[A case of Parkinsonism possibly associated with long-term methamphetamine use].

We report the case of a 60-year-old male who developed parkinsonism following approximately 32 years of methamphetamine (MA) use. The patient had used MA since age 18. He initially noted a mild resting tremor in his right upper limb around age 50, which remained relatively stable for nearly a decade. However, at age 59, gait disturbances emerged and progressed over the following six months. While brain magnetic resonance imaging (MRI) showed no remarkable findings, 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy demonstrated a reduction in the heart-to-mediastinum ratio. Additionally, dopamine transporter single-photon emission computed tomography (DAT-SPECT) revealed decreased uptake in the bilateral striatum. Treatment with levodopa resulted in significant clinical improvement. Given that MA is known to induce neurotoxicity in dopaminergic neurons through mechanisms such as oxidative stress and α-synuclein aggregation, these findings suggest that prolonged MA exposure may trigger a neurodegenerative process leading to parkinsonism with pathophysiological features similar to Parkinson's disease.