Opioidergic and Noradrenergic Systems in Central Parkisonian Pain

Inclusion criteria

• Diagnosis of Parkinson's disease based on MDS-UPDRS criteria (Group 1 and 2)
• Dopaminergic therapy stable with stable dose for at least 4 weeks prior to J0
• Affiliate to a social security or similar system
• Having given written consent to participate in the study, free and informed.
• Having chronic pain more than 3 month (Group 1)
• Without chronic pain (Groupe 2 and 3)
• Having central pain using specific algorithm (Marques et al., 2019)
• Having pain intensity at least 4 on VAS (Visual Analogue Scale) during the last month (Group 1)
• Having pain intensity lower than 3 on VAS (Visual Analogue Scale) during the last month (Group 2 and 3)

Exclusion criteria

• Having atypical Parkinson's disease (Group 1 and 2)
• Parkinson's disease with disabling dyskinesia and/or severe tremor (Group 1 and 2)
• Any contraindications to having a brain MRI or PET scan (e.g., pacemaker, metal foreign body, claustrophobia, deep brain stimulation or apomorphin pump unable to be turn off)
• History of head trauma with loss of consciousness lasting more than 30 minutes
• Not agreeing to be informed in the event of incidental discovery of an abnormality on MRI or during neuropsychological assessment
• Presence of cognitive dysfunction (defined as MoCA score < 24)
• Severe depression (BDI > 29)
• unable to stop the opioid treatment the week before the imaging exam ( e.g., Antarène codéine, Claradol codéine, Codoliprane, Dafalgan codéine, Euphon, Klipal, Lindilane, Néo-codion, Paderyl, Prontalgine, Pulmoserum, Tussipax ; Opium : Izalgi, Lamaline, Colchimax, Dropizal ; Morphine : Actiskenan, Moscontin, Oramorph, Sevredol, Skenan ; Buprénorphine : Bupensan, Buvidal, Orobupre, Sixmo, Suboxone, Subutex, Temgesic, Zubsolv ; Dihydrocodéine : Dicodin ; Hydromorphone : Sophidone ; Nalbuphine : Nalpain ; Fentanyl : Abstral, Actiq, Breakyl, Durogesic, Effentora, Instanyl, Matrifen, Pecfent, Recivit ; Méthadone : Methadone AP-HP, Zorvon ; Oxycodone : Oxsynia, Oxycontin, Oxynorm, Oxynormoro ; Tramadol : Biodalgic, Contramal, Ixprim, Monoalgic, Monocrixo, Orozamudol, Skudexum, Topalgic, Zaldiar, Zamudol, Zumalgic)
• unable to stop any treatment
• Treated with level 1 analgesics (NSAIDs, acetaminophen) or coanalgesics (antidepressants, antiepileptics) unless treatment has been stable for at least 4 weeks prior to the study and does not interfere with the noradrenergic system (list above).
• Presenting or having presented a dependence on any addictive substance according to DSM-IV-TR criteria, with the exception of tobacco.
• Having used recreational drugs interfering with the opioid and noradrenergic systems (cannabis, CBD, opiates, MDMA, ecstasy) in the last 3 months or chronic use
• Pregnant women, women in labor or nursing mothers
• Persons deprived of their liberty by judicial or administrative decision
• Under psychiatric care
• Admitted to a health or social institution for purposes other than research
• Under legal protection (guardianship, curatorship)
• Participant in another interventional study with an exclusion period still in progress at pre-inclusion
• Having exceeded the annual amount of compensation authorized for participation in research protocols