Dr. Young's Lab
Clustering of Symptoms Across the Offset of Seasonal Affective DisorderLaura A. Schmitt (Masters, 2000)
The goal of this study was to identify subgroups of symptoms that covary together over their offset because such subgroups suggest distinct underlying mechanisms. Ten participants who met criteria for seasonal affective disorder (SAD) completed 10 weeks of daily visual analogue scales. To analyze within-subject symptom covariation, a covariance matrix was calculated for each participant. A factor analysis of the average covariance matrix yielded three factors: Energy/Motivation, Affect/Cognition, and Appetite. Correlations were calculated between measures of sleep and the three factors, but no significant correlations were found. Results suggest that these subgroups may reflect different underlying mechanisms consistent with particular theories of the etiology of SAD.