SEASONAL-CHANGES IN AFFECTIVE STATE MEASURED PROSPECTIVELY AND RETROSPECTIVELY

Background. The study was designed to investigate whether seasonal moo d and behavioural changes are detectable prospectively in a non-clinic al population in the way they have been reported in retrospective stud ies. The specificity of any seasonal fluctuation in affective state wa s also investigated by measuring anxiety as well as depression. Method . To measure seasonal fluctuations in affect and behaviour prospective ly, 25 women were interviewed every month for one year using four scal es (depression, anxiety, stress, and behavioural change). Retrospectiv e accounts of mood and behaviour at the end of the year were collected with the Seasonal Pattern and Assessment Questionnaire (SPAQ). Result s. Seasonal depression peaked in winter as did atypical behaviour when measured either prospectively or retrospectively, but the difference between winter and summer was much more pronounced in the retrospectiv e data. No seasonal effect was found for anxiety or psychosocial stres sors. Conclusions. The results obtained by retrospective techniques ha ve limited reliability. In future, more prospective studies with unbia sed, standardised instruments are recommended to measure seasonal vari ations in affect and behaviour.