Pica (medicine)

Pica (medicine), disorder of eating behavior characterized by continual ingestion of nonnutritive substances such as plaster, paint, paper, dirt, string, wood, crayons, and cloth. Pica does not usually involve a refusal to eat normal food items. The term pica comes from the Latin word for magpie, a bird that once was believed to survive on earth and clay.

Pica is sometimes seen with mental retardation or in individuals who are developmentally disabled. It may be part of another mental illness such as schizophrenia. In children, the disorder is most common among those who are emotionally deprived or neglected. Many of these children are also economically disadvantaged and live in older and poorly maintained buildings, so they frequently ingest lead-based paint. Pica has become a significant medical concern in recent years because of its association with lead poisoning and neurological damage in disadvantaged children (see Lead: Lead Poisoning).

Pica may also be seen in nondeprived populations of children as one of several problem eating behaviors of early childhood, which may also include picky eating, disinterest in food, and struggles over the speed of eating and quantity of food consumed. In some cases these early eating disturbances may be related to the development of eating disorders in adolescence.

Pica was first described in 16th-century Europe, and it was then considered primarily a disorder of adolescent females and pregnant women. It was one of the symptoms of chlorosis, an iron-deficiency disease commonly diagnosed until the end of the 19th century that was also characterized by menstrual irregularities, weakness, poor appetite, and depression. Eating clay, starch, dirt, and chalk was also seen in some populations suffering from parasitic infestations and malnutrition.

Eating clay, chalk, and other substances is still considered beneficial in some areas of the rural southeastern United States today, even though malnutrition and parasitic infections are no longer prevalent. Such behavior is not considered pica because it is part of a culturally accepted practice. Additionally, pica does not refer to the occasional ingestion of nonfood substances by very young children, because such behavior is considered normal in children younger than about two years of age.