This case report describes a woman with young-onset Parkinson’s disease who developed extreme levodopa use after initially responding well to therapy. Her daily intake eventually reached up to 10,000 mg, far above typical treatment ranges, and she obtained prescriptions from multiple physicians. Although she did not report classic dopamine dysregulation syndrome features such as euphoria, craving, withdrawal, or substance use disorder, she did show behavioral dysregulation, including impulse control symptoms, pill hoarding, covert intake, and excessive deep brain stimulation controller manipulation. After bilateral subthalamic nucleus deep brain stimulation, her levodopa dose decreased substantially, though intermittent psychosis later emerged.
The report also highlights unusual complications, including severe black dental discoloration, extensive caries, and near-total tooth loss during the period of high-dose levodopa use. The authors note that the dental findings may have been multifactorial, potentially involving xerostomia, impaired oral hygiene, dietary factors, and possible medication-related effects, but causality could not be established. Genetic testing identified rare variants of uncertain significance, including a novel TENM4 variant, though no confirmed genetic diagnosis was made. The authors suggest this case may represent a non-hedonic, functionally driven form of dopaminergic dysregulation, where medication overuse is tied more to avoiding immobility, anxiety, or off-state distress than to reward-seeking behavior.
Reference: Oikarinen N, Ottela E, Rönkä J, et al. At the extreme limits of L-DOPA therapy: probable dopamine dysregulation and psychiatric complications in Parkinson’s disease. BMJ Neurol Open. 2026 Mar 18;8(1):e001498. doi: 10.1136/bmjno-2025-001498.
