5 Bilingualism and (developmental) language disorders. An overview.

Ca’ Foscari University of Venice, Department of Linguistics and Comparative Cultural Studies, Venice, Italy
ducoli.maria2000@gmail.com

During the last decade, linguistic research has started to investigate the cognitive advantages of bilingualism. Nowadays clinical linguists pay more and more attention to the bilingual population, arguing against the common misconceptions according to which bilingualism leads to confusion and linguistic delay in children. The same beliefs have led many teachers to discourage or even prohibit the usage of the L1 (in case of a heritage language) or the L2 especially in the case of learning difficulties or language impairment. Recent studies in the field of clinical linguistics (Kovelman et al., 2008; Marinis et al., 2017; Vender et al., 2018, Vender et al., 2019; Garraffa et al., 2020) provide evidence of the advantages of bilingualism for children with Developmental Language Disorder (DLD) but also with other types of language impairments, such as Dyslexia, Autistic spectrum disorder (ASD), Down syndrome (DS), Hypoacusis and Aphasia. Even in the presence of atypical development, in fact, bilingualism brings cognitive advantages but also entails difficulties in diagnosing a language impairment in bilingual children. This contribution provides a brief overview of the state of the art with the aim of supporting language policies that encourage bilingualism and multilingualism also in presence of language disorders.

Keywords: bilingualism; atypical language development; clinical linguistics; developmental language disorder; cognitive advantages; bilectalism; dyslexia; autism; Down syndrome; ADHD.

1. Introduction

Nowadays, bilingualism is a matter of debate. Even if linguistic research has made great progress and there are fewer misconceptions about the negative influence of bilingualism on the process of language acquisition, sometimes some ancient and obsolete assumptions are still heard. Commonly held beliefs and myths about bilingualism can have a strong influence on assessment, intervention, and decision-making processes (Espinosa, 2008), therefore this contribution aims to shed light on research progress in this field.

Even if in the last years the migratory waves resulted in new linguistic combinations, we still tend to make a distinction between the languages mastered by the bilingual, considering some language combinations as élite bilingualism and others as folk bilingualism (Garraffa et al., 2020). In the first case, the involved languages are prestigious and widely spread, such as English, French, Spanish, and German, and the children will be considered as “lucky”. In the second one, bilingualism is governed by circumstances, and it is the result of migration. In this case, society has a totally different perception of the bilingual child whose bilingualism is often unrecognized if the mastered language is a minority and less prestigious one, not included in school curricula nor used by media and spoken in a Country with low social prestige. It is a purely cultural difference, as the brain does not make any distinction between languages. In fact, at the cognitive level, no matter if the child speaks English, Farsi, or Venetian dialect: the benefits are present in any case (Antoniou et al., 2016; Garraffa et al., 2020)

In the last few years, clinical linguists started to focus more on the bilingual population, so as to contrast the common misconceptions which lead teachers to discourage or even prohibit the usage of the L1 or L2, especially in case of learning difficulties or language impairment. Not only is this a piece of advice not supported by any scientific evidence, but it may also be potentially damaging and counterproductive for the healthy psychophysical development of the child. Language, in fact, is more than a communicative system: it has an active role in the construction of identity, allowing the person to feel part of a social group and share with other members linguistic norms and habits. Prohibiting the child to use their L1 at home may have implications for the whole family system. Moreover, we should be aware that one of the basic factors of bilingualism is the quality of the input. In this sense, it would be counterproductive to ask the immigrant family to abandon their L1 to facilitate the acquisition of the new language.

Nowadays, clinical linguistics – defined by David Crystal as a branch of linguistics that apply linguistic theories and methods to the analysis and treatment of language disorders (Crystal, 1981) – joins the debate on bilingualism underlining the numerous benefits it has upon atypical population. The cognitive advantages seem to be cross-sectional to the different types of language impairments from Developmental Language Disorder (DLD) – which appears in children without any other cognitive or social impairments (Fleckstein et al., 2018; Tsimpli et al., 2016) – to dyslexia (Celentin & Daloiso, 2018; Vender et al. 2018) and hypoacusis (Bunta & Douglas, 2013).

