Altered hippocampal microstructure and function in children who experienced Hurricane Irma

Air pollution from biomass burning disrupts early adolescent cortical microarchitecture development

Exposure to outdoor particulate matter (PM2.5) represents a ubiquitous threat to human health, and particularly the neurotoxic effects of PM2.5 from multiple sources may disrupt neurodevelopment. Studies addressing neurodevelopmental implications of PM exposure have been limited by small, geographically limited samples and largely focus either on macroscale cortical morphology or postmortem histological staining and total PM mass. Here, we leverage residentially assigned exposure to six, data-driven sources of PM2.5 and neuroimaging data from the longitudinal Adolescent Brain Cognitive Development Study (ABCD Study®), collected from 21 different recruitment sites across the United States. To contribute an interpretable and actionable assessment of the role of air pollution in the developing brain, we identified alterations in cortical microstructure development associated with exposure to specific sources of PM2.5 using multivariate, partial least squares analyses. Specifically, average annual exposure (i.e., at ages 8-10 years) to PM2.5 from biomass burning was related to differences in neurite development across the cortex between 9 and 13 years of age.

Air pollution from biomass burning disrupts early adolescent cortical microarchitecture development

Exposure to outdoor particulate matter (PM 2.5 ) represents a ubiquitous threat to human health, and particularly the neurotoxic effects of PM 2.5 from multiple sources may disrupt neurodevelopment. Studies addressing neurodevelopmental implications of PM exposure have been limited by small, geographically limited samples and largely focus either on macroscale cortical morphology or postmortem histological staining and total PM mass. Here, we leverage residentially assigned exposure to six, data-driven sources of PM 2.5 and neuroimaging data from the longitudinal Adolescent Brain Cognitive Development Study (ABCD Study®), collected from 21 different recruitment sites across the United States. To contribute an interpretable and actionable assessment of the role of air pollution in the developing brain, we identified alterations in cortical microstructure development associated with exposure to specific sources of PM 2.5 using multivariate, partial least squares analyses. Specifically, average annual exposure (i.e., at ages 8-10 years) to PM 2.5 from biomass burning was related to differences in neurite development across the cortex between 9 and 13 years of age.

Shared and unique heritability of hippocampal subregion volumes in children and adults

Behavioral genetic analyses have not demonstrated robust, unique, genetic correlates of hippocampal subregion volume. Genetic differentiation of hippocampal longitudinal axis subregion volume has not yet been investigated in population-based samples, although this has been demonstrated in rodent and post-mortem human tissue work. The following study is the first population-based investigation of genetic factors that contribute to gray matter volume along the hippocampal longitudinal axis. Twin-based biometric analyses demonstrated that longitudinal axis subregions are associated with significant, unique, genetic variance, and that longitudinal axis subregions are also associated with significant shared, hippocampus-general, genetic factors. Our study's findings suggest that genetic differences in hippocampal longitudinal axis structure can be detected in individual differences in gray matter volume in population-level research designs.

The functional and structural changes in the hippocampus of COVID-19 patients

Since the hippocampus is predominantly susceptible to injuries caused by COVID-19, there are increasing data indicating the likelihood of post-infection memory loss and quickening neurodegenerative disorders, such as Alzheimer's disease. This is due to the fact that the hippocampus has imperative functions in spatial and episodic memory as well as learning. COVID-19 activates microglia in the hippocampus and induces a CNS cytokine storm, leading to loss of hippocampal neurogenesis. The functional and structural changes in the hippocampus of COVID-19 patients can explain neuronal degeneration and reduced neurogenesis in the human hippocampus. This will open a window to explain memory and cognitive dysfunctions in "long COVID" through the resultant loss of hippocampal neurogenesis.

Hippocampal-Prefrontal Connectivity Prior to the COVID-19 Pandemic Predicts Stress Reactivity

BACKGROUND

By adolescence, foundational cognitive and affective neurobehavioral processes specialize based on environmental demands, such as stress, to determine the basis of adult trajectories. The ongoing COVID-19 pandemic has increased stress for everyone, particularly adolescents who face unique stressors such as restrictions in socialization and education. However, variability in brain processes supporting stress reactivity is not well understood. Here, we leverage pre-pandemic brain development studies to identify how maturity of prefrontal connectivity with the amygdala and hippocampus (HPC) is associated with response to COVID-19. We hypothesized that age-related changes in connectivity of affective and cognitive brain systems may underlie the emotional response of adolescents during the pandemic.

METHODS

In this study, 10- to 31-year-old participants (n = 111) completed resting-state functional magnetic resonance imaging scans prior to the pandemic and then completed a questionnaire 9 months into the pandemic measuring worry, COVID-related stress, sadness, perceived stress, and positive affect. Associations between pairwise functional connectivity of HPC/amygdala subregions with prefrontal cortex subdivisions and affective reactivity during the pandemic were examined.

RESULTS

Regression analyses indicated that both worry and COVID-19-related stress increased with age (false discovery rate-corrected p < .05). Furthermore, greater connectivity between the anterior ventromedial prefrontal cortex and posterior HPC was associated with greater worry and COVID-19-related stress (p < .05 corrected), which was primarily driven by individuals younger than 18 years.

CONCLUSIONS

Taken together, our results indicate that increases in stress reactivity to the COVID-19 pandemic across the transition to adulthood are driven by maturation of posterior HPC-ventromedial prefrontal cortex coupling, which integrates stress response and emotional memory processing.