Glutamate levels of the right and left anterior cingulate cortex in autistics adults.

Scientists measured brain chemicals called glutamate in 19 autistic adults and 25 non-autistic adults using brain scans. They looked at a specific brain area called the anterior cingulate cortex. They found no differences in glutamate levels between autistic and non-autistic people. This suggests that glutamate may not be altered in this brain region in high-functioning autistic adults.

This study used magnetic resonance spectroscopy to measure glutamate levels in the anterior cingulate cortex (ACC) of 19 high-functioning autistic adults compared to 25 controls. Researchers examined both left and right ACC regions separately, based on their distinct functional roles. No significant differences in glutamate + glutamine (Glx) concentrations were found between autistic individuals and controls in either brain region. The findings do not support alterations in glutamate metabolism in the ACC of high-functioning autistic adults.

The authors suggest future research should focus on the GABAergic pathway to better understand excitatory/inhibitory imbalances in autism neurobiology.

Results suggest glutamate alterations in the anterior cingulate cortex may not be a primary neurobiological feature in high-functioning autism. Future research should investigate GABAergic pathways and excitatory/inhibitory balance in other brain regions to better understand autism neurobiology.

Small sample size (19 autistic participants), limited to high-functioning autistic adults only, single brain region examined, and study design not clearly specified in the abstract.

The neurobiology of Autism Spectrum Disorder (ASD) is still unknown. Alteration in glutamate metabolism might translate into an imbalance of the excitation/inhibition equilibrium of cortical networks that in turn are related to autistic symptoms, but previous studies using voxel located in bilateral anterior cingulate cortex (ACC) failed to show abnormalities in total glutamate level. Due to the functional differences in the right and left ACC, we sought to determine whether a difference between right and left ACC glutamate levels could be found when comparing ASD patients and control subjects. Using single-voxel proton magnetic resonance spectroscopy (H-MRS), we analyzed the glutamate + glutamine (Glx) concentrations in the left and right ACC of 19 ASD patients with normal IQs and 25 matched control subjects.

No overall group differences in Glx were shown, in the left ACC (p = 0.24) or in the right ACC (p = 0.11). No significant alterations in Glx levels were detected in the left and right ACC in high-functioning autistic adults. In the excitatory/inhibitory imbalance framework, our data reinforce the critical need to analyze the GABAergic pathway, for better understanding of basic neuropathology in autism.