(P12) Deprescribing for Management of Delusional Parasitosis

Introduction: Hallucinations are troubling symptoms often reported in residents of long-term care facilities, including up to one third of all patients with dementia. When patients report seeing worms, insects, or other parasites, symptoms may represent delusional parasitosis, a rare psychiatric disorder that can be seen on its own (primary) or in connection with other psychiatric or neurodegenerative disease (secondary). Of dementia subtypes, delusional parasitosis is more commonly observed in Dementia with Lewy Bodies and HIV dementia than Alzheimer’s disease. Here we present a case of a 73-year-old male with Alzheimer’s dementia and depression with no history of psychotic features who developed visual hallucinations of worm infestation concerning for delusional parasitosis.

Case Description : Patient was a 73-year-old male with a history of Alzheimer’s dementia (MOCA 14/30) and depression. He began complaining of worms infesting his food and burrowing in his skin despite no evidence of organisms. Reassurance was unhelpful and exacerbated the patient’s agitation. Oral intake was reduced by 25 - 50% due to patient complaints of worms infesting food.
Physical exam was notable for scattered superficial wounds on his arms from frequent picking due to concern of worm infestation. He demonstrated intact attention and no evidence of delirium. Fixed false belief regarding infestation of worms was suggestive of delusional parasitosis. Staff were encouraged to validate the patient's distress without challenging or reinforcing delusions.
Psychiatric medications and other centrally acting agents were reviewed for possible contributors to symptoms. Due to agitation and complaints of nighttime insomnia, activating effects of bupropion were thought to be possible drivers. Bupropion was reduced to 100 mg twice daily, AM and noon.
Within one week of dose reduction, delusions resolved. Oral intake returned to baseline and superficial wounds resolved.

Discussion: Consider delusional parasitosis when patients present with new visual hallucinations involving infestation with living organisms, such as parasites, insects, or worms, despite absence of objective evidence .
Complications of delusional parasitosis include self-inflicted skin lesions due to scratching or picking as well as malnutrition from reduced oral intake due to concern for infestation.
Review medications in patients with hallucinations and/or delusional parasitosis for possible contributing agents. Medications including anti-parkinsonian drugs, antiepileptics, stimulants, some antibiotics, and antidepressants, such as bupropion, have been implicated in delusional parasitosis. Dose reduce or discontinue offending agents if appropriate.
Management of delusional parasitosis also involves establishing a therapeutic alliance and validating symptoms without reinforcing or directly challenging delusions. Antipsychotics are often effective in refractory cases and may be required long term.