4 recherche sur le mot-clé 'Anisotropy'

Altered Neural Connectivity in Females, But Not Males with Autism: Preliminary Evidence for the Female Protective Effect from a Quality-Controlled Diffusion Tensor Imaging Study / Jiedi LEI in Autism Research, 12-10 (October 2019)  

Public ISBD [article]  inAutism Research > 12-10 (October 2019) . - p.1472-1483 Titre : Altered Neural Connectivity in Females, But Not Males with Autism: Preliminary Evidence for the Female Protective Effect from a Quality-Controlled Diffusion Tensor Imaging Study Type de document : texte imprimé Auteurs : Jiedi LEI, Auteur ; Emma LECARIE, Auteur ; Jane JURAYJ, Auteur ; Sarah BOLAND, Auteur ; Denis G. SUKHODOLSKY, Auteur ; Pamela VENTOLA, Auteur ; Kevin A. PELPHREY, Auteur ; Roger J. JOU, Auteur Article en page(s) : p.1472-1483 Langues : Anglais (eng) Mots-clés : anisotropy  autism spectrum disorder  diffusion tensor imaging  female  motion  sex characteristics Index. décimale : PER Périodiques Résumé : Previous studies using diffusion tensor imaging (DTI) to investigate white matter (WM) structural connectivity have suggested widespread, although inconsistent WM alterations in autism spectrum disorder (ASD), such as greater reductions in fractional anisotropy (FA). However, findings may lack generalizability because: (a) most have focused solely on the ASD male brain phenotype, and not sex-differences in WM integrity; (b) many lack stringent and transparent data quality control such as controlling for head motion in analysis. This study addressed both issues by using Tract-Based Spatial Statistics (TBSS) to separately compare WM differences in 81 ASD (56 male, 25 female; 4-21 years old) and 39 typically developing (TD; 23 males, 16 females; 5-18 years old) children and young people, carefully group-matched on sex, age, cognitive abilities, and head motion. ASD males and females were also matched on autism symptom severity. Two independent-raters completed a multistep scan quality assurance to remove images that were significantly distorted by motion artifacts before analysis. ASD females exhibited significant widespread reductions in FA compared to TD females, suggesting altered WM integrity. In contrast, no significant localized or widespread WM differences were found between ASD and TD males. This study highlights the importance of data quality control in DTI, and outlines important sex-differences in WM alterations in ASD females. Future studies can explore the extent to which neural structural differences might underlie sex-differences in ASD behavioral phenotype, and guide clinical interventions to be tailored toward the unique needs of ASD females and males. Autism Res 2019, 12: 1472-1483. (c) 2019 The Authors. Autism Research published by International Society for Autism Research published by Wiley Periodicals, Inc. LAY SUMMARY: Previous Diffusion Tensor Imaging (DTI) studies have found atypical brain structural connectivity in males with autism, although findings are inconclusive in females with autism. To investigate potential sex-differences, we studied males and females with and without autism who showed a similar level of head movement during their brain scan. We found that females with autism had widespread atypical neural connectivity than females without autism, although not in males, highlighting sex-differences. En ligne : http://dx.doi.org/10.1002/aur.2180 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=408 [article] Altered Neural Connectivity in Females, But Not Males with Autism: Preliminary Evidence for the Female Protective Effect from a Quality-Controlled Diffusion Tensor Imaging Study [texte imprimé] / Jiedi LEI, Auteur ; Emma LECARIE, Auteur ; Jane JURAYJ, Auteur ; Sarah BOLAND, Auteur ; Denis G. SUKHODOLSKY, Auteur ; Pamela VENTOLA, Auteur ; Kevin A. PELPHREY, Auteur ; Roger J. JOU, Auteur . - p.1472-1483. Langues : Anglais (eng) in Autism Research > 12-10 (October 2019) . - p.1472-1483 Mots-clés : anisotropy  autism spectrum disorder  diffusion tensor imaging  female  motion  sex characteristics Index. décimale : PER Périodiques Résumé : Previous studies using diffusion tensor imaging (DTI) to investigate white matter (WM) structural connectivity have suggested widespread, although inconsistent WM alterations in autism spectrum disorder (ASD), such as greater reductions in fractional anisotropy (FA). However, findings may lack generalizability because: (a) most have focused solely on the ASD male brain phenotype, and not sex-differences in WM integrity; (b) many lack stringent and transparent data quality control such as controlling for head motion in analysis. This study addressed