There are may environmental risk factors factors for schizophrenia such as drug use, stress before birth and in some cases exposure to infectious diseases (a disease that spreads from person to person). In addition, living in a city during childhood or as an adult has been found to double the risk of schizophrenia . This is true even after taking into account drug use, race, and the size of one’s social group. Other factors that play an important role include whether the person feels socially isolated, as well as social adversity, racial discrimination (treating a person badly because of their race), the person's family not working properly, unemployment, and poor housing conditions. There is evidence that childhood experiences of abuse or trauma are risk factors for developing schizophrenia later in life.