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

Abstract

Histological abnormalities of the brain in autism have been investigated extensively. We studied metabolites in the hippocampus-amygdala (HA) region and cerebellum. We examined the right HA region and left cerebellar hemisphere of 27 autistic patients 2-18 years old, 21 boys and 6 girls and 10 normal children 6-14 years old, 4 boys and 6 girls, using the STEAM sequence. This sequence was used to minimise the influence of relaxation times. The N-acetyl 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 0.616. The decreased NAA concentration may be due to neuronal hypofunction or immature neurons. The NAA concentration in the HA region and cerebellum may be related, because of neuronal circuits or networks.

N-acetyl aspartate in autism spectrum disorders: Regional effects and relationship to fMRI activation

“…Significant group differences in individual regions were limited to the left middle frontal gyrus, although the ASD group average was lower than the control group in all the brain regions assayed (frontal, parietal, occipital, and cerebellar) and when all brain areas were averaged, suggesting the possibility of widespread abnormalities. This study extended prior work in this area by establishing that neural abnormalities, which have been identified using 1 H-MRS predominantly in younger and likely lower functioning autistic individuals (Chugani et al, 1999;Friedman et al, 2003;Friedman et al, 2006;Hashimoto et al, 1997;Hashimoto et al, 1995;Hisaoka et al, 2001;Otsuka et al, 1999), may also be present in a higher functioning broadly inclusive ASD sample. None of the individuals in our sample had IQs in the mentally retarded range and the sample included individuals with diagnoses in the less severe end of the autism spectrum; approximately 43% of the sample was diagnosed as PDD-NOS or Asperger's disorder.…”

“…However, inconsistent results have been reported. For example, other studies did not find abnormally reduced levels of NAA in the frontal gray matter (Chugani et al, 1999;Levitt et al, 2003;Otsuka et al, 1999), temporal lobes (Levitt et al, 2003), bilateral thalamus (Levitt et al, 2003) and the amygdala-hippocampal and parietal regions (Page et al, 2006) in autism. These inconsistencies are difficult to interpret because studies differ widely in age range and level of functioning of their participants, and technical methodology.…”

“…Reduced levels of N-acetyl aspartate (NAA), a neuronal marker which can serve as an index of neuron density and viability (Danielsen and Ross, 1999), have been reported in the left frontal lobe white matter (Friedman et al, 2003;Levitt et al, 2003), bilateral cingulate (Friedman et al, 2003), left body of the caudate (Levitt et al, 2003), right thalamus (Friedman et al, 2003), right temporal lobe (Friedman et al, 2003;Hisaoka et al, 2001) left temporal lobe (Hisaoka et al, 2001), right parietal white matter (Friedman et al, 2003;Levitt et al, 2003), and the cerebellum (Chugani et al, 1999;Otsuka et al, 1999) in ASD. However, inconsistent results have been reported.…”

Motion and Form Coherence Detection in Autistic Spectrum Disorder: Relationship to Motor Control and 2:4 Digit Ratio

“…Given the role of the cerebellum in postural control, it has been suggested that autism is characterised by a visual motion integration impairment, and that this may reflect defective visuo-cerebellar circuitry (Gepner & Mestre, 2002b). Since several neuroimaging (Courchesne, 1997;Otsuka, Harada, Mori, Hisaoka, & Nishitani, 1999) and postmortem studies (Bauman & Kemper, 1994) have shown cerebellar abnormalities in autism, this may represent an anatomical correlate for abnormalities in balance and motor control. A second aspect of this study is therefore to measure fine and gross motor control in children with autistic spectrum disorder, and to investigate whether a relationship exists between the performance of these tasks and tasks of visual motion coherence sensitivity.…”

Proton MR Spectroscopy: Higher Right Anterior Cingulate N-Acetylaspartate/Choline Ratio in Asperger Syndrome Compared with Healthy Controls

“…5 The authors postulated that a hypermetabolic energy state and undersynthesis of brain membranes may underlie this in individuals with autism. Some studies found decreased NAA levels in the hippocampus-amygdala, 6 temporal cortex, 7 and cerebellum 8 of children with autism. Another study reported an association between 1 H-MR spectroscopy Cho/Cr ratios and severity of autism.…”