both issues by using Tract-Based Spatial Statistics (TBSS) to separately compare WM differences in 81 ASD (56 male, 25 female; 4-21 years old) and 39 typically developing (TD; 23 males, 16 females; 5-18 years old) children and young people, carefully group-matched on sex, age, cognitive abilities, and head motion. ASD males and females were also matched on autism symptom severity. Two independent-raters completed a multistep scan quality assurance to remove images that were significantly distorted by motion artifacts before analysis. ASD females exhibited significant widespread reductions in FA compared to TD females, suggesting altered WM integrity. In contrast, no significant localized or widespread WM differences were found between ASD and TD males. This study highlights the importance of data quality control in DTI, and outlines important sex-differences in WM alterations in ASD females. Future studies can explore the extent to which neural structural differences might underlie sex-differences in ASD behavioral phenotype, and guide clinical interventions to be tailored toward the unique needs of ASD females and males. Autism Res 2019, 12: 1472-1483. (c) 2019 The Authors. Autism Research published by International Society for Autism Research published by Wiley Periodicals, Inc. LAY SUMMARY: Previous Diffusion Tensor Imaging (DTI) studies have found atypical brain structural connectivity in males with autism, although findings are inconclusive in females with autism. To investigate potential sex-differences, we studied males and females with and without autism who showed a similar level of head movement during their brain scan. We found that females with autism had widespread atypical neural connectivity than females without autism, although not in males, highlighting sex-differences. En ligne : http://dx.doi.org/10.1002/aur.2180 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=408

A diffusion-weighted imaging tract-based spatial statistics study of autism spectrum disorder in preschool-aged children / Derek Sayre ANDREWS in Journal of Neurodevelopmental Disorders, 11-1 (December 2019)  

Public ISBD [article]  inJournal of Neurodevelopmental Disorders > 11-1 (December 2019) . - 32 Titre : A diffusion-weighted imaging tract-based spatial statistics study of autism spectrum disorder in preschool-aged children Type de document : texte imprimé Auteurs : Derek Sayre ANDREWS, Auteur ; Joshua K. LEE, Auteur ; Marjorie SOLOMON, Auteur ; Sally J. ROGERS, Auteur ; David G. AMARAL, Auteur ; Christine Wu NORDAHL, Auteur Article en page(s) : 32 Langues : Anglais (eng) Mots-clés : Anisotropy  Autism Spectrum Disorder/diagnostic imaging/pathology  Brain/diagnostic imaging/pathology  Child, Preschool  Cross-Sectional Studies  Diffusion Magnetic Resonance Imaging  Female  Humans  Image Processing, Computer-Assisted  Male  Sex Characteristics  White Matter/diagnostic imaging/pathology Index. décimale : PER Périodiques Résumé : BACKGROUND: The core symptoms of autism spectrum disorder (ASD) are widely theorized to result from altered brain connectivity. Diffusion-weighted magnetic resonance imaging (DWI) has been a versatile method for investigating underlying microstructural properties of white matter (WM) in ASD. Despite phenotypic and etiological heterogeneity, DWI studies in majority male samples of older children, adolescents, and adults with ASD have largely reported findings of decreased fractional anisotropy (FA) across several commissural, projection, and association fiber tracts. However, studies in preschool-aged children (i.e., < 30-40 months) suggest individuals with ASD have increased measures of WM FA earlier in development. METHODS: We analyzed 127 individuals with ASD (85♂, 42♀) and 54 typically developing (TD) controls (42♂, 26♀), aged 25.1-49.6 months. Voxel-wise effects of ASD diagnosis, sex, age, and their interaction on DWI measures of FA, mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were investigated using tract-based spatial statistics (TBSS) while controlling mean absolute and relative motion. RESULTS: Compared to TD controls, males and females with ASD had significantly increased measures of FA in eight clusters (threshold-free cluster enhancement p < 0.05) that incorporated several WM tracts including regions of the genu, body, and splenium of the corpus callosum, inferior frontal-occipital fasciculi, inferior and superior longitudinal fasciculi, middle and superior cerebellar peduncles, and corticospinal tract. A diagnosis by sex interaction was observed in measures of AD across six significant clusters incorporating areas of the body, genu, and splenium