title: Presynaptic striatal dopamine dysfunction in people at ultra-high risk for psychosis: findings in a second cohort.
abstract: BACKGROUND
  Using positron emission tomography (PET), we previously observed increases in 3,4-dihydroxy-6-[(18)F]fluoro-L-phenylalanine ((18)F-DOPA) uptake in the striatum of subjects at ultra-high risk (UHR) for psychosis, indicating elevated presynaptic dopamine synthesis capacity. The purpose of this study was to test if this finding would be replicated in a second UHR cohort.
  
  
  METHODS
  (18)F-DOPA PET was used to estimate dopamine synthesis capacity in the striatum of an entirely new cohort of 26 individuals at UHR for psychosis (14 males, mean±SD age = 22.7±4.7 years) and 20 healthy volunteers matched for age and gender (11 males, mean±SD age = 24.5±4.5 years).
  
  
  RESULTS
  Dopamine synthesis capacity was elevated in the whole [t(44) = 2.6; p = .01, effect size = .81] and associative striatum [t(44) = 2.6; p = .01, effect size = .73] of UHR compared with control subjects. When the two samples were combined to give a final sample of 32 control and 50 UHR subjects, the higher levels of dopamine synthesis capacity in the UHR group reached significance across the whole [F(1,81) = 11.0; p = .001], associative [F(1,81) = 12.7; p = .001], and sensorimotor [F(1,81) = 4.7; p = .03], but not the limbic [F(1,81) = 2.1; p = .2], striatum.
  
  
  CONCLUSIONS
  The findings indicate that elevated dopamine synthesis capacity in the dorsal striatum is a robust feature of individuals at UHR for psychosis and provide further evidence that dopaminergic abnormalities precede the onset of psychosis.
authors: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, United Kingdom. Alice.Egerton@kcl.ac.uk
authors: Alice
authors: A
authors: Egerton
authors: Christopher A
authors: CA
authors: Chaddock
authors: Toby T
authors: TT
authors: Winton-Brown
authors: Michael A P
authors: MA
authors: Bloomfield
authors: Sagnik
authors: S
authors: Bhattacharyya
authors: Paul
authors: P
authors: Allen
authors: Philip K
authors: PK
authors: McGuire
authors: Oliver D
authors: OD
authors: Howes
mesh_terms: D000328:Adult; D001479:Basal Ganglia / Q000000981:diagnostic imaging; D015331:Cohort Studies; D003342:Corpus Striatum / Q000000981:diagnostic imaging; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives; D004298:Dopamine / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D008297:Male; D017729:Presynaptic Terminals / Q000737:chemistry / Q000000981:diagnostic imaging*; D062706:Prodromal Symptoms; D011618:Psychotic Disorders / Q000175:diagnosis / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D012307:Risk Factors; D055815:Young Adult
chemical_list: C043437:fluorodopa F 18; D004295:Dihydroxyphenylalanine; D004298:Dopamine