# Delusional Infestation in Parkinson's Disease Secondary to Piribedil Escalation: An Uncommon Case Report

## TL;DR

An 81-year-old Parkinson's patient developed delusional infestation after increasing piribedil, a dopamine agonist, highlighting a rare side effect of the drug.

## Contribution

This case report highlights a rare instance of delusional infestation in Parkinson's disease linked to piribedil escalation.

## Key findings

- Delusional infestation occurred in a Parkinson's patient after increasing piribedil dosage.
- Withdrawing the implicated drug is the recommended treatment for drug-induced delusional infestation.
- Piribedil, a dopaminergic agonist, is rarely associated with delusional infestation in Parkinson's disease.

## Abstract

Delusional infestation (DI) is characterized by delusions of being infested by small microorganisms or even inanimate objects without any medical or microbiological evidence. The pathophysiology of DI is not well understood, and there are two types of DI: the primary form, where there is no underlying cause, and the secondary form, which is related to an associated psychiatric disorder, medical condition, or substance use. DI in Parkinson's disease (PD) is rarely reported, and most published cases are due to antiparkinsonian drugs. Piribedil is a dopaminergic agonist used for the symptomatic treatment of PD either as monotherapy or as adjuvant therapy with other antiparkinsonian treatments. We report the case of an 81-year-old man followed for PD at our institution who developed DI after piribedil dose escalation. When DI is secondary to an antiparkinsonian drug, the treatment of choice is based on withdrawing the implicated drug.