title: Aetiology of fatigue in Sri Lanka and its overlap with depression.
abstract: BACKGROUND
  Fatigue is a common symptom in Western high-income countries but is often medically unexplained and little is known about its presentation in other populations.
  
  
  OBJECTIVE
  To explore the epidemiology and aetiology of fatigue in Sri Lanka, and of its overlap with depression.
  
  
  METHODS
  A total of 4024 randomly selected twins from a population-based register in Sri Lanka (Colombo district) completed home interviews including the Chalder Fatigue Questionnaire.
  
  
  RESULTS
  The prevalence of fatigue was similar to that in other countries, although prolonged fatigue may be less common. There was substantial comorbidity with a screen for lifetime depression. Non-shared environmental factors made the largest contributions, although genetic/family factors also contributed. The aetiology appeared consistent across the spectrum of severity.
  
  
  CONCLUSIONS
  The aetiology of fatigue is broadly similar in Sri Lanka and Western high-income countries. Abnormal experiences of fatigue appear to be the extreme form of more common fatigue, rather than representing independent entities with different genetic or environmental risk factors.
authors.affiliation: MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, De Crespigny Park, London SE5 8AF. harriet.ball@kcl.ac.uk
authors.forename: Harriet A
authors.initials: HA
authors.lastname: Ball
authors.forename: Athula
authors.initials: A
authors.lastname: Sumathipala
authors.forename: Sisira H
authors.initials: SH
authors.lastname: Siribaddana
authors.forename: Yulia
authors.initials: Y
authors.lastname: Kovas
authors.forename: Nick
authors.initials: N
authors.lastname: Glozier
authors.forename: Peter
authors.initials: P
authors.lastname: McGuffin
authors.forename: Matthew
authors.initials: M
authors.lastname: Hotopf
mesh_terms: D000293:Adolescent; D000328:Adult; D015897:Comorbidity; D003866:Depressive Disorder / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D003906:Developing Countries; D004200:Diseases in Twins; D005221:Fatigue / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D010641:Phenotype; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012720:Severity of Illness Index; D012931:Social Environment; D012959:Socioeconomic Factors; D013188:Sri Lanka / Q000453:epidemiology; D011795:Surveys and Questionnaires; D013997:Time Factors