This award supports research on children and families affected by Hurricane Irma, which hit the Southeastern United States in September 2017. This research project will study how natural disasters affect brain, thinking, and mood. Natural disasters are disruptive and affect millions of people worldwide each year, including children. Disaster experiences are associated with youth feeling vulnerable and experiencing problems at school, at home, and with peers, as well as problems with mental health and substance use. This research also examines how pre-disaster brain functioning and thinking may protect against some of the effects of disaster-related stress on youth. The funded work will likely inform local, state, and national responses to disasters, identify youth at greatest risk after a disaster, reveal patterns of resilience, and strengthen our understanding of typical child development.In the year before Hurricane Irma's landfall, a large sample of children in Florida and South Carolina--who were later affected by the hurricane--began participating in a large, multisite longitudinal investigation of brain and cognitive development, the Adolescent Brain and Cognitive Development (ABCD) study. Also studied was a large sample of control children in California, who were not affected by the hurricane. The current study will take advantage of data collected prior to the hurricane in the ABCD study, which used a battery of neuropsychological, interview, genetic, and structural and functional neuroimaging tests. Because disasters are rarely predictable, most prior studies of the effects of disaster exposure do not have access to important information about research participants' pre-disaster statuses or levels of functioning; the prospective design of the current research will avoid this problem. In addition, this research will enable data to be collected very soon after the hurricane, while the experiences of the hurricane and its aftermath are fresh. As a result, the researchers will be able to compare pre- and post-hurricane brain functioning, mood, and thinking, to test hypotheses about the effects of disaster-related stress on several developmental processes. Key predictions are that in addition to causing elevated posttraumatic stress symptoms in both cognitive and affective domains, increased hurricane-associated stress will have caused loss of volume, reduced cortical thickness, and impaired neural transmission in specific brain areas (for example, in the hippocampus, amygdala, prefrontal cortex, and other areas). Neural measurements will be taken using T1- and T2-weighted MRI scans and diffusion-weighted MRI scans. By studying children's Irma-related experiences, traumatic exposure, and evacuation-related stress, this study will afford a unique opportunity to longitudinally examine the effects of disaster exposure and disaster-related stress on youth development. This study will help the general public better understand the effects of disasters on children and identify youth at greatest risk in the aftermath of disasters.