Attention deficit hyperactivity disorder (ADHD) is a serious psychiatric disorder (1) that is developmental and heterogeneous. Individuals with ADHD may show signs of inattention, impulsiveness, and hyperactivity (2). ADHD prevalence varies from 2–14% in school children with the higher prevalence among males (3). Many children with ADHD experience long-term disability in different aspects of life (2). ADHD is associated with challenges in individual life, social skills, parent–child relationships, academic achievement, and communication skills associated with speech and language deficits (4).
With respect to communication disorders, different aspects of language might be compromised in children with ADHD. Proficiency in both receptive and expressive language is necessary for establishing effective communication and conveying meaning. Although language impairments are not the main criterion of ADHD diagnosis, language deficits might negatively impact occupation, behaviors, social aspects of life and wellbeing in people with this disorder (5). Therefore, detecting the possible language deficits in different language domains is necessary to provide the appropriate support and intervention before adulthood.
Literature indicates insufficiency in several domains of language including pragmatics, semantics, morphology, phonology, and syntax in children with ADHD. However, the extent to which each language domain is affected and which language aspect shows the most deficiency has not been specifically detailed. Considerable diversity characterizes the scientific methodologies of related studies and their findings. Limited evidence and variability in methodologies means that it is difficult to interpret and generalize results from studies pertaining to language domains in ADHD.
Syntax is a complex aspect of language with multiple components and different complexity levels that explain how words in conjunction with each other make well-formed sentences. Among identified language deficits in ADHD, impairment of syntax has been reported in several research studies (6–9). However, this impairment is not exclusive to these individuals and is observed in many clients with developmental language disorders (DLD) (5).
In a study conducted by Montgomery et al. (2009) on the association between comprehension of grammar and attention in children with specific language impairment aged approximately 8 years, the centrality of sustained attention in this task was realized (10). The authors explained that during the performance of this task processes that are specific to language and a variety of other information processing processes are invoked. Children need to perform some operations at the same time: they need to sustain their attention on the target sentence until an appropriate linguistic representation is produced. Further, they are required to scan and process each image visually which is not possible without sustaining attention. Also, an accurate linguistic representation should be produced for each image, and the best image matching the target sentence should be selected. The weaker performance of children with SLI in understanding complex sentences stems from both a less competent language processing system and reduced capacity of attention. The required time for processing complex sentences is longer than simple ones. Therefore, there is a greater time pressure for children with SLI to perform the linguistic and attentional operations. Hence, the cognitive and language processing surpass the children's cognitive and linguistic limits.
Several studies have been conducted to investigate the syntactic skills of children with ADHD. In Kim and Kaiser’s study (2000) on 11 TD and 11 ADHD children who were monolingual English-speaking children in the age range of 6–8 years, syntax assessment showed findings approached a statistically significant difference (6). Helland et al. (2014) studied the syntactic skills in the Norwegian-speaking children. Twenty-one children with ADHD, 19 children with specific language impairment and 19 TD children aged 6–12 years were studied. ADHD and TD peers performed similarly on syntax evaluation, but children with DLD had the weakest results among the three groups. El Sady and colleagues (2013) showed 36 Arabic-speaking children with ADHD and 25 ‘late talking’ children (Mean (SD) of age in ADHD group: 51.14 (11.54) months, Mean (SD) of age in control group: 53.52 (11.38) months) were similar for the total scores of syntactic scales (8). Moreover, Stanford and Delage (2020) looked at morphosyntactic abilities of 60 French-speaking participants (20 TD, 20 DLD, and 20 ADHD) in the 6–12 year age range. Findings showed children with ADHD performed more poorly than their peers when they were assessed by standardized tests (9). Vassiliu and associates (2023) also studied the morphosyntactic skills of 29 Greek-speaking children with ADHD and 29 TD children aged from 4.02 to 8.15 years. Children with ADHD performed more poorly than TD ones (11). What can be understood from the literature review on syntactic skills is that findings have been conflicting in this population.
In this research, we aimed to explore the syntactic characteristics of Persian-speaking children with ADHD. Furthermore, syntactic structures were studied in terms of complexity level. As far as we know, none of the relevant studies have explained the syntactic skills of this population in more detail. Hence, we compared two groups for all components of syntax comprehension to form a comprehensive profile of syntactic skills in children with ADHD.