title: ADHD familial loading and abnormal EEG alpha asymmetry in children with ADHD.
abstract: OBJECTIVE
  Abnormal brain laterality (ABL) is indicated in ADHD. ADHD and brain laterality are heritable. Genetic factors contributing to lateralization of brain function may contribute to ADHD. If so, increased ADHD family loading should be associated with greater ABL. Previous studies have shown increased rightward alpha asymmetry in ADHD. We tested whether this was more pronounced in ADHD children with increased ADHD family loading.
  
  
  METHODS
  We compared EEG alpha asymmetry at rest and during the Conner's Continuous Performance Test (CPT) in ADHD children with and without ADHD affected parents, and replicated our findings in a second larger sample. The replication study additionally stratified the parent-affected sample by parental persistent versus non-persistent ADHD status, increased spatial resolution of EEG measures, and assessed low versus high-alpha.
  
  
  RESULTS
  Study-1: the parent-affected group showed increased rightward asymmetry across frontal and central regions and reduced rightward parietal asymmetry during an eyes closed (EC) condition, as well as increasing rightward parietal asymmetry with advancing age during the CPT. Study-2 replicated these findings and further delineated influences of low versus high-alpha, recording site, and effects of parental persistent versus non-persistent ADHD status.
  
  
  CONCLUSIONS
  Increased ADHD familial loading was associated with increased rightward frontal asymmetry. In contrast, increased rightward parietal asymmetry was associated with reduced ADHD family loading. Frontal results are consistent with an ADHD endophenotype. Parietal results suggest an ADHD adaptive trait prevalent with less ADHD family loading. Age effects indicate a unique developmental course among ADHD children whose parents have non-persistent ADHD.
authors.affiliation: Division of Child and Adolescent Psychiatry and Center for Neurobehavioral Genetics at the UCLA Semel Institute, 760 Westwood Plaza, Room 47-448, Los Angeles, CA 90095, United States. sig@ucla.edu
authors.forename: T Sigi
authors.initials: TS
authors.lastname: Hale
authors.forename: Susan L
authors.initials: SL
authors.lastname: Smalley
authors.forename: Jeff
authors.initials: J
authors.lastname: Dang
authors.forename: Grant
authors.initials: G
authors.lastname: Hanada
authors.forename: James
authors.initials: J
authors.lastname: Macion
authors.forename: James T
authors.initials: JT
authors.lastname: McCracken
authors.forename: James J
authors.initials: JJ
authors.lastname: McGough
authors.forename: Sandra K
authors.initials: SK
authors.lastname: Loo
mesh_terms: D000293:Adolescent; D000513:Alpha Rhythm; D001289:Attention Deficit Disorder with Hyperactivity / Q000473:pathology / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D002648:Child; D004569:Electroencephalography; D005192:Family Health; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male