Cognitive and learning aspects of Duchenne Muscular Dystrophy: An integrative reviewABSTRACT
Purpose: to investigate cognitive and learning aspects, particularly those related to written language, in children with Duchenne Muscular Dystrophy (DMD).
Methods: an integrative literature review conducted through searches in PubMed, SciELO, Revista Brasileira de Neurologia, and the Brazilian Virtual Health Library between February 5-10, 2025, using the following descriptors: learning, reading, social cognition, literacy, and DMD. The selected articles were analyzed both quantitatively and qualitatively.
Literature Review: out of the 52 studies identified, 9 were included. The findings highlight significant deficits in working memory, executive functions, and phonological decoding skills in patients presented with DMD. Such difficulties have a marked impact on reading and learning.
Conclusion: the scarcity of studies underscores the need for further research in this area. Beyond motor impairments, DMD also significantly affects the learning of written language. Additional studies are necessary to better investigate and support reading acquisition in individuals with DMD.
Keywords:
Learning; Reading; Social Cognition; Literacy; Muscular Dystrophy, Duchenne
RESUMO
Objetivo: investigar na literatura os aspectos cognitivos e de aprendizagem, especialmente da linguagem escrita, de crianças com Distrofia Muscular de Duchenne (DMD).
Métodos: revisão integrativa da literatura, com buscas aplicadas à quatro bases de dados: PubMed, SciELO, Revista Brasileira de Neurologia e Biblioteca Virtual em Saúde (BVS), entre 5 e 10 de fevereiro de 2025, utilizando os descritores: aprendizagem, leitura, cognição social, alfabetização e DMD. Os artigos foram analisados quantitativa e qualitativamente.
Revisão da Literatura: dos 52 estudos encontrados, 9 foram selecionados. Os achados destacam déficits relevantes em memória de trabalho, funções executivas e habilidades de decodificação fonológica em pacientes com DMD. Tais dificuldades impactam significativamente a leitura e a aprendizagem.
Conclusão: a escassez de artigos mostra a importância de mais estudos na área. Além dos comprometimentos motores, a DMD também afeta significativamente a aprendizagem da linguagem escrita. Novos estudos são necessários para melhor investigar e intervir a aprendizagem de leitura em DMD.
Descritores:
Aprendizagem; Leitura; Cognição Social; Alfabetização; Distrofia Muscular de Duchenne
INTRODUCTION
Duchenne Muscular Dystrophy (DMD) is a recessive, fatal neuromuscular condition linked to the X chromosome. It is caused by mutations in the DMD gene, which is responsible for the synthesis of the dystrophin protein. DMD has a low incidence, estimated at 1 in 3,600-6,000 live births1.
In addition to symptoms of muscle weakness, DMD is also associated with cognitive and linguistic challenges, as observed in studies describing language delay in this population2. The presence of non-progressive cognitive impairment is widely recognized as a common characteristic in a substantial proportion of patients. Intellectual disability (ID) is a frequent feature among children with DMD, affecting approximately 30% of this population. This prevalence is higher than that observed in the general population, in which ID rates are approximately 1%3.
Delays in global developmental disorders and language development may constitute early signs of disease onset4. Some studies5˒6 indicate that language acquisition appears to be impaired in boys with DMD, highlighting speech delay as a possible early indicator of this impairment5˒7. Since the initial description of DMD by Duchenne in 1868, a significant incidence of intellectual and language developmental disorders has been observed among patients with Duchenne de Boulogne, with early descriptions referring to a “monotonous intellect and difficult speech” 8.
Recent studies2 have identified a higher rate of intellectual disability (52%) in patients with DMD when compared with earlier studies9˒10. This difference may reflect intrinsic genetic background, unfavorable social environments, and difficulties in accessing healthcare, education, and stimulation therapies.
Reading, a milestone in the evolution of human cognition, provides a gateway to understanding and interacting with the world around us. Throughout human evolution, the ability to interpret symbols, associate them with visual features, and integrate them into existing knowledge has been fundamental. Reading requires guidance and formal instruction to be effectively internalized11. Understanding the mechanisms underlying reading acquisition allows for the implementation of more effective interventions for individuals who face challenges in this process.
