Early Indicators of Learning Disabilities in Children with Developmental Language Disorder Compared to Their Typically Developing Peers

Abstract

Developmental language disorder (DLD) is a language deficit affecting approximately 7% of the general population and does not associate with any hearing impairment, neurological damage, or mental disorder. In DLD, the complications arise over time due to the learning difficulties experienced, which causes eventual cognitive delay compared to peers. Therefore, early diagnosis is important in children with DLD. In this study, the objective was to screen for early signs of learning disability in children aged 4 to 6 years with DLD. The study included 30 normal developing children and 26 children with DLD. The children with normal development comprised 17 boys and 13 girls, while the group of children with DLD included 16 boys and 10 girls. Learning disability was evaluated using the Learning Disability Early Symptoms Screening Scale (LDESSS) and Test of Early Literacy (TEL). Children with DLD scored higher on all subscales of LDESSS and lower on all subscales of TEL than the normal developing group (p < .001). According to LDESSS and TEL scores, the risk of learning disability in children with DLD was significantly higher than the normal developing group. In addition, gender had no significant association in terms of learning disability. Since the risk of learning disabilities in children with DLD is higher than normal developing peers, early diagnosis and early therapy is recommended to prevent academic and social problems in the future.

Keywords

developmental language disorder learning disability typically developing peers learning disorder developmental language

Introduction

Developmental language disorder (DLD) is a long-standing language deficit not associated with any hearing impairment, neurological damage, intellectual disability, or autism spectrum disorder, and is also defined as specific language disorder (SLD). According to epidemiological studies, DLD is the largest category of language disorders, affecting approximately 7% of the general population (Thordardottir et al., 2011). The prevalence of language impairment in five-year-old children in the UK has been documented as 7.58% (Norbury et al., 2016). In the US, researchers found that 7.4% of 5-year-old children (n = 2,009) met diagnostic criteria (Tomblin et al., 1997). Between 2008 and 2013, a study was carried out on a sample of ~10,000 Italian primary school kids at the ages of 8 to 10 years. The results showed that, while 3.5% of the sample had previously received an SLD diagnosis, just 1.3% of them had been diagnosed (Barbiero et al., 2019). Unfortunately, studies on the prevalence of DLD in Turkey are limited. However, according to our clinical experience, the rate of individuals with DLD in Turkey is similar to the rate in other countries.

Although children with DLD are clearly a vulnerable group, they frequently go undiagnosed and are not provided with specialized care (Zhang & Tomblin, 2000). This is especially true for female DLD patients, whose referral rates are lower than those of male patients (Morgan et al., 2017). The language problem children experience is not a short-term complication rather, a long-term issue that results in cognitive delay compared to peers (Rice & Hoffman, 2015). DLD causes declines in academic performance, poor reading comprehension, difficulties in mathematical problems, an increase in the risk of social withdrawal, and emotional problems in adolescents (Reilly et al., 2014). Females with DLD are three times more likely to experience sexual abuse, and males with the disorder are four times more likely to participate in anti-social behavior (Brownlie et al., 2004, 2007).

Deficits Observed in Children with DLD

Children with DLD may have difficulties in learning words, keeping words in mind, comprehending the contextual relationships of words, and comprehending and forming phonological representations of language (Norbury, 2004). Due to these difficulties, there are important problems in the morphological and syntactic structure of the language. The morphosyntactic structure is the most affected area in children with developmental language disorders (Norbury, 2004). Less evident, yet easily identified through methodical investigation, are the difficulties these children have learning words. The vocabulary-related deficiencies that these children have are very diverse. DLD know comparatively little about many of the words they do use, and they have a smaller vocabulary (Cummings & Ceponiene, 2010; Kail & Leonard, 1986; Leonard et al., 1983; McCormack et al., 2019).

Children with DLD may have deficiencies in cognitive skills such as short-term memory problems in both verbal and non-verbal areas, procedural memory deficits, working memory, and executive dysfunctions (Botting, 2020). In addition, they may have difficulties in phonological working memory and tasks that assess cognitive flexibility (Marini et al., 2020). Moreover, decreases in nonverbal IQ can be observed in children with DLD. Deficiencies in cognitive skills in children with DLD also affect academic performance. Academic success refers to the understanding, knowledge, and skills acquired through the learning process that includes literacy and numeracy at school (Cross et al., 2019). Non-verbal IQ, spoken language, and literacy are potential determinants of performance in school according to longitudinal studies (Ziegenfusz et al., 2022). The low average nonverbal IQ of children with DLD is a strong predictor of performance on academic exams. Nonverbal IQ is also significantly correlated with student performance in numeracy, literacy, and classroom-based learning. Non-verbal IQ, verbal language, and literacy affect student learning performance in core curriculum areas such as science, mathematics, and English (Durkin et al., 2015). Children with DLD have deficiencies in executive functioning and theory of mind and language development deficits from early childhood. Executive functioning and theory of mind are accepted as predictors of social-emotional functioning. Children with DLD have social-emotional developmental deficiencies due to difficulties in social and internal dialogue (Arts et al., 2022). DLD is not just a delayed speech disorder, it is a language learning and use disorder, which negatively affects children’s social and academic lives, and requires immediate diagnosis and intervention. Early intervention can help to strengthen a childs vocabulary so that they can use these words in the right contexts, learn the grammar rules they have not mastered, and gain social communicative skills. In addition, intervention for school-age children can improve capacity to follow academic instructions, understand language and comprehension, organize information, and improve speaking, reading and writing skills.