Moreover, the benefits appear also in cases of Autistic spectrum disorder (Hambly & Fombonne, 2012; Ohashi et al., 2012), Down syndrome (Bird et al., 2005, Burgoyne et al., 2016) and schizophrenia (Seeman, 2016).  Cognitive advantages of bilingualism are also found in case of ADHD – one of the most common neurodevelopmental disorders of childhood, characterized by attention deficits – but in this case further research is needed to better understand the issues (Bialystok et al., 2016; Köder et al., 2022; Shamra et al., 2022).

The present article aims to present a general overview of the topic. It is articulated as follows: in the first section the cognitive advantages of bilingualism in both cases of typical and atypical development will be analysed, as well as the difficulties in diagnosing the language impairment in bilingual children. In the second one, different situations of atypical development will be considered. In the last section it will provide a description of a phenomenon widely spread in Italy, that is bilectalism and its benefits in case of language disorders.

2. Bilingualism between advantages and difficulties: the two sides of the coin

2.1 Cognitive and social advantages

Adopting a functional definition, bilingualism could be described as the usage of two (or more) languages on a regular basis, and bilingual children are those who use two (or more) languages in their everyday life (Armon-Lotem et al., 2015).

Recent research (Bialystok et al., 2007; Costa et al., 2014; Branchini & Donati, 2016) tried to answer an important question: what happens in the bilingual brain while using one of the mastered languages? Are both languages still active or is the one not in use temporarily inhibited? There is a solid amount of evidence (Armon-Lotem, et al., 2015; Garraffa et al., 2020) showing that both languages are active, and bilinguals develop mechanisms of inhibition allowing them to keep the two languages separated, since they cannot use them simultaneously due to the constraints of the phono-articulatory apparatus, but also because they have to choose the language to use depending on the interlocutor. The direct consequence of such “exercise” results in advantages in executive-control tasks, such as the Simon Task (Simon & Rudell, 1967) which is a behavioural measure of interference and conflict resolution. Participants are asked to respond to visual stimuli by making a rightward response to one stimulus (i.e., a circle) and a leftward response to another (i.e., a square). The stimuli are sometimes presented on the right side of the display and sometimes on the left. The location on which the stimuli appear on the display is irrelevant for the accuracy of the performance, but it influences participants’ patterns of responding by either matching (i.e., congruent trials) or not matching (i.e., incongruent trials) the side of the correct button press associated with the shape. The Simon Effect is indicated by a lower accuracy and/or longer reaction time for incongruent vs congruent trials. Bilingual children, who are used to constantly inhibiting the non-active language, are less subject to the Simon Effect. (Garraffa, Beveridge, Sorace, 2015).

No advantages in executive-control functions have been found in bimodal bilinguals (Branchini & Donati, 2016), namely competent users of a sign and a vocal language which can be (and as a matter of fact often are) simultaneously produced during code-mixing exchanges, called code-blending (Emmorey et al., 2008). The simultaneous production of the two language strings is possible due to the physical independence of the linguistic channels involved in the two languages (the hands and the face for the sign language, the vocal tract for the spoken language).

If in the past code-mixing was considered a signal of confusion  of the two languages (Poplack, 1980; Cummins, 1981; Cheng & Butler, 1989; Harry, 1992), more recent studies (Poplack & Walker, 2003; Emmorey et al., 2008, Paradis, 2001) show that code-mixing and code-blending follow specific rules and are correlated with specific-interactional situations or linguistic properties (Sorace et al., 2009; Branchini & Donati, 2016).

