Does cadmium exposure contribute to depressive symptoms in the elderly population?

Abstract

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.

Blood cadmium and depressive symptoms: Confounded by cigarette smoking

“…In support of this decision, mean blood cotinine level in non-smokers is 10.93 ng/ml in our study, suggesting that it is present in nonsmokers and is important to include in the model. Another recent study of 395 elderly (age > 60) people living in Seoul, South Korea, also found a positive association between BCd and depressive symptoms, and while they did attempt to stratify by smoking status, they had very few current (23 people) and former (24) smokers in their sample (Han et al, 2016). Taken as a whole, these studies generally controlled for urine or serum cotinine, a sensitive and specific biomarker of current tobacco exposure (Bramer and Kallungal, 2003) but they did not control for pack-years, an indicator of long-term smoking exposure.…”

“…Although recent studies that have shown a link between BCd and depressive symptoms did adjust for smoking (Berk et al, 2014; Han et al, 2016; Scinicariello and Buser, 2015), their models may still have been susceptible to residual confounding. The Berk et al (2014) study using NHANES 2005–2010- the same population as our study - found an association between BCd and depressive symptoms, defined like our study as PHQ-9 score ≥ 10, for the upper quartile of BCd (OR 1.48 95% CI 1.16–1.90).…”

“…It has been associated with various psychiatric disorders including schizophrenia, bipolar disorder, and major depressive disorder (Mendez-Armenta and Rios, 2007; Olabanji, 2011; Orisakwe, 2014). In particular, previous studies have shown a positive association between elevated blood cadmium (BCd) levels and depressive symptoms (Berk et al, 2014; Han et al, 2016; Scinicariello and Buser, 2015). The link between urine cadmium (UCd) levels and depressive symptoms is less clear (Shiue, 2015)-possibly due to the fact that BCd is more indicative of short term mixed with long-term exposure and UCd is more representative of lifetime exposure (Jarup et al, 1998).…”

Author response: ‘Does cadmium exposure contribute to depressive symptoms in the elderly population?’

“…We thank Dr Tomoyuki Kawada1 for his interest in our manuscript entitled ‘Does cadmium exposure contribute to depressive symptoms in the elderly population?’2 In the letter, Dr Kawada depicted three possible reasons for the inconsistent results of our study: limited statistical power, use of blood cadmium as marker of cadmium exposure and the presence of other potential confounding variables.…”

Blood cadmium level in the elderly population: perspective for the cause of inconsistent results

“…Han et al 1 investigated the association between blood cadmium levels (B-Cd) and depression in 395 people, aged 60 years or older. Survey was conducted three times, and positive association between B-Cd and depression was only observed in the first visit.…”