Scientific literature has emphasized how the acquisition of written language modifies cognition and linguistic abilities12. In reading, written codes are decoded and assigned meaning. Comprehension is considered the goal of reading and is important not only for the subject of Portuguese language, but also for all other academic disciplines, such as mathematics, geography, and history. The relationship between decoding/reading comprehension and phonological processing skills is widely recognized in the literature, reinforcing that difficulties in these skills may compromise reading development13-15.
Phonological processing skills include phonological awareness (PA), rapid automatized naming (RAN), and working memory (WM). Phonological awareness refers both to the awareness that speech can be segmented and to the ability to manipulate these segments, and it develops concomitantly with the literacy process16. Through RAN, it is possible to measure the speed with which a child can access the meaning of words stored in long-term memory, by observing the time required to visually perceive a stimulus, recognize it, and retrieve its meaning from long-term memory17. Finally, working memory temporarily stores information in a phonological code, allowing for the manipulation of such information18.
Although the production of knowledge related to DMD has increased in recent years, linguistic and neuropsychological aspects remain scarce when compared with studies focused on neuromuscular impacts19. The observation of linguistic deficits and the recognized importance of reading acquisition for human cognition and interaction with the world highlight the need to also investigate the linguistic profile of these children20. Thus, this study aimed at investigating cognitive and learning aspects, particularly written language, in children presented with DMD, through a literature review.
METHODS
This study is an integrative literature review, consisting of the systematic search for and critical evaluation of published studies related to the proposed hypothesis. The research question guiding this investigation was: What cognitive and learning aspects are described in the scientific literature regarding individuals with DMD?
In order to ensure methodological rigor, the six stages proposed by Mendes, Silveira, and Galvão (2008)21 were followed, namely: (1) identification of the hypothesis or research question; (2) sampling or literature search; (3) categorization of the studies; (4) evaluation of the studies included in the review; (5) interpretation of the results; and (6) synthesis of knowledge or presentation of the review. For this purpose, the following virtual databases were consulted: SciELO, PubMed, Revista Brasileira de Neurologia (RBN), and the Virtual Health Library (VHL).
The search for studies included in this literature review was guided by the combination of five descriptors indexed in DeCS (Health Sciences Descriptors). The search was conducted between February 5-10, 2025. For the screening process, the descriptors were used as presented in Chart 1.
Data analysis followed inclusion criteria based on the proposed theme: (1) availability of the full text online; (2) publication in English or Portuguese; and (3) addressing cognitive and learning aspects of patients with DMD. Due to the scarcity of articles on the topic, no restrictions were applied regarding year of publication.
The construction of the analyzed data sample, based on the search strategies described above, is presented in Figure 1.
Characterization of Studies
This integrative review comprised a total of 52 articles: 27 (51.9%) identified in the VHL database; 18 (34.6%) in PubMed; six (11.5%) in RBN; and one (1.92%) in SciELO. Chart 2 presents the distribution of the identified articles. After reviewing the titles, abstracts, and full texts, the final sample consisted of nine (17.3%) articles. Of these, seven (77.8%) were retrieved from the PubMed database, one (11.1%) from the RBN database, and one (11.1%) from the VHL database.
Regarding the year of publication of the articles included in the final sample, as presented in Chart 2, it is noted that publications were not evenly distributed across the years.
About the design of the studies included in the final sample, as proposed by Stillwell22, Chart 3 presents their characterization, according to their level of evidence.
Thematic Categorization
The full reading of the articles allowed the studies to be categorized according to the thematic approaches adopted by the author-researchers regarding the difficulties encountered in the acquisition of written language in children with DMD. These categories reflect the skills most frequently investigated on the topic. Thus, five thematic areas were identified, as presented in Chart 4.
Category A: Phonological Working Memory
This was the most frequently addressed theme, present in seven (77.7%) of the studies. These investigations demonstrate that working memory, the ability to temporarily store information in a phonological code, allowing for the manipulation of such information18, is impaired in the majority of studies involving children presented with DMD.
Category B: Learning Skills
In this category, two (22%) of the studies showed that patients with DMD presented significant deficits in the learning skills assessed.
Category C: Cognitive Deficit
Cognitive deficit was identified in two (22%) of the studies and highlights intellectual disability (ID) as a frequent feature among children with DMD, with a prevalence of approximately 30%3.
Category D: Phonological Decoding
One (11.11%) of the studies emphasizes the need for early interventions to improve decoding skills in this population.
