10.1371/journal.pone.0305495.g002

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Table 1. Findings of the study based on population, host countries, sex and age distributions, prevalence, and diagnostic indicators, as well as risk predictors.

https://doi.org/10.1371/journal.pone.0305495.t001

Description of the major conditions and the psychometric instruments used in the examination

A wide range of mental and psychiatric conditions have been examined in the studies reviewed in this article. Across all studies, PSTD or CPSTD was the most frequently studied condition. Study focus, however, may vary from assessing a specific condition such as PSTD or depression to assessing the overall mental health of the study population, which may include anxiety, depression, and PSTD together. Fig 3 summarizes the number of studies that examined different mental disorders. It should be noted that each study examined more than one condition, thus the number of studies does not equal 38 when taken as the total number of all studies included.

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Fig 3. Number of studies conducted for each mental disorder condition examined.

https://doi.org/10.1371/journal.pone.0305495.g003

Studies often used more than one set of instruments to assess the prevalence and patterns of a particular condition, such that different instruments were used for different conditions. An overview of the main instruments used to assess the different conditions is provided in Table 2.

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Table 2. A summary of the key diagnostic instruments used in all 38 studies along with their abbreviations.

https://doi.org/10.1371/journal.pone.0305495.t002

The prevalence of MH disorders among African asylum seekers, migrants, and refugees

It is evident from Table 2 that mental health disorders have a high prevalence in all studies, varying according to the demographics of the study population, the specific mental health condition, and the location of the study population. Although it is difficult to compare prevalence across these factors since different instruments are used for evaluating prevalence, as well as the different contexts and conditions assessed in each study, certain patterns are evident. Firstly, women have a higher prevalence of specific mental health conditions. According to a study conducted on Congolese populations in Uganda [26], 94% of women reported symptoms of PTSD, compared to 84% of men [26]. A similar observation was made in another study examining female Congolese and Somali populations in Uganda, where 92% and 71.1% of men and women reported having PTSD and depression, respectively. Additionally, research conducted within African countries tends to show a greater prevalence of different conditions than research conducted elsewhere in the world. It is difficult, however, to draw any definitive conclusions based on the different tools used.

Second, higher prevalence is associated with specific mental health conditions. There is a high prevalence of PSTDs and CPSTDs across the included studies (range: 19.8% to 94%), perhaps due to the fact that they are the most studied conditions [26, 31]. There was a similar trend in the 17 studies that examined the prevalence of depression. Most studies reported a prevalence of less than 50%, with a range between 20 and 67.9%. In other studies, similar trends have been observed, however, suicidal ideation (7.3–31%) has been reported to be the least common trend (which is not high when viewed in conjunction with the prevalence of conditions associated with suicidal ideation, including depression). These data indicate that asylum seekers, migrants, and refugees’ groups from African countries suffer from higher rates of mental illness, specifically PTSD and depression, than the general population.

Qualitative studies overview

A qualitative examination of specific mental health conditions was conducted in three of the studies in this review. Anakwenze and Rasmussen [29], investigated the effect of parental trauma on the externalizing behavior of children using parent-child dyads. In another study by Gakuba and colleagues s [37], examined the mental health of young adult refugees, as well as the factors that predispose this population to poor mental health (Table 2). As part of their study, a semi-structured interview process conducted with youth and professionals working in the mental health field among asylum seekers, migrants, and refugees, themes for reasons for poor mental health among these populations were identified, including immigration, and living conditions, as well as the lengthy asylum process.

Results of the study in children and unaccompanied minors

Children were involved in five studies, either as unaccompanied minors (two studies) or adolescents (one study) or as participants in studies in which one or both parents took part (two studies). There is a marked difference in the prevalence of mental health problems among unaccompanied minors in Africa and Europe; Eritrean minors in Sudan showed 88.9% anxiety and depression, and African minors in Austria demonstrated 17 to 29% depression [25, 61]. One interesting study is that by Scharpf and colleagues [58] which shows that when examining the whole Burundian families for suicidality, mothers and fathers showed different discrepancies, with mothers being most affected than fathers, and children exhibiting lower rates when living with their parents. According to these findings, suicide is predicted differently by family members, with children more likely to commit suicide if they suffer from externalizing disorders, mothers mostly due to violence, and fathers due to war-related trauma.

Predictors of different conditions’ prevalence

The studies that were included provided snapshot prevalence data, which cannot be used for developing a mathematical model that can be used for predicting the prevalence of the disease. The term "predictors" is therefore used to describe the factors and conditions associated with the occurrence of a variety of mental health disorders, rather than to refer to predictive models or factors that can be used to predict their prevalence.

