Widespread alterations in white matter microstructure in autism: A multilevel meta-analysis

Area of Science:

• Neuroimaging
• Neurodevelopmental Disorders
• Brain Connectivity

Background:

• Disrupted brain connectivity is a core feature of autism spectrum disorder (ASD).
• Diffusion Tensor Imaging (DTI) is crucial for studying white matter microstructure in ASD.
• DTI studies often show reduced fractional anisotropy (FA) and increased mean diffusivity (MD) in individuals with ASD.

Purpose of the Study:

• To meta-analyze white matter microstructure alterations in ASD using FA and MD measures.
• To assess how participant characteristics and laterality moderate these differences.
• To evaluate changes across 11 white matter tracts.

Main Methods:

• Multivariate random-effects meta-analysis with a multilevel structure.
• Included 680 effect sizes from 59 studies (N_ASD = 1,750, N_TD = 1,484).
• Analyzed data from individuals aged 2 to 50 years.

Main Results:

• Significant moderate effect size for reduced FA in eight white matter tracts in individuals with ASD.
• Significant moderate-to-large effect size for increased MD in six white matter tracts in individuals with ASD.
• Moderators indicated tract- and metric-specific effects.

Conclusions:

• White matter alterations in ASD are complex and multidimensional.
• Findings underscore neurobiological differences in brain microstructure in ASD.
• Further research is needed to explore sex and lifespan differences.