Category E: Executive Functions
This theme, present in one (11.11%) of the studies, identifies deficits in executive functions in children with DMD, with implications for the learning of written language.
Chart 5 presents the selected articles along with their objectives, results, main implications, and principal limitations.
Even though the production of knowledge related to DMD has increased in recent years, linguistic aspects remain scarce when compared to studies focused on the neuromuscular impacts of DMD19. The present integrative review shows that out of the 52 articles initially identified, only nine met the inclusion criteria, highlighting the scarcity of studies specifically addressing this topic. Considering that a large proportion of children with DMD present important deficits relevant to the acquisition of written language, working memory being the most frequently described, it is essential to consolidate findings from the scientific literature to better understand whether other related deficits exist and to identify the most appropriate strategies to address them.
The analysis of the results demonstrated that 66.7% of the studies employed analytical observational methodological designs (case-control or cohort), while 33.3% were purely descriptive. No clinical trials or systematic reviews were identified, reinforcing the fragility of the available level of evidence.
Phonological working memory was the most frequently investigated aspect, appearing in 77.7% of the studies. Working memory (WM), also referred to as operational memory, is responsible for the temporary storage of information necessary for the performance of a range of cognitive tasks18. Some studies indicate that poor performance in WM correlates with impairments in higher cognitive functions, such as intelligence quotient (IQ)30 and reading31. This finding is consistent with research associating mutations in brain dystrophin, particularly the Dp140 and Dp71 isoforms, with deficits in phonological processing and temporary storage of verbal information.
In contrast, another study28 identified impairments in the repetition of long words, while lexical and syntactic comprehension remained within the expected range for age. Although WM was below expected levels in this study, no interference was observed in the goal of reading, namely reading comprehension.
Learning skills were described in 22% of the studies, indicating that a significant proportion of patients present impairments that extend beyond the motor domain. Since Duchenne’s initial description of DMD in 1868, a common occurrence of intellectual and language developmental disorders has been observed among affected individuals. Duchenne de Boulogne described the intellect of the first patients observed as “monotonous and with difficult speech” 8.
In a sample of 30 patients with DMD aged between 8 and 22 years, 33% met all clinical criteria for moderate to severe intellectual disability according to the DSM-5, with subtests related to orientation, calculation, and language being the most impaired25. In another, more recent study2, a high rate of intellectual disability (52%) was found, reinforcing the need for systematic neuropsychological assessment.
Phonological decoding and executive functions were the least explored categories, each appearing in 11% of the studies. The findings suggest that children with DMD may present patterns similar to those observed in phonological dyslexia, as well as deficits in planning and attention, directly impacting the learning of reading and writing.
Executive functions are described as the cognitive skills that allow an individual to guide and manage cognitive, emotional, and behavioral processes in a more conscious, flexible, and adaptive manner in response to internal and external demands. Significant difficulties in executive functions are expected to result in deficits in reading comprehension, which is the goal of reading32. One of the studies9 demonstrated that boys with DMD exhibit significant deficits in tasks involving executive functions.
The analyzed studies indicate that, even in children without global intellectual disability, DMD is associated with significant difficulties in reading, writing, and reading comprehension24. Such difficulties have repercussions for academic performance and social development, underscoring the need for further studies to determine the most appropriate pedagogical and therapeutic strategies.
Limitations of Literature
The most prevalent limitations across the reviewed studies are small and heterogeneous samples, which compromise the generalizability of the results. However, DMD is a rare disease with a fatal outcome typically occurring around the second decade of life1. If stricter inclusion criteria were applied, sample sizes would likely be even smaller.
The predominance of cross-sectional study designs does not allow for the observation of the progression of deficits over time. Nevertheless, mobility difficulties in individuals with DMD tend to increase as the disease progresses1, which may constitute a significant barrier to attending assessment locations.
The absence of healthy control groups in some of the studies also represents an important limitation, as it restricts broader and more robust comparisons.
CONCLUSION
This study reinforces that the challenges faced by individuals with DMD are not limited to the neuromuscular domain but also involve the acquisition of written language. Based on this integrative review, deficits related to working memory, executive functions, and phonological decoding skills, which have a significant impact on learning, reading, and writing, were found to be highly prevalent among children with DMD, in addition to the presence of intellectual disability in a substantial proportion of the sample. Furthermore, few studies addressing this topic were identified, and those available presented heterogeneous methodological designs, with limited multicenter investigations and relatively small sample sizes.
