Multivariate Assessment of Inhibitory Control in Youth: Links With Psychopathology and Brain Function.

Inhibitory control is central to many theories of cognitive and brain development, and impairments in inhibitory control are posited to underlie developmental psychopathology. In this study, we tested the possibility of shared versus unique associations between inhibitory control and three common symptom dimensions in youth psychopathology: attention-deficit/hyperactivity disorder (ADHD), anxiety, and irritability. We quantified inhibitory control using four different experimental tasks to estimate a latent variable in 246 youth (8-18 years old) with varying symptom types and levels. Participants were recruited from the Washington, D.C., metro region. Results of structural equation modeling integrating a bifactor model of psychopathology revealed that inhibitory control predicted a shared or general psychopathology dimension, but not ADHD-specific, anxiety-specific, or irritability-specific dimensions. Inhibitory control also showed a significant, selective association with global efficiency in a frontoparietal control network delineated during resting-state functional magnetic resonance imaging. These results support performance-based inhibitory control linked to resting-state brain function as an important predictor of comorbidity in youth psychopathology.

Cross-Sectional and Longitudinal Relations Among Irritability, Attention-Deficit/Hyperactivity Disorder Symptoms, and Inhibitory Control.

OBJECTIVE: Irritability and attention-deficit/hyperactivity disorder (ADHD) symptoms frequently co-occur in youth. Although ADHD has been associated with inhibitory control deficits, the literature on irritability and inhibitory control is mixed. Examining how irritability, ADHD symptoms, and inhibitory control interrelate both cross-sectionally and longitudinally across development could shed light on common and distinct mechanisms of youth psychopathology. METHOD: We utilized a cross-lagged panel model with data from 2 time points (at ages 10 and 12 years) of the Adolescent Brain and Cognitive Development (ABCD) Study (N = 7,444, or ∼63% of the baseline sample with full data at each time point) to test cross-sectional and longitudinal associations among parent-reported irritability and ADHD symptoms and behaviorally assessed inhibitory control. This was performed separately across discovery and replication subsamples, each n = 3,722. RESULTS: As expected, irritability and ADHD symptoms exhibited strong cross-sectional and reciprocal cross-lagged associations. Higher ADHD symptoms at age 10 years were associated concurrently with poorer inhibitory control and predicted poorer inhibitory control at age 12. Contrary to predictions, inhibitory control was not significantly associated with irritability cross-sectionally, nor was it predictive of later irritability or ADHD symptoms. CONCLUSION: These findings highlight strong links between irritability and ADHD. Although inhibitory control deficits were linked to ADHD and predictive of its symptom course, inhibitory control had no significant associations with irritability. Future research should investigate other candidate mechanisms of the co-occurrence of irritability and ADHD symptoms and predictors of their developmental trajectories. PLAIN LANGUAGE SUMMARY: This study investigated how irritability, ADHD symptoms, and inhibitory control interrelate both cross-sectionally and longitudinally in a sample of youth from the Adolescent Brain and Cognitive Development (ABCD) Study (N = 7,444). Results indicate that irritability and ADHD symptoms exhibit strong reciprocal predictive relationships; however, inhibitory control does not predict later irritability or ADHD, though ADHD symptoms predicted later inhibitory control deficits. These findings corroborate the predictive relations between irritability and ADHD over development and highlight the need for continued exploration of mechanisms underlying their co-occurrence.

Reducing the Nitrogen Footprint of a Small Residential College.

The release of reactive nitrogen contributes to its accumulation in the environment, causing a variety of harmful effects. To measure Dickinson College's contribution to nitrogen pollution, and quantify the potential to reduce its contribution, we calculated the college's nitrogen footprint and simulated the effects of selected nitrogen mitigation measures. The analysis was obtained using the Nitrogen Footprint Tool, developed at the University of Virginia. Food production is by far the largest contributor to Dickinson's footprint, followed by heat and power. Transportation, sewage, and groundskeeping contribute relatively small amounts. Breaking food down into different food categories, meat and fish is the largest source of nitrogen, accounting for two-thirds of the food footprint. Simulations of individual mitigation measures showed that measures targeting food are the most impactful for reducing the college's nitrogen footprint. Two policy scenarios that combine multiple measures, one representing moderate action and the other more aggressive action, were also analyzed. They are projected to reduce Dickinson's footprint by roughly 15 and 25 percent, respectively, while reducing operating costs. Achieving these reductions would require substantial changes in dietary choices by members of the campus community.