BACKGROUND: As an important mediator by which the brain receives information about the body's energy state, leptin may be associated with subjectively perceived health. OBJECTIVE: The main aim of the present study was to investigate concurrent and prospective associations between leptin and self-rated health (SRH), a strong predictor of morbidity and mortality, in a random population sample. An additional aim was to examine whether sick leave was associated with leptin and poor SRH. METHODS: In a prospective, population-based cohort study in Sweden, men and women underwent a medical examination in 1998, at which time blood was drawn and participants were asked to respond to a questionnaire concerning demographics, health behavior, and psychosocial factors. In 2000, the participants responded to a second questionnaire sent by postal mail. Spearman rank correlations were used to investigate the relationships between leptin, SRH, sick leave, and background variables. Partial Spearman coefficients were then calculated to investigate the patterns of association between leptin, SRH, and sick leave independent of age, body mass index (BMI), presence of diagnosis, and testosterone or estradiol. RESULTS: A total of 98 men and 104 women, aged 23 to 76 years, and 91 men and 96 women at follow-up, participated in the study. In men, relatively higher levels of leptin were prospectively associated with relatively worse SRH (rho = 0.20; P = 0.05), but the relationship was not significant in the cross-sectional analysis (rho = 0.18; P = 0.07). This association was not found in women. When controlling for age, BMI, presence of diagnosis, and testosterone, higher levels of leptin were associated with poor SRH in men in cross-sectional analysis (rho = 0.27; P < 0.01) but not prospectively. In women, leptin was not associated with SRH in cross-sectional analysis, but relatively higher levels were prospectively associated with better SRH when adjusted for background factors and estradiol (rho = -0.26; P < 0.05). SRH was independently associated with future sick leave in both men (rho = 0.34; P < 0.01) and women (rho = 0.30; P < 0.05), whereas no association between leptin and future sick leave was found. CONCLUSIONS: Contrasting associations were found between men and women in the relationship between leptin and SRH. Based on the finding that higher leptin levels were associated with better SRH in women than in men, along with corroboration from recent studies, we propose that leptin may serve different psychobiological functions in men than in women.
2010. Vol. 7, no 3, 261-9 p.