Effect of dopamine on learning and cognition

INTERVENTION: Oral administration of a single dose of Madopar (100 mg levodopa / 25 mg benserazide) or placebo, administered in a randomised, double‐blind design. Madopar is a dopamine precursor that increases dopamine availability in the brain. Placebo will be a vitamin C tablet. Dose: Madopar (100mg levodopa / 25 mg benserazide) Duration of treatment: single dose, one session. Adherence ensured by supervised in‐person ingestion. Mode of delivery: Oral tablet (crushed tablet dispersed in orange juice) CONDITION: Neurological ‐ Parkinson's disease Parkinson's disease; ; Parkinson's disease SECONDARY OUTCOME: Blood pressure and heart rate. This will be assessed as a composite secondary outcome. [Measured via standard blood pressure monitors Baseline (pre‐intervention), at 30 minute intervals post intervention during the first (intervention) session (the Madopar/Placebo session)] Subjective mood[Bond and Lader Mood Rating Scale Baseline (pre‐intervention), at 30 minute intervals post intervention during the first (intervention) session (the Madopar/Placebo session)] INCLUSION CRITERIA: Aged 18 years or older Neurologically intact No current or past diagnosis of neurological or psychiatric conditions PRIMARY OUTCOME: Brain activity during motor learning and cognitive tasks, assessed via electroencephalography (EEG; 64‐channel active electrode system), measured within a single session approximately 30–45 minutes post‐ingestion.[Brain activity will be assessed within a single session, starting approximately 30–45 minutes post‐drug/placebo ingestion (coinciding with peak drug levels), continuing for up to of 2 hours post‐ingestion. Assessed within a single session, approximately 30–45 minutes post‐ingestion (coinciding with peak drug levels), with physiological monitoring (blood pressure and heart rate) continuing for up to of 2 hours post‐ingestion. Follow‐up sessions of up to 6 months after the intervention will be used to assess lasting effects of the intervention. ] Eye‐tracking [Eye position and movement metrics (fixations, saccades, gaze patterns) will be collected using eye‐tracking devices such as the Eyelink 3000, and extracted and analyzed using appropriate eye tracking analysis software. Assessed within a single session, approximately 30–45 minutes post‐ingestion (coinciding with peak drug levels), with physiological monitoring (blood pressure and heart rate) continuing for up to of 2 hours post‐ingestion. Follow‐up sessions of up to 6 months after the intervention will be used to assess lasting effects of the intervention. ] Performance on behavioural tasks assessing learning and cognition. Learning and cognition are assessed as a composite primary outcome.. [Performance on tasks assessing learning and cognition will be assessed via reaction time, accuracy, and movement kinematics information. These will be collected via movement recording devices such as computer mice, keyboards, digitising tablet (e.g., the WACOM digitising tablets), force transducers, KinArm robotic arm. Assessed starting approximately 30–45 minutes post‐drug/placebo ingestion (coinciding with peak drug levels), continuing for up to of 2 hours post‐ingestion. Follow‐up sessions of up to 6 months after the intervention will be used to assess lasting effects of the intervention. ]