Pica is a term that refers to cravings for substances that are not foods. Materials consumed by patients with pica include dirt, ice, clay, glue, sand, chalk, beeswax, chewing gum, laundry starch, and hair.
Pica is the craving or ingestion of nonfood items. The cravings found in patients diagnosed with pica may be associated with a nutritional deficiency state, such as iron-deficiency anemia; with pregnancy; or with mental retardation or mental illness. The word pica is derived from the Latin word for magpie, a species of bird that feeds on whatever it encounters.
The mental health professional's handbook, the Diagnostic and Statistical Manual of Mental Disorders , fourth edition, text revision (2000), which is abbreviated as DSM-IV-TR, classifies pica under the heading of "Feeding and Eating Disorders of Infancy or Early Childhood." A diagnosis of pica requires that the patient must persist in eating nonfood substances for at least one month. This behavior must be inappropriate for the child's stage of development. Further, it must not be approved or encouraged by the child's culture.
Causes and symptoms
The cause of pica is not known. Many hypotheses have been developed to explain the behavior. These have included a variety of such factors as cultural influences; low socioeconomic status; deficiency diseases; and psychological disorders.
Malnutrition is often diagnosed at the same time as pica. A causal link has not been established. Eating clay has been associated with iron deficiency; however, whether decreased iron absorption is caused by eating clay or whether iron deficiency prompts people to eat clay is not known. Some cultural groups are said to teach youngsters to eat clay. Persons with iron deficiency anemia have also been reported to chew on ice cubes. Again, the mechanism or causal link is not known.
Eating paint is most common among children from families of low socioeconomic status. It is often associated with lack of parental supervision. Hunger also may result in pica.
Among persons with mental retardation, pica has been explained as the result of an inability to tell the difference between food and nonfood items. This explanation, however, is not supported by examples of nonfood items that were deliberately selected and eaten by persons with limited mental faculties.
Pica, iron deficiency, and a number of other physiological disturbances in humans have been associated with decreased activity of the dopamine system in the brain . Dopamine is a neurotransmitter, or chemical that helps to relay the transmission of nerve impulses from one nerve cell to another. This association has led some researchers to think that there may be a connection between abnormally low levels of dopamine in the brain and the development of pica. No specific underlying biochemical disorders have been identified, however.
Risk factors for pica include the following:
- parental/child psychopathology
- family disorganization
- environmental deprivation
- brain damage
- mental retardation
- pervasive developmental disorders
Infants and children diagnosed with pica commonly eat paint, plaster, string, hair, and cloth. Older children may eat animal droppings, sand, insects, leaves, pebbles and cigarette butts. Adolescents and adults most often ingest clay or soil.
The symptoms of pica vary with the item ingested.
- Sand or soil is associated with gastric pain and occasional bleeding.
- Chewing ice may cause abnormal wear on teeth.
- Eating clay may cause constipation.
- Swallowing metal objects may lead to bowel perforation.
- Eating fecal material often leads to such infectious diseases as toxocariasis, toxoplasmosis, and trichuriasis.
- Consuming lead can lead to kidney damage and mental retardation.
Pica tends to taper off as children grow older. The disorder occasionally continues into adolescence but is rarely observed in adults who are not disabled.
Pica is observed more commonly during the second and third years of life and is considered to be developmentally inappropriate in children older than 18–24 months. Research findings indicate that the disorder occurs in 25%–33% of young children and 20% of children in mental health clinics. Among individuals with mental retardation, pica occurs most often in those between the ages of 10–20 years. Among young pregnant women, the onset of pica is frequently associated with a first pregnancy in late adolescence or early adulthood. Although pica usually stops at the end of the pregnancy, it may continue intermittently for years.
Pica usually occurs with equal frequency among males and females. It is relatively uncommon, however, among adolescent and adult males of average intelligence who live in developed countries.
Pica is often diagnosed in a hospital emergency room, when the child or adolescent develops symptoms of lead poisoning, bowel perforation, or other medical complications caused by the nonfood items that have been swallowed. Laboratory studies may be used to assess these complications. The choice of imaging or laboratory studies depends on the characteristics of the ingested materials and the resultant medical problems.