A particularly interesting situation has been described by Donati & Branchini (2013) and Branchini & Donati (2016) analysing the code-blending production of CODAs (hearing Children Of Deaf Adults) native users of Italian and Italian Sign Language (LIS), typologically different languages as far as word order is concerned (Italian: SVO; LIS: SOV). Branchini and Donati found 4 different types of code-blending in the data: two simultaneous language strings following the grammar and word order of one of the two languages (Italian or LIS); two simultaneous language strings each one displaying the grammar and word order dictated by its language; and a single proposition composed of fragments provided by the two languages (i.e., the subject in one language, the object in the other language). The code-blending typologies were not produced by chance, rather, they were context-dependent: the child chooses them depending on the interlocutors present during the exchange. According to Branchini & Donati (2016), their use also depends on the set involving the presence of a cognitive and more demanding representation involved in the different types of code-blending. Type 1 involves the full activation of one language and one derivation, while both Type 2 and Type 3 involve the full activation of two languages and in Type 2 two parallel derivations. These differences lead bimodal bilingual children to prefer Type 1 since it is less cognitively demanding.

The enriched cognitive control that comes along with the bilingual experience represents just one of the advantages that bilingual people display. They also show major cognitive flexibility, and they are more successful than their monolingual peers in adopting more successful lexical learning strategies (Garraffa et al., 2020). Moreover, there is evidence in favor of the hypothesis of bilingualism effects on decision-making behavior: Costa et al. (2014) pointed out a reduction of heuristic biases in decision-making as well as a reduction of emotional resonance.

Other advantages involved in bilingualism concern attention and ageing which are not exclusive to people who were raised bilingual, they are also noticed in people who learn a second language later in life (Linck et al., 2008).  Bialystok et al. (2007) proved that the increasing cognitive reserve consequent to bilingualism confers protection against the onset of Alzheimer disease’s symptoms.

Furthermore, beyond these cognitive and neurological advantages, there are also valuable social benefits that come from being bilingual, among them the ability to understand mental states, known as Theory of Mind (ToM). These abilities arise during development, but special conditions such as bilingualism may enhance ToM development or other capacities required by ToM tasks. Bilingual children seem to be able to understand others’ point of view around one year before their monolingual peers. The precocious success of bilinguals may be associated with their well-developed control functions formed during monitoring and selecting languages (Kovács, 2009).

2.2 The difficult diagnosis: Developmental Language Disorder in bilingual children

If on one hand advantages related to bilingualism have been widely discussed in the previous section, it is now necessary to focus on the difficulty in diagnosing a developmental language disorder (DLD) in bilingual children. DLD is a primary deficit in linguistic ability and language development, unrelated to other types of deficits (Bishop et al., 2000); Bishop, 2006). DLD population is very heterogeneous, with differing criteria and controversy about what linguistic aspects are affected and to what extent (Bishop et al., 2000; Armon-Lotem et al. (2015). The deficit can manifest at different levels but not all the skills are equally impaired (Friedmann & Novogrodsky, 2009). Syntax and morphology are the most established indicators of DLD and studies on Bi-DLD often show that DLD in sequential bilinguals share the same patterns as in monolinguals (Chondrogianni & Marinis, (2012).

Studies on bilingualism (Vender 2018; Garraffa et al., 2020), show not only the advantages of mastering more than one language but also other implications. Bilingual children show a reduced vocabulary, and they may display morphosyntactic difficulties similar to those of children with DLD. These similarities may result in overdiagnosis of DLD in children who do not have a real language impairment or, on the contrary, underdiagnosis of DLD, reconducting the child’s difficulties to bilingualism.

Moreover, the difficulties in diagnosing the language deficit are also due to the fact that tools assessing the language development even in monolingual children are available only for a limited number of languages and they are not comparable across languages or normed for bilingual children, who generally do not conform to monolingual norms (Armon-Lotem et al., 2015).

Recently, the overlap among features of bilingual and impaired language, which causes methodological and clinical confusion, led also to the founding of the European Cooperation in Science and Technology  (COST) Action IS0804 “Language Impairment in a Multilingual Society: Linguistic Patterns and the Road to Assessment” whose aim is to profile bilingual DLD by establishing a network to coordinate research on the linguistic and cognitive abilities of bilingual children with DLD across different migrant communities.

