DIFFERENCES IN BRAIN-METABOLITES BETWEEN PATIENTS WITH AUTISM AND MENTAL-RETARDATION AS DETECTED BY IN-VIVO LOCALIZED PROTON MAGNETIC-RESONANCE SPECTROSCOPY

We performed volume-selective proton magnetic resonance spectroscopy ( H-1-MRS) of the brain with a 1.5 T magnet in 28 patients with autism, and compared the results with those from 28 age-matched patients with unclassified mental retardation and 25 age-matched healthy children. P eaks for N-acetylaspartate, choline and creatine, but not lactate, wer e observed in each group on H-1-MRS. The N-acetylaspartate/choline rat io was lower in patients with mental retardation than in patients with autism and controls (P = .05, respectively). However, there were no d ifferences in the N-acetylaspartate/choline ratios between patients wi th autism and controls, and the N-acetylaspartate/creatine and choline /creatine ratios did not differ among the three groups. These results suggest that N-acetylaspartate is decreased in patients with mental re tardation and that a disorder or dysfunction of neurons in the brain e xists. There also appear to be differences in the brain lesions or dys functions found in patients with autism and mental retardation.