title: Clinical Implications of a Dimensional Approach: The Normal:Abnormal Spectrum of Early Irritability.
abstract: OBJECTIVE
  The importance of dimensional approaches is widely recognized, but an empirical base for clinical application is lacking. This is particularly true for irritability, a dimensional phenotype that cuts across many areas of psychopathology and manifests early in life. We examine longitudinal, dimensional patterns of irritability and their clinical import in early childhood.
  
  
  METHODS
  Irritability was assessed longitudinally over an average of 16 months in a clinically enriched, diverse community sample of preschoolers (N = 497; mean = 4.2 years; SD = 0.8). Using the Temper Loss scale of the Multidimensional Assessment Profile of Disruptive Behavior (MAP-DB) as a developmentally sensitive indicator of early childhood irritability, we examined its convergent/divergent, clinical, and incremental predictive validity, and modeled its linear and nonlinear associations with clinical risk.
  
  
  RESULTS
  The Temper Loss scale demonstrated convergent and divergent validity to child and maternal factors. In multivariate analyses, Temper Loss predicted mood (separation anxiety disorder [SAD], generalized anxiety disorder [GAD], and depression/dysthymia), disruptive (oppositional defiant disorder [ODD], attention-deficit/hyperactivity disorder [ADHD], and conduct disorder [CD]) symptoms. Preschoolers with even mildly elevated Temper Loss scale scores showed substantially increased risk of symptoms and disorders. For ODD, GAD, SAD, and depression, increases in Temper Loss scale scores at the higher end of the dimension had a greater impact on symptoms relative to increases at the lower end. Temper Loss scale scores also showed incremental validity over DSM-IV disorders in predicting subsequent impairment. Finally, accounting for the substantial heterogeneity in longitudinal patterns of Temper Loss significantly improved prediction of mood and disruptive symptoms.
  
  
  CONCLUSIONS
  Dimensional, longitudinal characterization of irritability informs clinical prediction. A vital next step will be empirically generating parameters for the incorporation of dimensional information into clinical decision-making with reasonable certainty.
authors.affiliation: Department of Medical Social Sciences and the Institute for Policy Research, Northwestern University, IL. Electronic address: lauriew@northwestern.edu.
authors.forename: Lauren S
authors.initials: LS
authors.lastname: Wakschlag
authors.affiliation: Northwestern University, Chicago.
authors.forename: Ryne
authors.initials: R
authors.lastname: Estabrook
authors.affiliation: Northwestern University, Chicago.
authors.forename: Amelie
authors.initials: A
authors.lastname: Petitclerc
authors.affiliation: Institute for Health Research and Policy, University of Illinois at Chicago.
authors.forename: David
authors.initials: D
authors.lastname: Henry
authors.affiliation: Northwestern University, Chicago.
authors.forename: James L
authors.initials: JL
authors.lastname: Burns
authors.affiliation: University of Pittsburgh, Pittsburgh, PA.
authors.forename: Susan B
authors.initials: SB
authors.lastname: Perlman
authors.affiliation: Northwestern University, Chicago.
authors.forename: Joel L
authors.initials: JL
authors.lastname: Voss
authors.affiliation: National Institute of Mental Health, Bethesda, MD.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Pine
authors.affiliation: National Institute of Mental Health, Bethesda, MD.
authors.forename: Ellen
authors.initials: E
authors.lastname: Leibenluft
authors.affiliation: University of Connecticut, Farmington.
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Briggs-Gowan
mesh_terms: D019958:Attention Deficit and Disruptive Behavior Disorders / Q000175:diagnosis / Q000523:psychology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005717:Games, Experimental; D006801:Humans; D007508:Irritable Mood; D008137:Longitudinal Studies; D008297:Male; D000066553:Problem Behavior / Q000523:psychology; D011569:Psychiatric Status Rating Scales; D002666:Psychology, Child; D015203:Reproducibility of Results; D013694:Temperament
keywords: developmental psychopathology; dimensional; irritability; longitudinal modeling; normal:abnormal spectrum