of the corpus collosum. In these tracts, females with ASD showed increased AD compared to TD females, while males with ASD showed decreased AD compared to TD males. CONCLUSIONS: The current findings support growing evidence that preschool-aged children with ASD have atypical measures of WM microstructure that appear to differ in directionality from alterations observed in older individuals with the condition. To our knowledge, this study represents the largest sample of preschool-aged females with ASD to be evaluated using DWI. Microstructural differences associated with ASD largely overlapped between sexes. However, differential relationships of AD measures indicate that sex likely modulates ASD neuroanatomical phenotypes. Further longitudinal study is needed to confirm and quantify the developmental relationship of WM structure in ASD. En ligne : https://dx.doi.org/10.1186/s11689-019-9291-z Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=573 [article] A diffusion-weighted imaging tract-based spatial statistics study of autism spectrum disorder in preschool-aged children [texte imprimé] / Derek Sayre ANDREWS, Auteur ; Joshua K. LEE, Auteur ; Marjorie SOLOMON, Auteur ; Sally J. ROGERS, Auteur ; David G. AMARAL, Auteur ; Christine Wu NORDAHL, Auteur . - 32. Langues : Anglais (eng) in Journal of Neurodevelopmental Disorders > 11-1 (December 2019) . - 32 Mots-clés : Anisotropy  Autism Spectrum Disorder/diagnostic imaging/pathology  Brain/diagnostic imaging/pathology  Child, Preschool  Cross-Sectional Studies  Diffusion Magnetic Resonance Imaging  Female  Humans  Image Processing, Computer-Assisted  Male  Sex Characteristics  White Matter/diagnostic imaging/pathology Index. décimale : PER Périodiques Résumé : BACKGROUND: The core symptoms of autism spectrum disorder (ASD) are widely theorized to result from altered brain connectivity. Diffusion-weighted magnetic resonance imaging (DWI) has been a versatile method for investigating underlying microstructural properties of white matter (WM) in ASD. Despite phenotypic and etiological heterogeneity, DWI studies in majority male samples of older children, adolescents, and adults with ASD have largely reported findings of decreased fractional anisotropy (FA) across several commissural, projection, and association fiber tracts. However, studies in preschool-aged children (i.e., < 30-40 months) suggest individuals with ASD have increased measures of WM FA earlier in development. METHODS: We analyzed 127 individuals with ASD (85♂, 42♀) and 54 typically developing (TD) controls (42♂, 26♀), aged 25.1-49.6 months. Voxel-wise effects of ASD diagnosis, sex, age, and their interaction on DWI measures of FA, mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were investigated using tract-based spatial statistics (TBSS) while controlling mean absolute and relative motion. RESULTS: Compared to TD controls, males and females with ASD had significantly increased measures of FA in eight clusters (threshold-free cluster enhancement p < 0.05) that incorporated several WM tracts including regions of the genu, body, and splenium of the corpus callosum, inferior frontal-occipital fasciculi, inferior and superior longitudinal fasciculi, middle and superior cerebellar peduncles, and corticospinal tract. A diagnosis by sex interaction was observed in measures of AD across six significant clusters incorporating areas of the body, genu, and splenium of the corpus collosum. In these tracts, females with ASD showed increased AD compared to TD females, while males with ASD showed decreased AD compared to TD males. CONCLUSIONS: The current findings support growing evidence that preschool-aged children with ASD have atypical measures of WM microstructure that appear to differ in directionality from alterations observed in older individuals with the condition. To our knowledge, this study represents the largest sample of preschool-aged females with ASD to be evaluated using DWI. Microstructural differences associated with ASD largely overlapped between sexes. However, differential relationships of AD measures indicate that sex likely modulates ASD neuroanatomical phenotypes. Further longitudinal study is needed to confirm and quantify the developmental relationship of WM structure in ASD. En ligne : https://dx.doi.org/10.1186/s11689-019-9291-z Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=573

Heritability of abnormalities in limbic networks of autism spectrum disorder children: Evidence from an autism spectrum disorder twin study / Linyan FU in Autism Research, 15-4 (April 2022)  

