title: Increased striatal dopamine transporter density in moderately severe old restless legs syndrome patients.
abstract: OBJECTIVE
  Dopamine dysregulation in restless legs syndrome (RLS) may be varied by the severity of RLS, which could contribute to the conflicting results from previous functional neuroimaging studies on the central dopaminergic neurotransmission of RLS. The aim of this study was to observe whether reduced striatal dopaminergic neurotransmission is associated with moderate to moderately severe RLS.
  
  
  METHODS
  Thirteen elderly patients with RLS and 12 normal elderly controls were enrolled in the study. All the subjects were dopaminergic-drug naïve and twelve patients with RLS had the severity of moderate to moderately severe degree based on the International Restless Legs Syndrome Study Group (IRLSSG) Severity Scale. We compared dopamine transporter density (DAT) availability and D2 receptor density in the striatum between patients with RLS and controls using [(123)I]2β-carbomethoxy-3β-(4-iodophenyl)tropane single-photon emission computed tomography (SPECT) and [(123)I]iodobenzamide SPECT.
  
  
  RESULTS
  Dopamine transporter density of patients with RLS was increased in the caudate (P = 0.037), posterior putamen (P = 0.041), and entire striatum (P = 0.046) compared with that of normal controls. DAT density was higher in the anterior putamen of patients with RLS than controls, although statistically not significant (P = 0.079). There was no difference in the D2 receptor density between patients with RLS and normal controls in the whole striatum or any of subregions.
  
  
  CONCLUSIONS
  Dysregulation rather than simple upregulation or downregulation of central dopaminergic neurotransmission may underlie the pathogenesis of RLS, and decreased dopaminergic neurotransmission may cause moderate to moderately severe RLS in the elderly.
authors.affiliation: Department of Neuropsychiatry, Seoul National University Bundang Hospital, Gyeonggi, Korea.
authors.forename: K W
authors.initials: KW
authors.lastname: Kim
authors.forename: J H
authors.initials: JH
authors.lastname: Jhoo
authors.forename: S B
authors.initials: SB
authors.lastname: Lee
authors.forename: S D
authors.initials: SD
authors.lastname: Lee
authors.forename: T H
authors.initials: TH
authors.lastname: Kim
authors.forename: S E
authors.initials: SE
authors.lastname: Kim
authors.forename: Y K
authors.initials: YK
authors.lastname: Kim
authors.forename: I-Y
authors.initials: IY
authors.lastname: Yoon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002421:Caudate Nucleus / Q000000981:diagnostic imaging / Q000378:metabolism; D003042:Cocaine / Q000031:analogs & derivatives; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007462:Iodobenzenes; D008297:Male; D011699:Putamen / Q000000981:diagnostic imaging / Q000378:metabolism; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012148:Restless Legs Syndrome / Q000000981:diagnostic imaging / Q000378:metabolism*; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D007462:Iodobenzenes; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2; C426805:idobenzamide; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; D003042:Cocaine