Increased serum levels of glutamate in adult patients with autism

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-serme, 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 mu M, 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 mu M, 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. (c) 2006 Elsevier Inc. All rights reserved.