Public ISBD [article]  inAutism Research > 15-4 (April 2022) . - p.628-640 Titre : Heritability of abnormalities in limbic networks of autism spectrum disorder children: Evidence from an autism spectrum disorder twin study Type de document : texte imprimé Auteurs : Linyan FU, Auteur ; Chunyan LI, Auteur ; Yun LI, Auteur ; Xin CHENG, Auteur ; Xiwen CUI, Auteur ; Jiying JIANG, Auteur ; Ning DING, Auteur ; Hui FANG, Auteur ; Tianyu TANG, Auteur ; Xiaoyan KE, Auteur Article en page(s) : p.628-640 Langues : Anglais (eng) Mots-clés : Anisotropy  Autism Spectrum Disorder/diagnostic imaging/genetics  Child  Child, Preschool  Diffusion Magnetic Resonance Imaging  Diffusion Tensor Imaging/methods  Humans  White Matter  autism spectrum disorder  environmental effects  genetic factors  limbic tracts  twins Index. décimale : PER Périodiques Résumé : Although the limbic system is closely related to emotion and social behaviors, little is known about the integrity of limbic pathways and how genetics influence the anatomical abnormalities of limbic networks in children with autism spectrum disorder (ASD). Therefore, we used an ASD twin study design to evaluate the microstructural integrity and autism-related differences in limbic pathways of young children with ASD and to estimate the heritability of limbic tracts microstructure variance. We obtained diffusion tensor imaging scans from 33 pairs of twins with ASD aged 2-9 years and 20 age-matched typically developing children. The ACE model was used to estimate the relative effects of additive genetic factors (A), shared environmental factors (C) and specific environmental factors (E) on the variability of diffusivity measurements. We found a significant decrease in fractional anisotropy (FA) in the bilateral fornix and uncinate fasciculus (UF), as well as increased mean diffusivity (MD) and radial diffusivity (RD) in the bilateral fornix and right UF of ASD children. Correlation analysis showed that FA, MD, and lateralization indices of UF were correlated with autism diagnostic observation schedule scores. The ACE model revealed that genetic effects may drive some of the variability of microstructure in the bilateral fornix, cingulum, and left UF. In conclusion, in children with ASD, there are abnormalities in the white matter microstructure of the limbic system, which is related to the core symptoms; these abnormalities may be related to the relative contribution of genetic and environmental effects on specific tracts. LAY SUMMARY: Autism spectrum disorder (ASD) children have abnormal white matter structure in limbic system related to ASD symptoms, and genetic factors play an important role in the development of limbic tracts. En ligne : https://dx.doi.org/10.1002/aur.2686 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=473 [article] Heritability of abnormalities in limbic networks of autism spectrum disorder children: Evidence from an autism spectrum disorder twin study [texte imprimé] / Linyan FU, Auteur ; Chunyan LI, Auteur ; Yun LI, Auteur ; Xin CHENG, Auteur ; Xiwen CUI, Auteur ; Jiying JIANG, Auteur ; Ning DING, Auteur ; Hui FANG, Auteur ; Tianyu TANG, Auteur ; Xiaoyan KE, Auteur . - p.628-640. Langues : Anglais (eng) in Autism Research > 15-4 (April 2022) . - p.628-640 Mots-clés : Anisotropy  Autism Spectrum Disorder/diagnostic imaging/genetics  Child  Child, Preschool  Diffusion Magnetic Resonance Imaging  Diffusion Tensor Imaging/methods  Humans  White Matter  autism spectrum disorder  environmental effects  genetic factors  limbic tracts  twins Index. décimale : PER Périodiques Résumé : Although the limbic system is closely related to emotion and social behaviors, little is known about the integrity of limbic pathways and how genetics influence the anatomical abnormalities of limbic networks in children with autism spectrum disorder (ASD). Therefore, we used an ASD twin study design to evaluate the microstructural integrity and autism-related differences in limbic pathways of young children with ASD and to estimate the heritability of limbic tracts microstructure variance. We obtained diffusion tensor imaging scans from 33 pairs of twins with ASD aged 2-9 years and 20 age-matched typically developing children. The ACE model was used to estimate the relative effects of additive genetic factors (A), shared environmental factors (C) and specific environmental factors (E) on the variability of diffusivity measurements. We found a significant decrease in fractional anisotropy (FA) in the bilateral fornix and uncinate fasciculus (UF), as well as increased mean diffusivity (MD) and radial diffusivity (RD) in the bilateral fornix and right UF of ASD children. Correlation analysis showed that FA, MD, and lateralization