Protective factors against depression during the transition from adolescence to adulthood: findings from a national Canadian cohort.

Objective: This study sought to identify factors protective against the onset or recurrence of depression in early adulthood, and to describe their interactions with stressors during this transitional period.

Methods: 1137 members of Canada's National Population Health Survey were followed from ages 12 to 17 in 1994/95 and contacted every two years until 2008/09. Protective factors measured at age 16/17 included social support, physical activity, mastery, self-esteem, and education level. General linear mixed models were used to examine the relationship between the protective factors and five assessments of depression, including interactions between protective factors and four types of stress: stressful life events, and work, financial, and personal stress.

Results: High mastery in adolescence had a significant protective effect against depression in early adulthood. Participants with high social support in adolescence were significantly less likely to become depressed after experiencing work or financial stress, compared to those with low social support. Those who were physically active in adolescence were less likely to become depressed after experiencing work stress, and higher overall education level reduced depression risk following personal stress or major life events.

Conclusion: Social support and physical activity may be ideal targets for school-based depression interventions during a potentially stressful transitional period.