Platelet serotonin levels in pervasive developmental disorders and mental retardation: diagnostic group differences, within-group distribution, and behavioral correlates

J Am Acad Child Adolesc Psychiatry. 2004 Apr;43(4):491-9. doi: 10.1097/00004583-200404000-00016.


Objective: To investigate group differences, the within-group distributions, and the clinical correlates of platelet serotonin (5-HT) levels in pervasive developmental disorders (PDD).

Method: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Analysis of Variance
  • Behavior / physiology*
  • Blood Platelets / metabolism*
  • Case-Control Studies
  • Child
  • Child Development Disorders, Pervasive / blood*
  • Child Development Disorders, Pervasive / epidemiology
  • Child, Preschool
  • Female
  • Humans
  • Intellectual Disability / blood*
  • Intellectual Disability / epidemiology
  • Language Development
  • Linear Models
  • Male
  • Netherlands / epidemiology
  • Serotonin / blood*
  • Statistics, Nonparametric


  • Serotonin