There are certain demographic characteristics that are associated with a higher prevalence of MH disorders and depression, namely older age, female gender, having no formal education, being unemployed, and living in poor housing conditions [11]. Further, it has been found that displacement history, poor social support, separation of the family during migration, post-migration isolation, and hostile attitudes from host populations are all important predictors that have been identified to explain the change in behavior [11]. A number of conditions indicated different predictors that could be attributed to migration or refugee factors, which are mainly traumatic events, as well as postmigration refugee factors, primarily the length of time spent as a refugee or the time spent waiting for asylum, the difficulty of getting medical care, as well as discrimination. Women are more likely to be affected by various forms of gender-based violence, such as sexual violence, rape, or interpersonal violence than men, which may explain why this review found a higher prevalence of PTSD in women across a number of studies.

In regards to refugee populations in host countries outside Africa, a qualitative study found that there are certain daily stressors that lead to mental health disorders and higher levels of psychosocial stress for these populations [25]. There were several themes identified, including harassment (verbal, sexual, and physical), racism, financial difficulties, acculturation distress, and restricted freedom. Table 3 summarizes the major predictors of the various conditions across all the studies.

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Table 3. Summary of the major predictors and reasons of common mental health disorders in asylum seekers, migrants, and refugees’ groups from African countries derived from 38 studies.

https://doi.org/10.1371/journal.pone.0305495.t003

Economic burden of mental health disorders among African asylum seekers, migrants, and refugees

Despite our comprehensive review of the economic ramifications of mental health disorders among African asylum seekers, migrants, and refugees, we identified only one study that examined the specific economic impacts of mental health interventions [62]. The study used the Youth Readiness Intervention (YRI), a behavioral intervention designed to reduce functional impairment (expressed in terms of quality-adjusted life years ‐ QALYs) among war-affected young people in Freetown, Sierra Leone who were not able to attend school (Table 4). In the secondary analysis, financial and economic costs were analyzed as well as incremental cost-effectiveness ratios (ICERs) based on gains across mental health and education dimensions. In the YRI group, school retention was higher, functional impairments were lower, and the ICER per QALY gained was $7260. According to the authors, when the willingness-to-pay threshold exceeds three times the average gross domestic product per capita, the YRI is not cost-effective. Despite this, the results of the YRI indicate that a range of benefits were derived, including an increase in enrollment in schools, which was not captured in the cost-effectiveness analysis.

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Table 4. Study findings regarding the economic burden of MH for Sierra Leonean refugees.

https://doi.org/10.1371/journal.pone.0305495.t004

Refugees, asylum seekers, and migrants from African countries are more likely to suffer from mental health disorders

Based on this research, African asylum seekers, migrants, and refugees suffer from high rates of PTSD (19.8% to 94%) and depression (20% to 67%). The prevalence of both conditions in African populations is significantly higher than in global migrant and refugee populations (PTSD prevalence = 31.5%; depression prevalence = 31.5%) [63]. One possible explanation is that most forced migrations within the continent are the result of war or violence. Our research shows that war survivors and refugees from conflict-affected regions suffer from higher PTSD rates [64, 65]. Nevertheless, African populations also have significantly higher prevalence rates than other war-affected migrant and refugee groups such as Syrians resettled in Western countries, who report prevalence of PTSD and depression at 31.5% [66]. The reason for this observation is unclear and warrants further research, however, we hypothesize that the poor living conditions of African refugees and migrants in host African countries and the challenges faced by racism and social integration in Western host countries may contribute to higher mental health conditions.

Moreover, the prevalence rates of PTSD and depression in African refugee and migrant populations are higher than those in the general population, where lifetime prevalence is estimated at 3.9% and 10.8%, respectively [67, 68]. In light of this evidence, the migration morbidity hypothesis [69] is supported and the healthy migrant hypothesis [70] may be contested. There are two possible explanations for this. First, African refugee and migrant populations in host African countries continue to live in poor conditions and suffer from unemployment, both of which contribute to the prevalence of morbidity. Secondly, it is notable that a significant portion of the population in these select studies has experienced forced migration rather than voluntary migration, which, according to the literature, is highly selective of the younger and healthier migrants.

Similarly, we establish that anxiety disorders and psychosis are less prevalent among African asylum seekers, migrants, and refugees. This is consistent with the results of systematic reviews of global refugee and migrant populations that indicate a lower prevalence of anxiety disorders and psychosis (11% and 1.51% respectively) as well as a lower prevalence than those in the general population of 16% [71] and 3% [72]. Although the reason for this is unclear, we believe that perhaps anxiety disorders and psychosis are less researched in these populations due to a lack of research focus or a bias in selection of study participants. Also, according to Derek Summerfield, western notions of anxiety and psychosis, and therefore the criteria and tools used to diagnose them, may not be applicable to African settings [73].

