title: Trajectories of cortical thickness maturation in normal brain development--The importance of quality control procedures.
abstract: Several reports have described cortical thickness (CTh) developmental trajectories, with conflicting results. Some studies have reported inverted-U shape curves with peaks of CTh in late childhood to adolescence, while others suggested predominant monotonic decline after age 6. In this study, we reviewed CTh developmental trajectories in the NIH MRI Study of Normal Brain Development, and in a second step, evaluated the impact of post-processing quality control (QC) procedures on identified trajectories. The quality-controlled sample included 384 individual subjects with repeated scanning (1-3 per subject, total scans n=753) from 4.9 to 22.3years of age. The best-fit model (cubic, quadratic, or first-order linear) was identified at each vertex using mixed-effects models. The majority of brain regions showed linear monotonic decline of CTh. There were few areas of cubic trajectories, mostly in bilateral temporo-parietal areas and the right prefrontal cortex, in which CTh peaks were at, or prior to, age 8. When controlling for total brain volume, CTh trajectories were even more uniformly linear. The only sex difference was faster thinning of occipital areas in boys compared to girls. The best-fit model for whole brain mean thickness was a monotonic decline of 0.027mm per year. QC procedures had a significant impact on identified trajectories, with a clear shift toward more complex trajectories (i.e., quadratic or cubic) when including all scans without QC (n=954). Trajectories were almost exclusively linear when using only scans that passed the most stringent QC (n=598). The impact of QC probably relates to decreasing the inclusion of scans with CTh underestimation secondary to movement artifacts, which are more common in younger subjects. In summary, our results suggest that CTh follows a simple linear decline in most cortical areas by age 5, and all areas by age 8. This study further supports the crucial importance of implementing post-processing QC in CTh studies of development, aging, and neuropsychiatric disorders.
authors.affiliation: Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada; McGill University Health Centre, Department of Psychiatry, McGill University, 1025 Pine Avenue West, Montreal, QC H3A 1A1, Canada. Electronic address: simon.ducharme@mcgill.ca.
authors.forename: Simon
authors.initials: S
authors.lastname: Ducharme
authors.affiliation: Vermont Centre for Children, Youth and Families, Fletcher Allen Pediatric Psychiatry, University of Vermont, 1 South Prospect Street, Arnold, Level 3, Burlington, VT 05401, USA. Electronic address: matthew.albaugh@med.uvm.edu.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Albaugh
authors.affiliation: McGill University Health Centre, Department of Psychiatry, McGill University, 1025 Pine Avenue West, Montreal, QC H3A 1A1, Canada; McGill University Health Centre, Department of Obstetrics-Gynecology, McGill University, Montreal, QC H3A 1A1, Canada. Electronic address: tuong.v.nguyen@mcgill.ca.
authors.forename: Tuong-Vi
authors.initials: TV
authors.lastname: Nguyen
authors.affiliation: Vermont Centre for Children, Youth and Families, Fletcher Allen Pediatric Psychiatry, University of Vermont, 1 South Prospect Street, Arnold, Level 3, Burlington, VT 05401, USA. Electronic address: james.hudziak@med.uvm.edu.
authors.forename: James J
authors.initials: JJ
authors.lastname: Hudziak
authors.affiliation: Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada. Electronic address: jose.mateosperez@mcgill.ca.
authors.forename: J M
authors.initials: JM
authors.lastname: Mateos-Pérez
authors.affiliation: Douglas Mental Health University Institute, Department of Psychiatry, McGill University, 6875 Lasalle Boulevard, Verdun, QC H4H 1R3, Canada; Douglas Mental Health University Institute, Department of Epidemiology, Biostatistics and Occupational Health, McGill University, 6875 Lasalle Boulevard, Verdun, QC H4H 1R3, Canada. Electronic address: aurelie.labbe@mcgill.ca.
authors.forename: Aurelie
authors.initials: A
authors.lastname: Labbe
authors.affiliation: Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada. Electronic address: alan.evans@mcgill.ca.
authors.forename: Alan C
authors.initials: AC
authors.lastname: Evans
authors.affiliation: Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada; Douglas Mental Health University Institute, Department of Psychiatry, McGill University, 6875 Lasalle Boulevard, Verdun, QC H4H 1R3, Canada. Electronic address: sherif.karama@mcgill.ca.
authors.forename: Sherif
authors.initials: S
authors.lastname: Karama
mesh_terms: D000293:Adolescent; D002540:Cerebral Cortex / Q000254:growth & development*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods / Q000592:standards*; D008279:Magnetic Resonance Imaging; D008297:Male; D011786:Quality Control; D012727:Sex Characteristics; D055815:Young Adult
keywords: Brain development; Cortical surface area; Cortical thickness; Cortical volume; Magnetic resonance imaging; Maturation; Quality control