title: Annual Research Review: Understudied populations within the autism spectrum - current trends and future directions in neuroimaging research.
abstract: BACKGROUND
  Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopmental conditions that vary in both etiology and phenotypic expression. Expressions of ASD characterized by a more severe phenotype, including autism with intellectual disability (ASD + ID), autism with a history of developmental regression (ASD + R), and minimally verbal autism (ASD + MV) are understudied generally, and especially in the domain of neuroimaging. However, neuroimaging methods are a potentially powerful tool for understanding the etiology of these ASD subtypes.
  
  
  METHODS
  This review evaluates existing neuroimaging research on ASD + MV, ASD + ID, and ASD + R, identified by a search of the literature using the PubMed database, and discusses methodological, theoretical, and practical considerations for future research involving neuroimaging assessment of these populations.
  
  
  RESULTS
  There is a paucity of neuroimaging research on ASD + ID, ASD + MV, and ASD + R, and what findings do exist are often contradictory, or so sparse as to be ungeneralizable. We suggest that while greater sample sizes and more studies are necessary, more important would be a paradigm shift toward multimodal (e.g. imaging genetics) approaches that allow for the characterization of heterogeneity within etiologically diverse samples.
authors.affiliation: Autism and Neurodevelopmental Disorders Institute, The George Washington University, Ashburn, VA, USA.|Department of Pharmacology and Physiology, The George Washington University, Washington, DC, USA.
authors.forename: Allison
authors.initials: A
authors.lastname: Jack
authors.affiliation: Autism and Neurodevelopmental Disorders Institute, The George Washington University, Ashburn, VA, USA.|Department of Pharmacology and Physiology, The George Washington University, Washington, DC, USA.|Children's National Health System, Washington, DC, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: A Pelphrey
mesh_terms: D000293:Adolescent; D000067877:Autism Spectrum Disorder / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D035843:Biomedical Research / Q000639:trends*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D059906:Neuroimaging / Q000639:trends*
keywords: Autism spectrum disorders; intellectual disability; neuroimaging