The diagnostic dilemma has led to the increase of research (Haman et al., 2015; Schulz, 2015; Peristeri et al., 2017; J. Paradis et al., 2017) which focuses on the study of bi-DLD, with the aim of disentangling the effects of bilingualism from those of the language impairment.

3. Bilingualism in atypical conditions

Among the parameters to consider in case of language disorders, one of the most important is the onset which permits distinguishing between developmental and acquired impairments. Even if the causes of the formers are not clear, they seem to have a genetic component and they appear during childhood. The language deficit could, therefore, be a consequence of chromosomal diseases (i.e., Down syndrome) or neurodevelopmental disorders (i.e., dyspraxia). In all these cases, the language disorder is correlated to other deficits. The acquired language disorders, instead, appear later in the life of the person who shows a solid linguistic competence. They may be caused by permanent or transitional clinical conditions, such as neurological diseases (i.e., aphasia) and phono-articulatory dysfunctions, which consist in functional or organic alterations of larynx, as dysphonia (Gagliardi, 2021).

In the present section it will be provided an overview of the cognitive advantages of bilingualism observed even in case of atypical development. The clinical situations considered will be the Developmental Language Disorder (DLD), dyslexia, Autistic Spectrum Disorder (ASD), hypoacusis, Down Syndrome (DS) and aphasia.

3.1 Bilingualism and Developmental Language Disorder  

The term Developmental Language Disorder (DLD) [1] refers to a belated acquisition of language abilities in absence of any other cognitive or sensory deficit. In particular, the child with DLD has important difficulties both in the production and in the comprehension of complex morphosyntactic structures, but also in the phonological, morphological, and lexical competence (Leonard, 2014). Around 7% of the anglophone population show a language disorder, which leads to consider DLD as the neurodevelopmental disorder with the highest predominance in preschool age (Tomblin et al., 1997). The same results were found for italophone population by Clasta’s Consensus Conference (2019).

Not all the belated speakers – namely, those children who in the first three years of life have difficulties in language acquisition – receive a diagnosis of DLD. Most of them manage to recover the delay with logopaedic treatment which allows them to reach the same level of competence as their peers.

On the contrary, in case of persistence of difficulties the specialist may arrive to diagnose a DLD. The child with DLD shows difficulties with some specific structures, considered as clinical markers for diagnosing the linguistic deficit. In particular, in Italian, one of the most used clinical markers is the production of object clitic pronouns (e.g., lo, la, li, le). Nevertheless, according to Smith et al. (2022), clitic pronouns were found to be vulnerable in heritage speakers of Italian who produced approximately 35% of the target clitics against the 80% of adult immigrants – who moved from Italy to an English-speaking country in adulthood – suggesting that clitic pronouns may not be reliable structures to test language competence in heritage Italian.

Clitics are complex structures also for typically developed children, who manage to establish their use around 3-4 years old. Atypically developed children show an omission of clitics which persist also in school age. Generally, the production results show that clitics are compromised during the whole childhood and sometimes also during adolescence (Arosio, 2010). Even if various research tried to explain the difficulty of children with DLD in the production and comprehension of clitics, the most convincing is the explanation of Jakubowicz et al. (1998), who abandoned the Surface Hypothesis theorized by Leonard (1989) – who attributed the difficulty with clitics to their phonological properties, namely to the fact that they are monosyllabic, unstressed and they can never appear in isolation – and the one of  Guilfoyle (1991), according to which children with DLD have problems with all functional categories, not only with clitics. Jakubowicz et al. (1998) showed that the difficulties with clitics are not in the comprehension as proposed by Leonard but in their syntactic and binding properties, which are confirmed by the major production of reflexives in comparison with accusatives. It demonstrates that, contrary to Guilfoyle’s hypothesis, the difficulties are not generalized to all functional categories.

