RESUMEN
Background: There are no studies that measure the prevalence and real comorbidities of neurodevelopmental disorders (NDDs) according to the DSM-5-TR in 6-year-old children in population and clinical samples or studies that measure them as a whole. The data on the prevalence of these disorders are usually disparate because of the estimation methods (direct/indirect), the type of sample (population/clinical/school), and the ages studied. Methods: The initial sample (289 subjects) was representative of 6-year-old children in the entire population of Menorca, obtained from pediatric primary care services (100% of the sample). The patients were divided into two groups based on the criterion of verification of clinical warning signs. One of the groups represented the clinical or experimental sample (EG) (81 subjects) at risk of NDDs; the other group was considered the control sample (CG) (210 subjects), and they were subjects without risk of suffering NDDs. A direct clinical assessment of the clinical sample was carried out, and they were administered the Wechsler Intelligence Scale for Children (WISC-V), the Clinical Evaluation of Language Fundamentals (CELF-5), the Battery for the evaluation of the processes of revised reading (Batería para la evaluación de los procesos de lectura revisada - PROLEC-R), the Test for the Diagnosis of Basic Mathematical Competences, (TEDI-MATH), and the Developmental Coordination Disorder Questionnaire (DCDQ). Results: A total of 21.5% of the initial sample suffered from an NDD. A total of 2.4% presented autism spectrum disorder (ASD); 14% presented attention-deficit hyperactivity disorder (ADHD); 0.34% presented mild intellectual disability; 9.54% presented communication disorder (CD) (5.8% language disorder, 3.4% phonological disorder, and 0.34% stuttering); 10% presented learning disorder with reading difficulties; 5.8% presented learning disorder with difficulties in writing; 3.11% presented learning disorder with difficulties in mathematics; 1% presented transitory tic disorder; 0.34% presented chronic tic disorder; 1% presented Tourette syndrome; 2% presented motor coordination disorder (MCD); and 0.34% presented stereotypic movement disorders. Male children were more affected than female children in general, with male/female ORs of 0.14/0.92 for the presence of comorbidities, 0.11/0.88 for combined ADHD, 0.06/0.87 for language disorder, 1.02/1.27 for MCD, and 1.39/1.02 for inattentive ADHD. Conclusion: In disadvantaged contexts, there was a higher prevalence of NDDs and comorbidities, unless the disorder was extreme, in which case only the NDD manifestations were presented. A significant proportion of the sample had not been previously diagnosed (88.6%); therefore, early detection programs are recommended to identify warning signs and develop policies that help and support the most disadvantaged sectors of the population.
RESUMEN
OBJECTIVE: To interpret the current evidence on the prevalence of neurodevelopmental disorders (NDDs) through a systematic review based on both DSM-5 (2013) and PRISMA criteria. METHOD: Empirical studies complying with the PRISMA guidelines were identified from four databases (PubMed, Scopus, Science Direct, and ProQuest) and systematically reviewed. In total, 17 articles were selected for the study. RESULTS: In the scientific literature, there have been only a few studies measuring the prevalence of NDDs according to the DSM-5 (2013) criteria in people under 18 years old. The reported prevalence rates were as follows: intellectual disability (ID), 0.63%; attention-deficit/hyperactivity disorder (ADHD), 5-11%; autism spectrum disorder (ASD), 0.70-3%; specific learning disorder (SLD), 3-10%; communication disorders (CDs), 1-3.42%; and motor disorders (MDs), 0.76-17%. Although there is extensive literature on specific disorders, NDDs have rarely been assessed as a whole. All of the reviewed studies support the idea that such disorders can be considered chronic, heterogeneous, underdiagnosed conditions and that comorbidity of multiple NDDs is the norm. Likewise, it is estimated that the prevalence of the most studied disorders, such as ADHD, ASD and SLD, remains stable over time and is consistent in different cultures, ages, ethnicities and sexes. CONCLUSION: The studies reviewed lead us to conclude that the prevalence rate of NDDs fluctuates globally between 4.70 and 88.50%; these variations depend on methodological aspects such as estimation procedures, as well as on sociocontextual phenomena. It is also important to consider that the prevalence found is probably highly influenced by the activity of the countries in the diagnosis and training of professionals who care for children and adolescents. Hence, there is a need for a secondary intervention in the fields of public health and education to minimize socioemotional consequences, prevent academic failure, and reduce the economic cost to society.