title: Parental age and the risk of attention-deficit/hyperactivity disorder: a nationwide, population-based cohort study.
abstract: OBJECTIVE
  An increasing number of studies has shown an association between parental age and psychiatric disorders. However, there are inconsistent results regarding whether age at parenthood is associated with attention-deficit/hyperactivity disorder (ADHD). The aim of this study is to examine whether low or advanced parental age is associated with ADHD.
  
  
  METHODS
  In this nested case-control study, we identified 10,409 individuals with ADHD born in Finland during 1991 to 2005 and diagnosed with ADHD between 1995 and 2011, along with 39,125 controls matched on sex, date, and place of birth, from nationwide population-based registers. Conditional logistic regression was used to examine the association between parental age and ADHD in offspring, adjusting for potential confounding due to parental psychiatric history, maternal socioeconomic status, marital status, maternal smoking during pregnancy, number of previous births, and birth weight for gestational age.
  
  
  RESULTS
  Fathers younger than 20 years had a 1.5-fold (odds ratio [OR] = 1.55, 95% CI = 1.11-2.18, p = .01) increased risk of having offspring with ADHD as compared to fathers aged 25 to 29 years. Mothers of the same age group had a 1.4-fold (OR = 1.41, 95% CI = 1.15-1.72, p =.0009) increased risk. Advanced maternal age was inversely associated with ADHD (OR = 0.79, 95% CI = 0.64-0.97, p = .02).
  
  
  CONCLUSIONS
  ADHD was associated with young fathers or mothers at the time of birth. Health professionals working with young parents should be aware of the increased risk of ADHD in offspring. This will improve early detection; however, for the development of preventive measures and appropriate interventions, more information on the developmental pathways is needed.
authors.affiliation: University of Turku, Finland. Electronic address: roschu@utu.fi.
authors.forename: Roshan
authors.initials: R
authors.lastname: Chudal
authors.affiliation: University of Turku, Finland.
authors.forename: Petteri
authors.initials: P
authors.lastname: Joelsson
authors.affiliation: University of Turku, Finland; Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York.
authors.forename: David
authors.initials: D
authors.lastname: Gyllenberg
authors.affiliation: University of Turku, Finland.
authors.forename: Venla
authors.initials: V
authors.lastname: Lehti
authors.affiliation: University of Turku, Finland; Pediatric Neurology, University of Helsinki and Helsinki University Hospital.
authors.forename: Susanna
authors.initials: S
authors.lastname: Leivonen
authors.affiliation: University of Turku, Finland.
authors.forename: Susanna
authors.initials: S
authors.lastname: Hinkka-Yli-Salomäki
authors.affiliation: University of Turku, Finland; Nordic School of Public Health, Gothenburg, Sweden, and National Institute for Health and Welfare, Helsinki.
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.affiliation: University of Turku, Finland; Turku University Hospital, Finland and RKBU, UiT The Arctic University of Norway, Tromsø
authors.forename: Andre
authors.initials: A
authors.lastname: Sourander
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000209:etiology*; D001724:Birth Weight; D016022:Case-Control Studies; D015331:Cohort Studies; D042241:Early Diagnosis; D005260:Female; D005387:Finland; D005865:Gestational Age; D006801:Humans; D016015:Logistic Models; D008297:Male; D008423:Maternal Age; D008875:Middle Aged; D016017:Odds Ratio; D010331:Paternal Age; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D055815:Young Adult
keywords: ADHD; epidemiology; parental age; register-based; young parents