Language delay and phonological disorders : a continuum or two distinct disease ?

Objetivo: estudar e verificar se o desvio fonológico é um continuum do atraso de linguagem, ou seja, se crianças com desenvolvimento fonológico atípico possuíam anteriormente algum atraso no desenvolvimento de linguagem. Métodos: os dados foram coletados e organizados em dois grupos, sendo o Grupo1 composto por 10 crianças com atraso de linguagem que realizaram terapia fonoaudiológica para estimulação e evoluíram após tratamento, sendo remanejados para o grupo de fala. Já o Grupo2 foi constituído por 554 sujeitos apresentando características de desvio fonológico e assim foram diagnosticados após realização das avaliações. Resultados: os achados deste estudo não mostram associação significante entre sexo e hipótese diagnóstica, sendo que a distribuição entre meninos e meninas foi semelhante. Na análise realizada entre idade de surgimento das primeiras palavras também não foram encontrados resultados significantes. No entanto, na comparação realizada entre idade de surgimento das primeiras palavras e hipótese diagnóstica houve resultado significante, sendo a idade de surgimento no grupo com atraso de linguagem mais tardio do que nas demais hipóteses diagnósticas. Conclusão: os achados deste trabalho corroboram a literatura, no sentido de que o desvio fonológico se refere a uma alteração no nível fonológico apenas, não sendo considerado como um continuum do atraso de linguagem.


INTRODUCTION
Language development occurs gradually; thus, it is part of an evolutionary process [1][2][3] .It is known that, in a cognitive perspective, language will be developed upon the interaction between the child and the environment.Symbolism emerges by such exploration of the environment, and the child uses it to mentally represent their schemes of action, even in the absence of the object in question 4 .Therefore, language development occurs in the representative period, at about two years of age 5 .However, in order for language to develop normally, and for the representative period to occur, the first words should also appear at the appropriate time.Appropriate not meet the inclusion criteria, information on age of onset of first words.
For evaluation of language, both Behavioral Observation Protocol (PROC) 6 , and observational assessment of language were performed.Speech samples were collected with the "Phonological Assessment of Child Speech (AFC) -" 7 , which is based on spontaneous picture naming of 125 words represented by five thematic pictures.The speech sample from each child was transcribed and later revised.
To analyze the data, the Statistics 9.1 software was used with a significance level of less than or equal to 0.05.Nonparametric Kruskal-Wallis and Mann-Whitney U tests and the chi-square test were performed.Intersections of the following variables were performed: gender and diagnosis; age and diagnosis; age and gender.

RESULTS
The graph below shows the distribution of subjects in each group.It was found that only 10 subjects participated in this sample of group G1 (with language delay).In G2, subjects with phonological disorders, the onset of first words by two years of age occurred in 359 children, while the onset of first words between 2 and 3 years of age occurred in 107 subjects.The onset after three years of age occurred in 88 children.
When analyzing the gender variable with the two groups analyzed, it was found that there was no significant association for the data of this study.
Although there was no significant association between gender and the different groups, Figure 2 shows that there are more males than females in all groups.
a continuum of language delay.It aimed to investigate whether children with atypical phonological development had some previous delay in language development and evolved to a change only at the phonological level of language.

METHODS
This paper was developed from collection of data on children with abnormal speech, in a clinic of a higher education institution.Data were collected from all patients with atypical phonological development, who have been treated at the speech therapy department of that institution since 1991.
The database was comprised of records of patients screened and treated since 1991, and children who were still being treated in the speech therapy department.Parents and/or guardians signed an authorization for compilation of the database and use of data from therapy in the research.This study was authorized by the Research Ethics Committe of the Federal University of Santa Maria (UFSM), under number 0202.0.243.000-11.Therefore, it is a retrospective study.
Data collection discarded subjects with other changes such as disfluency, verbal and/or buccolingual-facial dyspraxia, cleft palate or neurological disorders.Thus, data from 644 children were collected over a period of 10 months, between September 2012 and June 2013.The data were categorized into two groups -G1 and G2.G1 was composed of 10 children who came to the clinic with language delay, underwent speech therapy for language stimulation and progressed after treatment, and were relocated from the language department to the speech department.So after the progress of patients, i.e., when the language features that were previously lagged (pragmatics, morphology, syntax, semantics) were adequate, patients were then transferred to the speech department because they still had changes at the phonological level, i.e., phonological disorders.G2 consisted of 554 subjects who came to the clinic and had phonological disorders.In this group, 80 subjects were excluded from G2 because they did   Figure 3 shows that there was no significant outcome between the performance of male and female children for age of onset of first words, since the distribution was quite similar between subjects.
The result obtained by the Mann-Whitney test showed that there is no significant difference between the performance of male and female children for age of onset of first words.In addition, the age of onset of first words in the group with language delay was quite late compared with the other groups, as can be seen in Figure 4.Moreover, when examining the median, it was found that data distribution is not uniform, and late onset of first words in the group with language delay is evident.
Table 3 shows a significant difference when comparing the age of onset of first words of children in the different groups studied (phonological disorder, phonetic and phonological disorder, phonetic disorder associated with environmental/ emotional factors and language delay).

