title: Platelet serotonin levels in pervasive developmental disorders and mental retardation: diagnostic group differences, within-group distribution, and behavioral correlates.
abstract: OBJECTIVE
  To investigate group differences, the within-group distributions, and the clinical correlates of platelet serotonin (5-HT) levels in pervasive developmental disorders (PDD).
  
  
  METHODS
  Platelet 5-HT levels were measured in Dutch children and young adults, recruited from 2001 through 2003, with PDD (autism, Asperger's, and PDD-not otherwise specified [PDD-NOS]; n = 81) or with mental retardation (MR; n = 54) but without PDD, and in normal controls (n = 60). The distribution of platelet 5-HT levels was assessed using mixture-modeling analyses. Relationships between platelet 5-HT levels and a full range of demographic, clinical, and behavioral variables were examined.
  
  
  RESULTS
  Group mean (+/- SD) platelet 5-HT levels (nmol/10 platelets) were significantly higher in the autistic (4.51 +/- 1.61, n = 33) and PDD-NOS (4.90 +/- 1.54, n = 43) groups compared to the MR (3.48 +/- 1.33, n = 54) or the normal control (3.58 +/- 1.08, n = 60) groups (F4,190 = 9.35, p <.001). Platelet 5-HT values in the combined PDD group showed a bimodal distribution, and an empirical cutpoint for hyperserotonemia was determined. None of the behavioral variables examined was significantly associated with platelet 5-HT levels.
  
  
  CONCLUSIONS
  The platelet hyperserotonemia of autism was replicated in Dutch subjects. Platelet 5-HT levels were also increased in PDD-NOS, while no elevation was seen in MR. Platelet 5-HT levels appeared to be bimodally distributed in the PDD group, with an apparent hyperserotonemic subgroup.
authors.affiliation: Child and Adolescent Psychiatry Center, University of Groningen, The Netherlands. e.j.mulder@accare.nl
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Mulder
authors.forename: George M
authors.initials: GM
authors.lastname: Anderson
authors.forename: Ido P
authors.initials: IP
authors.lastname: Kema
authors.forename: Annelies
authors.initials: A
authors.lastname: de Bildt
authors.forename: Natasja D J
authors.initials: ND
authors.lastname: van Lang
authors.forename: Johan A
authors.initials: JA
authors.lastname: den Boer
authors.forename: Ruud B
authors.initials: RB
authors.lastname: Minderaa
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001519:Behavior / Q000502:physiology*; D001792:Blood Platelets / Q000378:metabolism*; D016022:Case-Control Studies; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000097:blood* / Q000453:epidemiology; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000097:blood* / Q000453:epidemiology; D007804:Language Development; D016014:Linear Models; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D012701:Serotonin / Q000097:blood*; D018709:Statistics, Nonparametric
chemical_list: D012701:Serotonin