Function of the frontal lobe in autistic individuals : a proton magnetic resonance spectroscopic study

Purpose. In this investigation, we studied differences in chemical metabolites in certain brain regions between autistic patients and normal control subjects. Methods. Proton magnetic resonance spectroscopy (H-1-MRS) was used to evaluate functional activity in these regions. Specific regions studied were right and left dorsolateral prefrontal cortex(DLPFC) and the anterior cingulated cortex(ACC). Results. In the ACC, the N-acetylaspartate (NAA)/creatine/phosphocreatine(Cr) ratio in autistic patients (n=31) was significantly lower than that in control subjects (n=28). The decrease in the NAA/Cr ratio for the ACC was much greater in the group with worst social ability. NAA/Cr for the left DLPFC and social ability of autistic patients also correlated well. Furthermore, NAA/Cr for the left DLPFC in the group with intelligence quotient (IQ) below 50 was significantly less than in controls. NAA/Cr for the right DLPFC in autistic patients was not decreased compared to controls, and did not correlate with IQ or social ability. Conclusions. These findings suggest neuronal dysfunction in the ACC and left DLPFC in autism, and also a relationship between social disability and metabolic dysfunction in these regions. Dysfunction in the ACC and the left DLPFC may contribute to the pathogenesis of autism.