Hanan El Marroun, PhD is a professor in Biological Psychology with a focus on substance use and brain development at the Department of Psychology, Education and Child Studies, Erasmus School of Social and Behavioural Sciences (ESSB) at the Erasmus University. She is also affiliated at the Department of Child and Adolescent Psychiatry at the Erasmus MC – Sophia Children’s Hospital. She has a background in neuroscience and epidemiology. Her research focuses on two sensitive periods of brain development: pregnancy/the first 1000 days of life and adolescence. In population-based studies, Hanan examines the short- and long-term consequences of maternal, fetal and child health on brain developmental features, including behaviour and cognition, as well as brain morphology and connectivity. Next to her research, she disseminate knowledge and general research skills to bachelor and master students in teaching. In HappyMums, together with dr. Charlotte Cecil, Hanan co-leads WP4on biological mediators and environmental moderators of offspring risk and resilience.