Relationship Between DLD and Learning Disabilities

Learning disabilities are the most frequently seen disorders in school-age children and are observed at a rate of approximately 5% to 15% (American Psychiatric Association, 2013). Children with learning disabilities generally have average intelligence but have problems processing information or producing output. Learning disabilities, which can affect neurocognitive processes, may involve defects in reading, writing, listening, speaking, spelling, solving math problems, concentrating, reasoning, and/or organizing information. Moreover, some children may develop difficulties with motor coordination. Recent studies revealed that approximately 20% of the population has some degree of learning disability. Dyslexia (reading disability), dyscalculia (mathematics disability), and dysgraphia (writing disability) have been identified as the most common SLD (Handler et al., 2011).

Children’s academic, cognitive, and emotional-behavioral skills begin to develop at an early age and pave the way for their further development. In particular, the development of academic and cognitive skills at an early age is interrelate (Jylanki et al., 2022). Literacy difficulties in dyslexic people cause problems in academic achievement as well as feelings of anxiety and depression (Bazen et al., 2023). Studies have reported that children with SLD have a higher risk of experiencing socio-emotional and academic difficulties than normal developing peers. It has been observed that the reading skills of children with DLD are weaker than their normal developing peers (Boudreau & Hedberg, 1999), and children with DLD also exhibit weaker mathematics skills and verbal working memory in comparison to their peers (Foster et al., 2023).

Developmental language disorder and SLD are two independent neurodevelopmental disorders that appear somewhat similar and related, often causing difficulties in the diagnosis process. Because the two disorders are clinically similar, it is difficult for clinicians to decide whether they are the same or two separate language disorders (Rice & Hoffman, 2015) or overlapping disorders (Catts et al., 2005). Short-term memory deficits, morphosyntax, and difficulties in reading comprehension, phonological processing, and rapid automatic naming are symptoms that may be evident in children with both DLD and SLD. Therefore, while SLD can be observed in children with DLD, children with SLD may exhibit symptoms of DLD (Bonti et al., 2021). In a recent longitudinal study conducted in Italy, the prevalence of SLD was determined to be seven percent. Researchers have also determined that approximately two-thirds of children with SLD have typical language development, while approximately 30% of children with SLD have a history of SLD (Rinaldi et al., 2023).

The approach that deals with learning disability from a phonological perspective states that learning disability is a language-based neurological disorder, and many problems such as language delays, expressive language difficulties, weakness in phonological awareness, and phonological processing difficulties are risk factors for early learning disability (Snowling, 1995). Considering these definitions and relationships, developmental language disorders and learning disabilities are thought to be consecutive disorders. Therefore, language skills may be a predictor of learning disability. We believe that children with DLD will have learning disabilities compared to their normal developing peers. Early recognition of learning disabilities is very important for early therapy. In this study, we hypothesized that children with DLD would score worse on screening tests than their normal developing peers. We also hypothesized that DLD can be recognized by measurements at early stages of language development. Based on previous study results (Mascheretti et al., 2018; Rinaldi et al., 2023), we hypothesized that male gender would increase the likelihood of a child being diagnosed with SLD, and that gender would not affect screening test results. In this study, it was aimed to screen for early signs of learning disability in children aged 4 to 6 years old with DLD. For this purpose, language development and communication skills, cognitive skills, psychomotor development skills and social-emotional skills of typically developing children and children with developmental language disorders were evaluated with Learning Disability Early Symptoms Screening Scale (LDESSS), and early literacy skills were evaluated with Test of Early Literacy (TEL).

Material and Methods

Fifty-six children participated in the study, including 30 with typical language abilities (typically developing children) and 26 children with DLD. Research data were collected between March 2023 and April 2023. This research was approved by Bahçeşehir University Scientific Research and Publication Ethics Committee (E-20021704-604.02.02-48470). The parents/legal guardians of the participants were informed about the study by the researchers and informed that their participation was based on the principle of voluntariness, and their verbal and written consents were obtained. Inclusion criteria for children with typical development were determined as being monolingual, native language being Turkish, age between 48 and 72 months, not having been diagnosed with developmental language disorder, no additional cognitive, motor or sensory problems, scoring at or above the expected level from the TELDT receptive language and expressive language subtests (≥90 points) and attending any pre-school education institution. Inclusion criteria for children with DLDs were defined as being monolingual, native language being Turkish, age between 48 and 72 months, having been diagnosed with DLD, no additional cognitive, motor or sensory problems, scoring below the expected level in the TELDT expressive language or receptive and expressive language subtests (≤89 points) and attending any pre-school education institution. The demographic characteristics of the participants and their TELDT results are presented in Table 1.

