The Seasonal Health Questionnaire: a preliminary validation of a new instrument to screen for seasonal affective disorder

BACKGROUND: The main screening tool for Seasonal Affective Disorder (SAD) is the Seasonal Pattern Assessment Questionnaire, but its reliability and validity have been thrown into doubt by several studies. METHOD: In this study we developed a new questionnaire, the Seasonal Health Questionnaire (SHQ), which is scored by computer to derive the four main operational criteria for diagnosis of SAD. A group of clinically diagnosed SAD patients was contrasted with a group of patients with recurrent non-seasonal depressive disorder using the SPAQ and the SHQ. RESULTS: The SHQ could be completed without difficulty by patients with long histories of recurrent mood disorder. The SPAQ and the Rosenthal Criteria were the least specific of the criteria for identifying SAD - misclassifying many non-seasonal patients. CONCLUSIONS: After further development the SHQ may be a more appropriate screening instrument for SAD. The SPAQ should no longer be used for this purpose as it gives misleadingly high estimates of prevalence.