Background To date, the association of the neurotoxic agent cadmium (Cd) with depression in elderly people has been poorly evaluated. By investigating the relationship between blood cadmium levels and scores on a depression screening test, we aimed to investigate the impact of cadmium exposure on elderly depression.

Methods From 2008 to 2010, a total of 395 elderly participants residing in Seoul, Korea, were evaluated 3 times. Demographic data and lifestyle information were obtained via a systemised questionnaire, and blood samples were collected for analysis. Participants underwent the Korean Version of the Short Form Generic Depression Scale test (SGDS-K) for screening depression and associations were estimated using logistic regression models adjusted for potential confounders.

Results Blood cadmium levels were associated with depressive symptoms in the first visit data analysis. By analysing the first visit data, the highest quartile blood cadmium group (Q4) showed increased risk for depressive symptoms compared to the lowest quartile group (Q1) (OR 3.50, 95% CI 1.22 to 10.00). However, the data of the second and third visits suggested that blood cadmium may be protective against depressive symptoms (second visit data, Q4 vs Q1, OR 0.78, 95% CI 0.19 to 3.14; third visit data, Q4 vs Q1, OR 0.58, 95% CI 0.04 to 8.77).

Conclusions Owing to inconsistent results in analyses between blood cadmium levels and depressive symptoms, we cannot conclude any solid association between blood cadmium levels and depressive symptoms in the elderly population. To clarify the relationship, other prospective studies are needed in the future.