Table 1.

Demographic Characteristics and Turkish Early Language Development Test (TELDT) Results of All Participants Included in the Study.

Participant	Gender	Age (month)	TELDT results
Participant	Gender	Age (month)	RLS	ELS	VLP
DLD1	Female	48	86	82	80
DLD2	Male	49	86	84	81
DLD3	Female	48	92	82	83
DLD4	Female	51	93	86	87
DLD5	Female	50	90	82	86
DLD6	Male	58	89	78	73
DLD7	Male	54	89	81	84
DLD8	Male	52	95	84	87
DLD9	Female	58	80	74	72
DLD10	Female	53	93	80	82
DLD11	Male	48	90	87	87
DLD12	Female	49	88	88	83
DLD13	Male	48	87	76	77
DLD14	Male	49	92	81	83
DLD15	Male	48	82	82	78
DLD16	Male	53	92	86	87
DLD17	Male	50	84	85	81
DLD18	Female	58	74	68	66
DLD19	Male	57	91	82	84
DLD20	Male	52	81	72	71
DLD21	Male	58	92	83	86
DLD22	Male	53	81	83	78
DLD23	Female	49	72	73	67
DLD24	Male	48	84	71	72
DLD25	Male	54	82	81	78
DLD26	Female	52	82	81	79
TDP1	Male	58	111	111	115
TDP2	Male	53	110	110	117
TDP3	Male	48	98	100	97
TDP4	Male	49	100	106	104
TDP5	Female	48	99	98	98
TDP6	Male	49	95	103	99
TDP7	Male	48	97	102	98
TDP8	Female	53	108	105	110
TDP9	Male	50	106	112	109
TDP10	Male	58	107	101	102
TDP11	Female	57	111	115	115
TDP12	Male	48	99	94	95
TDP13	Male	49	96	114	117
TDP14	Female	48	94	95	94
TDP15	Female	51	99	104	105
TDP16	Male	50	94	95	94
TDP17	Male	58	97	101	101
TDP18	Female	54	97	93	95
TDP19	Male	52	99	107	106
TDP20	Female	48	103	100	104
TDP21	Male	49	99	100	102
TDP22	Female	48	100	92	93
TDP23	Female	51	106	96	105
TDP24	Female	50	92	94	93
TDP25	Male	58	105	104	108
TDP26	Male	54	102	99	100
TDP27	Male	52	99	114	115
TDP28	Female	48	100	94	96
TDP29	Female	57	102	98	99
TDP30	Female	52	98	95	97

Note. DLD = developmental language disorder; TDP = typically developing peers; RLS = receptive language score; ELS = expressive language score; VLP = verbal language performance.

To receive a special needs report related to developmental language disorder from the Guidance and Research Centers (RAM), hearing assessment, developmental assessment, and intelligence assessments must be performed in the Child Psychiatric Clinic, Ear Nose Throat Clinic, Developmental Pediatrics clinic, and Audiology departments. These assessments were not applied during the research process, as children who were included in the study had participated in these assessments and already had RAM reports.

Participants were divided into two groups: DLD and TDP. Then, LDESSS was filled in according to the families’ statements and answers. Other tests were administered to the participants themselves. A 15-minute break was given after each test application. The study design is shown in Figure 1.

Figure 1.

Study design.

Turkish Early Language Development Test (TELDT)

The Turkish Early Language Development Test, which aims to evaluate receptive and expressive language skills in children between 2 years 0 months and 7 years 11 months, was adapted to Turkish in 2014 and standardized (Topbaş & Güven, 2013). The test has two subsections that evaluate receptive and expressive language skills. The receptive language subscale consists of 37 items, with 24 items measuring semantic knowledge and 13 items measuring grammar. The expressive language subscale consists of 39 items, with 24 items measuring semantic knowledge and 15 measuring grammar. In younger age groups, test items are scored based on the parent report.

Ankara Articulation Test (AAT)

This test was developed by Ege et al. (2004) to evaluate articulation in children aged 2 to 12 years. Construct validity was ensured by comparing the absence of another test similar to the AAT in Turkish and the data obtained from the AAT with the information on the acquisition of phonemes in children aged 2 to 12 years. In construct validity, it is expected that the number of errors in articulation acquisition will be high at early ages; these errors will decrease rapidly in the school period, and there will be differences between the ages. It was determined that in AAT, the articulation error averages of the students decreased with age, and the differences between the age groups were especially high in the early age groups. Regarding internal validity, AAT includes most of the phonemes used in Turkish. Ankara Articulation Test consists of 48 standardized color images that allow using sounds in five positions. Errors are counted by testing 19 consonant phonemes and 4 consonant clusters in 31 words and in different positions in Turkish.

