Implementing evidence-based treatments for developmental dyslexia: a comparison between different approaches

Developmental Dyslexia (DD) is one of the most common neurodevelopmental disorders across cultures. Children affected by DD struggle to read fluently and/or correctly, despite normal intelligence, the absence of other psychological or neurological symptoms, and standard reading education. Not only does this condition affect academic achievement, but it is also associated with a number of other negative consequences across the lifespan, such as an enhanced risk of psychological distress and mental health problems. Despite considerable efforts to identify the underlying cause of dyslexia, agreement on a single interpretation has not yet been reached. DD is commonly described as a languagerelated disorder, with compromised phonological abilities being considered as the core deficit. Nonetheless, a growing body of evidence supports multifactorial models: reading is a complex cognitive process, involving not only phonological skills, but also auditory sensory processes, visual-spatial abilities, attention and memory. In this regard, various studies have documented a relationship between dyslexia and deficits in the Executive Functions (hereafter EFs), which can be defined as a cluster of general-purpose control mechanisms that modulate various cognitive sub-processes. However, the relationship between cognitive correlates and reading impairments is still a controversial issue. The present project aims to analyse the fundamental characteristics and the efficacy of different rehabilitation methods for Developmental Dyslexia. Although the neurocognitive causes of DD are still hotly debated, researchers agree that the main challenge is the remediation, that is, how to improve children’s reading fluency and accuracy. The most common approach has been to devise sophisticated remediation programs that train sub-skills of reading, especially phonological skills and auditory perception. Despite the promising results, the improvements in these sub-skills do not automatically transfer in better reading abilities in all subjects (especially regarding reading fluency), thus giving rise to the issue related to "non-responders" or "poor responders". Since the present data gives firm indications of the need to individualize intervention based on neuropsychological testing, the aim of this project is to investigate the efficacy of new types of treatment based on a multifactorial, probabilistic, model of the disorder. Consequently, this project consisted of two parts: specifically, in the first study, we compared phonological-based treatment with computerized cognitive training of the executive functions (e.g., attention, working memory, planning, inhibition). The results of this study clearly pointed out an advantage both in terms of improvements in EFs and literacy skills for the group who undertook the Integrated training, i.e., the group that underwent 12 hours of Cognitive training prior to 12 hours of Phonological-based treatment. Next, the second study aimed to explore the efficacy of a video game Skies of Manawak purposefully designed to train several EFs. Indeed, it has been showed that the existing treatments are not sufficiently captivating and motivating and, thus, we developed a tool ex novo in order to obtain overall improvement and higher chances of transfer to untrained tasks. Our goal was to investigate whether playing this video game may enhance EFs following intervention, and whether these improvements transfer to important literacy skills in typically developing (Study 2 – Part A) and dyslexic children (Study 2 – Part B). All children underwent 12 hours of training, distributed over 6 weeks, either on Skies of Manawak or on a control computerized activity (Scratch). Assessments upon training completion indicated greater improvements in executive functioning and reading efficiency after Skies of Manawak than after the control training in both studies. Interestingly, the advantage in reading skills was maintained in a follow-up test 6 months later and seemed to generalize to academic performance (i.e., Italian marks). Overall findings highlighted promising effects of the training programs on children’s cognition, making way for future studies investigating the underlying brain mechanisms and the factors leading to treatment success.