Objective: Early age at menarche has been found to be associated with higher oestrogen levels among girls around the onset of puberty and in early adulthood. The role of oestrogen in depression is not clear, although it affects serotonergic functions in the central nervous system (CNS). We wanted to test the hypothesis that age at menarche is associated with depression in young adulthood.
Methods: The material consisted of 3952 women born in 1966 in Northern Finland. Depression was defined by the Hopkins Symptom Checklist-25 (HSCL-25), the use of antidepressants and by self-reported lifetime depression diagnosed by physician. Menarcheal age was divided as 9-11, 12-15 and 16 years or over.
Results: The prevalence of depression was 1.8-fold in current depression, 2.8-fold in the use of antidepressants and 2.1-fold in self-reported physician-diagnosed depression in women with menarche at the age of 16 years or later. After adjusting for confounders, the significant positive association between current depression and late menarche remained, but the use of antidepressants and depression diagnosed by physician had not statistically significant association with the age of menarche.
Conclusion: A possible explanation for the result may be oestrogen as a protective factor against depression.