Learning Disability Early Symptoms Screening Scale (LDESSS)

This test was developed to evaluate children aged 4 to 6 years who may be at risk for learning disabilities (Okur, 2019). The Learning Disability Early Symptoms Screening Scale is a tool based on parental view. The items in the LDESSS were developed based on DSM 5, developmental, cognitive, and phonological approaches. It is more focused on observable behavioral symptoms. The scale has four subscales consisting of a total of 52 items. The subscales are Language Development and Communication Skills, Cognitive Skills, Psychomotor Development Skills, and Social-Emotional Skills. Items are scored as 1—Completely disagree, 2—Disagree, 3—Undecided, 4—Agree, and 5—Completely agree. The higher the score, the higher the risk of learning disabilities. Language Development and Communication subscale includes 14 items covering general language and speech development that may be associated with learning disability. The Cognitive Skills subscale consists of 19 items covering areas such as memory, working memory, attention, and executive functions. The Psychomotor Developmental Skills subscale consists of 13 items covering areas such as fine and gross motor skills and balance. The Social-Emotional Skills subscale consists of seven items covering areas such as peer communication, family communication, and social interaction. Total learning disability risk can be measured by summing the learning disability risk level for each subscale and the raw scores of the subscales. Thus, participants can be evaluated in detail according to the contents of the subscales. Cronbach’s alpha value for LDESS was .835.

Test of Early Literacy (TEL)

This test consists of seven subscales to determine the children who are in the risk group for early literacy skills and who need to be supported in terms of these skills in the pre-school period (Kargın et al., 2015). The subscales are 1. Receptive Language 2. Expressive Language, 3. Category Naming, 4. Function Knowledge, 5. Letter Knowledge, 6. Phonological Awareness, and 7. Listening Comprehension. There is a sample item and 15 question items in the receptive language subscale. Children were asked to point to the object whose name was mentioned among the four pictures shown to them. The options next to each target word are selected from the semantic category in which the target word is found. There is a sample item and 15 question items in the expressive language subscale. In this section, children are asked to name the picture shown to them. There is a sample item and 10 question items in the category naming subscale. Children are expected to say categorically how the pictures shown to them are named. There is a sample item and 10 question items in the functional knowledge subscale. Children are asked to say what the objects shown and named to them do. In TEL, letter knowledge is handled in two different dimensions as letter knowledge in the receiving language and letter knowledge in the expressive language. The knowledge of letters in the receptive language consists of seven questions and the children were asked to show the letter that was told to them from among four options. There are also seven questions in the knowledge of letters in expressive language, and the children were asked to name the letter shown to them. Phonological awareness skills are measured in eight sub-dimensions: (a) rhyme awareness, (b) initial sound matching, (c) final sound matching, (d) splitting a sentence into words, (e) splitting a words into syllables, (f) combining syllables into words, (g) removing the initial sound of words, and (h) removing the final sound of words. In the listening comprehension subscale, there is a story consisting of 11 sentences and 80 words and questions about the story (what, where, why, when, how, who). During the application of the test, the child is first asked a sample item question and is expected to respond within the next 3 s. If there is no response from the child or an incorrect answer is given, the question is answered by the practitioner to set an example for the child. In the test items, when the child does not answer or gives an incorrect answer, the practitioner proceeds to the next question without reacting or using neutral answers. Cronbach’s alpha value for TEL was .832.

In this study, application reliability data were collected. Application reliability means that each step of the application is carried out precisely and consistently as intended (Gresham, 1989). In this study, the reliability of the application was made in terms of whether the practitioner complied with the instructions while applying the tests and whether the participant correctly evaluated the answers and recorded them in the evaluation form completely and accurately. The audio recordings collected in this context were monitored by independent observers, and the practitioner’s process of administering the tests and the children’s responses were recorded in the Application Reliability Form, which is separate for each test. Compliance percentages were calculated by using the formula “Agreement/Agreement + Disagreement × 100” for application reliability calculations (Kırcaali-Iftar & Tekin, 1997). The application reliability was found to be 91.10%.

The profession of speech and language therapy is a newly developing profession in Turkey. Therefore, valid and reliable tests and scales are quite limited. The only detailed assessment tool for childhood language disorders is TELDT. Similarly, among the two articulation evaluation tests, the use of AAT was chosen because it is fast and practical and can be used after many scales. The LDESSS scale was recently defined and was preferred because it addresses learning disabilities with many subdomains and different dimensions. Similarly, the TEL used is also the only test developed in this field. Therefore, the above-mentioned tests were used in this study. LDESSS is filled in according to the families’ statements and answers. Other tests were administered to the participants themselves. Although the items were short and eye-catching, it was difficult for the participants to concentrate their attention during the application. For this reason, a 15-minute break was given after each test application. The practice tests used in this study are also used in evaluation and diagnosis processes in related areas such as speech sound disorder, developmental language disorders diagnosis and early literacy skills.

