Dr O’Donnell is a leading expert in perinatal influences on early-childhood development, and the biological embedding of early adversity. His work examines how the early environment shapes child development. This multidisciplinary work combines genetic, epigenetic and epidemiological approaches to identify those at-risk for adverse mental health outcomes. He also seeks to better understand the molecular mechanisms by which positive and nurturing environments mediate their positive effects on child neurodevelopment.