A number of the predictors of MH disorders identified in this study, such as socio-demographic factors, social and interpersonal relationships, as well as exposure to traumatic experiences and violence, are supported by evidence in the literature [74]. PTSD, the most frequently studied condition, is present in more than 50% of these groups, due to their exposure to severe traumatic experiences related to displacement in conflict-ridden African countries.

Our findings highlight specific gender patterns. The majority of asylum seekers, migrants, and refugees leaving Africa are young males. Furthermore, females are more likely to suffer from PTSD than males due to the significant trauma they have experienced due to gender-based sexual violence. According to studies on PTSD and gender, women are more likely than men to suffer from PTSD [75, 76]. It is more likely that women will experience sexual violence during times of conflict [77, 78], which may increase their risk of PTSD, as well as childrearing pressures, safety concerns, and exploitation. Despite this, studies from countries that have been reported to commit systematic sexual violence do not adequately describe the type of trauma associated with PTSD diagnosis [79]. Furthermore, there are major gaps in the literature when it comes to disaggregating data by gender for other mental health conditions, whereas gender disaggregated data for PTSD is readily available. According to best reporting practices, future research in this field should disaggregate outcome measures by gender.

In accordance with findings from a global systematic review in 2020 [80], our review also identified several predictors of post-migration mental health disorders in host countries, including prolonged detention, long waits for refugee permits, limited healthcare access, acculturation difficulties, and low social support and integration. The West underestimates these challenges, as do African nations. The prevalence of postmigration mental health disorders is higher in countries with harsh immigration policies, such as detention, deportation, and delays in refugee determination and resettlement processes. Likewise, local population shifts against immigration host countries and increased hostility towards refugee populations negatively impact social integration and increase the risk of mental illness. Furthermore, MH disorders in asylum seekers, migrants, and refugees’ groups can have long-lasting impacts on the next generation. It appears that there are gaps in the existing literature, such as the lack of longitudinal studies in these groups and assessments of the economic costs associated with MH disorders in African populations.

MH disorders are more prevalent among children, adolescents, and their families from African asylum seekers, migrants, and refugees

The prevalence of depression, anxiety, emotional problems, and behavioral problems among refugee and asylum seeker children and adolescents was generally higher than that of native children and adolescents [81–84]. It is possible for these differences to vary depending on the type of trauma experienced in the country of origin or during migration, as well as the challenges and problems faced by the host country [85]. The development of psychiatric disorders in children and adolescents is affected by several factors [85–87]. Among them: pre-migration factors such as poverty, violence, wars, warlike conditions, education, family values, social and cultural values; peri-migration issues such as separation, abuse, and trafficking; and post-migration issues such as schooling, social support, stable settlement, parental mental health, and legal aspects of immigration. This scoping review found that unaccompanied minors suffer from more anxiety disorders, depressions, and PTSD than accompanied minors [88], which indicates that they require special care. As a result, while this review summarizes migration factors’ associations with mental health disorders, it does not provide an in-depth analysis of this complex interplay.

The prevalence of PTSD and depression in the postmigration environment suggests that ongoing stressors may contribute to MH problems. In particular, Anakwenze and Rasmussen’s [29] study indicates that mental illness in parents of asylum seekers, migrants, and refugees’ groups can manifest in their children, who are born and raised there without having to deal with displaced conditions or volition in their original countries. Foreign environments can present several challenges, including social and cultural isolation, reorganization of family relationships, difficulty adjusting to the culture, and limited economic and social opportunities.

MH in postmigration environments may also be hampered by low social support, accumulation challenges, and other factors. In contrast to depression or post-traumatic stress disorder, displaced individuals were more likely to experience anxiety. Fazel and colleagues’ study on the mental health of displaced and refugee children resettled in high-income countries [85] reported a higher prevalence of posttraumatic stress disorder (PTSD) and depression in children. It is likely that this is due to the fact that we included studies of refugees’ populations in low- and middle-income countries, where there may be a greater number of predictors and risk factors. Another explanation is based on methodology. It is likely that there is a difference in prevalence because it was not aggregated into a single figure, as in systematic reviews, but described as a range of values from individual studies that were highly heterogeneous in nature.

Literature gaps regarding African asylum seekers, migrants, and refugees

During our review, we identified that there is a lack of comprehensive assessment of the economic burden of MH diseases among asylum seekers, migrants, and refugees, especially in African countries. In the literature, there are only a few studies that examine the economic impact of restructuring on the health sector, including mental health services, without considering the burden on those services. The absence of empirical studies on the economic dimensions of mental health in African asylum seekers, migrants, and refugees underscores the urgent need to understand the intricate relationship between mental health challenges and economic outcomes. Accordingly, future research should focus on unraveling the nuanced complexities of how mental health issues manifest and influence the economic landscape of African asylum seekers, migrants, and refugees. Additionally, a deeper understanding of these dynamics may assist us in developing supportive interventions that are tailored to these groups’ specific needs.

