Motion and morphometry in clinical populations

16 Introduction 17 The relationship between participant motion, demographic variables and MRI-derived 18 morphometric estimates was investigated in autism spectrum disorder (ASD), attention 19 deficit hyperactivity disorder (ADHD) and schizophrenia. Participant motion was 20 estimated using resting state fMRI and used as a proxy measure for motion during T1w 21 MRI acquired in the same session. Analyses were carried out in scans qualitatively 22 assessed as free from motion-related artifact. 23 Methods 24 Whole brain T1-weighted MRI and resting state fMRI acquisitions from the ABIDE, 25 ADHD-200 and COBRE databases were included in our analyses. Motion was estimated 26 using coregistration of sequential resting state volumes. Morphometric estimates were 27 obtained using Freesurfer v5.3. We investigated if motion is related to diagnosis, age and 28 gender, and scanning site. We further determined if there is a relationship between 29 participant motion and cortical thickness, contrast, and volumetric estimates. 30 Results 31 2131 participants were included in our analyses. Participant motion was higher in all 32 clinical groups compared with healthy controls. Younger (age < 20 years) and older (age 33 > 40 years) people move more than individuals aged 20 – 40 years. Increased motion is 34 associated with reduced average cortical thickness (-0.02 mm thickness per mm motion, p 35 = 4.03×10) and cortical contrast (0.95% contrast reduction per mm motion, p = 5.25×10 36 ) in scans that have been qualitatively assessed as free from motion artifact. 37 Conclusions 38 PeerJ PrePrints | https://dx.doi.org/10.7287/peerj.preprints.1363v1 | CC-BY 4.0 Open Access | rec: 12 Sep 2015, publ: 12 Sep 2015 P re P rin ts Participant motion is increased in clinical groups and is systematically associated with 39 morphometric estimates. These findings indicate that accounting for participant motion 40 may be important for improving the statistical validity of morphometric studies. 41 42 PeerJ PrePrints | https://dx.doi.org/10.7287/peerj.preprints.1363v1 | CC-BY 4.0 Open Access | rec: 12 Sep 2015, publ: 12 Sep 2015 P re P rin ts 43