Statistical Analysis

Statistical analysis was performed using SPSS 20 statistical software. Kolmogorov–Smirnov test was used to evaluate the fit of the measured data to the normal distribution. The mean, standard deviation, median, minimum, and maximum values of continuous variables, and n and percentage values of categorical variables were given. The Mann-Whitney U test was used for pairwise comparisons of data that did not show normal distribution. Pearson Chi-Square test was used to compare categorical variables. The limit of significance for all statistics was set at p-value of less than .05. The following formula was used to calculate the effect size (r) of the variables that were significant in the Mann-Whitney U test (Corder & Foreman, 2009).

Results

Of the children included in the study, 30 were typically developing children and 26 were DLD. In the group of typically developing children, 17 (56.7%) were boys and 13 (43.3%) were girls, while in the group of children with DLD, 16 (61.5%) were boys and 10 (38.5%) were girls. There was no significant difference between the groups in terms of gender (χ² = 0.137, p = .712). The children with typical development and those with DLD were similar in age, and there was no significant difference between them (51.60 ± 3.60 months and 51.81 ± 3.57 months, respectively; Table 2).

Table 2.

Comparison of Demographic Data of Children with Typical Development and Developmental Language Disorders (DLD), and Overall and Subsection Scores of Learning Disability Early Symptoms Screening Scale (LDESSS) and Test of Early Literacy (TEL).

Demographics	Typical development	DLD	p
Gender
Male	17 (56.7%)	16 (61.5%)	χ² = 0.137
Female	13 (43.3%)	10 (38.5%)	p = .712
Age (months)	51.60 ± 3.60	51.81 ± 3.57	Z = −0.308
Age (months)	50.50 (48–58)	51.50 (48–58)	p = .758
LDESSS
Language development and communication skills	19.56 ± 1.35	42.50 ± 5.81	Z = −6.441; p < .001; r = .86
Language development and communication skills	20.0 (18–23)	44.0 (30–51)	Z = −6.441; p < .001; r = .86
Cognitive skills	39.83 ± 7.64	62.84 ± 10.39	Z = −5.989; p < .001; r = .80
Cognitive skills	36.0 (28–55)	60.5 (46–80)	Z = −5.989; p < .001; r = .80
Psychomotor skills	15.30 ± 2.90	35.30 ± 6.82	Z = −6.419; p < .001; r = .85
Psychomotor skills	14.0 (13–22)	35.5 (22–48)	Z = −6.419; p < .001; r = .85
Social sensory skills	7.20 ± 0.55	14.50 ± 8.17	Z = −6.694; p < .001; r = .89
Social sensory skills	7.0 (7–9)	12.0 (9–49)	Z = −6.694; p < .001; r = .89
Overall score	81.90 ± 9.68	155.15 ± 22.39	Z = −6.411; p < .001; r = .85
Overall score	79.50 (71–100)	149 (120–200)	Z = −6.411; p < .001; r = .85
TEL
Vocabulary knowledge	49.83 ± 0.46	26.65 ± 2.48	Z = −6.765; p < .001; r = .90
Vocabulary knowledge	50 (48–50)	26 (21–31)	Z = −6.765; p < .001; r = .90
Phonological awareness	31.56 ± 0.62	13.07 ± 2.29	Z = −6.556; p < .001; r = .87
Phonological awareness	32 (30–32)	13 (9–18)	Z = −6.556; p < .001; r = .87
Letter knowledge	13.23 ± 1.07	1.65 ± 0.62	Z = −6.565; p < .001; r = .87
Letter knowledge	14 (10–14)	2 (1–3)	Z = −6.565; p < .001; r = .87
Listening comprehension	5.70 ± 0.46	3.42 ± 0.50	Z = −6.692; p < .001; r = .89
Listening comprehension	6 (5–6)	3 (3–4)	Z = −6.692; p < .001; r = .89
Overall score	100.33 ± 1.58	44.80 ± 3.16	Z = −6.437; p < .001; r = .86
Overall score	100.5 (96–102)	44 (38–50)	Z = −6.437; p < .001; r = .86

Note. Z = Mann-Whitney U test; χ² = chi-square test.

The receptive language, expressive language, and verbal language performance scores of the children were determined with the TELDT performed for the diagnosis of DLD. The receptive language scores of typically developing children were 119 at the highest and 98 at the lowest, expressive language scores were 122 at the highest and 96 at the lowest, and verbal language performance scores were 130 at the highest and 100 at the lowest. Receptive language scores of children with DLD were 92 at the highest and 50 at the lowest, expressive language scores were 90 at the highest and 48 at the lowest, and verbal language performance scores were 83 at the highest and 41 at the lowest.

