Olanzapine‐associated pica in a schizophrenia patient

Abstract

PICA IS DEFINED as the persistent eating of non-nutritive substances in an inappropriate and culturally unacceptable manner. To date, there is a lack of acceptable pathogenic mechanism underlying this behavior. Olanzapine, a commonly used antipsychotic, can block the central 5-HT2c and H1 receptors, therefore it has side-effects of increased bodyweight and appetite. There have been no reports, however, on pica occurring during olanzapine treatment. We here report on a schizophrenia patient who developed pica during the administration of olanzapine, which gradually remitted after this atypical antipsychotic had been discontinued. The present patient was a 35-year-old man with schizophrenia who had no medical or surgical diseases, eating disorders, drug abuse history or other psychiatric history. It had been 15 years since the first incidence and the patient had had several acute attacks during this period, but none of them resulted in pica. This time he developed negative symptoms of poor appetite, silence, social withdrawal; his medication had been changed from haloperidol 5 mg/day to olanzapine 10 mg/day, other medication remained unchanged. After he had taken olanzapine for 3 weeks, the negative symptoms and his appetite significantly improved without developing any positive symptoms. Of note, the patient started exhibiting pica by eating garbage, sand and pebble (based on the patient's statement, his behavior was unexplainable and uncontrollable, he just had a craving for eating them). The pica persisted for approximately 3 weeks. He was also found to have an increased appetite that even exceeded the amount of food that he could handle. No other hallucinations, delusions, or positive symptoms occurred. The patient also denied having intention of suicide or self-hurt. Nevertheless, the symptoms of pica persisted. Olanzapine was replaced by his previous medicine. After that, the pica gradually disappeared. Although we do not know the exact underlying mechanism of pica, there is increasing evidence that the craving for eating non-nutritional material could be considered as an obsessive–compulsive spectrum disorder.1 In addition, there are studies suggesting that some atypical antipsychotics may induce or aggravate the obsessive–compulsive symptoms.2 Given this, the mechanism of pica development in the present case could have been due to the blockade of olanzapine on the 5-HT2a receptors, resulting in an increase of dopamine release in the mid-brain and frontal cortex, and further causing the cortico-basal ganglia dysfunction. In conclusion, the present case suggests that pica may occur during the use of olanzapine in schizophrenia patients, which is similar to obsessive–compulsive symptom. Further studies are warranted to explore the relationship between pica and the use of olanzapine.