The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) defines pica as eating nonnutritive, nonfood substances over a period of at least one month. The term is derived from "pica pica," the Latin word for the magpie bird, because of the bird's indiscriminate gathering and eating a variety of objects for the sake of curiosity. For diagnosis, the behavior must persist for at least one month, not be in keeping with the child's developmental stage (and age cut off of 24 months or more is suggested by DSM V), and not be socially normative or culturally acceptable behavior. The nature of ingested items is variable, including but not limited to earth (geophagy), raw starches (amylophagy), ice (pagophagia), charcoal, ash, paper, chalk, cloth, baby powder, coffee grounds, and eggshells.
Many factors have been implicated in the etiology of pica; however, no direct causality has been established. Studies of psychological factors have reported an association between pica and stress, child neglect and abuse, and maternal deprivation.. Iron deficiency anemia has also been implicated. Many population-based studies have found a low level of serum iron/ferritin (and other micronutrients) among patients with pica.. Despite this, studies conducted on substances consumed by pica patients failed to show increased iron bioavailability among these substances. This suggests that the idea that these cravings stem from a need for serum iron is an inadequate pathophysiological explanation for this phenomenon. Another proposed hypothesis that is gaining more attention is that pica for non-nutritive substances offers protection from harmful toxins during the most vulnerable stages of human cell replication and embryogenesis (childhood and pregnancy). The proposed mechanism of protection is binding to toxins and decreasing its intestinal absorption. In pagophagia, a Japanese study hypothesized that when a patient with anemia chews ice, it increases perfusion thus improving brain function. They contributed that to the activation of the dive reflex which would lead to peripheral vasoconstriction and an increase in central perfusion. Another explanation would be sympathetic activation which would also increase blood flow to the brain.
A variety of reasons make it challenging to estimate the exact prevalence of pica; for example, studies use variable definitions of pica, under-reporting is common among affected subjects, and a strong cultural and social influence adds further difficulty to detection. For the most part, the condition seems to affect women who are pregnant and young children. A German prevalence study of 804 children found that 99 children (12.3%) have engaged with a pica behavior at some point in their lives. A meta-analysis of studies of the prevalence of pica during pregnancy estimated that 27.8% of pregnant women reported experiencing pica. The study also stated that the sample was heterogeneous throughout the world, with a higher prevalence in Africa compared to other continents. A high prevalence of pica seems to be reported in patients with mental retardation (approximately 10%); it correlates with the severity of mental retardation.
A comprehensive history should be pursued along with caregiver interviews. The details of the exposure should be sought, including the type of substance, amount, duration of exposure, settings where behavior usually happens, the source of the substance, any co-ingestions, and symptoms of toxicity.
While, in most cases, the physical exam will be normal, one should look for signs of poisoning or complications. Bezoar ingestion could lead to obstruction and, possibly, ulceration and perforation. Lead poisoning manifests with neurological signs such as lethargy, headache, seizure, encephalopathy, cranial nerve palsy, and papilledema. Infectious agents that could present in clay include Toxocara and Ascaris. Signs of such parasitic infections include fever, cough, myocarditis and encephalitis, hepatomegaly, and visual disturbance.
Laboratory evaluation should be tailored according to the suspected substances ingested. Iron studies in patients with pica should be performed, especially in women who are pregnant and children. Lead (in pica for paint and chalk) and zinc levels should be checked where appropriate. A basic metabolic panel should be obtained, especially in clay ingestion which can cause metabolic disturbances such as hypokalemia.
Primary prevention should be utilized to identify at-risk patients such as children who live in old homes with lead paint and woman who are pregnant. This could be achieved by screening for the condition among such populations. Strategies should be utilized to decrease exposure to the craved substance, such as reducing access or providing an appropriate substitute with a similar texture. Iron, zinc, and other nutrient supplementation should be provided when a deficiency is identified. Behavioral and aversive treatment might be effective in patients with mental disability. Differential reinforcement is a commonly used strategy to induce different patient responses to pica by redirecting the undesired behavior to other activities.
Careful screening should be performed for mental health problems in the setting of pica. Several psychiatric illnesses should be considered in the differential diagnosis including other eating disorders, schizophrenia and psychosis, autism and developmental delay in children, and substance abuse and addiction.
The complications of pica can be categorized according to the type of substance ingested:
Pica during pregnancy can have dire consequences on the growing fetus. There are case reports of intrauterine toxicity due to maternal pica. Lead poisoning has been implicated in long-term neurological disability. Maternal geophagy has been associated with childhood motor function delay.
Treatment of patients with pica should utilize a multidisciplinary team approach. A team consisting of a physician, psychiatrist/psychologist, behavioral therapist, social worker, and dietitian. Patients should be treated in a nonjudgmental manner, with particular attention to their cultural and social background.