This work provides a comprehensive overview of cognition and learning in DMD, highlighting both the advances achieved and the areas that require greater scientific exploration, to guide clinical and educational practices as well as future research. Although scientific advances have enabled a broader understanding of the neuromuscular aspects of DMD, increased attention to the linguistic and educational needs of these patients is still required. Early diagnosis and targeted interventions, such as therapies focused on working memory and learning strategies, are essential to improve academic performance and quality of life in these children.
REFERENCES
-
1 Beytía ML, Vry J, Kirschner J. Drug treatment of Duchenne muscular dystrophy: Available evidence and perspectives. Acta Myol. 2012;31(1):4-8. https://pubmed.ncbi.nlm.nih.gov/22655510/ PMID: 22655510 e PMCID: PMC3440798.
» https://pubmed.ncbi.nlm.nih.gov/22655510/ -
2 Nardes F, Araújo APQC, Ribeiro MG, Bittar M, Gomes HF. O Mini-Exame do Estado Mental (MEEM) como ferramenta de triagem cognitiva na DMD. Ann Child Neurol. 2020;28(2):57-65. https://doi.org/10.2223/JPED.2148
» https://doi.org/10.2223/JPED.2148 -
3 Nardes F, Araújo APQC, Ribeiro MG. Mental retardation in Duchenne muscular dystrophy. J Pediatr (Rio J). 2012;88(1):6-16. https://doi.org/10.2223/JPED.2148 PMID: 22344614
» https://doi.org/10.2223/JPED.2148 -
4 Ciafaloni E, Fox DJ, Pandya S. Diagnóstico tardio na DMD: dados da Rede de Vigilância, Rastreamento e Pesquisa de Distrofia Muscular (MD STARnet). J Pediatr. 2009;155(3):380-5. https://doi.org/10.1016/j.jpeds.2009.02.007 PMID: 19394035 PMCID: PMC5884059.
» https://doi.org/10.1016/j.jpeds.2009.02.007 -
5 Snow WM, Anderson JE, Jakobson LS. Neuropsychological and neurobehavioral functioning in Duchenne muscular dystrophy: A review. Neurosci Biobehav Ver. 2013;37(5):743-52. https://doi.org/10.1016/j.neubiorev.2013.03.016 PMID: 23545331.
» https://doi.org/10.1016/j.neubiorev.2013.03.016 -
6 Pane M, Mazzone ES, Sormani MP, Messina S, D'Amico A, Pelliccioni M, et al. 6 Minute walk test in Duchenne MD patients with different mutations: 12 month changes. PLoS One. 2014;9(1):e83400. https://doi.org/10.1371/journal.pone.0083400 PMID: 24421885 PMCID: PMC3885414
» https://doi.org/10.1371/journal.pone.0083400 -
7 D'Amico A, Mercuri E, Tiziano FD, Bertini E. Diagnosis of Duchenne Muscular Dystrophy in Italy in the last decade: Critical issues and areas for improvements. Neuromuscul Disord. 2017;27(5):447-51. https://doi.org/10.1016/j.nmd.2017.02.006 Epub 2017 Feb 14. PMID: 28262469.
» https://doi.org/10.1016/j.nmd.2017.02.006 - 8 Duchenne GBA. De la paralysie musculaire pseudo-hypertrophique ou paralysie myo sclérosique. [S.l.: s.n.]; 1868.
-
9 Cotton SM, Voudouris NJ, Greenwood KM. Intelligence and Duchenne muscular dystrophy: Full-scale, verbal, and performance intelligence quotients. Dev Med Child Neurol. 2001;43(7):497-501. https://doi.org/10.1017/S0012162201000913 PMID: 11463183.
» https://doi.org/10.1017/S0012162201000913 -
10 Cotton SM, Voudouris NJ, Greenwood KM. Association between intellectual functioning and age in children and young adults with Duchenne muscular dystrophy: Further results from a meta-analysis. Dev Med Child Neurol. 2005;47(4):257-65. https://doi.org/10.1017/s0012162205000496 PMID: 15832549.
