title: Twin study on transplacental-acquired antibodies and attention deficit/hyperactivity disorder--a pilot study.
abstract: OBJECTIVE
  We hypothesize that maternal transplacentally acquired antibodies may cause Attention Deficit/Hyperactivity Disorder (ADHD) symptoms years after birth, and tested the hypothesis in twins discordant for ADHD symptoms.
  
  
  METHODS
  In a pre-screened sample of 7793 same sex twin pair's (4-18 years) questionnaire data on hyperactivity and inattention was collected. Blood samples taken 5 days after birth from 190 ADHD-score discordant pairs (15% MZ) were analyzed for antibodies.
  
  
  RESULTS
  Pneumococcus Polysaccaride 14 (PnPs14) was present in the ADHD high scoring twin more often than in the lower scoring twin (P=0.04).
  
  
  CONCLUSIONS
  Although the study provides no strong support for the hypothesis, infection or immunological factors may be one among several causes of ADHD. The genetic control obtained in a twin design may reduce the exposure contrast and a larger sample is needed to further explore the role of PnPs14 in the etiology of ADHD.
authors: Child and adolescent Psychiatric Dept., University of Southern Denmark, Odense, Denmark. niels.bilenberg@psyk.regionsyddanmark.dk
authors: Niels
authors: N
authors: Bilenberg
authors: David
authors: D
authors: Hougaard
authors: Bent
authors: B
authors: Norgaard-Pedersen
authors: Claudia Maria
authors: CM
authors: Nordenbæk
authors: Jørn
authors: J
authors: Olsen