With respect to bilingualism and DLD, it was proved that there is no evidence of cross-linguistic influence on grammatical performances (Gutiérrez-Clellen et al., 2008) but, on the contrary, bilinguals have language-specific difficulties in the two mastered languages (Paradis, 2010). Therefore, there are reasons to believe that the displayed difficulties are attributable to DLD and not to bilingualism. Conversely, cognitive and social advantages resulting from bilingualism are present also in the case of atypical language acquisition (Marinis et al., 2017).

Tsimpli et al. (2016) by using the Greek version of the Multilingual Assessment Instrument for Narratives, demonstrated that bilingual children with DLD had better results than their monolingual peers with DLD in the production of referential pronouns. Even if results showed differences between typically developed children and children with DLD in microstructure, bilinguals with DLD outperform monolinguals with language impairment. Moreover, bilinguals present advantages in the usage of [+ToM] terms, namely the ones which refer to the Theory of Mind, a system of interference that allow the individual to understand and attribute mental states such as beliefs, desires and emotions to others. Even if these terms represent a challenge of memory, the habits of bilinguals to express them in different languages makes children more sensitive to their use, also in the case of DLD.

Another clinical marker of DLD is the repetition of non-words, particularly difficult because it requires intact phonological memory and it addresses lexical processing, stress patterns and phonotactic rule (Bishop et al., 1996).

Thordardottir & Brandeker’s (2013) study of non-word repetitions in monolingual and bilingual 5-year-olds acquiring French and English simultaneously but with varied levels of exposure to the two languages, revealed very little effect of language experience on bilinguals’ performance. Their study found good differentiation between TD monolinguals and monolinguals with DLD.

In contrast, Engel de Abreu (2011) found that bilingual children with different European languages as L1, performed less well than their monolingual peers on a Luxembourgish test of non-word repetition. Interestingly, the difference disappeared once vocabulary was controlled, suggesting that reduced language exposure was responsible for the difference in non-word repetition.

3.2 Bilingualism and Dyslexia

Dyslexia is a neurodevelopmental learning disorder characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities and it appears in children who do not have any other neurological deficit.

Even if the main difficulty concerns reading skills, children with dyslexia often display other linguistic deficits related to phonological competence, lexical access as well as working memory and processing resources, implied in complex syntactic structures (Vender, 2017).

Moreover, 63% of children with dyslexia also show a DLD (Celentin & Daloiso, 2018). Given the high percentage of comorbidity of dyslexia and DLD, it is easy to assume that benefits brought by bilingualism in case of DLD, could be extended to children with dyslexia. This hypothesis has been confirmed by recent research (Klein & Doctor, 2003; Kovelman et al., 2008; Cummins, 2012; Vender 2018, 2019).

Even when using only one of their languages, bilinguals often have access to the linguistic and orthographic representations of their other language (Kroll & Bialystok, 2013).

Such interaction between the two languages facilitates the bidirectional transfer of literacy knowledge gained in one language towards learning to read in the other (Cummins 2012). For examples, studies comparing bilinguals learning English and a more phonologically transparent language (i.e., Italian or Spanish) have shown that these bilinguals outperform English monolinguals on phonological literacy tasks, such as nonword reading (Kovelman et al., 2008).

Similar results were found by Vender (2018a), who demonstrated that bilinguals with and without dyslexia have better performances than their monolingual peers in the pluralization of non-words. The cognitive advantage of bilingualism, therefore, can be observed also in the case of dyslexia. The advantages occur also at the level of the executive function, such as the Simon Task (Vender, 2019). Moreover, some evidence in support of the role played by bilingualism was provided by studies of bilingual children learning to read in two alphabetic orthographies have shown that children with dyslexia have similar reading deficits in both languages (Klein & Doctor, 2003).

The diagnosis of dyslexia in an L2 context is particularly difficult because poor performance in reading may be caused by poor language proficiency in the L2, limited schooling or poor reading ability per se.

To disentangle difficulties related to bilingualism from reading deficits, Elbro et al., (2012) proposed a dynamic evaluation of decoding skill – fundamental for the diagnosis – which, differently from the traditional one, is not based on lists of words and pseudowords’ recognition but on the level of learning of non-existent orthographic patterns, compatibles with more than one languages. This measure provides results in accordance with the definition of dyslexia adopted by International Dyslexia Association (IDA), while significantly reducing the influence of second language vocabulary and amount of schooling.

