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Prog Neuropsychopharmacol Biol Psychiatry. 2006 Dec 30;30(8):1472-7. Epub 2006 Jul 24.

Increased serum levels of glutamate in adult patients with autism.

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Department of Psychiatry and Neurology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-3192, Japan.

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  • Prog Neuropsychopharmacol Biol Psychiatry. 2007 Mar 30;31(2):590.



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.


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.


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.


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

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