The effect of bilingualism on Attention Deficit Hyperactivity Disorder (ADHD)-related behaviour, ADHD symptoms, and executive functions in a general primary school population

Curtis Jon Manooj Sharma

It is well established that there is association between Attention Deficit Hyperactivity Disorder (ADHD) and deficits in executive functions. Simultaneously, a large body of research has found advantages in measures of executive functions, leading to the controversial claim that bilingual language processing leads to advantages in executive function skills in neurotypical bilinguals. It is therefore important to uncover whether and how bilingual cognition may affect behaviours associated with ADHD.

This dissertation contributes to this emerging interdisciplinary area on the premise that as all three constructs are dimensional in nature, a dimensional approach to investigating any relations between them may uncover valuable that might be overlooked in categorical investigations. The dissertation takes inspiration from the Research Domain Criteria (RDoC, NIMH, 2018) and transdiagnostic approaches, seeking to focus on the cognitive and behavioural profile of the child to understand what this could reveal about bilingualism and ADHD-related behaviour, and bilingualism, inattentiveness, hyperactivity/impulsivity, emotional dysregulation, and so-called “hot” and “cool” executive functions.

I report here two studies. In study-1, ADHD-related behaviour between bilinguals and monolinguals were compared, and a bilinguals-only comparison also carried out. In study-2 ADHD symptom levels were compared for a sub-sample drawn from study-1, along with measures of “hot” and “cool” executive function. In study-1 bilinguals showed a small but significantly lower level of ADHD-related behaviour. Study-2 showed no differences between bilinguals and monolinguals in ADHD symptom levels, and no association between executive functions and symptom levels. However, an advantage in cognitive flexibility was found for bilingualism both as a binary category and as a measure of proficiency. These findings may have implications for discussions of bilingual cognition, the Executive Function model of ADHD, and developmental disorders in bilinguals.