3.3 Bilingualism and Autistic Spectrum Disorders

The DSM-5, namely the Diagnostical and Statistical Manual of Mental Disorders, which is the principal authority for psychiatric diagnoses, include Autistic Spectrum Disorder (ASD), a syndrome which comprehends different disorders, such as autism, Asperger syndrome, pervasive developmental disorder and childhood disintegrative disorder. ASD is a neurodevelopmental disability characterized by difficulties in social communication, both verbal and nonverbal, deficit in social interaction, compromission of the theory of mind and restricted and repetitive patterns of behavior, interests or activities. Many children with ASD also show poor motor coordination and attention weaknesses (Hyman et al., 2020).

As in the previously mentioned situations of atypical development, bilingualism does not represent a difficulty for children with ASD.  Hambly & Fombonne (2012) stated that bilingually exposed children with ASD did not experience additional delays in language development. Vanegas (2019) investigated the impact of bilingual experience on the academic development of children with ASD and she found that monolinguals had higher scores on word reading skills if compared to bilinguals. However, in numerical operations, ASD children with bilingual experience outperform their monolingual peers, while no differences were found between groups on spelling skills. These results suggest that bilingual language experience may be related to early literacy and math skills in children with autistic spectrum disorders. The delay in word reading skills in bilinguals may be related to the development of two linguistics profiles while math skills may be enhanced in children with ASD through the mediation of other cognitive skills, such as executive functioning. It is important evidence against the hypothesis that bilingualism negatively affects the development of academic skills in children with ASD. Also Ohashi et al. (2012) underlined that the exposition of two languages does not inhibit the social development of children with ASD, nor exacerbate their pragmatic competence. Also Gonzalez-Barrero & Nadig (2019) remarked that bilingualism can reduce the difficulties in executive functions tasks, as well as improve verbal abilities, as attested in the Dimensional Change Card Sort – DCCS (Zelazo, 2006). From the test, Zelazo noticed that mastering more than one language resulted also in the improvement of cognitive flexibility.

Therefore, scientific evidence shows that depriving bilingual children with ASD of one of their languages may not only result in an impoverished linguistic input with the consequent absence of cognitive advantages which come along with bilingualism, but also in the exacerbation of the characteristic features of ASD, namely social isolation in both linguistic environment and familiar setting.

3.4 Bilingualism and hypoacusis

The medical term hypoacusis refers to partial or total inability to hear due to a conductive or sensorineural problem. In the first case, it is an alteration of the external auditory canal and the eardrum. In the second case, it is a change in the inner ear that also affects the auditory nerve.

One of the most common clinical treatments used to recover auditory functions is an auditory prosthesis, while in case of severe hearing impairment the most common treatment is the cochlear implant. The latter is a device implanted to bypass the damaged area of the cochlea to directly stimulate the acoustic nerve.

In these situations, clinicians may discourage the child’s exposure to two languages, with the incorrect belief that bilingualism divides the child’s linguistic resources with the consequent delay in language development, already aggravated by hypoacusis.

Even if linguistic research in this field is still at the beginning, the majority of the studies underlined that bilingualism does not exacerbate language development and linguistic competence, but on the contrary, it can bring benefits.

Thomas et al. (2008) showed that monolingual and bilingual children’s performances were very similar. This result was confirmed also by Bunta & Douglas (2013), who reported similar performances in children who spoke English and Spanish and monolingual English, aged 4 years old with cochlear implant or acoustic prosthesis. Moreover, bilinguals seemed to have a similar competence in the two mastered languages which may lead to hypothesize that the exposition to an L2 does not obstruct the acquisition of the other.

Furthermore, Bunta et al. (2016) found better performances in bilinguals with cochlear implants or acoustic prostheses who had received treatment in both languages.

