Parkinson's Disease

General information

The theme of 2025/26 is Parkinson's disease and levodopa monitoring. Parkinson's disease is a progressive neurodegenerative disorder caused by the loss of dopamine-producing neurons in the substantia nigra region of the brain. This results in a severe dopamine deficiency in the basal ganglia, which are critical for initiating and smoothing movement. The primary motor symptoms advancing from this deficit include tremor, muscle rigidity, slowness of movement, and postural instability.[1] Generally, the management of motor symptoms relies on the administration of levodopa (L-Dopa), a dopamine precursor that can cross the blood-brain barrier, unlike dopamine itself.[2] Levodopa is absorbed from the gastrointestinal tract and transported via the bloodstream to the brain, where it is decarboxylated into dopamine to restore motor function. Consequently, the concentration of levodopa in the blood serum directly influences the therapeutic effect and the onset of motor complications. A standard therapeutic range for plasma levodopa is typically considered to be between 1 - 3 µg/mL (approximately 5 - 15 µmol/L) following a dose.[3] As the disease progresses, the relationship between dose and clinical response becomes unpredictable, leading to motor fluctuations and dyskinesias. Therefore, monitoring levodopa levels serves as a crucial tool for optimizing dosing regimens. There is no cure for Parkinson's disease, although medications and therapies can manage the symptoms. In advanced cases, patients may undergo surgical treatments like deep brain stimulation to help control motor symptoms.[4]