Seasonal affective disorder: prevalence, detection and current treatment in North Wales

Background There is a paucity of information concerning the prevalence and detection of seasonal affective disorder (SAD) in UK populations. Aims To determine the prevalence, detection and current treatment of SAD within a general population sample. Method The study was conducted in conjunction with the Outcomes of Depression International Network (ODIN) project, a large European study of depression. At the North Wales arm of the project, 1999 adults were randomly selected from a health authority database and screened by post for SAD with the Seasonal Patterns Assessment Questionnaire (SPAQ). Those scoring above cut-off were offered diagnostic interview, after which diagnosis of SAD according to DSM-IV criteria could be made. Results The prevalence rate of SAD was calculated to be 2.4% (95% CI 1.4-1.3). The majority of identified cases had not previously received a diagnosis of SAD from their general practitioner, although over half had been diagnosed with other forms of depression and had been prescribed antidepressant medication. Conclusions Although SAD was found to be common in this general population sample it appeared to be largely underdiagnosed and/or misdiagnosed.