Pharmacologically Modulating the Noradrenergic Arousal System to Reduce Freezing of Gait in Parkinson's Disease: a Multi-centre and Multi-modal Approach

Inclusion Criteria: * Aged 18 years or older; * Diagnosis of idiopathic PD according to MDS Diagnostic Criteria; * Stabilised on optimal dopaminergic PD treatment for a minimum of four weeks prior to the baseline visit (Visit 1) and for the duration of the trial; * Presence of FOG symptoms on a daily basis; * Ability to walk for 10-meters unaided in the dopaminergic ON-state; * Ability to provide written informed consent in accordance with ICH-GCP and local regulations; * Willing and able to undergo all clinical trial assessments. Exclusion Criteria: * Current and/or previous (within 3 months) participation in a clinical trial; * Any contra-indications for undergoing MRI-scanning (e.g. claustrophobia or metal parts within the body such as DBS, an infusion pump or a pacemaker); * Co-morbidity that significantly impacts ambulation (e.g. orthopaedic or rheumatological ailments); * Severe cognitive impairment hampering the ability to comply with the study protocol; * Active psychosis that would impact the ability to comply with the study protocol; * Severe cardiovascular disorders: severe hypertension (Sustained (Sitting) hypertension of ≥180 mmHg systolic or ≥110 mmHg diastolic, defined by the average of three observations, each at least 3 minutes apart, with the participant having assumed the required position for at least 3 minutes), heart failure, arterial occlusive disease, angina, haemodynamically significant congenital heart disease, cardiomyopathies, myocardial infarction, potentially life-threatening arrhythmias, long QT interval syndrome (QTc \> 500ms Bazett-formula) and channelopathies that in the opinion of the study PI would significantly compromise participant safety; * Severe cerebrovascular disorders: cerebral aneurysm or recent/significant stroke; * Hepatic or renal insufficiency that in the opinion of the Principal Investigator would impact on the ability of the participant to safely participate; * Narrow angle glaucoma; * (History of) pheochromocytoma; * Use of noradrenergic agents; * Use of CYP2D6 inhibitors (SSRIs, quinidine, terbinafine); * Use of high dose salbutamol (or other beta2 agonists) that in the opinion of the Principal Investigator would impact on the ability of the participant to safely participate; * Pregnancy and/or breastfeeding; * Known hypersensitivity to atomoxetine.