The results of LDESSS in children with typical development and children with DLD are shown in Table 2. Children with DLD scored 42.50 ± 5.81 in the language development and communication skills section, while children with typical development scored 19.56 ± 1.35 points. The difference between the groups in terms of language development and communication skills subsection was significant (Z = −6.441, p < .001, r = .86). While children with typical development scored 39.83 ± 7.64 in the cognitive skills subsection, children with DLD scored 62.84 ± 10.39, and the difference was significant (Z = −5.989, p < .001, r = .80). The score of children with DLD on the psychomotor skills subsection was 35.30 ± 6.82, which was significantly higher than the score of children with typical development (15.30 ± 2.90) (Z = −6.419, p < .001, r = .85). Children with DLD scored 14.50 ± 8.17 on the social sensory skills subsection, while children with typical development scored 7.20 ± 0.55, and the scores of children with typical development were significantly lower than those of children with DLD (Z = −6.694, p < .001, r = .89). As in the subsection results of LDESSS, the scores of children with DLD in overall score results (155.15 ± 22.39) were significantly higher than the scores of children with typical development (81.90 ± 9.68) (Z = −6.411, p < .001, r = .85).

The test of early literacy scores of the children are given in Table 2. The vocabulary knowledge score of typically developing children was 49.83 ± 0.46, and the vocabulary knowledge score of the children with DLD was 26.65 ± 2.48, and the difference was significantly higher (Z = −6.765; p < .001, r = .90). The phonological awareness score of typically developing children was significantly higher than the phonological awareness score of children with DLD, 31.56 ± 0.62 versus 26.65 ± 2.48 (Z = −6.556, p < .001, r = .87), respectively. Similarly, letter knowledge and listening comprehension scores of children with typical development were significantly higher than letter knowledge and listening comprehension scores of children with DLD, 13.23 ± 1.07 versus 1.65 ± 0.62 and 5.70 ± 0.46 versus 3.42 ± 0.50 (Z = −6.565, p < .001, r = .87; Z = −6.692, p < .001, r = .89), respectively. The TEL general score of the typically developing children was 100.33 ± 1.58, and the TEL general score of the children with DLD was 44.80 ± 3.16, and the difference was significantly higher (Z = −6.437, p < .001, r = .86).

Comparison of LDESSS and TEL subsections and overall scores by gender is given in Table 3. There were no significant differences by gender in terms of all subsections and overall scores of both LDESSS and TEL.

Table 3.

Comparison of Overall and Subsection Scores of Learning Disability Early Symptoms Screening Scale (LDESSS) and Test of Early Literacy (TEL) According to Gender.

Age	Male	Female	p
Age (months)	51.61 ± 3.63	51.83 ± 3.53	Z = −0.152
Age (months)	50 (48–58)	51 (48–58)	p = .879
LDESSS
Language development and communication skills	30.66 ± 12.51	29.56 ± 12.05	Z = −0.285
Language development and communication skills	21 (18–49)	22 (18–51)	p = .776
Cognitive skills	50.39 ± 14.73	50.69 ± 14.79	Z = −0.175
Cognitive skills	50 (32–80)	50 (28–79)	p = .861
Psychomotor skills	25.81 ± 12.59	22.82 ± 9.00	Z = −0.285
Psychomotor skills	22 (13–48)	22 (13–43)	p = .776
Social sensory skills	10.27 ± 4.50	11.04 ± 8.96	Z = −0.246
Social sensory skills	9 (7–24)	8 (7–49)	p = .806
Overall score	117.15 ± 42.30	114.13 ± 38.50	Z = 0.000
Overall score	99 (72–200)	99 (70–187)	p = 1.000
TEL
Vocabulary knowledge	38.09 ± 12.33	40.47 ± 11.07	Z = −1.380
Vocabulary knowledge	48 (21–50)	50 (26–50)	p = .167
Phonological awareness	22.69 ± 9.52	23.39 ± 9.52	Z = −0.060
Phonological awareness	31 (9–32)	30 (9–32)	p = .952
Letter knowledge	7.57 ± 5.76	8.26 ± 6.18	Z = −0.179
Letter knowledge	10 (1–14)	13 (1–14)	p = .858
Listening comprehension	4.57 ± 1.22	4.73 ± 1.28	Z = −0.513
Listening comprehension	5 (3–6)	5 (3–6)	p = .608
Overall score	72.93 ± 28.50	76.86 ± 27.83	Z = −1.062
Overall score	96 (38–102)	99 (42–102)	p = .288

Note. Z = Mann-Whitney U test.

Table 4 shows the comparison of the risk of learning disability according to the subsection and the overall score of LDESSS in children with typical development and DLD. According to LDESSS scores, the risk of learning disability in language development and communication skills (χ² = 56.000, p < .001), cognitive skills (χ² =32.534, p < .001), psychomotor skills (χ² = 52.109, p < .001), and overall score (χ² = 42.598, p < .001) of children with DLD was found to be significantly higher than that of children with normal development. No difference was observed in terms of the risk of learning disability related to social-emotional skills.

Table 4.

The Results of the Analysis Regarding the Risk of Learning Disability According to the Overall and Subsection Scores of Learning Disability Early Symptoms Screening Scale (LDESSS) Among the Groups.