indices of UF were correlated with autism diagnostic observation schedule scores. The ACE model revealed that genetic effects may drive some of the variability of microstructure in the bilateral fornix, cingulum, and left UF. In conclusion, in children with ASD, there are abnormalities in the white matter microstructure of the limbic system, which is related to the core symptoms; these abnormalities may be related to the relative contribution of genetic and environmental effects on specific tracts. LAY SUMMARY: Autism spectrum disorder (ASD) children have abnormal white matter structure in limbic system related to ASD symptoms, and genetic factors play an important role in the development of limbic tracts. En ligne : https://dx.doi.org/10.1002/aur.2686 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=473

Transcallosal white matter and cortical gray matter variations in autistic adults aged 30-73 years / Danielle CHRISTENSEN ; Jingying WANG ; Desirae J. SHIRLEY ; Ann-Marie ORLANDO ; Regilda A. ROMERO ; David E. VAILLANCOURT ; Bradley J. WILKES ; Stephen A. COOMBES ; Zheng WANG in Molecular Autism, 16 (2025)  

Public ISBD [article]  inMolecular Autism > 16 (2025) . - 16 Titre : Transcallosal white matter and cortical gray matter variations in autistic adults aged 30-73 years Type de document : texte imprimé Auteurs : Danielle CHRISTENSEN, Auteur ; Jingying WANG, Auteur ; Desirae J. SHIRLEY, Auteur ; Ann-Marie ORLANDO, Auteur ; Regilda A. ROMERO, Auteur ; David E. VAILLANCOURT, Auteur ; Bradley J. WILKES, Auteur ; Stephen A. COOMBES, Auteur ; Zheng WANG, Auteur Article en page(s) : 16 Langues : Anglais (eng) Mots-clés : Humans  Male  Gray Matter/diagnostic imaging/pathology  White Matter/diagnostic imaging/pathology  Female  Adult  Middle Aged  Aged  Case-Control Studies  Autistic Disorder/diagnostic imaging/pathology  Corpus Callosum/diagnostic imaging/pathology  Autism Spectrum Disorder/diagnostic imaging/pathology  Anisotropy  Diffusion Magnetic Resonance Imaging  Aging  Autism spectrum disorder  Autistic adults  Diffusion MRI  Free water  Free water corrected fractional anisotropy  Free water corrected mean diffusivity  Gray matter  Transcallosal tracts  White matter  in this study were approved by the Institutional Review Board (IRB) at the  University of Florida following the Declaration of Helsinki. The IRB number is  202100659, with an approval date of July 26, 2022. Consent for publication: All  authors have read and approved the submission. Competing interests: The authors  declare no competing interests. Index. décimale : PER Périodiques Résumé : BACKGROUND: Autism spectrum disorder (ASD) is a lifelong condition that profoundly impacts health, independence, and quality of life. However, research on brain aging in autistic adults is limited, and microstructural variations in white and gray matter remain poorly understood. To address this critical gap, we assessed novel diffusion MRI (dMRI) biomarkers, free water, and free water corrected fractional anisotropy (fwcFA), and mean diffusivity (fwcMD) across 32 transcallosal tracts and their corresponding homotopic grey matter origin/endpoint regions of interest (ROIs) in middle and old aged autistic adults. METHODS: Forty-three autistic adults aged 30-73 and 43 age-, sex-, and IQ-matched neurotypical controls underwent dMRI scans. We examined free water, fwcFA, fwcMD differences between the two groups and age-related pattern of each dMRI metric across the whole brain for each group. The relationships between clinical measures of ASD and free water in regions that significantly differentiated autistic adults from neurotypical controls were also explored. In supplementary analyses, we also assessed free water uncorrected FA and MD using conventional single tensor modeling. RESULTS: Autistic adults exhibited significantly elevated free water in seven frontal transcallosal tracts compared to controls. In controls, age-related increases in free water and decreases in fwcFA were observed across most transcallosal tracts. However, these age-associated patterns were entirely absent in autistic adults. In gray matter, autistic adults showed elevated free water in the calcarine cortices and lower fwcMD in the dorsal premotor cortices compared to controls. Lastly, age-related increases in free water were found across all white matter and gray matter ROIs in neurotypical controls, whereas no age-related associations were detected in any dMRI metrics for autistic adults. LIMITATIONS: We only recruited cognitively capable autistic adults, which limits the generalizability of our findings across the full autism spectrum. The cross-sectional