DISCUSSION
The initial hypothesis of this research was that if there were more cases with language delay, and that the other levels of language were adjusted when these subjects performed speech therapy, change in phonological level could remain.This finding was not observed in this study, because only 10 subjects in the speech department had a history of language delay.Thus, the results had no significant difference between different groups.However, this finding agrees with the literature, which reports that phonological disorder refers only to a change at the level of phonology, with no change in the other linguistic levels, no mechanical alteration of speech production, i.e., there is a flaw in the organization of the sound system of language, even in the absence of detectable organic changes [8][9][10][11][12] .
Nevertheless, although there are few subjects with language delay, many children in the present study began speaking their first words later, after two years of age, as can be seen in the frequency graph (Figure 1).Given this outcome, it is worth noting that parents should be attentive to the emergence of the language of their children, because during the first years of life, significant acquisitions occur.Thus, the sooner early intervention occurs, the more effective it will be for the proper development of the child 4,13,14 .
Therefore, in this study, the onset of first words was expected to occur earlier in girls and later in boys.However, the results agree with a study in which there was no significant difference for gender as regards phonological acquisition 22 .
For the comparison between age of onset of first words and diagnosis, the result showed a significant difference in the comparison, since children with language delay had later ages of onset of first words than children with phonological disorder.This finding is consistent with the pathology of language delay, since the emergence of language occurs later, while language development starts within the expected period for phonological disorder, but there are changes in the phonological system 3,13,23 .

CONCLUSION
According to the results presented in this study, it was found that phonological disorder does not refer to a continuum of language change, i.e., it is not identified as a final step to overcome linguistic difficulty.Thus, the findings from this study support the literature, because phonological disorder refers to a change at the phonological level only, while the other language levels are adequate and, therefore, not due to a delay in language.
It should be noted that the number of subjects with language delay (G1) and phonological change could be more common if the families of the 195 children (whose emergence of first words occurred after 2 years of age, which can be considered late) had sought treatment earlier.Thus, when they were to start speech therapy, they would have probably already overcome language delay, and only phonological change would have to be treated.
There was no significant association, either, in the comparison of performance between boys and girls and different groups.Such fact disagrees with the literature 15,16 , which shows that phonological disorder happens more often among boys.There are studies where girls show better outcomes than boys with regard to tasks involving language skills [17][18][19][20][21] .However, although there was no significant association, there has been a prevalence of males with phonological disorders, phonetic phonological disorders, phonological disorders associated with environmental/emotional factors and language delay/disorder (Figure 2) .
Similarly, in this study, no statistical correlation was found between the variables "age" and "gender".The results obtained were similar among boys and girls, as regards the onset of first words.This result does not agree with the literature, because girls often excel in activities involving language skills [17][18][19][20][21] .

Figure 1 -
Figure 1 -Distribution of subjects by age of onset of first words in group 1 and group 2

Figure 2 -
Figure 2 -Distribution of subjects according to gender and the different groups

Table 2 -Figure 3 -
Figure 3 -Graph of the distribution of subjects according to age of onset of first words and gender

Figure 4 -
Figure 4 -Distribution of subjects according to age of onset of first words and groups

Table 1 -Association between boys and girls (gender variable) in the different groups Gender
vs. GROUPS 1 AND 2 p = 0.038 Caption: Statistical software: Statistics; Chi-square test with a significance level of 5% (p <0.05)