Pica is an eating disorder typically defined as the persistent ingestion of nonnutritive substances for at least 1 month at an age for which this behavior is developmentally inappropriate. It may be benign or may have life-threatening consequences.
The clinical presentation of pica is highly variable and is associated with the specific nature of the resulting medical conditions and the ingested substances. In poisoning or exposure to infectious agents, the reported symptoms are extremely variable and are related to the type of toxin or infectious agent ingested.
Physical findings may include the following:
Complications of pica must be addressed, including the following:
See Presentation for more detail.
Diagnosis of pica can be made clinically based on history. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) criteria[1] for pica are as follows:
No specific laboratory studies are indicated in the evaluation of pica. However, workup to investigate sequelae of pica may be necessary. Based on clinical presentation, helpful diagnostic studies include:
See Workup for more detail.
A multidisciplinary approach involving psychologists, social workers, and physicians is recommended for effective treatment.
Currently, behavioral strategies are considered the most effective in the treatment of pica. Such strategies include the following:
No medical treatment is specific for pica. Some evidence suggests that drugs that enhance dopaminergic functioning (eg, olanzapine) may provide treatment alternatives in individuals with pica that is refractory to behavioral intervention.
Additional management measures include the following:
See Treatment for more detail.
Pica is typically defined as persistent ingestion of nonnutritive substances for at least 1 month at an age for which this behavior is developmentally inappropriate, and the behavior must not be part of a culturally sanctioned practice.[1] The definition is occasionally broadened to include the mouthing of nonnutritive substances.
Individuals who present with pica have been reported to mouth or ingest a wide variety of nonfood substances, including, but not limited to, clay, dirt, sand, stones, pebbles, hair, feces, lead, laundry starch, vinyl gloves, plastic, pencil erasers, ice, fingernails, paper, paint chips, coal, chalk, wood, plaster, light bulbs, needles, string, cigarette butts, wire, and burnt matches.[2, 3, 4] Complications from pica may range from benign to life-threatening complications, depending on the quantity and nature of the substance ingested.
Pica is observed most frequently in children and may last to adolescence. It is most common in individuals with developmental disabilities, such as autism spectrum disorder (ASD) and intellectual disability (ID). Less frequently, pica is comorbid with schizophrenia and obsessive-compulsive disorder (OCD). The hair or skin is typically ingested when pica exists with trichotillomania or excoriation disorder.
Pica has also been observed in females during pregnancy, individuals with sickle cell disease, or in patients with micronutrient deficiencies.[3, 5, 6] Pica may also coexist with avoidant/restrictive food intake disorder, especially when there is a strong sensory component to the presentation.
The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR), classifies pica under feeding and eating disorders and notes that it may be present in conjunction with other feeding and eating disorders.[1] DSM-5-TR criteria for pica are as follows:
A minimum age of 2 years is suggested for the diagnosis. In children aged 18 months to 2 years, the ingestion and mouthing of nonnutritive substances is common and is not considered pathologic.
Although the etiology of pica is unknown, numerous hypotheses have been advanced to explain the phenomenon, including nutritional, psychosocial, and biochemical origin.
Deficiencies in iron, calcium, zinc, and other nutrients (eg, thiamine, niacin, and vitamins C and D) have been associated with pica,[2] although no firm empiric data support any of the nutritional etiologic hypotheses. One meta-analysis revealed that pica was associated with a 2.4-fold increase in the odds of anemia and lower plasma zinc levels compared to controls. These findings are similar to the risks posed by other nutritional factors that contribute to anemia. Associations between pica and micronutrient deficiencies could be used as early warning of deficiency in those that exhibit the behavior.[7] In some patients with malnutrition who eat clay, iron deficiencies have been diagnosed, but the direction of this causal association is unclear. Whether the iron deficiency prompted the eating of clay or whether the inhibition of iron absorption caused by the ingestion of clay produced the iron deficiency is unknown.[2]
Ingestion of clay, soil, or starch may be regarded as culturally acceptable by certain social groups. Clay eating and starch eating are seen in the United States in some southern, rural, African American communities, primarily among women and children.[4] Starch eating, in particular, is frequently started in pregnancy as a treatment for morning sickness and may be continued into the postpartum period. Parents may proactively teach their children to eat these and other substances. Pica behavior may also be learned via modeling and reinforcement.
While not completely proven, there previously was an assumption that pica represented a persistence of Freud’s oral stage of development (based on his psychoanalytic model).[8] The increased occurrence of pica in individuals with disabilities is hypothesized to be a learned behavior maintained by the consequences of that behavior.[2] It has been suggested that in individuals with intellectual disability (ID), pica may result from an inability to discriminate between food and nonfood items; however, the findings that individuals select pica items and that they often search aggressively for nonfood items of choice do not support this theory.
