The Adverse Childhood Experiences Study is a long-running investigation into the relationship between childhood adversity, including various forms of abuse and neglect, and health problems in later life. The initial phase of the study was conducted in San Diego, California from 1995 to 1997. The World Health Organization summarizes the study as: "childhood maltreatment and household dysfunction contribute to the development – decades later – of the chronic diseases that are the most common causes of death and disability in the United States... A strong relationship was seen between the number of adverse experiences (including physical and sexual abuse in childhood) and self-reports of cigarette smoking, obesity, physical inactivity, alcoholism, drug abuse, depression, attempted suicide, sexual promiscuity and sexually transmitted diseases in later life."