3.5 Bilingualism and Down Syndrome

Down Syndrome (DS) is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21. DS varies in severity among individuals, causing lifelong intellectual disability and developmental delays. Language-learning difficulties, especially expressive language problems, are an important component of the phenotype of this population and often present a lack of morphosyntactic production.

Even if research in this domain is still at an initial stage, several studies (Bird et al., 2005; Burgoyne et al., 2016; Ward & Sanoudaki, 2021) demonstrate that bilingualism does not prevent the linguistic development of children with DS. On the contrary, learning a second language later in life is possible also in the case of DS (Vallar & Papagno, 1993).

Burgoyne et al. (2016) studied the development of reading skills, analyzing the case of a bilingual child with DS who knew Russian and English. The child had been monitored from 6 years old to 10. She presented in both languages the same linguistic difficulties of monolinguals with DS and, at the same time, she presented good reading skills both in the L1 and in the L2, similar to those of their typically developed peers. Given that it is a case study, it is difficult to generalize the results and it would be premature to talk about the advantages of bilingualism in reading skills in children with DS. However, it is undeniable that, as in other cases of atypical development, bilingualism brings positive effects also in people with DS.

Bird et al. (2005) compared the language abilities of 8 children with DS being raised bilingually with those of 3 control groups and still in this case they notice a similar profile of language abilities in bilingual as well as monolingual children with DS. Moreover, the study did not result in any detrimental effect of bilingualism.  That is, the bilingual children with DS scored at least as well on all English tests as their monolingual DS counterparts.

Ward & Sanoudaki (2021) tested bilingual and monolingual children with and without DS on expressive and receptive language abilities and phonological awareness. It resulted that language impairments were evident for both DS groups, particularly for expressive morphosyntax. Welsh receptive vocabulary scores of the bilinguals with DS were comparable to the TD bilinguals. Working memory, phonological awareness and chronological age were the strongest predictors of receptive language outcomes in both DS groups, explaining 90% of the variability.

3.6 Bilingualism and ADHD 

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders of childhood. It is usually first diagnosed in childhood and often lasts into adulthood. Children with ADHD may present trouble paying attention, controlling impulsive behaviors, or being overly active and it is also common to present weaknesses in executive function. In this respect, there has been some research into how bilingualism affects cognitive skills and behavior in individuals with attention deficits, but the question is still very much open.

Köder et al. (2022) proposed a general overview of the topic, considering nine different studies and showing both sides of the argument. In fact, it could be claimed that bilingual speakers with attention problems might experience a bilingual advantage in their ability to control functions and other cognitive domains and exhibit less severe symptoms linked to ADHD than their monolingual peers. This hypothesis is based on the idea that bilinguals’ constant need to inhibit one language trains executive function skills (Bialystok, 2008). Adopting this view, it may be concluded that being bilingual might offset some ADHD-related symptoms.

Opposed to that, bilingualism could be an additional burden for children with attention deficits, as it may affect both executive functions and inattention symptoms. This could be due to their need to allocate parts of their already limited cognitive resources to inhibiting interference from their other language, making them slower in executive function abilities and more error-prone in cognitive tasks. Moreover, another hypothesis claims that bilinguals and monolinguals with ADHD do not differ in cognitive or behavioral aspects. It is based on the small or null effects reported in several meta-analyses (Lethonen et al., 2018; Paap, 2019), which failed to replicate findings of a bilingual advantage.  In this case, it could be expected to find an association between ADHD and executive function deficits, but no effect with bilingualism. Köder et al. (2022) concluded that the studies they considered do not provide evidence that bilingualism alleviates or intensifies attention difficulties in individuals with ADHD, therefore, they should not be concerned that learning another language has a negative impact on cognitive performance.

On the contrary, Shamra et al. (2022) in their analysis of parent reports for 394 primary school-age children on background and language experience, ADHD-related behavior, and structural language skill in English, concluded that bilingualism may be associated with lower levels of ADHD-related behavior. While the effect was small, that does not necessarily argue against this conclusion. Similar yet different results were also found in Bialystok (2016) in which young bilingual adults with ADHD scored lower – which means better – than monolinguals with ADHD on two ADHD rating scales used, significantly on one of them.

