Generic and health-related quality of life in patients with seasonal and nonseasonal depression

Although a relatively large body of research has now accumulated concerning the relationship between quality of life (QoL) and nonseasonal depression, there is a dearth of information about QoL in seasonal affective disorder (SAD). The aim of this study was to compare perceived levels of broad ('generic') and health-related QoL in patients with seasonal and nonseasonal depression. Participants were 72 patients with SAD enrolled in an on-going multicentre study in Canada, and 72 patients with nonseasonal major depressive disorder (MDD) matched for severity of depression attending an outpatient psychiatric clinic in Vancouver, British Columbia. All participants completed two measures of QoL (the 20-item Medical Outcomes Study [MOS] Short-Form General Health Survey [SF-20] and the Quality of Life Enjoyment and Satisfaction Questionnaire [Q-LES-Q]) at baseline prior to treatment. The results of the study indicated that both generic and health-related QoL were compromised in patients with SAD compared with general population norms. For example, mean Q-LES-Q scores (range 0-100, where higher scores indicate better QoL) were 44%, compared with scores of 83% reported for the general population. Patients with nonseasonal depression showed significantly poorer functioning in several domains on the SF-20, but no significant differences in Q-LES-Q scores emerged. Perceived QoL is impaired in patients with SAD. Degree of impairment between seasonal and nonseasonal depressives is equivalent when assessed using the Q-LES-Q, but significant inter-group differences are apparent in SF-20 domain scores. Future research is required to determine whether perceived QoL is improved by treatment interventions for seasonal depression such as light therapy or antidepressant medication.