A variety of psychosocial factors are thought to contribute to pica. Immigrants and refugees have increased risk of pica behaviors. Maternal deprivation, parental separation, parental neglect, child abuse, and insufficient amounts of parent-child interaction have been associated with pica.[3]
Ingestion of paint is most common in children from families of low socioeconomic status and is associated with lack of parental supervision. Malnutrition and hunger may also place children at higher risk for these behaviors.
Some have hypothesized that pica resembles addiction conditions, albeit towards ingestion of inedible items, with aberrations in the dopamine motive system. The association between iron deficiency anemia and pica seems to point in this direction, as the former has been associated with reduced concentration of D2 receptors in the nucleus accumbens.[9]
Pica occurs throughout the world. Geophagia (deliberate consumption of earth, soil, or clay) is the most common form of pica in people who live in poverty and people who live in the tropics and in tribe-oriented societies. Pica is a widespread practice in western Kenya, southern Africa, and India. It has been reported in Australia, Canada, Israel, Iran, Uganda, Wales, Turkey, and Jamaica. In some countries (eg, Uganda) soil can be purchased for the purpose of ingestion.
It is thought that pica behaviors are underreported due to several factors; caregivers may not note the behavior until patients present with sequelae. Pica behaviors may be considered normal in certain societies. As such, pica prevalence varies widely.
Pica is reported most commonly in children, and typically occurs with equal frequency in boys and girls. Pica is most frequently observed during the second and third years of life and is considered developmentally inappropriate in children older than 18–24 months. About 4% of typically developing children are reported to have pica, but this increases significantly in those with developmental disabilities: 10% in those with intellectual disability (ID), 14% in those with autism spectrum disorder (ASD), and 28% in those with combined ASD and ID.[10] Among individuals with ID, pica is the most common eating disorder and is most frequently seen in those aged 10–20 years.[11] The risk for and severity of pica increase as the severity of the disability increases. Additionally, there are physiologic and neurodevelopmental associations with pica. Iron malabsorption and micronutrient deficiencies have demonstrated increased pica behaviors in individuals with ID and ASD, impaired expressive communication, fetal alcohol syndrome, severity of disability, increased aggression, and males. There are some associations that decrease the likelihood of pica, including if the individual has trisomy 21, or is not reliant on others for care.[12] A linear decrease in pica occurs with increasing age.[3] Pica occasionally extends into adolescence but is rarely observed in adults who are not mentally disabled. Infants and children commonly ingest paint, plaster, string, hair, and cloth. Older children tend to ingest animal droppings, sand, insects, leaves, pebbles, and cigarette butts. Adolescents and adults most often ingest clay or soil.
Pica was associated with undereating, overeating, and food fussiness in young children in a longitudinal cohort study.[13] It is reported to be more common in lower socioeconomic status.[3]
Pica is common in young pregnant women.[3] The onset of pica frequently occurs during their first pregnancy in late adolescence or early adulthood. Although the pica usually remits at the end of the pregnancy, it may continue intermittently for years.[14] Worldwide prevalence of pica during pregnancy and the postpartum period has been estimated at 27.8%.[15]
In patients with sickle cell disease (SCD), pica has been found to be prevalent. Several studies have found about 34% of patients with SCD demonstrated pica behaviors. Individuals who demonstrated pica behaviors tended to have lower hemoglobin and higher reticulocyte count than the individuals without pica. There is also increased risk for lead toxicity, which can be difficult to detect due to overlapping symptoms.[16]
Pica is rare in adolescent and adult males of average intelligence who live in developed countries.
Although no specific data exist regarding the racial predilection of pica, the practice is reported to be more common among certain cultural and geographic populations. For example, geophagia is accepted culturally among some families of African lineage and is reported to be problematic in 70% of the provinces in Turkey.
Pica often remits spontaneously in young children and pregnant women; however, it may persist for years if untreated, especially in individuals with intellectual and developmental disabilities.
Pica is a serious behavioral problem because it can result in significant medical sequelae, which are determined by the nature and amount of the ingested substance. Pica has been shown to be a predisposing factor in accidental ingestion of poisons, particularly in lead poisoning. The ingestion of bizarre or unusual substances has also resulted in other potentially life-threatening toxicities, such as hyperkalemia after cautopyreiophagia (ingestion of burnt match heads).