	Low	Light	Medium	High	χ²	p
Risk of learning disabilities associated with language development and communication skills
Typical development	30 (100%)	0 (0.0%)	0 (0.0%)	0 (0.0%)	56.0	<.001
Developmental language disorders	0 (0.0%)	7 (26.9%)	19 (73.1%)	0 (0.0%)	56.0	<.001
Risk of learning disabilities associated with cognitive skills
Typical development	1 (3.3%)	25 (83.3%)	4 (13.4%)	0 (0.0%)	32.5	<.001
Developmental language disorders	0 (0.0%)	3 (11.5%)	15 (57.7%)	8 (30.8%)	32.5	<.001
Risk of learning disabilities associated with psychomotor skills
Typical development	30 (100%)	0 (0.0%)	0 (0.0%)	0 (0.0%)	52.1	<.001
Developmental language disorders	1 (3.8%)	17 (65.4%)	8 (30.8%)	0 (0.0%)	52.1	<.001
Risk of learning disabilities associated with social-emotional skills
Typical development	30 (100.0%)	0 (0.0%)	0 (%0.0)	0 (0.0%)	1.2	.464
Developmental language disorders	25 (96.2%)	1(3.8%)	0 (%0.0)	0 (0.0%)	1.2	.464
Overall risk of learning disabilities
Typical development	25 (83.3%)	5 (16.7%)	0 (0.0%)	0 (0.0%)	42.6	<.001
Developmental language disorders	0 (0.0%)	10 (38.5%)	15 (57.7%)	1(3.8%)	42.6	<.001

Note. χ² = chi square test.

The results of the AAT, which evaluated the pronunciation problems in all children with DLD and in two children with typical development, are shown in Table 5. In total, errors were detected in the pronunciation of 13 letters (k, g, l, r, s, ş, n, f, v, z, m, c, ç). The letter with the most mistakes was the letter “z,” which was seen in 24 of the 28 participants, and the letter with the fewest mistakes was the letter “c,” which was observed in two people.

Table 5.

Sounds with Faulty Production According to Ankara Articulation Test.

Answer	k	g	l	r	s	ş	n	f	v	z	m	c	ç
Yes	12 (42.9%)	10 (35. 7%)	20 (71.4%)	7 (25%)	17 (60.7%)	17 (60.7%)	20 (71.4%)	18 (64.3%)	23 (82.1%)	24 (85.7%)	20 (71.4%)	2 (7.1%)	22 (78.6%)
No	16 (57.1%)	18 (64.3%)	8 (28.6%)	21 (75%)	11 (39.3%)	11 (39.3%)	8 (28.6%)	10 (35.7%)	5 (17.9%)	4 (14.3%)	8 (28.6%)	26 (92.9%)	6 (21.4%)

Discussion

One of the most important criteria in determining social and academic success in school years and even in adulthood is school preparation skills. Among the school readiness skills, early literacy skills has been directly linked to behavioral, social, and academic success at school (Pears et al., 2016). Listening comprehension, name writing ability, alphabet knowledge and phonological awareness, which have been evaluated in early literacy development, were significantly associated with future reading success (Justice et al., 2015). Language skills may be a predictor of learning disability.

In this study, we aimed to compare children with DLD and children with normal development in terms of early signs of learning disability. Our hypothesis before the study was that children with DLD would have learning difficulties compared to their normal developing peers, and therefore children with DLD would receive worse scores in screening tests than their normal developing peers. Thus, in this study, it was determined that children with DLD had higher scores on the language development and communication skills, cognitive skills, psychomotor skills, and social sensory skills subsections of LDESSS than the children with normal development. In addition, it was determined that children with DLD scored lower in the vocabulary knowledge, phonological awareness, letter knowledge, and listening comprehension sub-sections of TEL than children with normal development. The high scores obtained from both the subsections and the overall score of the LDESSS in children with DLD indicate a high risk of learning disability.

Another hypothesis of our study was that DLD would be observed more frequently in boys and gender would not affect the screening test results. In our study, it was determined that the number of boys diagnosed with DLD was higher than girls, but this was not statistically significant. However, we think that the lack of significance was due to the study not investigating the prevalence of DLD in the general population, but only children diagnosed with DLD in a specific center. However, the fact that male’ LDESSS and TEL scores were similar to female’ LDESSS and TEL scores shows that gender was not an effective factor in terms of learning disabilities in children with DLD.

Children with SLD have a higher risk of socio-emotional and academic difficulties than their peers without SLD (National Assessment of Educational Progress, 2022). Children with DLD should be evaluated in terms of learning disabilities because they show inadequacy in areas such as reading, writing, mathematics, and science (Foster et al., 2023). It is thought that children who have problems with the semantic and syntactic components of language may have more disabilities in reading (Bishop & Adams, 1990). In a study conducted with 41 children with DLD in the preschool period, the children were in the high-risk group for reading disabilities during the school period. Moreover children with DLD had poorer reading skills than their normal developing peers (Catts, 1991). Boudreau and Hedberg (1999) examined early reading-related skills in 18 children with DLD and compared them to their normal developing peers. They found that children with DLD had insufficient reading skills compared to their normal developing peers.

