Background: While physical health has improved considerably over recent decades in Finland, the disease burden of mental health, especially that of depression, has become increasingly demanding. However, we lack long-term data on the natural course of subjective well-being in the general population. The aim of this study was to investigate the long-term course of self-reported life satisfaction.
Methods: This was a 15-year prospective cohort study on a nationwide sample of adult Finnish twins (N = 9679), aged 18-45 and healthy at baseline, who responded to postal questionnaires in 1975, 1981 and 1990 including a 4-item life satisfaction scale (happiness/easiness/interest in life and feelings of loneliness). Life satisfaction score (range: 4-20) was classified into three categories: satisfied (4-6), intermediate (7-11) and dissatisfied group (12-20). The associations between life satisfaction scores during the follow-up were studied with linear/logistic regression.
Results: Moderate stability and only a slight effect of age or birth-cohort on mean life satisfaction score (LS) were detected. In 1990, 56% of all and 31% of the dissatisfied remained in the same LS category as at baseline. Only 5.9% of the study subjects changed from being satisfied to dissatisfied or vice versa. Correlations between continuous scores (1975, 1981 and 1990) were 0.3-0.4. Baseline dissatisfaction (compared to satisfaction) predicted dissatisfaction in 1981 (OR = 10.4; 95%CI 8.3-13.1) and 1990 (5.6; 4.6-6.8). Multiple adjustments decreased the risk only slightly.
Conclusions: Life satisfaction in adult Finns was moderately stable during 15 years. Among an identifiable group (i.e. the dissatisfied) life dissatisfaction may become persistent, which places them at a greater risk of adverse health outcomes.