title: ADHD, circadian rhythms and seasonality.
abstract: We evaluated whether the association between Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Seasonal Affective Disorder (SAD) was mediated by the circadian rhythm.
  
  
  
  Data of 2239 persons from the Netherlands Study of Depression and Anxiety (NESDA) were used. Two groups were compared: with clinically significant ADHD symptoms (N = 175) and with No ADHD symptoms (N = 2064). Sleep parameters were sleep-onset and offset times, mid sleep and sleep duration from the Munich Chronotype Questionnaire. We identified the prevalence of probable SAD and subsyndromal SAD using the Seasonal Pattern Assessment Questionnaire (SPAQ). Clinically significant ADHD symptoms were identified by using a T score>65 on the Conners Adult ADHD Rating Scale.
  
  
  
  The prevalence of probable SAD was estimated at 9.9% in the ADHD group (vs. 3.3% in the No ADHD group) and of probable s-SAD at 12.5% in the ADHD group (vs 4.6% in the No ADHD group). Regression analyses showed consistently significant associations between ADHD symptoms and probable SAD, even after adjustment for current depression and anxiety, age, sex, education, use of antidepressants and benzodiazepines (B = 1.81, p < 0.001). Late self-reported sleep onset was an important mediator in the significant relationship between ADHD symptoms and probable SAD, even after correction for confounders (total model effects: B = 0.14, p ≤ 0.001).
  
  
  
  Both seasonal and circadian rhythm disturbances are significantly associated with ADHD symptoms. Delayed sleep onset time in ADHD may explain the increase in SAD symptoms. Treating patients with SAD for possible ADHD and delayed sleep onset time may reduce symptom severity in these complex patients.
authors.affiliation: PsyQ Expertise Center Adult ADHD, The Hague, The Netherlands. Electronic address: d.wynchank@psyq.nl.
authors.forename: Dora S
authors.initials: DS
authors.lastname: Wynchank
authors.affiliation: PsyQ Expertise Center Adult ADHD, The Hague, The Netherlands. Electronic address: D.Bijlenga@psyq.nl.
authors.forename: Denise
authors.initials: D
authors.lastname: Bijlenga
authors.affiliation: Department of Psychiatry and EMGO, Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: f.lamers@ggzingeest.nl.
authors.forename: Femke
authors.initials: F
authors.lastname: Lamers
authors.affiliation: PsyQ Expertise Center Adult ADHD, The Hague, The Netherlands. Electronic address: Annet.Bron4@psyq.nl.
authors.forename: Tannetje I
authors.initials: TI
authors.lastname: Bron
authors.affiliation: Department of Psychiatry, University Medical Center Groningen, University of Groningen, The Netherlands. Electronic address: w.h.winthorst@umcg.nl.
authors.forename: Wim H
authors.initials: WH
authors.lastname: Winthorst
authors.affiliation: PsyQ Expertise Center Adult ADHD, The Hague, The Netherlands. Electronic address: S.Vogel@psyq.nl.
authors.forename: Suzan W
authors.initials: SW
authors.lastname: Vogel
authors.affiliation: Department of Psychiatry and EMGO, Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: B.Penninx@vumc.nl.
authors.forename: Brenda W
authors.initials: BW
authors.lastname: Penninx
authors.affiliation: Department of Psychiatry and EMGO, Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: A.Beekman@ggzingeest.nl.
authors.forename: Aartjan T
authors.initials: AT
authors.lastname: Beekman
authors.affiliation: PsyQ Expertise Center Adult ADHD, The Hague, The Netherlands. Electronic address: s.kooij@psyq.nl.
authors.forename: J Sandra
authors.initials: JS
authors.lastname: Kooij
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology* / Q000503:physiopathology*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D016574:Seasonal Affective Disorder / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Attention deficit/hyperactivity disorder; Circadian rhythm; Delayed sleep phase; Seasonal affective disorder