Exposure to infectious agents via ingestion of contaminated substances is another potential health hazard associated with pica, the nature of which varies with the content of the ingested material. In particular, geophagia (soil or clay ingestion) has been associated with soil-borne parasitic infections (eg, toxoplasmosis and toxocariasis). Gastrointestinal (GI) tract complications (eg, mechanical bowel problems, constipation, ulcerations, perforations, and intestinal obstructions) have resulted from pica.
It is vital to educate patients regarding healthy nutritional practices, including the dangers of eating nonnutritive substances.
Families should be educated on possible lead exposures both in and outside of the home. Certain toys, hand-painted ceramics, and jewelry may contain lead. Hobbies involving lead-based products may bring lead exposure to the home, and certain water pipes contain lead. Certain inks on candy wrappers or labels contain lead that might be ingested with the food item. Families who live near airports are at high risk of lead exposure from aviation gas in the air or soil. Lead-based paint poses a risk if it is ingested, but also contributes to lead content in dust, which can be inhaled or swallowed.[17]
In some areas, homeowners and landlords are legally responsible for lead hazard reduction in homes where hazardous lead-based paint conditions have been discovered either after direct testing or after a child inhabitant is found to have elevated blood lead levels. Remediation of the residence by licensed lead abatement professionals may eliminate lead hazards by removing, sealing, or enclosing lead-based paint with special materials. Temporary relocation of the child may be required.
The clinical presentation of pica is highly variable and is associated with the specific nature of the resulting medical conditions and the ingested substances. In poisoning or exposure to infectious agents, the reported symptoms are related to the type of toxin or infectious agent ingested. Gastrointestinal (GI) tract symptoms may include constipation, chronic or acute abdominal pain that may be diffuse or focused, nausea and vomiting, abdominal distention, and loss of appetite.
The broad range of complications arising from the various forms of pica and the delay in accurate diagnosis may result in mild–to–life-threatening sequelae.
One concern is that both in primary care and specialty developmental-behavioral pediatric care there are no systematic strategies to screen or inquire for pica. Even when single-item screeners are used. such as the Eating Disorders in Youth-Questionnaire (EDY-Q) and Screening Tool of Feeding Problems (STEP), they do not capture all the DSM-5-TR diagnostic criteria for pica.[18]
The physical findings associated with pica are extremely variable and are related directly to the materials ingested and the subsequent medical consequences. These findings may include the following:
Pica, particularly geophagia, increases chances of intake of lead. Lead toxicity, which is the most common poisoning associated with pica, presents with physical exam findings that are nonspecific and subtle, and most children with lead poisoning are asymptomatic. These manifestations can include neurologic symptoms such as irritability, lethargy, ataxia, incoordination, headache, cranial nerve paralysis, papilledema, encephalopathy, seizures, coma, or death, and GI tract symptoms (eg, constipation, abdominal pain, colic, vomiting, anorexia, or diarrhea). Lead encephalopathy is a potentially fatal complication of severe lead poisoning, presenting with headache, vomiting, seizures, coma, and respiratory arrest.
Ingestion of high doses of lead can cause significant intellectual impairment and behavioral and learning problems. It has been demonstrated that neuropsychologic dysfunction and deficits in neurologic development can result from very low lead levels, even levels once considered safe. A hypochromic microcytic anemia resembling iron deficiency anemia can also be seen with lead toxicity; lead interferes with heme synthesis, beginning at blood lead concentrations of about 25 µg/dL.
Various infections and parasitic infestations, ranging from mild to severe, are associated with the ingestion of infectious agents via contaminated substances, such as feces or dirt. In particular, geophagia has been associated with soil-borne parasitic infections. Toxocariasis (including visceral larva migrans and ocular larva migrans) and ascariasis are the most common soil-borne parasitic infections associated with pica. Manifestations of toxocariasis are diverse and appear to be related to the number of larvae ingested and the organs to which the larvae migrate. Physical findings associated with visceral larva migrans may include fever, hepatomegaly, malaise, coughing, myocarditis, and encephalitis. Ocular larva migrans can result in retinal lesions and loss of vision. Other potential parasitic infections include toxoplasmosis and tichuriasis.
GI tract manifestations may be evident secondary to mechanical bowel problems, constipation, ulcerations, perforations, and intestinal obstructions caused by bezoar formation and the ingestion of indigestible materials into the GI tract. These may require surgical intervention.
