Crawling Beneath the Surface: Exploring the Medical Conditions Associated With Delusional Infestation

ABSTRACT Background Delusional infestation is characterized by a fixed false belief of infestation despite no objective evidence. Although traditionally considered a primary psychiatric disorder, it may occur secondary to underlying medical conditions. This review examined medical disorders associated with delusional infestation and their implications for diagnosis and management. Methods The literature was reviewed for endocrine, neuropsychological, substance‐related, renal, hematologic, metabolic, and infectious conditions associated with delusional infestation, with emphasis on proposed mechanisms, diagnostic evaluation, and treatment response. Results Delusional infestationwas associated with thyroid dysfunction, diabetes and peripheral neuropathy, dementia, Parkinson's disease and dopaminergic medications, cerebrovascular disease, major depressive disorder, stimulant use, end stage renal disease, iron deficiency, and HIV associated neurocognitive disorders. Proposed mechanisms included dopaminergic dysregulation, neuroinflammation, cognitive impairment, and misinterpretation of abnormal sensory stimuli. Improvement or resolution was frequently reported after treatment of the underlying condition, discontinuation of causative medications or substances, and use of antipsychotic therapy. Conclusion Delusional infestation may represent a manifestation of an underlying and potentially reversible medical condition, supporting comprehensive evaluation and individualized, multidisciplinary management.