The examining doctor may order a variety of imaging studies in order to identify the ingested materials and treat the gastrointestinal complications of pica. These imaging studies may include the following:
- abdominal x rays
- barium examinations of the upper and lower gastrointestinal (GI) tracts
- upper GI endoscopy to diagnose the formation of bezoars (solid masses formed in the stomach) or to identify associated injuries to the digestive tract
Films and studies may be repeated at regular intervals to track changes in the location of ingested materials.
As of 2002, there is no standard treatment for pica. Currently, the most effective strategies are based on behavior modification , but even these treatments have achieved limited success. Pica associated with a nutritional deficiency often clears up when the missing nutrient is added to the patient's diet.
Few studies have examined the efficacy of drug treatments for pica. Ongoing research, however, is exploring the relationship between pica and abnormally low levels of the neurotransmitter dopamine. This line of research may help to identify new medications for the treatment of pica. There is some evidence that medications used to manage severe behavioral problems in children may be useful in treating coexisting pica.
Lead poisoning resulting from pica may be treated by chelating medications, which are drugs that remove lead or other heavy metals from the bloodstream. The two medications most often given for lead poisoning are dimercaprol, which is also known as BAL or British Anti-Lewisite; and edetate calcium disodium (EDTA). A medical toxicologist (a doctor who specializes in treating poisoning cases) may be consulted regarding children's dosages of these drugs.
In some cases, surgery may be required to remove metal objects from the patient's digestive tract or to repair tissue injuries. It is particularly important to remove any objects made of lead (fishing weights, lead shot, pieces of printer's type, etc.) as quickly as possible because of the danger of lead poisoning.
Pica frequently ends spontaneously in young children and pregnant women. Untreated pica, however, may persist for years, especially in persons with mental retardation and developmental disabilities.
There is no known way to prevent pica at the present time. Educating people, particularly young couples with children, about healthy nutritional practices is the best preventive strategy.
American Psychiatric Association. "Pica." In Diagnostic and Statistical of Mental Disorders. 4th edition, text revised. Washington, DC: American Psychiatric Association, 2000.
Herrin, Marcia, and Nancy Matsumoto. The Parent's Guide to Childhood Eating Disorders. New York: Henry Holt and Company, 2002.
Palmer, Robert L. Helping People With Eating Disorders: A Clinical Guide to Assessment and Treatment. New York: John Wiley and Sons, 2002.
Woolsey, Monika M. Eating Disorders: A Clinical Guide to Counseling and Treatment. Chicago: American Dietetic Association, 2002.
Grewal P. and B. Fitzgerald. "Pica with learning disability." Journal of the Royal Society of Medicine 95, no. 1(2002): 39-40.
Hamilton S., S. J. Rothenberg, F. A. Khan, M. Manalo, and K. C. Norris. "Neonatal lead poisoning from maternal pica behavior during pregnancy." Journal of the National Medical Association 93, no. 9 (2001): 317-319.
Roberts-Harewood M. and S. C. Davies. "Pica in sickle cell disease: 'She ate the headboard.'" Archives of Diseases of Children 85, no. 6 (2001): 510.
American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. Telephone:(913) 906-6000. Web site: <http://www.aafp.org> .
American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007-1098. Telephone: (847) 434-4000. Fax: (847) 434-8000. Web site: <http://www.aap.org/default.htm> .
American College of Physicians, 190 N Independence Mall West, Philadelphia, PA 19106-1572, Phone: (800) 523-1546, x2600 or (215) 351-2600, Web site: <http://www.acponline.org> .
American Medical Association. 515 N. State Street, Chicago, IL 60610. Telephone: (312) 464-5000. Web site: <http://www.ama-assn.org> .
Anorexia Nervosa and Related Eating Disorders, Inc.: <http://www.anred.com/pica.html> .
Support, Concern and Resources For Eating Disorders: <http://www.eating-disorder.org/pica.html> .
L. Fleming Fallon, Jr., M.D., Dr.P.H.