One factor that makes depression more likely is depression itself. Depression tends to deepen life’s problems, for example, making work and relationships harder, and also sensitises the brain by reinforcing neural circuits that underpin negative thinking. Depression, therefore, smooths the path to its own recurrence. On the other hand, depression may also increase resilience by provoking positive life changes and summoning inner resources that can insulate a person against future attacks. Which direction the illness goes depends largely on the treatment patients receive and the choices they make.