INHIBITORY PROCESSES IN INDIVIDUALS WITH DOWN SYNDROME AND IN TYPICALLY DEVELOPING CHILDREN

Given the progressive increase in the life expectancy of people with Down syndrome (DS), an increasing number of studies are focusing on neuropsychological developmental trajectories in this population. In particular, executive functions (EFs) plays a crucial role in multiple contexts in which automatic behaviours are not required. The role of inhibition both in typical development (TD) and in individuals with DS has been investigated especially in recent years. Analysing the literature on inhibition in individuals with DS, it reports contradictory results which are also difficult to compare given the lack of reference to a theoretical model and the different types of inhibitory measures used. The general aim of the present dissertation, which is articulated in seven studies, is to investigate in depth and promote inhibitory processes in individuals with DS matched for a measure of mental age (MA) with TD children. In the first study, a meta-analysis was conducted to investigate if people with DS show more impairments on inhibition abilities, compared to TD children matched on a measure of MA. In the second study, individuals with DS matched for MA with two TD control groups, respectively of 5 and 6 year-olds, were assessed using a battery of tasks tapping on response inhibition and interference suppression (see Gandolfi et al., 2014). The third study aimed to investigate response inhibition, interference suppression, and delay of gratification in a broader sample of individuals with DS matched for a measure of MA with TD children. Furthermore, in order to explore the developmental trajectories of inhibitory abilities in individuals with DS, a cross-sectional analysis of inhibitory strengths and weaknesses was conducted dividing the sample of individuals with DS into two groups basing on their chronological age (i.e., children and adolescents vs adults). The fourth study of the present dissertation, aimed to explore in depth interference suppression abilities – less investigated in individuals with DS – with an adapted and computerized version of the Navon task in which the high-familiarity stimuli (i.e., hearts and stars) and the response do not include verbal components in order to reduce language-based difficulties. In the fifth study, the relationship between specific aspects of autonomy in everyday life and tasks measuring response inhibition, interference suppression, and working memory was investigated. Finally, the studies number six and seven describe the creation and the implementation of a training program, respectively for TD pre-school children aged 4 and for individuals with DS. While the first one – for TD children -– aimed to jointly improve cool EFs, hot EFs, and emotion regulation, the main goal of the second one – for individuals with DS – is to improve response inhibition, interference suppression, and delay of gratification considering also their impact on the general construct of EFs in everyday life. Unfortunately, the seventh study has not been completed due to the Covid-19 pandemic situation and for this reason it will be described only the experimental design and the structure of the intervention. General conclusions will include a discussion of the main findings in light of the current literature and finally clinical and educational implications will be argued.

Given the progressive increase in the life expectancy of people with Down syndrome (DS), an increasing number of studies are focusing on neuropsychological developmental trajectories in this population. In particular, executive functions (EFs) plays a crucial role in multiple contexts in which automatic behaviours are not required. The role of inhibition both in typical development (TD) and in individuals with DS has been investigated especially in recent years. Analysing the literature on inhibition in individuals with DS, it reports contradictory results which are also difficult to compare given the lack of reference to a theoretical model and the different types of inhibitory measures used. The general aim of the present dissertation, which is articulated in seven studies, is to investigate in depth and promote inhibitory processes in individuals with DS matched for a measure of mental age (MA) with TD children. In the first study, a meta-analysis was conducted to investigate if people with DS show more impairments on inhibition abilities, compared to TD children matched on a measure of MA. In the second study, individuals with DS matched for MA with two TD control groups, respectively of 5 and 6 year-olds, were assessed using a battery of tasks tapping on response inhibition and interference suppression (see Gandolfi et al., 2014). The third study aimed to investigate response inhibition, interference suppression, and delay of gratification in a broader sample of individuals with DS matched for a measure of MA with TD children. Furthermore, in order to explore the developmental trajectories of inhibitory abilities in individuals with DS, a cross-sectional analysis of inhibitory strengths and weaknesses was conducted dividing the sample of individuals with DS into two groups basing on their chronological age (i.e., children and adolescents vs adults). The fourth study of the present dissertation, aimed to explore in depth interference suppression abilities – less investigated in individuals with DS – with an adapted and computerized version of the Navon task in which the high-familiarity stimuli (i.e., hearts and stars) and the response do not include verbal components in order to reduce language-based difficulties. In the fifth study, the relationship between specific aspects of autonomy in everyday life and tasks measuring response inhibition, interference suppression, and working memory was investigated. Finally, the studies number six and seven describe the creation and the implementation of a training program, respectively for TD pre-school children aged 4 and for individuals with DS. While the first one – for TD children -– aimed to jointly improve cool EFs, hot EFs, and emotion regulation, the main goal of the second one – for individuals with DS – is to improve response inhibition, interference suppression, and delay of gratification considering also their impact on the general construct of EFs in everyday life. Unfortunately, the seventh study has not been completed due to the Covid-19 pandemic situation and for this reason it will be described only the experimental design and the structure of the intervention. General conclusions will include a discussion of the main findings in light of the current literature and finally clinical and educational implications will be argued.