» https://doi.org/10.1017/s0012162205000496 -
11 Sargiani RA, Maluf MR. Linguagem, cognição e educação infantil: contribuições da psicologia cognitiva e das neurociências. Psicol Esc Educ. 2018;22(3):477-84. https://doi.org/10.1590/2175-35392018033777
» https://doi.org/10.1590/2175-35392018033777 - 12 Dehaene S. Os neurônios da leitura: como a ciência explica a nossa capacidade de ler. Porto Alegre: Penso; 2012.
-
13 Anthony JL, Williams JM, McDonald R, Francis DJ. Phonological processing and emergent literacy in younger and older preschool children. Ann Dyslexia. 2007;57(2):113-37. https://doi.org/10.1007/s11881-007-0008-8 Epub 2007 Dec 4. PMID: 18058023.
» https://doi.org/10.1007/s11881-007-0008-8 -
14 Capellini SA, Padula NA, Santos LC, Lourenceti MD, Carrenho EH, Ribeiro LA. Phonological awareness, working memory, reading and writing performances in familial dyslexia. Pró-fono R. Atual. Cientif. 2007;19(4):374-80. https://doi.org/10.1590/S0104-56872007000400009 PMID: 18200387.
» https://doi.org/10.1590/S0104-56872007000400009 -
15 Goff D, Pratt C, Ong B. The relations between children's reading comprehension, working memory, language skills and components of reading decoding in a normal sample. Read Writ. 2005;18:583-616. https://doi.org/10.1007/s11145-004-7109-0
» https://doi.org/10.1007/s11145-004-7109-0 - 16 Capovilla AGS, Capovilla FC, Silveira FB. O desenvolvimento da consciência fonológica, correlações com leitura e escrita e tabelas de estandardização. Ciência Cognitiva: Teoria, Pesquisa e Aplicação. 1998;2(3):113-60.
-
17 Stivanin L, Scheue CI. Tempo de latência e exatidão para leitura e nomeação em crianças escolares: estudo piloto. Educação e Pesquisa, São Paulo. 2005;31(3):425-36. https://doi.org/10.1590/S1517-97022005000300007
» https://doi.org/10.1590/S1517-97022005000300007 - 18 Xavier GF. Memória: correlatos anátomo-funcionais. In: Nitrini R, Caramelli P, Mansur LL, editors. Neuropsicologia: das bases anatômicas à reabilitação. São Paulo: Clínica Neurológica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo; 1996. p. 107-29.
-
19 Arruda CM, Chaves DRP, Biermann MC. Características cognitivas e comportamentais associadas à DMD: revisão integrativa. Estud Pesqui Psicol. 2023;23(1):180-204. https://doi.org/10.12957/epp.2023.75307
» https://doi.org/10.12957/epp.2023.75307 -
20 D'Angelo MG, Lorusso ML, Civati F, Comi GP, Magri F, Del Bo R et al. Neurocognitive profiles in Duchenne muscular dystrophy and gene mutation site. Pediatr Neurol. 2011;45(5):292-9. https://doi.org/10.1016/j.pediatrneurol.2011.08.003 PMID: 22000308; PMCID: PMC3200430.
» https://doi.org/10.1016/j.pediatrneurol.2011.08.003 -
21 Mendes KDS, Silveira RCCP, Galvão CM. Revisão integrativa: Método de pesquisa para a incorporação de evidências na Saúde e na Enfermagem. Texto Contexto Enferm. 2008;17(4):758-64. https://doi.org/10.1590/S0104-07072008000400018
» https://doi.org/10.1590/S0104-07072008000400018 -
22 Stillwell SB, Fineout-Overholt E, Melnyk BM, Williamson KM. Evidence-based practice, step by step: Searching for the evidence. Am J Nurs. 2010;110(5):41-7. https://doi.org/10.1097/01.NAJ.0000372071.24134.7e PMID: 20520115.
» https://doi.org/10.1097/01.NAJ.0000372071.24134.7e -
23 Billard C, Gillet P, Barthez M, Hommet C, Bertrand P. Reading ability and processing in Duchenne muscular dystrophy and spinal muscular atrophy. Dev Med Child Neurol. 1998;40(1):12-20. https://doi.org/10.1111/j.1469-8749.1998.tb15351.x PMID: 9459212.
