According to the DSM-IV-TR (APA, 2000), the Attention Deficit Hyperactivity Disorder (ADHD) is characterized by persistent and severe levels of hyperactivity/impulsivity and/or symptoms of inattention, interfering with normal functioning in social, educational and working environments. Even if not included in the core diagnostic criteria of ADHD, language disturbances may often be present (Baker & Cantwell, Reference Baker and Cantwell1992; Camarata & Gibson, Reference Camarata and Gibson1999), affecting both linguistic and pragmatic domains. Indeed, hyperactive/impulsive symptoms may result in speaking without thinking or respecting the conversational turn in conversations, interrupting others' speech and talking excessively. These symptoms may reflect an association between ADHD and difficulties in pragmatic aspects of communication. Interestingly, such kinds of impairments (i.e. inappropriate and impulsive behaviours in conversations and relationships), which have been reported in ADHD (Oram et al. Reference Oram, Fine, Okamoto and Tannock1999; Kim & Kaiser, Reference Kim and Kaiser2000) (Table 1), are somewhat similar to those described in pervasive developmental disorders (Bishop & Baird, Reference Bishop and Baird2001; Geurts & Embrechts, Reference Geurts and Embrechts2008) (Table 1) and schizophrenia (Tavano et al. Reference Tavano, Sponda, Fabbro, Perlini, Rambaldelli, Ferro, Cerruti, Tansella and Brambilla2008; Bellani et al. Reference Bellani, Perlini and Brambilla2009, Reference Bellani, Dusi and Brambilla2010).

Table 1. Studies exploring the association between language disturbances and ADHD

ADHD-C, ADHD-Combined subtype; ASD, Autism Spectrum Disorder; CCC, Children's Communication Checklist; CELF-R, Clinical Evaluation of Language Fundamentals-Revised; DTLA-3, Detroit Test of Learning Aptitude-3; EOWPVT-R, Expressive One Word Picture Vocabulary Test-Revised; EVT, Expressive Vocabulary Test; K-ABC, Kaufman Assessment Battery for Children; LI, Language Impairment; OPD, Other Psychiatric Diagnoses; PAT, Photo Articulation Test; PDDNOS, Pervasive Disorder Not Otherwise Specified; RD/LI, Reading Disorder/Language Impairment; PPVT, Peabody Picture Vocabulary Test; PPVT-R, Peabody Picture Vocabulary Test-Revised; SL, Speech-Language; SLD, Specific Learning Disability; SLI, Specific Language Impairment; TAAS, Test of Auditory Analysis Skills; TD, Typical Developing; TOLD, Test of Language Development; TOLD-2I, Test of Language Development-2 Intermediate; TOPL, Test of Pragmatic Language; TROG, Test for the Reception of Grammar; WISC-III, Wechsler Intelligence Scales for Children-III; WRAML, Wide Range Assessment of Memory and Learning; WRMT-R, Woodcock Reading Mastery Test-Revised.

Inattentive symptoms appear to be linked also with language comprehension difficulties, since children do not apparently listen and do not follow teacher's instructions. In their study, Baker & Cantwell (Reference Baker and Cantwell1992) realized indeed that there is a strong association between language impairments (LI) and ADHD (Table 1). Achievement and cognition problems are related to both conditions, and so it is a challenge to define which deficits belong to ADHD, which ones to LI alone and which ones are shared by the two conditions, although the presence of LI is suggested to represent the crucial factor (Cohen et al. Reference Cohen, Vallance, Barwick, Im, Menna, Horodezky and Isaacson2000).

Other authors have mainly focused on working memory abilities in ADHD children, with or without language impairments, reporting different results (McInnes et al. Reference McInnes, Humphries, Hogg-Johnson and Tannock2003; Jonsdottir et al. Reference Jonsdottir, Bouma, Sergeant and Scherder2005; Martinussen & Tannock, Reference Martinussen and Tannock2006) (Table 1). For example, McInnes et al. (Reference McInnes, Humphries, Hogg-Johnson and Tannock2003) described altered listening comprehension, spatial span, and verbal and spatial working memory in ADHD children without comorbid LI. In contrast, Jonsdottir et al. (Reference Jonsdottir, Bouma, Sergeant and Scherder2005) showed that working memory abilities were impaired only in ADHD children with language problems. Martinussen & Tannock (Reference Martinussen and Tannock2006) noted that working memory may be compromised independently of comorbid reading or language deficits in ADHD. Additionally, in 2006, Mathers analysed the texts of ADHD children observing more abandoned utterances, spelling and punctuation errors, avoidance, tangential and unconnected information in comparison with typical developing children (Table 1).

In conclusion, pragmatic aspects, verbal working memory and discourse analysis seem to be affected in ADHD, being related to language abilities but, partially, also to general executive functions (Cohen et al. Reference Cohen, Vallance, Barwick, Im, Menna, Horodezky and Isaacson2000). Therefore, comorbidity with language disorders in children with ADHD should consistently be detected and, when present, taken into account for intervention strategies, being a good indicator of inattention. Future studies should further characterize the correlations between language impairments and higher cognitive dimensions, trying to plan innovative and specific interventions for ADHD with or without LI.