DESENSITIZE-PD: Intestinal Levodopa + Entacapone Therapy (Lecigon®) to Support Dopaminergic Desensitization in PD

20 patients with idiopathic Parkinson's disease, who are planned to undergo intestinal L-Dopa + entacapone (Lecigon®) treatment will be included into this observational single-armed study. These patient will be observed for hyperdopaminergic complications and neuropsychiatric fluctuations postprocedure at 3, 6 and 12 months.

This study is planned as non-interventional observational single-armed study in patients that are planned to undergo intestinal L-Dopa + entacapone (Lecigon®) treatment as regular treatment choice outside the study protocol and under the accepted regulatory approval and indication criteria (according to German "Fachinformation Lecigon®"). Patients will be observed at the pre-interventional baseline (oral treatment, before treatment initiation with Lecigon®), 3-month, 6-month follow-up, and final 12-month follow-up. As primary interest, the investigator will analyze the contrast of the pre-interventional baseline and 12-month follow-up in terms of the Ardouin Behavioural Scale which evaluates the hyperdopaminergic complications and neuropsychiatric fluctuations in a semi-structured interview. As additional exploratory outcomes, the investigator will study the "Neuropsychiatric fluctuation scale", impulse control disorders with the "QUIP rating scale (QUIP-RS)". Moreover, the investigator will study apathy outcomes using the "Apathy Evaluation Scale" that mainly relates to the dopaminergic off-state. Outcomes of post-interventional apathy are particularly important, since i) they may coincide with hypodopaminergic off-states, and ii) since outcomes of postoperative apathy are a limitation of existing DBS therapy. Avoiding worsening of apathy might be a strength of intestinal L-Dopa therapy in this regard. Further, the investigator will study established measures of motor sensitization/de-sensitization in particular motor fluctuations and dyskinesia (MDS-UPDRS IV) and Unified Dyskinesia Rating Scale (UDysRS). For completeness, the investigator will characterize MDS-UPDRS III motor state in addition.

Since dopaminergic desensitization occurs with considerable delay of rather weeks and months after changing oral to continuous treatment, the investigator expect a reduction of dopaminergic motor and neuropsychiatric complications within the first 6 months from introducing Lecigon® together with a stable course until final 12-month follow-up. The outcomes will be decided as contrast of the pre-interventional baseline (V0) in best oral treatment compared to 12 month follow-up of Lecigon® treatment.

Eligibility Criteria:
Inclusion Criteria:

* Written declaration of consent
* Age \> 18 years and \< 80 years
* Idiopathic Parkinson's syndrome (according to British Brain Bank criteria), including genetic forms
* L-dopa responsive Parkinson's syndrome
* Duration of disease \> 5 years
* The treatment decision for Lecigon® was made as a regular treatment decision according to the established indication criteria outside the study
* Motor fluctuations on oral dopaminergic therapy with uncontrolled motor off symptoms
* Presence or history of dyskinesia based on available medical records or self-reported history
* History of dopaminergic neuropsychiatric therapy complications based on available physician's letters or self-reported history:

  * impulse control disorders or
  * dopamine dysregulation syndrome or
  * off-condition apathy or
  * affective response fluctuations or
  * affective hypomanic or manic complications
  * hyperdopaminergic behavioral complications (such as binge eating or hobbyism or punding or increased creativity or risk seeking behavior; analogous to Ardouin Behaviour Scale Chapter IV - hyperdopaminergic behaviors).

Exclusion Criteria:

* Dementia according to ICD-10 criteria; mild cognitive impairment (MCI) according to screening tools such as MoCA or MMSE is not considered an exclusion criterion as long as ICD-10 criteria for dementia are not met regardless of MoCA/MMSE score.
* Acute paranoid psychosis or suicidality (however, impulse control disorder or dopamine dysregulation syndrome is not an exclusion criterion; illusions or (pseudo)-hallucinations are also not an exclusion criterion, as long as there is no risk to the patient or others according to clinical judgment; patients may be allowed to participate in the study after remission of the psychosis/suicidality)
* Pregnancy
* Contraindications to therapy with Lecigon® according the Summary of Product Characteristics (SmPC)

  * Hypersensitivity to the active ingredients of Lecigon®.
  * Narrow-angle glaucoma
  * Severe heart failure
  * Severe cardiac arrhythmia
  * Acute stroke
  * Severe impairment of liver function
  * Non-selective MAO inhibitors and selective type A MAO inhibitors must not be used concomitantly with Lecigon®. These inhibitors must have been discontinued at least two weeks prior to starting treatment with Lecigon®. Lecigon® may be used concomitantly with the manufacturer's recommended dose of an MAO inhibitor with selectivity for MAO type B (e.g., selegiline hydrochloride)
  * Conditions in which sympathomimetics (adrenergics) are contraindicated, e.g., pheochromocytoma, hyperthyroidism, and Cushing's syndrome.
  * Previous malignant neuroleptic syndrome (NMS) and/or nontraumatic rhabdomyolysis.
  * Suspected undiagnosed skin lesions or history of melanoma (levodopa could activate malignant melanoma).