Furthermore, in studies using certain diagnostic assessments such as the PDS, PTSD and depression were more prevalent than in studies using the ITQ or PHQ. It should be noted that most of these instruments are self-admitted; however, the PDS is detailed and includes subscale scores for intrusions, avoidance, and arousal symptoms, so it can report a higher prevalence rate. The same trend can be observed in instruments for other conditions as well. Overall, we found no difference between interviews conducted with interpretation assistance and those conducted in a native language. As a result of my study, it was found that although the diagnostic measures are perceived to be similar in their accuracy and performance, they differ in certain respects. Therefore, it is critical that the method and instrument used to assess refugee populations’ mental health be carefully selected. Due to clinicians’ reliance on self-reported symptoms when diagnosing mental illness, this difference may be caused by a number of factors, including language proficiency. It is necessary to conduct research to determine whether native interviewers conducting interpreter-assisted interviews and clinicians conducting assessments in their native language can grasp cultural and linguistic nuances that may affect diagnostic accuracy. It is important to note that we did not examine how diagnostic measures and tools may affect diagnosis of cases. In these studies, we acknowledge that western representations and understandings of psychiatric conditions have a great deal of influence on the tools developed. Consequently, either African populations’ mental health disorders are overmedicalized or underdiagnosed. It is therefore necessary to conduct further research in this area.

Strengths and limitations of the study

This study examined the prevalence, predictors, and economic burden of mental health disorders in this population and extends beyond post-traumatic stress disorder (PTSD) to include depression, anxiety, and psychosis. By specifically focusing on the African demographic, this study significantly contributes to the existing body of evidence regarding mental health disorders among asylum seekers, refugees, and migrants. This study sheds light on the substantial presence of African asylum seekers, migrants, and refugees in economically disadvantaged African nations, underscoring the urgent need for enhanced healthcare support in these regions in contrast to many studies conducted in high-income countries. Additionally, by emphasizing the significant mental health burden experienced by asylum seekers, migrants, and refugees, as well as the burgeoning displaced population, the study underscores the necessity for both short-term and long-term mental health services following resettlement, emphasizing the importance of comprehensive mental health support to address these pressing needs.

Similarly, our study has several limitations. As seen in our review and other systematic reviews, findings can vary considerably due to differences in methodological and clinical quality among included studies. Different ethnic groups in Africa, varying ages, and the use of a variety of diagnostic tools may all contribute to this heterogeneity. Despite this high degree of heterogeneity, as is expected when investigating and analyzing prevalence across the population of global refugees, a sense of accomplishment has been achieved in knowing that current prevalence estimates can provide a starting point for further research.

Specifically, our study revealed that self-reports and proxy-reports often indicated a higher point prevalence of mental health disorders than structured clinical interviews using standard diagnostic criteria, such as DSM. A psychological or psychiatric assessment may be necessary in this case. In addition, we did not conduct subgroup analyses or exclude studies reporting data on specific subgroups, such as male-female comparisons, which could have provided valuable insights into these distinctions. To enhance the accuracy and depth of our understanding of MH disorders among asylum seekers, migrants, and refugees from African populations within the context of our study, it is important to standardize assessment methods and consider subgroup differences. It is also possible that this variation may hinder the comparability of data among countries and international organizations. To enhance data exchange and cooperation among entities such as UNHCR, a unified methodology approach should be established, incorporating clear definitions and guidelines.

Recommendations

• Prioritize mental health: Research should focus on mental health concerns among refugees and asylum seekers, emphasizing that mental well-being needs to be prioritized over physical health.
• Special attention to women and unaccompanied minors: women and unaccompanied minors, considered high-risk groups, require special attention. In addition to expediting their asylum claims, host countries should offer them employment and educational opportunities. The psychological intervention that enhances coping strategies, self-esteem, and identity rebuilding is especially beneficial for refugee groups.
• Incorporating mental health into economic programs: Interventions such as Youth Readiness Intervention (YRI) have proven effective not just in improving refugee quality but also in terms of generating income-producing opportunities and school retention. Hence, it is important to integrate them into economic plans that target these groups of people.
• Methodological standardization and priorities for research: Comparable and validated methods and tools should be used when studying MH in these populations. Women, unaccompanied minors, and the economic aspects of the problem are important research areas. Despite evidence that MH can manifest in offspring of these human groups and be a long-term issue, our analysis found no longitudinal studies. Research in this area is also important. Without further high-quality research that examines the different components of MH needs, culturally appropriate and effective interventions, and longitudinal mental illness trajectory, which will have a significant impact on successful integration, untreated mental illnesses will adversely affect successful integration into host communities.