Pica is the pathological craving for and eating of a nonnutritive item (eg, clay, coal, paper) or food ingredients (flour, raw potatoes). It is a complex behavior that can present with any number of variations (Table 1), and multiple pica determinants range from demands of tradition and acquired tastes in the cultural context to presumptive neurobiological mechanisms (eg, iron deficiency, CNS neurotransmission, physiological conditioning).
The clinical consequences of pica may have broad epidemiological implications as in lead intoxication and geophagia in children, which lead to severe impairment of intellectual and physical development. In addition, acute and chronic medical complications may pose surgical emergencies (intestinal obstruction from bezoars) as well as more subtle encroaching symptoms such as parasitosis, intoxication, and nutritional deficits.
In the spectrum of eating disorders, pica may be viewed as a derailment of food selection and a driven, often chaotic, form of ingestive behavior. In this overview of pica, we review its causes and prevalence. In addition, we discuss some of the associated complications as well as current treatment strategies.
According to DSM-IV, pica is the action of nonnutritive ingestion that is repeated for a period of at least a month and is developmentally inappropriate. Pica is most frequently seen in children and pregnant women. In certain ethnic populations, pica is culturally acceptable and is not considered pathological.
Poor parental supervision and oral overstimulation, maternal pica, and cultural acceptance of pica—especially common in families with African lineage and in southern US communities—may represent the extra pressures that allow pica to become manifest in a child prone to intense oral focus of drive satisfaction.1,2 Certain psychosocial stressors have been reported to be significantly associated with pica, including maternal deprivation, joint family, parental neglect, pregnancy, impoverished parent-child interaction, and disorganized family structure.3
Pica is often seen in mentally or developmentally disabled persons. Several recent studies suggest significant psychiatric comorbidity as a determinant of pica.4,5 Kraeplin was the first to document an extraordinary array of inedible materials consumed by psychotic patients and felt that this behavior might be a vegetative sign of psychosis, "a perversion of the appetite." Delusional schizophrenic patients may ingest glass, pins, or various other nonnutritive items, and driven nonnutritive eating has been seen in disorganized schizophrenic patients.6,7
The prevalence of pica is difficult to establish because of differences in definition and the reluctance of patients to admit to abnormal cravings and ingestion. An incidence of pica greater than 50% is considered normal in children aged 18 to 36 months. Pica is thought to decrease with age; one study showed that about 10% of children older than 12 years engage in pica.8 Persistence of excessive hand-to-mouth movements observed in pica is abnormal in children older than 36 months.9
In the developmentally disabled, there are changes in incidence of pica with age, IQ, medication, and manifestations of behavior and appetite. An increased incidence of pica has been found to occur in patients with CNS congenital anomalies and associated medical problems, such as diabetes, deafness, and seizures.10 The incidence of pica has also been found to be increased in patients taking neuroleptics, which may be related to diminished postsynaptic dopamine receptor changes.11,12
Ethnic differences and societal norms
Geography, sociocultural factors, and developmental considerations are all significant in determining pica (Table 2). Demographic information reveals that pica has been associated with diets that are low in iron, zinc, and calcium compared with a balanced controlled diet.13
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