Dr Lewis is a psychiatric epidemiologist whose research focuses on the causes, prevention and treatment of common mental health problems including depression and anxiety. Her research also includes self-harm and suicidality, which are strongly associated with depression and anxiety. She uses large population-based datasets and advanced methods of causal inference to inform prevention. She analyses data from large pragmatic clinical trials, to inform treatment. As depression and anxiety often begin during adolescence, much of her research focuses on young people.