Table 8.

DTI-based studying of the ASD at adulthood.

Work	Autistic group			Control group			sMRI	Brain regions	Data analysis	Findings
	Age, y	IQ	Size	Age, y	IQ	Size
Catani et al., 2008	22–40	92–126	15 ASP	24–46	99–141	16	1.5 T; 2.5 mm	Inferior, middle, and superior cerebellar peduncles; intracerebellar fibers	DT; ROI; RMA; SPSS	ASD: Decreased FA in short intracerebellar fibers and right superior cerebellar (output) peduncle; negatively correlated FA of left superior cerebellar peduncle and ADI-R social scores ASD and control groups: no MD differences
Conturo et al., 2008	23–29	102–106	17 HFA	23–29	99–141	17	1.5 T; 2.5 mm; 7 GD	Hippocampo- and amygdalo-fusiform pathways	ROI; DT; JMP 7.0	ASD: Decreased λ⊥ in right hippocampo-fusiform pathway; increased λ⊥ and λ|| in left hippocampo-fusiform pathway and bilateral amygdalo-fusiform pathways; decreased across-fiber diffusivity related to poorer Benton face interpretation and performance IQ scores
Thakkar et al., 2008	19–41	VIQ: 112–136	12 ASP, NPDD	19–35	VIQ: 95–123	12	3 T; 2 mm; 700 b; 72 GD	Anterior cingulate cortex	ROI; FLIRT; FSL; TKregister2	ASD: Decreased FA in WM underlying rostra1 and dorsal anterior cingulate cortex bilaterally, dorsolateral prefrontal cortex, ventral prefrontal cortex, and intraparietal sulcus; increased FA in right insula; increased activation on correct trials and reduced FA in rostra1 anterior cingulate cortex WM, which is associated with higher ratings of repetitive ADI behavior
Pugliese et al., 2009	11–35	93–117	12 ASP	15–35	105–137	42	2.5 mm; 1300 b	Inferior longitudinal fasc.; inferior frontal occipital fasc.; uncinate fasc.; cingulum; fornix	DT; ROI; GLM; Z-observation analysis; SPSS	No significant between-group differences in FA and MD ASD: Increased number of streamlines in right and left cingulum, and right and left inferior longitudinal fasc.; decreased number of streamlines in right uncinate fasc Significant age-related differences in MD and number of streamlines, but not FA within each group; significant age-related between-group MD differences in left uncinate fasc,
Bloemen et al., 2010	29–49	94–126	13 ASP	27–47	101–129	13	3 T; 2.5 mm; 1300 b; 64 GD	Inferior fronto-occipital fasc.; minor and major forceps; anterior and posterior corona radiata; bilateral anterior thalamic radiation	VBA; ANCOVA; permutation-based testing; SPM2; SPSS 12.0; XBAM	ASD: Reduced FA and increased λ⊥ over large brain areas; decreased MD in brain-stem cluster
Beacher et al., 2012	22–42 m; 25–39 f	–	28 ASP	20–36 m; 24–40 f	–	30	1.5 T; 2.6 mm; 1000 b; 64 GD	CC; cingulum bundle; CST; cerebellum	ROI; ANOVA; Diffusion Toolkit	Significant sex–diagnosis interactions in total WM volume, regional GM volume in right parietal operculum, and FA in body of CC, cingulum, and corona radiata Post-hoc comparisons: increased FA in male controls w.r.t. females, but no sex difference in ASD subjects
Thomas et al., 2011	19–39	97–117	12 HFA	18–27	102–122	18	1.5 T; 3 mm; 850 b; 6 GD	Inferior longitudinal and fronto-occipital fasc.; uncinate fasc.; 3 sub-portions of major inter-hemispheric fiber tract; CC	DT; ROI; ANOVA; DTIstudio	ASD: Increased WM volume of intra-hemispheric fibers, particularly, in left hemisphere, and decreased WM volume of minor forceps and CC body; negatively correlated minor forceps WM volume and ADI-R repetitive and stereotypical behavior scores; no group FA differences
Langen et al., 2012	20–32	92–122	21 AD	22–34	96–124	22	3 T; 2.4 mm; 1300 b; 32 GD	Fronto-striatal WM tracts	DT; ROI; GLM; MANOVA; SROC; ExploreDTI; FLIRT; TrackVis; SPSS	Decreased total brain WM volume and FA and increased MD of the tracts connecting putamen and accumbens to frontal cortical areas in ASD subjects ASD subjects had worse performance than controls on a go/nogo task No significant relationship between differences in FA and on ADI-R or ADOS scores in ASD subjects
Pardini et al., 2012	21–23	47–51	22 LFA	–	–	–	3 T; 2 mm; 1000 b; 33 GD	uncinate fasciculus	VBA; FSL; SPM5; SPSS16	Independent from symptoms' severity and IQ at therapy onset and from subject's age at time of MRI scanning and significant correlation between clinical improvement and FA of two WM clusters in uncinate fasc.; independent of symptoms severity and IQ scores and significant correlation between increasing uncinate fasc. structural organization and clinical improvement, precocity, and intervention length; more significant clinical improvement and higher uncinate fasc. FA for highly therapy-adherent subjects w.r.t. moderately adherent ones
Lewis et al., 2013	22–42	68–108 VIQ	20 AD	22–42	–	22	3 T; 3 mm; 1400 b; 15 GD	CC	PT; ROI; RFTCS; CIVET	ASD: Negatively correlated CC fiber length, adjusted for intracranial volume, and CC size; positively correlated adjusted CC fiber length and λ⊥
Kana et al., 2014	20–22	102–112	8 AD	21–23	110–114	13	3 T; 3 mm; 1000 b; 12 GD	Posterior CC midbody; corona radiata; WM underlying right middle/superior temporal lobe	TBSS; ANOVA; FSL	ASD: Decreased FA in WM underlying temporal lobe; decreased functional connectivity participants in ToM-related areas and ventral premotor areas; no relationship between DTI and fMRI results
Perkins et al., 2014	15–25	–	12 HFA, ASP	16–22	–	12	3 T; 2.5 mm; 1000 b; 25 GD	Superior longitudinal fascicles; accurate fasc.; cingulum bundle; CC genu, splenium, and body; IC anterior and posterior limb	TBSS; SA; GLM; FSL	ASD: Decreased FA and Increased λ⊥ in left hemisphere, predominantly thalamic and fronto-parietal pathways; significantly increased WM disturbance in left w.r.t. right hemisphere, according to symmetry analysis

Additional abbreviations: b, b value unit (s/mm²); f, females; fasc., fascilus; m, males; y, year;

T, MRI magnetic field strength (tesla); w.r.t., with respect to

ADI -R, autism diagnostic interview – revised; ANCOVA, analysis of covariances;

ANOVA, analysis of variances; CC, corpus callossum; CST, cortico-spinal tract;

DT, deterministic tractography; GD, gradient directions; GLM, general linear models;

IC, internal caplsule; MANOVA, multivariate analysis of variances;

PT, probabilistic tractography; RMA, repeated measures analysis;

SROC, Spearman's rank-order correlation;; ToM, theory of mind;

CIVET, Diffusion Toolkit, DTIstudio, ExploreDTI, FiberViewer, FLIRT, FSL, JMP7, RFTCS, RMA, SPM, SPSS,

Tkregister2, TrackVis, XBAM, data processing packages.