Children with DLD also showed weaknesses in various areas of arithmetic skills such as verbal counting, number words, and written calculations (Bonti et al., 2021). Fyfe et al. (2019) observed that children with DLD exhibited poorer mathematics skills and verbal working memory than their normal developing peers. In addition to speech language and math difficulties, children with DLD also showed significant difficulties with the same writing skills. In a study by Cabell et al. (2009), which examined the name-writing skills of four-year-olds with DLD and four-year-olds without DLD, they found that 42% of children with DLD could not write any letters from their names and 44% wrote at least one recognizable letter. They also reported that normal developing children displayed more advanced name writing than children with DLD. Pavelko et al. (2017) documented that children with DLD who were given a lettering task had a poorer performance when compared to children with normal language development. In this study, the high scores obtained from both the subsections and the overall score of the LDESSS in children with DLD indicate a high risk of learning disability. Thus, the results of this study confirmed the results of previous studies showing that children with DLD have learning disabilities in reading, writing, and mathematics.

While there are many studies conducted in the preschool period, there are also longitudinal studies of children with DLD. Catts et al. (2005) followed more than 500 kindergarten students through the end of the eighth grade. They found that 14% to 19% of children with dyslexia in any of the later grades were diagnosed with DLD in kindergarten, and 17% to 36% of children with DLD developed dyslexia in a later grade (Adlof, 2020). Tomblin et al. (2003) evaluated children diagnosed with language disorders in the preschool period when they reached the 4th grade and found that 60% of the children had learning disabilities. Young et al. (2002) determined that children diagnosed with a DLD at the age of five had difficulties in academic skills such as spelling, reading comprehension, word discrimination, and calculation when they reached the age of 19. On account of inadequate diagnosis and intervention services for preschool children, the diagnosis of children with SLD can only be made when they exhibit a significant academic failure during the primary school years. This may lead to permanent learning problems in these children as it delays diagnosis and intervention. Due to the high incidence of DLD, and the fact that DLD causes learning disabilities in many areas that affect lifelong quality of life, early diagnosis and initiation of therapy processes are essential. Screening children with DLD with LDESSS and TEL and similar screening tests used in this study is important in terms of detecting learning disabilities and starting treatment as soon as possible.

Speech sound disorder is a term that includes articulation disorders, phonological disorders, dysarthria and childhood apraxia of speech (Littlejohn & Maas, 2023). Speech sound disorders are common in preschool and can cause academic difficulties with language, spelling, and reading later on. By assessing pronunciation problems with the AAT used in this study, it was observed that all children with DLD had certain pronunciation and phonological errors. A large number of phonetic/phonological errors should not be seen as just a simple articulation problem. It is recommended that children with these issues should be evaluated and followed up on using assessment tools to determine learning difficulties.

The strength of this study is that learning disabilities can be determined at an early age with the LDESSS, AAT, and TEL screening test in children with DLD. This study had several limitations that should also be considered. First of all, LDESSS was not a direct assessment of children, it was a test based on interviews with parents. Screening tests that can directly evaluate children need to be developed as soon as possible. Thus, information about learning disabilities can be obtained directly from children rather than indirectly from parents. Another limitation is that it is single-centered and the number of participants is small. Additionally, the study was conducted with participants in a certain location. The results of this study need to be confirmed by multicenter studies with larger participation.

Conclusion

In this study, it was first determined that children with DLD between the ages of 4 and 6 had higher scores in all subdomains of LDESSS and lower scores in all subdomains of TEL than their normal developing peers. Secondly, no effect of gender on learning disability was observed in children with DLD. Lastly, all children with DLD were found to have certain pronunciation and phonological errors. Longitudinal studies conducted with children with developmental language disorders at an early age have documented that these children may experience learning difficulties in later years. Thus, it is very important for early diagnosis to screen children with DLD with easily applied tests at an early age to prevent them from experiencing learning difficulties in the future. As a result, the earlier children are diagnosed, the earlier intervention will prevent academic and social difficulties in their later years. The results of our study are valuable in that they show that children with DLD can be diagnosed with learning disabilities in early childhood (4–6 years of age) with simple screening tests. The findings of this study will inform future studies. However, the academic and social achievements of children with DLD diagnosed at an early age should be evaluated through longitudinal, multicenter studies with larger participation.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Institutional Review Board Statement

The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of the Bahçeşehir University (protocol code E-20021704-604.02.02-48470, 07 Dec 2022).

Informed Consent Statement

Informed consent was obtained from all children’s parents and legal guardians involved in the study.

ORCID iD

İbrahim Can Yaşa

Data Availability Statement

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.

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