Motion and morphometry in clinical populations

Introduction The relationship between participant motion, demographic variables and MRI-derived morphometric estimates was investigated in autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and schizophrenia. Participant motion was estimated using resting state fMRI and used as a proxy measure for motion during T1-weighted MRI acquired in the same session. Analyses were carried out in scans qualitatively assessed as free from motion-related artifact. Methods Whole brain T1-weighted MRI and resting state fMRI acquisitions from the ABIDE, ADHD-200 and COBRE databases were included in our analyses. Motion was estimated using coregistration of sequential resting state volumes. Morphometric estimates were obtained using Freesurfer v5.3. We investigated if motion is related to diagnosis, age and gender, and scanning site. We further determined if there is a relationship between participant motion and cortical thickness, contrast, and volumetric estimates. Results 2131 participants were included in our analyses. Participant motion was higher in all clinical groups compared with healthy controls. Younger (age < 20 years) and older (age > 40 years) people move more than individuals aged 20 – 40 years. Increased motion is associated with reduced average cortical thickness (-0.02 mm thickness per mm motion, p = 4.03×10-5) and cortical contrast (0.95% contrast reduction per mm motion, p = 5.25×10-11) in scans that have been qualitatively assessed as free from motion artifact. Conclusions Participant motion is increased in clinical groups and is systematically associated with morphometric estimates. These findings indicate that accounting for participant motion may be important for improving the statistical validity of morphometric studies.