The Bizarre, Dangerous Urge: Decoding Pica

Pica. You might not know the name, but you probably know the behavior. It’s not just weird. It’s the persistent, undeniable urge to eat stuff that isn’t food. We’re talking dirt, clay, ice, starch, hair, even sharp objects. Think toddlers putting everything in their mouths – that’s normal for a while. But when it keeps going past age two, or shows up in adults, especially alongside other conditions, it becomes pica. And it’s a lot more common, and a lot more complicated, than you might think.

The term “pica” actually comes from the magpie, a bird known for eating pretty much anything. While the proper medical term is “allotriophagia,” you rarely see it. Pica has been around forever, a truly global phenomenon.

Not All Pica is Created Equal

Let’s get this straight, not every non-food bite is pathological. Some cultures, particularly non-Western ones, have forms of non-nutritive consumption that are considered normal. Eating clay or soil, known as geophagia, has deep historical roots, linked back to ancient Greece and Rome, and is still prevalent in places like sub-Saharan Africa. In Nigeria, it’s even seen as a sign of pregnancy. Eating raw starch (amylophagia) and compulsive ice eating (pagophagia) are also frequently linked to pregnancy. These forms are sometimes seen as potentially adaptive or even therapeutic during pregnancy.

But then you have the others. Eating wood (xylophagia), hair (trichophagia), dust (coniophagia), feces (coprophagia), and especially sharp objects (acuphagia) or glass (hyalophagia). These aren’t just unusual; they are often dysfunctional, dangerous, and can even kill you. These more extreme variants are heavily tied to conditions like dementia, schizophrenia, OCD, intellectual disability, and particularly, autism spectrum disorders (ASD).

The Baffling Connections: Deficiency, Pregnancy, and Brains

So, why do people do this? The sources offer a few intriguing possibilities, but no single, definitive answer.

One of the strongest links is to micronutrient deficiencies, especially iron deficiency anemia (IDA). Geophagia, amylophagia, and pagophagia have historically been tied to IDA. Deficiencies in zinc and calcium have also been associated with eating clay and starch. The thing is, it’s not clear if eating these substances helps. In fact, clay might actually reduce the availability of iron and zinc. So, perhaps pica isn’t fixing the deficiency, but rather a maladaptive craving caused by it – a weird signal error potentially mediated by things like hypothalamic dysfunction or altered taste. Oddly, treating iron deficiency helps with ice eating, but doesn’t always stop eating clay or starch.

Pregnancy is a major trigger for geophagia, amylophagia, and pagophagia. Women describe these as intense cravings. There’s a historical precedent for clays being seen as having medicinal properties, potentially binding toxins or pathogens in the gut, much like activated charcoal. Cornstarch has similar properties. The fact that geophagia is more common in tropical areas where foodborne pathogens are prevalent lends some weight to this idea of a protective function. But still, a clear physiological benefit remains elusive.

Then there’s the connection to neurological and psychiatric conditions. Pica is seen in schizophrenia, sometimes linked to OCD. It’s been observed in dementia, particularly frontotemporal dementia and Alzheimer’s disease. Semantic memory deficits and specific brain lesions have been associated with pica after brain injuries.

And significantly, pica is far more common in children with developmental disorders. A recent study found pica in 28% of children with both ASD and intellectual disability, 14% with ASD alone, and 10% with ID alone, compared to just 4% in typically developing kids. While micronutrient deficiencies can contribute in other chronic conditions, correcting them doesn’t necessarily fix pica in ASD.

The “Addiction” Hypothesis: A Compelling Parallel?

Here’s where it gets really interesting, and perhaps offers a framework for understanding this seemingly illogical behavior. Pica behaviors share characteristics with addictions. They are described as obsessive, driven, illogical, and often irresistible urges. Attempts to stop frequently result in failures and relapses, much like substance abuse. Pica is often a clandestine behavior, hidden due to fear of judgment.

This leads to a provocative question, “Could pica be a form of addiction?” The comparison is made to food cravings, which are nearly universal, intensify during pregnancy, and are also being explored through a neurobiological lens.

The underlying mechanism for addictive behaviors, including perhaps food cravings, is thought to involve the “dopamine motive system”. This complex network in the brain governs fundamental drives like eating and reproduction. Aberrations in this system are implicated in addictions like alcoholism, smoking, and compulsive gambling. The hypothesis is that this same system, particularly with disrupted dopamine transmission, might be involved in pica. The link between IDA and pica supports this, as IDA is associated with decreased dopamine receptors in a key part of this system (the nucleus accumbens).

Essentially, the theory is that pica might represent the dopamine motive system, which is supposed to drive survival actions, becoming deregulated and creating compulsive, rewarding (in an atypical way) drives towards inedible substances.

Finding a Way Forward: Behavior Over Pills?

Given the complexity and potential danger, finding effective treatments is critical, especially for children with conditions like ASD. Medical investigation is necessary to rule out things like lead toxicity, anemia, or obstructions.

However, pharmacological approaches for pica in ASD have limited success. One promising category of pharmaceuticals, SSRIs, show variable results, and some antipsychotics, while used for other ASD symptoms, may actually make pica worse.

On the other hand, Applied Behavioral Analysis (ABA) therapy shows real promise for reducing pica in ASD. Techniques involve reinforcement strategies and interrupting the behavior. Simple, practical steps like making the environment safe by removing objects and offering acceptable alternatives are also key. These methods are intensive, requiring significant time and effort.

The Enigma Endures

Despite the theories and associations, pica remains somewhat of an enigma. The exact neurological basis, especially for forms not linked to specific disorders, is still poorly understood. There’s a clear need for more research, particularly using advanced brain imaging to look at the connectivity within the dopamine motive system in people with pica.

Ultimately, understanding pica requires looking beyond just a strange habit. It might be a complex interplay of nutritional needs, cultural practices, developmental stage, underlying medical conditions, and perhaps, a fundamental drive gone awry, tapping into the same brain systems that govern our most basic survival instincts and our susceptibility to addiction. It’s a reminder that the lines between ‘behavior,’ ‘craving,’ and ‘addiction’ can be blurry, driven by powerful, often invisible, forces in the brain.

Source consulted:

Schnitzler, E. (2022). The neurology and psychopathology of pica. Current neurology and neuroscience reports, 22(8), 531-536.