Faculty Bibliography

Longitudinal imaging studies involve tracking changes in individuals by repeated image acquisition over time. The goal of these studies is to quantify biological shape variability within and across individuals, and also to distinguish between normal and disease populations. However, data variability is influenced by outside sources such as image acquisition, image calibration, human expert judgment, and limited robustness of segmentation and registration algorithms. In this paper, we propose a two-stage method for the statistical analysis of longitudinal shape. In the first stage, we estimate diffeomorphic shape trajectories for each individual that minimize inconsistencies in segmented shapes across time. This is followed by a longitudinal mixed-effects statistical model in the second stage for testing differences in shape trajectories between groups. We apply our method to a longitudinal database from PREDICT-HD and demonstrate our approach reduces unwanted variability for both shape and derived measures, such as volume. This leads to greater statistical power to distinguish differences in shape trajectory between healthy subjects and subjects with a genetic biomarker for Huntington's disease (HD).

The term prediction implies expected outcome in the future, often based on a model and statistical inference. Longitudinal imaging studies offer the possibility to model temporal change trajectories of anatomy across populations of subjects. In the spirit of subject-specific analysis, such normative models can then be used to compare data from new subjects to the norm and to study progression of disease or to predict outcome. This paper follows a statistical inference approach and presents a framework for prediction of future observations based on past measurements and population statistics. We describe prediction in the context of nonlinear mixed effects modeling (NLME) where the full reference population's statistics (estimated fixed effects, variance-covariance of random effects, variance of noise) is used along with the individual's available observations to predict its trajectory. The proposed methodology is generic in regard to application domains. Here, we demonstrate analysis of early infant brain maturation from longitudinal DTI with up to three time points. Growth as observed in DTI-derived scalar invariants is modeled with a parametric function, its parameters being input to NLME population modeling. Trajectories of new subject's data are estimated when using no observation, only the first or the first two time points. Leave-one-out experiments result in statistics on differences between actual and predicted observations. We also simulate a clinical scenario of prediction on multiple categories, where trajectories predicted from multiple models are classified based on maximum likelihood criteria.

This editorial presents an overview of the two books discussed in the issue Journal of the American Academy of Child & Adolescent Psychiatry. The first book is about fighting stigma that argues against several myths. It is important to keep debates around stigma alive and to investigate the myths and realities of stigma, rather than just assuming that stigma is an all-powerful force, that we are necessarily bound to our patients with a shared stigma, or that it explains more than it really does. The second book examines treatment for a behavior that has been imbued with all the hallmarks of stigma, including shame and secrecy.

This article provides an overview of the books featured in the present issue of Journal of the American Academy of Child & Adolescent Psychiatry book forum section. The books encounter some of the challenges that come with moving a unique identity into a diagnostic construct. Feng Liu reviews a book about evaluating and assessing autism spectrum disorders (ASD), which is how we as professional caregivers move individuals into a group. Janella Hong takes us in a different direction, looking at a book that explores identity from within a group whose members often found meaning by being part of that group; this particular book quickly became significantly dated, not because the experiences it describes belong to a different era, but because formally, in certain circles, that group vanished and became part of another group. Finally, Aaron Roberto reviews a novel about an adolescent with ASD who works "in the real world, " imaginative literature with a poignant message about how a child with an ASD might find it difficult to become the next Tommy Hilfiger. Three books, 3 genres, all of which explore the relationship of the individual to the group.