SEASONAL-CHANGES IN AFFECTIVE STATE IN SAMPLES OF ASIAN AND WHITE WOMEN

Seasonality of the affective state has been reported to vary in direct proportion to latitude in temperate regions. The frequency of seasona l affective disorder (SAD) and the severity of the symptoms associated with it have been reported to be greater in higher than in lower lati tudes. In addition, recent research has suggested a genetic loading fo r SAD. Most of the research on the seasonality of affect has been done in high latitude areas, seasonal mood cycles have been infrequently i nvestigated in tropical areas, and no study has so far measured and co mpared seasonal changes in affect and behaviour in indigenous and popu lations non-indigenous to high latitudes. To rule out the biases assoc iated with retrospective designs, a prospective longitudinal study was designed to investigate seasonal mood variations in indigenous white and non-indigenous Asian populations. Since previous research has indi cated the excessive vulnerability of women to winter depression, it wa s decided to measure seasonality of the affective state only in women. To examine the relative effects of genetic predispositions and physic al environment, the Asian group was further divided into ''Asian'' and ''Asian-British''. The former group comprised women who were living i n England but who had been born and had spent considerably more time i n their country of origin, while the latter group consisted of women w ho were born in England and who had lived there all their lives. The t hree groups of 25 women each were matched for age and socio-economic s tatus, and were interviewed every month for 1 year using the Hospital Anxiety and Depression Scale (HAD), a Behavioural Change Inventory (BC I), the Ladder Scale of General Well-being (LSW) and a Monthly Stress Inventory (MSI). One retrospective scale was administered at the end o f the study year to compare the extent of seasonal change in affect wi th that on the HAD-depression subscale. The results showed that season al depression peaked in winter in all three groups, with the incidence of winter depression being highest in the Asian group. Seasonal chang es on several dimensions of behaviour were in the direction of winter depression for all three groups. States other than depression (anxiety and general well-being) did not show any seasonal variation. Hours of daylight was found to be the best predictor of seasonal variation in mood among environmental and psychosocial variables. There was no evid ence to support a genetic hypothesis for SAD.