» https://doi.org/10.1111/j.1469-8749.1998.tb15351.x -
24 Vicari S, Piccini G, Mercuri E, Battini R, Chieffo D, Bulgheroni S et al. Implicit learning deficit in children with Duchenne muscular dystrophy: Evidence for a cerebellar cognitive impairment? PLoS One. 2018;13(1):e0191164. https://doi.org/10.1371/journal.pone.0191164 PMID: 29338029; PMCID: PMC5770044
» https://doi.org/10.1371/journal.pone.0191164 -
25 Nardes F, Araújo A, Gonçalves R. Desempenho cognitivo através do mini-exame do estado mental na distrofia muscular de Duchenne. Revista Brasileira de Neurologia. Rio de Janeiro. 2018;54(4):5-10. https://doi.org/10.46979/rbn.v54i4.22345
» https://doi.org/10.46979/rbn.v54i4.22345 -
26 Thangarajh M, Elfring GL, Trifillis P. Longitudinal evaluation of working memory in Duchenne muscular dystrophy. J Clin Med. 2020;9(9):2940. https://doi.org/10.3390/jcm9092940 PMID: 32933029; PMCID: PMC7563441.
» https://doi.org/10.3390/jcm9092940 -
27 Tyagi R, Arvind H, Goyal M, Anand A, Mohanty M. Working memory alterations plays an essential role in developing global neuropsychological impairment in Duchenne Muscular Dystrophy. Front Psychol. 2021; jan 15:11:613242. https://doi.org/10.3389/fpsyg.2020.613242 PMID: 33519636; PMCID: PMC7843380.
» https://doi.org/10.3389/fpsyg.2020.613242 -
28 Chieffo DPR, Moriconi F, Mastrilli L, Lino F, Brogna C, Coratti G et al. Language development in preschool Duchenne Muscular Dystrophy boys. Brain Sci. 2022;12(9):1252. https://doi.org/10.3390/brainsci12091252 PMID: 36138988; PMCID: PMC9497138.
» https://doi.org/10.3390/brainsci12091252 -
29 Gillenstrand J, Ekström AB, Kroksmark AK, Tulinius M, Broberg M. Behavioural strengths and difficulties in relation to intellectual functions and age in Swedish boys with Duchenne Muscular Dystrophy. Child Neuropsychol. 2023;29(6):959-72. https://doi.org/10.1080/09297049.2022.2144814 PMID: 36444135.
» https://doi.org/10.1080/09297049.2022.2144814 -
30 Unsworth N, Engle RW. The nature of individual differences in working memory capacity: Active maintenance in primary memory and controlled search from secondary memory. Psychol Rev. 2007;114(1):104-32. https://doi.org/10.1037/0033-295X.114.1.104 PMID: 17227183.
» https://doi.org/10.1037/0033-295X.114.1.104 -
31 Zheng G, Ni X, Kale LV. Periodic hierarchical load balancing for large supercomputers. Int J High Perform Comput Appl. 2011;25(4):371-85. https://doi.org/10.1177/1094342010394383
» https://doi.org/10.1177/1094342010394383 -
32 Uvo MF, Germano GD, Capellini SA. Performance of schoolchildren with attention deficit hyperactivity disorder in metalinguistic skills, reading, and reading comprehension. Rev. CEFAC. 2017;19(1):7-19. https://doi.org/10.1590/1982-0216201719115815
» https://doi.org/10.1590/1982-0216201719115815
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A study conducted at the Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil.
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Financial support
Nothing to declare
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Data sharing statement
All data used and analyzed in this bibliographic review article will be available for unrestricted sharing. The data include bibliographic references, synthesis tables, inclusion and exclusion criteria of the selected studies, as well as any supplementary files related to the review. The data will be available immediately after publication of the article for a minimum period of five years and may be accessed upon direct request to the authors. There are no restrictive criteria for data access; any interested party may request the data via email contact, with free and complete sharing of the material guaranteed.
All data used and analyzed in this bibliographic review article will be available for unrestricted sharing. The data include bibliographic references, synthesis tables, inclusion and exclusion criteria of the selected studies, as well as any supplementary files related to the review. The data will be available immediately after publication of the article for a minimum period of five years and may be accessed upon direct request to the authors. There are no restrictive criteria for data access; any interested party may request the data via email contact, with free and complete sharing of the material guaranteed.
