Brain metabolites in the hippocampus-amygdala region and cerebellum in autism: an H-1-MR spectroscopy study

Histological abnormalities of the brain in autism have been investigated ex tensively. We studied metabolites in the hippocampus-amygdala (HA) region a nd cerebellum. We examined the right HA region and left cerebellar hemisphe re of 27 autistic patients 2-18 years old, 21 boys and 6 girls and 10 norma l children 6-14 years old, 4 boys and 6 girls, using the STEAM sequence. Th is sequence was used to minimise the influence of relaxation times. The N-a cetyl aspartate (NAA) concentration was significantly lower (P = 0.042) in autistic patients than in normal children (9.37 and 10.95 mM, respectively) . There was no significant difference in other metabolites. The correlation coefficient (r value) of NAA between the HA region and cerebellum was 0.61 6. The decreased NAA concentration may be due to neuronal hypofunction or i mmature neurons. The NAA concentration in the HA region and cerebellum may be related, because of neuronal circuits or networks.