Chapter

Psychological and biological traits in seasonal affective disorder and seasonality

Michael A. Young and Bonnie J. Yap

in Seasonal Affective Disorder

Second edition

Published on behalf of Oxford University Press

Published in print October 2009 | ISBN: 9780199544288
Published online February 2013 | e-ISBN: 9780191754593 | DOI: http://dx.doi.org/10.1093/med/9780199544288.003.0013
Psychological and biological traits in seasonal affective disorder and seasonality

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Although the amount of research is limited, the evidence is substantial that some psychological traits are related to SAD/seasonality. Our confidence in these findings is enhanced by the facts that some studies include non-symptomatic SAD patients when comparing to norms and that some studies control for severity in comparing to non-seasonal depression. Similar to non-seasonal depression, individuals with SAD exhibit higher than normal levels of neuroticism, lower levels of extroversion, and lower levels of conscientiousness. Although elevated, neuroticism in SAD may be lower than that in non-seasonal depression.

As in studies of non-seasonal depression, elevated levels of harm avoidance appear to be mostly a function of a depressed state rather than a stable trait. Apparently unique to SAD is that openness to experience is elevated compared to both normal levels and those in non-seasonal depression. This finding is consistent with the suggestion that SAD patients are more psychologically sensitive to environmental changes (Murray et al. 2002) and the vegetative changes that accompany them (Young et al. 2008). However, no studies have examined whether this sensitivity is actually the process through which openness relates to SAD.

Evidence suggests that cognitive styles in SAD are both similar to and different from those in non-seasonal depression. The few studies of memory and attention vary in methods and results, but thus far there is no clear indication that SAD is associated with the biases and deficits exhibited by individuals with non-seasonal depression. Studies have failed to find these effects even in symptomatic SAD patients in whom one would expect a stronger effect, even if it were due to the depressed state and not a trait. More research is needed in this area. Somewhat stronger evidence suggests that explanatory style, dysfunctional attitudes, and attitudes toward winter and light may play a role in SAD. The strongest findings regarding cognitive styles are that a ruminative response style is associated with SAD, both when assessed in the winter and in other seasons. Results consistently show that a more ruminative style is associated with SAD/seasonality, predicts more severe winter symptoms, and interacts with vegetative symptoms in predicting cognitive and affective symptoms. Continuing research on rumination in unipolar depression is focusing on the specific consequences of ruminating that contribute to depression and what kinds of repetitive thinking are beneficial and detrimental (Nolen-Hoeksema 2008; Watkins 2008); applying these approaches to rumination in SAD also would be enlightening.

Chapter.  9693 words. 

Subjects: Psychiatry

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