Nutritional effects may also be evident. Theories regarding the direct nutritional effects of pica are related to characteristics of specific ingested materials that either displace normal dietary intake or interfere with the absorption of necessary nutritional substances. Nutritional effects that have been linked to severe cases of pica include iron and zinc deficiency syndromes; however, the data are only suggestive, and there is no firm empiric evidence to support these theories.[19] A meta-analysis of 43 studies including 6,407 individuals with pica behaviors and 10,277 controls found pica to be associated with 2.35 greater odds of anemia and low hemoglobin (Hb), hematocrit (Hct), or plasma zinc (Zn) concentrations.[7]
Dental abnormalities may be evident on physical examination, including severe tooth abrasion, abfraction, and surface tooth loss.[20, 21, 22]
No specific laboratory studies are indicated in the evaluation of pica. However, certain laboratory studies may be indicated to assess the consequences of the condition, depending on the characteristics and nature of the ingested materials and the resultant medical sequelae.
Children with geophagia are at risk of lead toxicity, so obtaining a lead level is indicated in these individuals. Universal screening of blood lead concentrations in all children aged 1–2 years is recommended in localities where at least 27% of houses were built before 1950. Screening is also recommended in places where the prevalence of elevated blood levels in children aged 1–2 years is 12% or higher. Targeted screening for high-risk 1- and 2-year-old children is otherwise recommended.
Additionally, consuming clay or soil puts these patients at increased risk of parasitic infection. Obtaining studies for ova and parasites may be necessary if clinically indicated.[2] If paper is the ingested material, the individual may be exposed to mercury and obtaining a mercury level may be indicated.[3]
Various imaging studies may be used to identify ingested materials and aid in the management of gastrointestinal (GI) tract complications of pica. These may include the following:[2]
Although pica in children often remits spontaneously, a multidisciplinary approach involving psychologists, social workers, and physicians is recommended for effective treatment.[23] Development of the treatment plan must take into account the symptoms of pica and any contributing factors, as well as the management of possible complications of the disorder. Treatment of pica is conducted primarily on an outpatient basis.
Assessment of nutritional beliefs may be relevant in the treatment of some patients with pica. Any nutritional deficiencies that are identified should be addressed. It must be kept in mind, however, that nutritional and dietary approaches have successfully helped prevent pica in only a very limited number of patients.
Consultation with a psychologist or psychiatrist is advisable. Consultation with a social worker is also helpful.
A dentist may be consulted as well. Attention to oral health is important for managing the detrimental effects pica may have on teeth from a young age onward.[24]
Careful analysis of the function of pica behavior in individual patients is critical for effective treatment. This can be done by paying special attention to the antecedent, pica behavior, and consequence of the behavior. Understanding the function can help inform behavioral intervention and treatment.[12] Behavioral interventions are considered to be the most effective for treating pica behaviors.
Behavioral interventions found to be successful in treating pica behaviors include reinforcement-based strategies. These strategies provide positive stimuli to replace pica behaviors, or reward the individual for not engaging in pica behaviors. Studies examining reinforcement-based strategies varied in success, and about half of these studies showed decreased pica behavior.[25]
Another behavioral intervention to decrease pica behaviors is response interruption. This strategy uses interventions that block the pica behavior, either through a person or a shield blocking the action. In a systematic review of behavioral interventions to treat pica, response interruption demonstrated only a 47% success rate in decreasing pica behaviors to near-zero.[25] As such, this intervention strategy alone may not be effective in pica treatment, though it may have some benefit when used in combination with other strategies.
Finally, punishment-focused interventions use removal of a positive stimulus or addition of a negative stimulus to decrease pica behaviors. A systematic review showed that 70% of studies using punishment-based strategies were successful in decreasing pica behavior.[25]
In toddlers and young children, pica behavior may provide environmental or sensory stimulation. Assistance in addressing these issues may prove beneficial, along with help in managing economic problems or alleviating deprivation and social isolation.
Assessment of cultural beliefs and traditions may reveal the need for education regarding the negative effects of pica. Removal of toxic substances—especially lead-based paint—from the environment is important.
No medical treatment is specific for pica. Few studies of pharmacologic therapy for pica have been performed; however, the hypothesis that diminished dopaminergic neurotransmission is associated with pica suggests that drugs that enhance dopaminergic functioning may provide treatment alternatives in individuals with pica that is refractory to behavioral intervention.[26]
In addition, a single case report found that olanzapine, an antipsychotic agent with prominent dopaminergic, serotoninergic, adrenergic, and cholinergic effects, reduced pica behaviors.[27] Another case reported improvement of pica with initiation of oral contraceptive pills in a female with autism spectrum disorder (ASD).[28] Yet another showed initiation of aripiprazole improved pica in a male with ASD. Medications used in the management of severe behavioral problems may have a positive impact on comorbid pica.[29]
In patients whose pica behaviors are thought to be linked to micronutrient deficiency, supplementation may help improve or resolve symptoms. Those with iron-deficiency anemia have shown improvement in pica behaviors with iron supplementation.[30]