title: Shared familial risk factors between attention-deficit/hyperactivity disorder and overweight/obesity - a population-based familial coaggregation study in Sweden.
abstract: BACKGROUND
  Despite meta-analytic evidence for the association between attention-deficit/hyperactivity disorder (ADHD) and overweight/obesity, the mechanisms underlying the association are yet to be fully understood.
  
  
  METHODS
  By linking multiple Swedish national and regional registers, we identified 472,735 index males born during 1973-1992, with information on body weight and height directly measured before they were conscripted for military service. We further identified 523,237 full siblings born during 1973-2002 for the index males. All individuals were followed up from their third birthday to December 31, 2009 for ADHD diagnosis. Logistic regression models were used to estimate the association between overweight/obesity in index males and ADHD in their full siblings.
  
  
  RESULTS
  Siblings of index males with overweight/obesity had increased risk for ADHD (overweight: OR = 1.14, 95% CI = 1.05-1.24; obesity: OR = 1.42, 95% CI = 1.24-1.63), compared with siblings of index males with normal weight. The results were adjusted for birth year of the index male and sex of the sibling. After further adjustment for ADHD status of the index male, the familial coaggregation remained significant (overweight: OR = 1.13, 95% CI = 1.04-1.22; obesity: OR = 1.38, 95% CI = 1.21-1.57). The results were similar across sex of the siblings.
  
  
  CONCLUSIONS
  Attention-deficit/hyperactivity disorder and overweight/obesity share familial risk factors, which are not limited to those causing overweight/obesity through the mediation of ADHD. Future research aiming at identifying family-wide environmental risk factors as well as common pleiotropic genetic variants contributing to both traits is warranted.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Qi
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Ralf
authors.initials: R
authors.lastname: Kuja-Halkola
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Arvid
authors.initials: A
authors.lastname: Sjölander
authors.affiliation: Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden.|Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Serlachius
authors.affiliation: Department of Psychology, Developmental Brain-Behavior Laboratory, University of Southampton, Southampton, UK.|Solent NHS Trust, Southampton, UK.|Langone Medical Center, New York University Child Study Center, New York, NY, USA.
authors.forename: Samuele
authors.initials: S
authors.lastname: Cortese
authors.affiliation: Departments of Psychiatry and Neuroscience and Physiology, SUNY Upstate Medical University, New York, NY, USA.|The K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Bergen, Norway.
authors.forename: Stephen V
authors.initials: SV
authors.lastname: Faraone
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.|Lung and Allergy Unit, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Catarina
authors.initials: C
authors.lastname: Almqvist
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.|School of Medical Sciences, Örebro University, Örebro, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Larsson
mesh_terms: D000293:Adolescent; D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology* / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology / Q000235:genetics; D050177:Overweight / Q000453:epidemiology* / Q000235:genetics*; D012042:Registries; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
keywords: Attention-deficit/hyperactivity disorder; family factors; genetics; obesity