Author, year, and place of study |
Diagnosis and instrument for data collection |
Sample characterization |
Main results |
Study conclusion |
Abreu et al. (2003),13 Sao Paulo, Sao Paulo, Brazil |
- Questionnaires addressed at: teachers on school performance (2nd half of 2001) and parents/guardians;- Medical and clinical assessment (the procedures used were not mentioned);- Statistical analysis: chi-squared test, with significance level of 5% |
- 330 students (ages, means, and gender distribution were not mentioned);- 30 mouth breathers with upper airway obstruction;- 300 nasal breathers (control);- Elementary School Students (2nd to 4th graders) and- Students were required to be attending the appropriate school year for age |
- Changes in academic performance were mentioned in 20% (n=6) of students in the study group and in 14% (n=42) of the control group, showing a p-value >5% |
Mouth breathing did not influence school performance of the assessed children |
Goodwin et al. (2003),14 Tucson, Arizona, United States of America |
- Standardized questionnaire, not validated, addressed to parents/guardians on sleep habits (TuCASA);- Polysomnography at home and- Statistical analysis: chi-squared (5% of significance), simple logistic regression, and odds ratio calculation (confidence interval not stated) |
1494 Caucasian and Hispanic children;- 613 males and 601 females (280 forms without gender identification);- Groups divided by age range: 1) Between 4 and 7 years (n=763, 53.9%) and between 8 and 11 years (n=653; 46.1%);- 78 forms without age identification. The mean age of the groups was not mentioned |
- There was no significant difference between groups for the presence of snoring, excessive daytime sleepiness and witnessed apnea, but there were significant differences regarding these characteristics with the reported learning disabilities;- Significant prevalence of learning disabilities in the group of older children;- There were no significant results when comparing the learning disabilities with the gender variable |
- Hispanic children had a higher frequency of symptoms of sleep-disordered breathing, snoring, excessive daytime sleepiness, witnessed apnea and learning disorders than white children;- Children with learning disorder complaints had higher chances of having snoring (2.4×) excessive daytime sleepiness (2.5×) and being in the age range between 8 and 11 years (2.1×) |
Di Francesco et al. (2004),15 Sao Paulo, Sao Paulo, Brazil |
- History and physical examination characteristic of allergic rhinitis (signs and symptoms);- Standardized questionnaire applied to the parents/guardians on the nocturnal symptoms;- Physical examination;- Positive hypersensitivity test (allergic rhinitis);- Profile teleradiography to assess nasopharyngeal obstruction and- Statistical analysis not described in the method, but specified in the tables of results, using ANOVA (statistical significance value was not declared), Kruskal-Wallis, Mann-Whitney and Spearman (all with 5% significance) |
- 142 patients;- Ages between 2 and 16 years (mean: 7.2);- 92 males and 50 females;- Study groups subdivided into three:1) Allergic rhinitis (n=51);2) Isolated tonsilar and pharyngeal hypertrophy (n=25)3) Tonsilar hypertrophy (n=66) |
- Snoring, apnea, nocturnal restlessness, bruxism and enuresis were more frequent in the group with tonsilar hyperplasia;- Attention deficit and poor school performance were more prevalent in the group with tonsilar hypertrophy |
The investigation of sleep apnea in mouth breathers is crucial, as well as determining the etiology of altered breathing pattern |
Vera et al. (2006),16 Sao Bernardo do Campo, Sao Paulo, Brazil |
- Survey of 77 records of subjects with learning disorders diagnosis made by a multidisciplinary team;- Applied questionnaire based on the DSM-IV criteria for classification of Attention Deficit Hyperactivity Disorder (ADHD) subtypes;- Assessment of breathing: Guided interview with family members and clinical evaluation of the patient, assessing breathing among other aspects, such as body posture, structures analysis and other functions of the stomatognathic system and- Statistical analysis: test for equality of two proportions, ANOVA, confidence interval for proportion and mean (significance ≤5%) |
- 77 subjects from the Outpatient Service of Neurological Disorders diagnosed with attention deficit hyperactivity disorder by the multidisciplinary team;- Ages 7 to 17 years (mean: not mentioned), with 63 males (81.8%) and 14 females (18.2%);- Most students from public schools (64-83%);- School failure (39%), school (87%) and respiratory (51%) complaints |
- There was prevalence of ADHD in males, children's ages between 7 and 11 years and the 1st grade to 6th grade- There was a high incidence of learning disabilities (62.3%) with school difficulty complaints (87%).- There was statistical significance for the presence of learning disorder, school difficulties and no school failure (61%).- There was high occurrence of altered breathing pattern (71.4%), which in association with the attention disorder, affected 41.6% of the sample.- There was a predominance of attention disorder and oronasal breathing for genders and types of ADHD |
There was an association between ADHD, poor school performance and altered breathing pattern in children and adolescents due to high presence of comorbidity with learning disabilities, regardless of gender, age or diagnosis of ADHD |
Uema et al. (2007),17 São Paulo, São Paulo, Brazil |
- Interview;- General physical examination;- Otorhinolaryngological assessment: clinical and instrumental examination (nasofibrolaryngoscopy and polysomnography);- Testing: learning (Rey) and cognitive (WISC-III, cancelation of symbols and letters (by Mesulam, previously validated in Brazil), the latter involving the graphic recognition of letters) and- Statistical analysis: Kruskal-Wallis test, adopting a significance level of 5% |
- 81 children;- Ages between 6 and 12 years (the mean was not stated);- 41 males and 36 females (4 subjects not mentioned), divided into three groups: one control (20), with obstructive sleep apnea syndrome (24) and another with primary snoring (37) |
