Screening and evaluating seasonal affective disorder: a systematic review of available assessment tools

Introduction

Seasonal Affective Disorder (SAD) is a frequent and severe disorder. The prevalence of SAD varies from 1 % to 10 %, influenced by latitude and assessment methods, and is higher in women and younger populations. SAD is also overrepresented in patients with bipolar disorders. In this context, screening for SAD appears crucial, particularly because specific treatments are available. We aimed to examine comprehensively and critically the existing scales and questionnaires for assessing and screening SAD.

Methods

A systematic literature review was performed using PRISMA guidelines and searching on PubMed, Cochrane Library, and PsycINFO databases up to April 2024.

Results

Out of 791 articles screened, 28 met the inclusion criteria. Seven scales were identified, divided into those for screening and those for severity measurement. The Seasonal Pattern Assessment Questionnaire (SPAQ) is widely used and validated in multiple languages and disorders. Of note, the SPAQ tends to overestimate SAD prevalence. It has good internal validity but limited reliability for diagnosing seasonal depression alone. The SIGH-SAD allows detailed symptom evaluation, with good psychometric properties, although the score interpretation can be complex. The SHQ is more specific and sensitive than SPAQ but longer and more complex. The ISV offers a detailed assessment of seasonal variations and a good reliability but is more complex and less studied than SPAQ. The SBQ provides specific cognitive assessment related to SAD, with good sensitivity and specificity, though more validation is needed. The BDI-add includes atypical symptoms for SAD assessment but lacks comprehensive psychometric data. Finally, the HIGH-SAD is useful for distinguishing unipolar from bipolar disorder in SAD patients, with good reliability but requiring more validation.

Conclusion

The SPAQ remains the reference scale despite some limitations. The review highlights the need for ongoing validation and potentially new scales integrating seasonal and mood dimensions for more accurate SAD diagnosis.