design precludes inferences about microstructural changes over time in middle and old aged autistic adults. CONCLUSIONS: Our findings revealed increased free water load in frontal white matter in autistic adults and identified distinct age-associated microstructural variations between the two groups. These findings highlight more heterogeneous brain aging profiles in autistic adults. Our study also demonstrated the importance of quantifying free water in dMRI studies of ASD. En ligne : https://dx.doi.org/10.1186/s13229-025-00652-6 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=555 [article] Transcallosal white matter and cortical gray matter variations in autistic adults aged 30-73 years [texte imprimé] / Danielle CHRISTENSEN, Auteur ; Jingying WANG, Auteur ; Desirae J. SHIRLEY, Auteur ; Ann-Marie ORLANDO, Auteur ; Regilda A. ROMERO, Auteur ; David E. VAILLANCOURT, Auteur ; Bradley J. WILKES, Auteur ; Stephen A. COOMBES, Auteur ; Zheng WANG, Auteur . - 16. Langues : Anglais (eng) in Molecular Autism > 16 (2025) . - 16 Mots-clés : Humans  Male  Gray Matter/diagnostic imaging/pathology  White Matter/diagnostic imaging/pathology  Female  Adult  Middle Aged  Aged  Case-Control Studies  Autistic Disorder/diagnostic imaging/pathology  Corpus Callosum/diagnostic imaging/pathology  Autism Spectrum Disorder/diagnostic imaging/pathology  Anisotropy  Diffusion Magnetic Resonance Imaging  Aging  Autism spectrum disorder  Autistic adults  Diffusion MRI  Free water  Free water corrected fractional anisotropy  Free water corrected mean diffusivity  Gray matter  Transcallosal tracts  White matter  in this study were approved by the Institutional Review Board (IRB) at the  University of Florida following the Declaration of Helsinki. The IRB number is  202100659, with an approval date of July 26, 2022. Consent for publication: All  authors have read and approved the submission. Competing interests: The authors  declare no competing interests. Index. décimale : PER Périodiques Résumé : BACKGROUND: Autism spectrum disorder (ASD) is a lifelong condition that profoundly impacts health, independence, and quality of life. However, research on brain aging in autistic adults is limited, and microstructural variations in white and gray matter remain poorly understood. To address this critical gap, we assessed novel diffusion MRI (dMRI) biomarkers, free water, and free water corrected fractional anisotropy (fwcFA), and mean diffusivity (fwcMD) across 32 transcallosal tracts and their corresponding homotopic grey matter origin/endpoint regions of interest (ROIs) in middle and old aged autistic adults. METHODS: Forty-three autistic adults aged 30-73 and 43 age-, sex-, and IQ-matched neurotypical controls underwent dMRI scans. We examined free water, fwcFA, fwcMD differences between the two groups and age-related pattern of each dMRI metric across the whole brain for each group. The relationships between clinical measures of ASD and free water in regions that significantly differentiated autistic adults from neurotypical controls were also explored. In supplementary analyses, we also assessed free water uncorrected FA and MD using conventional single tensor modeling. RESULTS: Autistic adults exhibited significantly elevated free water in seven frontal transcallosal tracts compared to controls. In controls, age-related increases in free water and decreases in fwcFA were observed across most transcallosal tracts. However, these age-associated patterns were entirely absent in autistic adults. In gray matter, autistic adults showed elevated free water in the calcarine cortices and lower fwcMD in the dorsal premotor cortices compared to controls. Lastly, age-related increases in free water were found across all white matter and gray matter ROIs in neurotypical controls, whereas no age-related associations were detected in any dMRI metrics for autistic adults. LIMITATIONS: We only recruited cognitively capable autistic adults, which limits the generalizability of our findings across the full autism spectrum. The cross-sectional design precludes inferences about microstructural changes over time in middle and old aged autistic adults. CONCLUSIONS: Our findings revealed increased free water load in frontal white matter in autistic adults and identified distinct age-associated microstructural variations between the two groups. These findings highlight more heterogeneous brain aging profiles in autistic adults. Our study also demonstrated the importance of quantifying free water in dMRI studies of ASD. En ligne : https://dx.doi.org/10.1186/s13229-025-00652-6 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=555