MRS measured brain metabolite alterations in autism: a meta-analysis.

Motivation: 1H-Magnetic Resonance Spectroscopy (MRS) studies have revealed alterations in neuro-metabolite concentrations in autism, but results have been inconsistent. Goal(s): Perform a comprehensive meta-analysis of previous MRS studies in autism. Approach: Data was included from 59 relevant studies. After assessment of data quality, data was grouped by metabolite, brain region and other demographic and methodological factors. Results: We find significantly lower concentrations of GABA and NAA in autism. These alterations were most pronounced in children and in limbic brain regions involved in processes relevant to autism phenotypes. We also investigate factors that contribute to effect size variation between studies, including MRS quantification method. Impact: Our meta-analysis comprehensively summarises previous MRS studies to provide evidence of regional disruptions to brain metabolite concentrations in autism. We also examine how MRS study outcome varies due to methodological and demographic factors.