title: Seasonality in affective disorders in Switzerland.
abstract: OBJECTIVE
  To estimate the prevalence of seasonal affective disorder (SAD) and its subsyndromal form (S-SAD) in Switzerland (47 degrees N).
  
  
  METHODS
  A representative sample from all three language areas of Switzerland (n = 980) were given a structured telephone interview using the extended Seasonal Pattern Assessment Questionnaire (SPAQ+). A smaller, but also representative sample in the city of Basel filled in the SPAQ+ form as well as undergoing a structured diagnostic interview.
  
  
  RESULTS
  In this Swiss sample, 2.2% of the population presented with symptom severity of SAD, 8.9% with S-SAD. In Basel, a much higher prevalence of SAD was found. Seasonal problems occurred more often in patients with the Diagnostic and Statistical Manual (DSM)-III diagnosis of major affective disorders than in those with pure anxiety disorders or no psychiatric diagnosis.
  
  
  CONCLUSIONS
  These estimates for SAD in Switzerland are similar to those found in the Zürich Study, using other methods, and for populations in the UK, with the limitations inherent in retrospective questionnaire studies.
authors.affiliation: Centre for Chronobiology, Psychiatric University Clinic and Outpatient Clinic, Basel, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Wirz-Justice
authors.forename: P
authors.initials: P
authors.lastname: Graw
authors.forename: K
authors.initials: K
authors.lastname: Kräuchi
authors.forename: H R
authors.initials: HR
authors.lastname: Wacker
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D016574:Seasonal Affective Disorder / Q000453:epidemiology*; D012720:Severity of Illness Index; D013557:Switzerland / Q000453:epidemiology; D013577:Syndrome