title: Differences in striatal dopamine transporter density between tremor dominant and non-tremor Parkinson's disease.
abstract: OBJECTIVE
  Parkinson's disease (PD) can manifest with a tremor-dominant or a non-tremor (akinetic-rigid) phenotype. Although the tremor-dominant subtype may show a better prognosis, there is limited information on the phenotypic differences regarding the level of striatal dopamine transmission. The present study investigated striatal dopamine transporter (DAT) binding characteristics in a large sample of patients with and without tremor.
  
  
  METHODS
  [(123)I]FP-CIT SPECT scans of 231 patients with a clinical diagnosis of PD and abnormal FP-CIT binding (157 with tremor, 74 without tremor) and 230 control patients with normal FP-CIT binding (148 with tremor, 82 without tremor) were analysed using an automated region-of-interest analysis of the scans (BRASS). Specific striatal binding ratios were compared between phenotypes and groups using age, sex, and symptom duration, predominant side of symptoms, dopaminergic medications and scanner as covariates.
  
  
  RESULTS
  Patients with PD had 28.1 - 65.0 % lower binding in all striatal regions compared to controls (p < 0.001). The mean FP-CIT caudate nucleus uptake and the left caudate nucleus uptake were higher in PD patients with tremor than in PD patients without tremor (mean 9.0 % higher, left 10.5 % higher; p < 0.05), whereas there were no differences between tremor and non-tremor control patients. No significant effects of tremor on DAT binding were observed in the anterior or posterior putamen.
  
  
  CONCLUSIONS
  The motor phenotype is associated with the extent of caudate dopamine terminal loss in PD, as dopamine function is relatively more preserved in tremor patients. Symptom type is related to caudate dopamine function only in association with Parkinsonian dopaminergic degeneration, not in intact dopamine systems in patients with non-PD tremor.
authors.affiliation: Division of Clinical Neurosciences, University of Turku and Turku University Hospital, POB 52, 20521, Turku, Finland, valtteri.kaasinen@tyks.fi.
authors.forename: Valtteri
authors.initials: V
authors.lastname: Kaasinen
authors.forename: Maija
authors.initials: M
authors.lastname: Kinos
authors.forename: Juho
authors.initials: J
authors.lastname: Joutsa
authors.forename: Marko
authors.initials: M
authors.lastname: Seppänen
authors.forename: Tommi
authors.initials: T
authors.lastname: Noponen
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017072:Neostriatum / Q000000981:diagnostic imaging*; D010300:Parkinson Disease / Q000175:diagnosis / Q000000981:diagnostic imaging*; D011485:Protein Binding; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015899:Tomography, Emission-Computed, Single-Photon; D014202:Tremor / Q000175:diagnosis* / Q000000981:diagnostic imaging; D014326:Tropanes / Q000493:pharmacokinetics
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D019275:Radiopharmaceuticals; D014326:Tropanes; C087552:2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane