Prevalence of self-reported seasonal affective disorders and the validity of the seasonal pattern assessment questionnaire in young adults Findings from a Swiss community study

Background: The objective of this study was to expand the knowledge on the prevalence of self-reported Seasonal Affective Disorder (SAD) and to further study the validity of the Seasonal Pattern Assessment Questionnaire (SPAQ). Methods: A total of N=844 young adults were assessed in a Swiss community study by use of the SPAQ, a Seasonal Affective Disorders Questionnaire (SADQ), the Young Adult Self Report (YASR), the Centre for Epidemiologic Depression Scale (CES-D), and scales for measuring self-esteem, self-awareness and life events. At a second stage, a total of N=534 screen positives and controls were subjected to the Composite International Diagnostic Interview (M-CIDI) for the assessment of mental disorders. According to the SPAQ classification a group of SAD subjects and a group of subsyndromal SAD subjects (S-SAD) were defined. In addition, a third group of high-scoring depressives (HSD) subjects scoring above the 75th percentile of the CES-D was defined. Comparisons included these three groups and the rest of the sample serving as controls. Results: The weighted prevalence for SAD in this sample was 7.94% based on the SPAQ alone. With the addition of the SADQ, weighted prevalence rates dropped to 2.22%. Weighted subsyndromal SAD was 33.04%. Across the vast majority of scales, the SAD group was indistinguishable from the HSD group. These two groups scored highest, whereas the S-SAD group had an intermediate position and the controls had the lowest scores. SAD was best predicted by the CES-D total score. Conclusions: The SPAQ as a single measure leads to an overestimation of SAD which, nevertheless, is a rather common phenomenon also in this central European population. The findings on the validity of the SPAQ are extended by showing that predominantly general aspects of depression are measured. (C) 2008 Elsevier B.V. All rights reserved.