Increased serum levels of glutamate in adult patients with autism

Prog Neuropsychopharmacol Biol Psychiatry. 2006 Dec 30;30(8):1472-7. doi: 10.1016/j.pnpbp.2006.06.013. Epub 2006 Jul 24.


Background: Precise mechanisms underlying the pathophysiology of autism are currently unknown. Given the major role of glutamate in brain development, we have hypothesized that glutamatergic neurotransmission plays a role in the pathophysiology of autism. In this study, we studied whether amino acids (glutamate, glutamine, glycine, D-serine, and L-serine) related to glutamatergic neurotransmission are altered in serum of adult patients with autism.

Methods: We measured serum levels of amino acids in 18 male adult patients with autism and age-matched 19 male healthy subjects using high-performance liquid chromatography.

Results: Serum levels (mean = 89.2 microM, S.D. = 21.5) of glutamate in the patients with autism were significantly (t = -4.48, df = 35, p < 0.001) higher than those (mean = 61.1 microM, S.D. = 16.5) of normal controls. In contrast, serum levels of other amino acids (glutamine, glycine, d-serine, l-serine) in the patients with autism did not differ from those of normal controls. There was a positive correlation (r = 0.523, p = 0.026) between serum glutamate levels and Autism Diagnostic Interview-Revised (ADI-R) social scores in patients.

Conclusions: The present study suggests that an abnormality in glutamatergic neurotransmission may play a role in the pathophysiology of autism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Autistic Disorder / blood*
  • Autistic Disorder / diagnosis
  • Autistic Disorder / psychology
  • Glutamic Acid / blood*
  • Humans
  • Male
  • Medical History Taking
  • Psychological Tests
  • Reference Values


  • Glutamic Acid