- Learning test (Rey test) showed worse results in immediate memory and in attention level in patients with obstructive sleep disorders |
Mouth-breathing children with obstructive sleep disorders had a poorer performance in the learning test than the control group |
Petry et al. (2008),18 Uruguaiana, Rio Grande do Sul, Brazil |
- Use of questionnaires about the symptoms of breathing sleeping disorders; asthma (database of the International Study of Asthma and Allergies in Childhood), educational and socio-economic aspects;- Skin tests with common environmental allergens in 2004 and- Statistical analysis: Chi-square test and multivariate logistic regression, with a significance level of 5% |
- 1011 schoolchildren from public schools- Aged between 9 and 14 years (mean: 11.2);- 507 males and 504 females;- Complaint of poor school performance: 8 (0.8%) |
- Presence of habitual snoring: 27.6%;- Presence of daytime mouth breathing: 15%;- Presence of excessive daytime sleepiness: 7.8%;- Schoolchildren with mouth breathing showed 13× higher risk of manifesting symptoms of excessive daytime sleepiness compared to controls |
- High prevalence of respiratory disorders.- Children with excessive daytime sleepiness seem to have an almost 10× higher risk of learning disorders than those without |
Kajihara and Nishimura (2012),19 Maringa, Parana, Brazil |
- Otorhinolaryngological assessment based on the analysis of medical records;- Analysis of the signs and symptoms of mouth breathing, through interviews;- Resolution of mathematical operations and problems (not validated) and- Statistical analysis: simple logistic regression model and odds ratio calculation (95% CI) |
- 63 schoolchildren (30 mouth and 33 nasal breathers);- Mouth breathers diagnosed with allergic rhinitis and pharyngeal tonsil hypertrophy;- Ages between 8 and 10 years (mean was not mentioned);- Sample distribution regarding gender was not mentioned;- Students between the third and fourth grade from public schools |
Mathematical mistakes:- Among mouth breathers: 334 (65.49%);- Control: 173 (30.84%).Through simple logistic regression, mouth breathers were more likely to show difficulties when compared to controls, in the tasks of:1) Mathematical operations (4 times), mainly involving attention (4×), algorithm (4×) and combined errors (18×);2) Resolution of mathematical problems (8×), with chance of attention errors (10×) and problems interpretation (9×) |
The mouth breathing pattern impairs the learning of mathematics |
Fensterseifer et al. (2013),20 Porto Alegre, Rio Grande do Sul, Brazil |
- Clinical neuropediatric, psychological, and social assessment;- Clinical otorhinolaryngological, instrumental and imaging assessment (oroscopy, anterior rhinoscopy, cavum X-ray, and echo-rhinometry);- Learning disability defined by history of, at least, two consecutive years of school failure for the experimental group and- Statistical analysis: Mann-Whitney test and Student's t-test with significance value of p<0.5 |
- 48 schoolchildren;- Ages between 8 and 12 years (mean: 9.1);- Group I - 24 students with learning disabilities;- Group II (Control) - 24 students without learning disabilities;- 18 (37.5%) were females and 30 males (62.5%);- All students attended public schools |
Nasal obstruction tended to be higher in patients with learning difficulties.There was a statistically significant association between learning disabilities and pharyngeal tonsillar and palatine hypertrophy |
Students with tonsillar hypertrophy, mouth breathers, have greater difficulty in learning compared to children without hypertrophy |
Perilo et al. (2013),21 Belo Horizonte, Minas Gerais, Brazil |
- Respiratory Characteristic Assessment Questionnaire;- Assessment of the usual lip position by observing the child for 5min (by two evaluators);- Protocol of Assessment of Cognitive-Linguistic Skills - collective version, Brazilian adaptation: alphabet recognition in sequence, copy of shapes, writing under dictation, arithmetic and short-term memory, and- Statistical analysis: Mann-Whitney and Kruskal Wallis test with p <0.01 for statistically significant correlations |
- 131 schoolchildren (66 4th graders and 65 3rd graders from elementary school);- Both genders (distribution was not mentioned);- Ages 9 to 10 years (mean not mentioned);- All students attended public schools |
There was no significant association between the performance of cognitive-linguistic skills and the presence of respiratory characteristics among the sample schoolchildren |
There was no association between mouth breathing and learning disabilities |
Kuroishi et al. (2015),22 Ribeirao Preto, Sao Paulo, Brazil |
- Clinical Interview;- Pure tone audiometry;- Otorhinolaryngological assessment by clinical and imaging assessment (oroscopy, rhinoscopy and nasoendoscopy);- Sentence reading competence test to evaluate reading comprehension; School achievement test (Arithmetic subtest); Illinois test of psycholinguistic abilities with Brazilian adaptation (auditory sequential memory subtest - number repetition) and repetition of pseudowords and- Statistical analysis: Mann-Whitney test, with significance level of 5% |
- 55 schoolchildren (42 mouth and 11 nasal breathers);- Gender: 29 females and 26 males;- Sample size calculation was performed (a minimum of 13 participants was determined per group);- Ages between 7 and 10 years (mean age: 8.7 years for the mouth breather group and 8.4 for the control);- Mouth breathers with one or more of the following characteristics: nasal obstruction or irritation (>3 months), hypertrophy (tonsillar or inferior turbinate) and deviated septum;- Educational level: 2nd and 3rd graders of elementary school attending public schools |
Students with mouth breathing showed significantly worse performance when compared to nasal breathing ones in reading comprehension, arithmetic and operational memory for pseudowords, but not for numbers |
Mouth breathers showed worse results at the tests of reading, writing, math skills and memory of pseudowords |