Diagnostic uncertainty: Avoidant/restrictive food intake disorder and co-occurring psychosis in a severely malnourished adolescent male

Diagnosing comorbid psychosis and avoidant/restrictive food intake disorder (ARFID) may be challenging among severely malnourished patients. Malnutrition is an identified medical cause of psychosis and in patients with ARFID, symptoms mirroring psychosis could be secondary to weight loss versus a “true” thought disorder. Conversely, dietary restriction has been demonstrated in patients with psychosis, which conceivably, could result in the development of ARFID. In this case report, we present a medically hospitalized adolescent male with severe malnutrition, diagnosed with ARFID after 12-months of food avoidance due to sensory sensitivities and fears of gastrointestinal discomfort. A significant decline in his emotional, interpersonal, and cognitive functioning was also reported and attributed to severe malnutrition. With nutritional rehabilitation, the patient's eating behaviors and mental state unexpectedly declined, and he was ultimately diagnosed with comorbid psychosis.