All the considered studies suggest that further research is needed to deeply understand the possible correlation between attention deficits and bilingualism, and, in particular, the benefits of mastering more than one language may have on reducing ADHD-related behavior.

4. Bilectalism and language disorders

Usually, the term bilingualism leads people to think about traditional combinations of prestigious languages such as French and German, Italian and English, Spanish and Russian. It is more demanding to think about other combinations, resulting from migrations, and a much more demanding effort would be to think about bilingualism in the sense of the coexistence of a standard language and a dialect. This situation could be described by the term bilectalism (Rowe & Grohmann, 2013). It refers to a situation in which the speaker has a high level of competence in very similar two languages with a different sociolinguistic statuses. This condition perfectly represents Italy, a country rich in linguistic variation.

Antoniou et al. (2016) conducted a study on bilectal children who grow up with Cypriot Greek and Standard Modern Greek, as well as multilingual children who grew up with the two dialects and Russian/English/Romanian/Arabic with DLD characterized by anomie, namely the difficulty in naming concrete entities and actions due to a deficit in lexical retrieval. From the study, it resulted that multiDLD as well as bilDLD had no significant difference in the performance in comparison to multiTLD. Also, multiDLD group scored considerably lower than the bilTLD, but the difference failed to reach the adjusted level of significance. It appears that mastering more languages results in better performances, no matter if some of the languages spoken by the child are dialects. Multilingual children with DLD, like their monolingual and bilectal language-impaired peers, perform analogously to language-matched children on naming accuracy for verbs and nouns on a picture-based naming task.

Antoniou et al. (2014), underlined the effects bilectalism had on the child’s cognitive and linguistic performance, which are very similar to those of bilingualism. In Italy there is only one study that investigates the cognitive advantages of bilectalism in case of dyslexia. De Gaudio, Cardinaletti & Volpato (2021) studied the narrative skills of three bilectal pre-adolescents with dyslexia using the LITMUS-MAIN tests (Gagarina et al., 2019), in both the mastered languages, namely Italian and  Calabrian dialect. From the study, it resulted that the errors produced by the experimental group – namely the repetition of NP/PP, omissions and errors in gender agreement – were caused by negative transfer between the two languages. It provided evidence in support of a dialectological approach to clinical practice, considering the pervasiveness of dialect in the linguistic repertoire and, in particular, its influence on the acquisition of the pronominal system in Italian.

5. Conclusions

In conclusion, this brief overview of language disorders and bilingualism shows that the two features are not too separated. On the contrary, scientific evidence underlines the relationship between the two. Mastering more than one language is an added value for the speaker from both a cognitive and social point of view, and the advantages can be found also in case of atypical development. This evidence contrasts the general belief according to bilingualism would increase the difficulties for the child with language disorders and recent studies showed that, on the contrary, bilingualism often reduces linguistic difficulties.

 Naturally, further research is still needed. If there are many studies on DLD in different languages, many others should be conducted on language deficits as a consequence of other disorders, such as ASD or Down syndrome.

Furthermore, it is important to study learning disorders in contexts of L2 or multilingualism, in which the dividing line between the deficit and the difficulties related to low proficiency is not clear.

Finally, further research is needed on atypical populations in situations of bilectalism, very common in Italy due to its rich diatopic variation. In fact, the Italian context can be described as a linguistic system in which standard Italian and dialects coexist in relation to endogenous bilingualism. Recent statistical surveys revealed that the exclusive usage of dialect or its alternation with Italian in a familiar context is still very common (32%), with a high percentage in some specific regions such as Campania (75,5%) and Veneto (62%) (ISTAT 2017).

It is clear that, in all these situations, having a diagnostic battery of tests that permits to the evaluation of the linguistic profile of the child also in dialect would have a fundamental importance, also for the treatment.

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