Lack of association between iron metabolism and depressive mood in an elderly general population

Alterations in iron metabolism have been suggested as potential pathological markers in patients with manifest depression. No data on the association between iron and depression exist from population-based studies, in which milder forms of depressive symptoms are much more common. The aim of this study was to analyze the relationship between six parameters of iron metabolism and depressive mood in a population-based cross-sectional study in Germany.

A total of 374 participants, aged 65-83 years, of the Memory and Morbidity in Augsburg Elderly (MEMO) Study were assessed using the Center for Epidemiologic Studies - Depression Scale (CES-D) for depression. Iron, ferritin, transferrin, soluble transferrin receptor, iron binding capacity, transferrin saturation and C-reactive protein were analyzed with standard laboratory methods. Linear and logistic regression analyses were applied to evaluate the relationship between iron parameters and depressive mood.

The 7-day prevalence of depressive mood was 10.2%, with a higher risk in women compared to men [odds ratio (OR) = 2.04; 95% confidence interval (95% CI) = 1.04-4.0]. Correlation and linear regression analyses adjusted for age, gender, hypertension and smoking yielded no significant relationship between any of the iron parameters and the CES-D scores. In gender-stratified analyses a statistically significant association between serum iron and depressive mood was observed in men only. This finding disappeared after applying a Bonferroni correction for multiple testing.

The lack of association of iron metabolism and depressive mood reported in this population-based study does not support previous findings in patients with major depression. This negative finding in milder forms of depression in elderly people indicates either the absence or a more complex nature of the interactions between iron metabolism, low-grade inflammation and depression.