Olive is a 68-year-old divorced woman who brings herself into the urgent care clinic complaining of “full body weakness” and “pain in my hands and feet.” She explains that for the past three years, she has become aware of numerous “environmental allergens” that she is being exposed to, such as “toxic chemicals” in the air in the hallways of her building, and “impure foods” at restaurants and supermarkets. She has been participating in online chat rooms about toxic environmental exposures and has been following an “elimination diet” prescribed by one of the “experts” she found online. She reports that she gets her food at her local health food store and that her diet currently consists of white rice, herbal tea, and coconut water. She feels that all other foods cause her to have negative “allergic reactions.” She also says that she wants to only eat food that is “healthy and pure” and spends hours reading and comparing the ingredient lists of other food items in the store. She admits that she is “quite thin” and denies wanting to lose weight. She complains of feeling like her legs are weak and that she has been dropping things from her hands; in addition, she describes burning pain in her hands and feet.

Olive is 5′3″ and weighs 95 lb (BMI 16.8). She appears very thin with evidence of temporal wasting. She is somewhat unkempt, with long hair in a loose braid, and ungroomed fingernails; her clothes appear too large for her body. She is alert and attentive. Her heart rate is regular though with two skipped beats over a 60 second period. Her blood pressure is 95/70 mm Hg without orthostatic changes. Subtle horizontal nystagmus is noted bilaterally, and her strength in her major motor groups is decreased (4+/5). The rest of her exam is unremarkable. An electrocardiogram shows sinus rhythm at 58 beats per minute, with occasional premature ventricular contractions (PVCs). Laboratory studies demonstrate a macrocytic anemia, with low potassium, magnesium, albumin, and vitamin B12 level; thyroid-stimulating hormone is at the upper limit of normal, but free thyroxine is normal; creatinine and blood urea nitrogen are both just above normal limits; blood alcohol level is undetectable.

Vitamin B12 deficiency has been demonstrated. Olive’s presentation may be consistent with a broad range of other medical and psychiatric conditions and requires further evaluation. Olive is presenting with low weight (and suspected weight loss, given her oversized clothes), specific and idiosyncratic beliefs and behaviors related to eating, and medical/neurologic abnormalities. Given her age, and physical exam and laboratory findings, a further medical work-up is essential.

Vitamin B12 deficiency may explain the macrocytic anemia, muscle weakness, and paresthesias. Vitamin B12 deficiency can be due to limited dietary intake (most common in vegan diets, which eliminate all animal products, as well as other highly restricted diets) or impaired absorption (e.g., due to changes in stomach and small bowel functioning, deficient intrinsic factor, or immune disorders such as Grave’s disease or lupus). It may present with anemia with elevated mean corpuscular volume, gastrointestinal symptoms, and neurologic findings, including abnormalities of reflexes, sensation, and strength, as well as fatigue, cognitive impairment, and psychiatric syndromes (e.g., mania, psychosis). Methylmalonic acid and homocysteine levels may be elevated. Olive’s restricted diet has likely caused her to be vitamin B12 deficient.

The clinician might be considering additional vitamin deficiencies, including vitamin B1 (thiamine), which may cause muscle weakness and atrophy, hypotension, heart failure, neurologic findings, and mental status changes. Wernicke’s encephalopathy, which classically has been associated with alcohol use but can develop in any individual with thiamine deficiency, is comprised of ophthalmoplegia, ataxia, and confusion. Impaired intake of thiamine deficiency occurs in restricted diets or general malnutrition; as many foods are fortified with thiamine, such as breads and cereal, a diet centered largely around white rice and processed foods might be more likely to lead thiamine deficiency. People who drink excessive alcohol often have impaired thiamine intake because they are largely consuming their calories through alcohol and eat poorly otherwise; in addition, alcohol may inhibit some of the necessary biochemical process required for thiamine absorption and metabolism. Thiamine deficiency may also be due to increased urinary losses in people with kidney disease.

Olive’s limited diet may also be causing her electrolyte abnormalities, which may be contributing to her cardiac findings (bradycardia, PVCs) and weakness. Her diet is not only restricted in nutritional value, but also severely deficient in calories, leading to her weight loss and general evidence of malnutrition, including temporal wasting. Other medical considerations should include heavy metal toxicity, neurodegenerative conditions, gastrointestinal disorders (such as Crohn’s disease), and cancer.

She’s odd—she says odd things, eats oddly, and looks a little odd… could there be an underlying psychiatric component to her presentation?

Indeed, as pointed out in Chap. 14, even in the presence of a medical condition there may be psychiatric or behavioral issues that are independent, related, or contributing. A medical problem such as vitamin deficiency may lead to physical findings and psychiatric signs and symptoms. Psychiatric disturbances may, analogously, lead to changes in behavior that then contribute to the development of medical issues. In Olive’s case, the evaluating clinician should absolutely be wondering whether her strange approach to diet, which subsequently may be contributing to her medical signs and symptoms, could be a function of mental health problem. If so, what?

Eating disorders:

Olive could have an eating disorder. She is rigid about what she eats and refers to spending a substantial amount of time thinking about what she eats. She denies wanting to lose weight and she does not demonstrate clear evidence of disordered body image, but she may not be forthcoming about these things. Her presentation could be consistent with anorexia nervosa [AN, see Chap. 1 for further discussion], with food restriction for the purpose of losing weight. As discussed in Chap. 14, patients with AN may obfuscate their symptoms behind philosophies about diet or nutrition plans that they report they are following for “health” reasons, while—in fact—the diets are primarily in place for the purpose of restricting calories.