title: Relationship among latitude, climate, season and self-reported mood in bipolar disorder.
abstract: OBJECTIVE
  Many researchers have analyzed seasonal variation in hospital admissions for bipolar disorder with inconsistent results. We investigated if a seasonal pattern was present in daily self-reported daily mood ratings from patients living in five climate zones in the northern and southern hemispheres. We also investigated the influence of latitude and seasonal climate variables on mood.
  
  
  METHODS
  360 patients who were receiving treatment as usual recorded mood daily (59,422 total days of data). Both the percentage of days depressed and hypomanic/manic, and the episodes of depression and mania were determined. The observations were provided by patients from different geographic locations in North and South America, Europe and Australia. These data were analyzed for seasonality by climate zone using both a sinusoidal regression and the Gini index. Additionally, the influence of latitude and climate variables on mood was estimated using generalized linear models for each season and month.
  
  
  RESULTS
  No seasonality was found in any climate zone by either method. In spite of vastly different weather, neither latitude nor climate variables were associated with mood by season or month.
  
  
  CONCLUSIONS
  Daily self-reported mood ratings of most patients with bipolar disorder did not show a seasonal pattern. Neither climate nor latitude has a primary influence on the daily mood changes of most patients receiving medication for bipolar disorder.
authors.affiliation: Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Germany Fetscherstr. 74, 01307 Dresden, Germany. Michael.Bauer@uniklinikum-dresden.de
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer
authors.forename: Tasha
authors.initials: T
authors.lastname: Glenn
authors.forename: Paul
authors.initials: P
authors.lastname: Grof
authors.forename: Natalie L
authors.initials: NL
authors.lastname: Rasgon
authors.forename: Wendy
authors.initials: W
authors.lastname: Marsh
authors.forename: Kemal
authors.initials: K
authors.lastname: Sagduyu
authors.forename: Martin
authors.initials: M
authors.lastname: Alda
authors.forename: Greg
authors.initials: G
authors.lastname: Murray
authors.forename: Danilo
authors.initials: D
authors.lastname: Quiroz
authors.forename: Yanni
authors.initials: Y
authors.lastname: Malliaris
authors.forename: Johanna
authors.initials: J
authors.lastname: Sasse
authors.forename: Maximilian
authors.initials: M
authors.lastname: Pilhatsch
authors.forename: Peter C
authors.initials: PC
authors.lastname: Whybrow
mesh_terms: D000328:Adult; D000339:Affect; D001315:Australia / Q000453:epidemiology; D001714:Bipolar Disorder / Q000453:epidemiology / Q000523:psychology*; D002980:Climate; D003863:Depression / Q000453:epidemiology / Q000523:psychology*; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D009656:North America / Q000453:epidemiology; D011569:Psychiatric Status Rating Scales; D012621:Seasons; D012720:Severity of Illness Index; D013020:South America / Q000453:epidemiology; D013997:Time Factors