title: Attention deficit/hyperactivity and comorbid symptoms in preschoolers: differences between subgroups in neuropsychological basic deficits.
abstract: BACKGROUND
  There is wide agreement on the heterogeneity of attention deficit/hyperactivity disorder (ADHD). Subgroups with specific comorbid problems, neuropsychological deficits, and developmental trajectories that start in preschool years have been assumed. We analyze whether corresponding subgroups at risk for ADHD development can be identified in a preschool sample and whether these subgroups show the assumed neuropsychological deficits.
  
  
  METHODS
  The study sample consisted in 141 preschool children (3-6 years; 68 boys), including 41 children at risk for ADHD development (because of high ADHD symptoms or first-degree relatives with an ADHD diagnosis). Parent- and teacher-reported symptoms of ADHD, ODD/CD, and anxiety/depression were assessed. Cluster analyses were conducted on the continuous symptom scores. Inhibitory control and delay aversion were measured by six neuropsychological tasks.
  
  
  RESULTS
  Cluster analyses resulted in four groups. Two of these groups showed high ADHD symptoms - one showing multiple comorbid symptoms, one showing hardly any further symptoms. The other two groups were characterized by no problems and by some sensorimotor deficits. A priori contrasts revealed that the "high comorbidity" cluster showed the worst inhibitory control performance while the "pure ADHD symptoms" cluster showed the highest delay aversion.
  
  
  CONCLUSIONS
  The ADHD-symptom clusters matched types that have been proposed in recent models. This description might help to identify different ADHD-related pathways in future longitudinal research.
authors.affiliation: a Department of Child and Adolescent Psychiatry , Psychosomatics and Psychotherapy, Philipps-University of Marburg , Marburg , Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Pauli-Pott
authors.forename: Silke
authors.initials: S
authors.lastname: Dalir
authors.forename: Tanja
authors.initials: T
authors.lastname: Mingebach
authors.forename: Alisa
authors.initials: A
authors.lastname: Roller
authors.forename: Katja
authors.initials: K
authors.lastname: Becker
mesh_terms: D001288:Attention / Q000502:physiology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D003071:Cognition; D015897:Comorbidity; D019955:Conduct Disorder / Q000453:epidemiology / Q000523:psychology*; D003863:Depression / Q000453:epidemiology; D056344:Executive Function; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D010290:Parents; D025341:Principal Component Analysis; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D013694:Temperament