Reduced neurite density index in the prefrontal cortex of adults with autism assessed using neurite orientation dispersion and density imaging.
NODDI shows autistic adults have fewer prefrontal brain-cell branches, and the fewer they have, the lower their empathy scores.
01Research in Context
What this study did
Zwiya et al. (2023) scanned adults with autism and matched controls. They used a newer MRI tool called NODDI. It measures tiny brain-cell branches called neurites.
The team focused on the left prefrontal cortex. This area helps us plan, feel for others, and talk. Standard scans miss the fine wiring changes that NODDI can see.
What they found
Adults with autism had lower neurite density in the left prefrontal cortex. Lower density means fewer tiny branches. The drop was big enough to show up on every scan.
Lower density also tracked with lower empathy scores. People with the sparsest branches rated themselves as less empathetic. The link gives a brain reason for social challenges.
How this fits with other research
Christensen et al. (2024) ran the same NODDI scan on autistic kids. They found the same low-density pattern in the cerebellum. The result extends the adult finding to younger brains.
Yasuno et al. (2020) used NODDI and saw low density in the corpus callosum. Poor density there linked to trouble reading faces. Together the studies show micro-wiring problems in many autism brain zones.
Maier et al. (2022) looked at the same left prefrontal spot but measured GABA, a brain chemical. They found more GABA, not less. More chemical but fewer branches seems opposite, yet the methods differ. One counts wires; one counts chemicals. Both point to an unbalanced left prefrontal system.
Why it matters
You now have a clearer brain picture to share with families. Low neurite density is invisible on regular scans, so explaining the NODDI finding helps them see why social skills can lag. When you write goals, target empathy and prefrontal tasks like turn-taking or perspective games. The link gives you a biological reason to keep those goals active and to celebrate small gains as real brain exercise.
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02At a glance
03Original abstract
<h4>Background</h4>Core symptoms of autism-spectrum disorder (ASD) have been associated with prefrontal cortex abnormalities. However, the mechanisms behind the observation remain incomplete, partially due to the challenges of modeling complex gray matter (GM) structures. This study aimed to identify GM microstructural alterations in adults with ASD using neurite orientation dispersion and density imaging (NODDI) and voxel-wise GM-based spatial statistics (GBSS) to reduce the partial volume effects from the white matter and cerebrospinal fluid.<h4>Materials and methods</h4>A total of 48 right-handed participants were included, of which 22 had ASD (17 men; mean age, 34.42 ± 8.27 years) and 26 were typically developing (TD) individuals (14 men; mean age, 32.57 ± 9.62 years). The metrics of NODDI (neurite density index [NDI], orientation dispersion index [ODI], and isotropic volume fraction [ISOVF]) were compared between groups using GBSS. Diffusion tensor imaging (DTI) metrics and surface-based cortical thickness were also compared. The associations between magnetic resonance imaging-based measures and ASD-related scores, including ASD-spectrum quotient, empathizing quotient, and systemizing quotient were also assessed in the region of interest (ROI) analysis.<h4>Results</h4>After controlling for age, sex, and intracranial volume, GBSS demonstrated significantly lower NDI in the ASD group than in the TD group in the left prefrontal cortex (caudal middle frontal, lateral orbitofrontal, pars orbitalis, pars triangularis, rostral middle frontal, and superior frontal region). In the ROI analysis of individuals with ASD, a significantly positive correlation was observed between the NDI in the left rostral middle frontal, superior frontal, and left frontal pole and empathizing quotient score. No significant between-group differences were observed in all DTI metrics, other NODDI (i.e., ODI and ISOVF) metrics, and cortical thickness.<h4>Conclusion</h4>GBSS analysis was used to demonstrate the ability of NODDI metrics to detect GM microstructural alterations in adults with ASD, while no changes were detected using DTI and cortical thickness evaluation. Specifically, we observed a reduced neurite density index in the left prefrontal cortices associated with reduced empathic abilities.
, 2023 · doi:10.3389/fneur.2023.1110883