Search

Executive functions (EFs) are highly heritable higher-order cognitive processes that govern goal-directed thoughts and behaviors and enable individuals to self-regulate. EFs are strongly related to academic achievement during childhood and adolescence. Equally, the quality of students’ social environments, including schools, is tied to student achievement. This dissertation aimed to answer two main questions: (1) Under typical circumstances, to what extent are students’ EFs tied to their performance on high-stakes, state-mandated academic tests across different socioeconomic contexts; and (2) To what extent did EF abilities and academic skills change over time during the coronavirus pandemic, an atypical period of prolonged disruption to formal schooling and related social and learning environments? In Study 1, using both phenotypic and genetic modeling approaches, we found that performance on state-mandated tests of math and reading was moderately heritable and closely linked with EF skills and processing speed, across a variety of environmental contexts. Moreover, EF and processing speed were more strongly related to high-stakes math and reading achievement than socioeconomic con-texts and, controlling for general EF, associations between high-stakes test performance and socioeconomic contexts were attenuated. In Study 2, comparing performance following pandemic-related disruption (peri-COVID) to longitudinal change during a pre-pandemic period (pre-COVID), we observed mean-level decline in cognitive (EF and processing speed) and academic (math and reading) task performance and increased individual variability in math and reading skills. While the rank-order stability of math decreased in the peri-COVID group, there was no significant reordering of child and adolescent performance over time across reading and cognitive tasks in either group. Similarly, the magnitude of association between baseline socio-economic status and change in performance on cognitive and academic tasks did not significantly differ between the pre-COVID and peri-COVID groups. The implications of these findings are discussed in the context of genetically-influenced differences, potential targets for instructional intervention, the role of EF in driving mechanisms of change, and utility of individual, relative, and population-level metrics of learning and development in childhood and adolescence. These studies contribute to the growing body of research that informs education policy and intervention related to individual differences in learning and achievement.

ADHD is a heterogeneous disorder that is highly impairing. Early, accurate diagnosis maximizes long-term positive outcomes for youth with ADHD. Tests of executive functioning (EF) are potential tools for screening and differential diagnoses for ADHD; however, previous research has been inconsistent regarding the specificity and magnitude of EF deficits across ADHD subtypes. Here we overcome these limitations by: (1) employing more rigorous methods to conceptualize ADHD in a way that better captures heterogeneity of expression, and (2) by applying a more comprehensive, reliable battery of EF tasks to this association. We tested 1548 children and adolescents (ages 7-15 years) from the Texas Twin Project, a population-based cohort with a diverse socioeconomic and ethnic composition. EF and processing speed were measured in-laboratory with a comprehensive test battery, while ADHD and sociodemographic characteristics were assessed via parent report. We show that EF deficits are isolated to the inattention domain of ADHD. Moreover, we found that the association between EF task performance and inattention remains stable across sociodemographic groups. Our results demonstrate that failures of executive control are selectively manifested as covert inattentive symptoms, such as trouble with organization, forgetfulness, and distractedness, rather than overt symptoms, such as inappropriate talkativeness and interruption. We anticipate that EF tests could be widely useful in clinical and educational settings due to their specificity regarding particular subtypes of ADHD behaviors and their broad predictive validity across key demographic subgroups