title: Impact of sunlight on the age of onset of bipolar disorder.
abstract: OBJECTIVE
  Although bipolar disorder has high heritability, the onset occurs during several decades of life, suggesting that social and environmental factors may have considerable influence on disease onset. This study examined the association between the age of onset and sunlight at the location of onset.
  
  
  METHODS
  Data were obtained from 2414 patients with a diagnosis of bipolar I disorder, according to DSM-IV criteria. Data were collected at 24 sites in 13 countries spanning latitudes 6.3 to 63.4 degrees from the equator, including data from both hemispheres. The age of onset and location of onset were obtained retrospectively, from patient records and/or direct interviews. Solar insolation data, or the amount of electromagnetic energy striking the surface of the earth, were obtained from the NASA Surface Meteorology and Solar Energy (SSE) database for each location of onset.
  
  
  RESULTS
  The larger the maximum monthly increase in solar insolation at the location of onset, the younger the age of onset (coefficient= -4.724, 95% CI: -8.124 to -1.323, p=0.006), controlling for each country's median age. The maximum monthly increase in solar insolation occurred in springtime. No relationships were found between the age of onset and latitude, yearly total solar insolation, and the maximum monthly decrease in solar insolation. The largest maximum monthly increases in solar insolation occurred in diverse environments, including Norway, arid areas in California, and Chile.
  
  
  CONCLUSIONS
  The large maximum monthly increase in sunlight in springtime may have an important influence on the onset of bipolar disorder.
authors.affiliation: Department of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany. michael.bauer@uniklinikim-dresden.de
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer
authors.forename: Tasha
authors.initials: T
authors.lastname: Glenn
authors.forename: Martin
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authors.lastname: Alda
authors.forename: Ole A
authors.initials: OA
authors.lastname: Andreassen
authors.forename: Raffaella
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authors.lastname: Bellivier
authors.forename: Michael
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authors.forename: Thomas D
authors.initials: TD
authors.lastname: Bjella
authors.forename: Letizia
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authors.lastname: Bossini
authors.forename: Maria
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authors.lastname: Del Zompo
authors.forename: Seetal
authors.initials: S
authors.lastname: Dodd
authors.forename: Andrea
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authors.lastname: Fagiolini
authors.forename: Mark A
authors.initials: MA
authors.lastname: Frye
authors.forename: Ana
authors.initials: A
authors.lastname: Gonzalez-Pinto
authors.forename: Chantal
authors.initials: C
authors.lastname: Henry
authors.forename: Flávio
authors.initials: F
authors.lastname: Kapczinski
authors.forename: Sebastian
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authors.lastname: Kliwicki
authors.forename: Barbara
authors.initials: B
authors.lastname: König
authors.forename: Mauricio
authors.initials: M
authors.lastname: Kunz
authors.forename: Beny
authors.initials: B
authors.lastname: Lafer
authors.forename: Carlos
authors.initials: C
authors.lastname: Lopez-Jaramillo
authors.forename: Mirko
authors.initials: M
authors.lastname: Manchia
authors.forename: Wendy
authors.initials: W
authors.lastname: Marsh
authors.forename: Mónica
authors.initials: M
authors.lastname: Martinez-Cengotitabengoa
authors.forename: Ingrid
authors.initials: I
authors.lastname: Melle
authors.forename: Gunnar
authors.initials: G
authors.lastname: Morken
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Munoz
authors.forename: Fabiano G
authors.initials: FG
authors.lastname: Nery
authors.forename: Claire
authors.initials: C
authors.lastname: O'Donovan
authors.forename: Andrea
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authors.lastname: Pfennig
authors.forename: Danilo
authors.initials: D
authors.lastname: Quiroz
authors.forename: Natalie
authors.initials: N
authors.lastname: Rasgon
authors.forename: Andreas
authors.initials: A
authors.lastname: Reif
authors.forename: Janusz
authors.initials: J
authors.lastname: Rybakowski
authors.forename: Kemal
authors.initials: K
authors.lastname: Sagduyu
authors.forename: Christian
authors.initials: C
authors.lastname: Simhandl
authors.forename: Carla
authors.initials: C
authors.lastname: Torrent
authors.forename: Eduard
authors.initials: E
authors.lastname: Vieta
authors.forename: Mark
authors.initials: M
authors.lastname: Zetin
authors.forename: Peter C
authors.initials: PC
authors.lastname: Whybrow
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D001714:Bipolar Disorder / Q000453:epidemiology*; D005260:Female; D062306:Geography, Medical; D006801:Humans; D008297:Male; D008875:Middle Aged; D017440:Photoperiod; D012189:Retrospective Studies; D012621:Seasons; D012993:Solar Energy; D013472:Sunlight