Does low-level cadmium exposure affect cognitive functions? Results from the Malmö Diet and Cancer Study

Background and aim: Elevated cadmium exposure is toxic for the brain, but it is unclear if low-level exposure is a risk factor for cognitive impairment. We aim at examining the association between blood cadmium and cognitive functions in a Swedish population-based cohort with a follow-up period of 20 years. Methods: The Malmö Diet and Cancer Study – Cardiovascular Cohort (aged 46-67 years) was recruited in 1991-1994. After 20 years, a subsample of individuals underwent a clinical reexamination including a global cognitive screening test (Mini-Mental State Examination, MMSE) and a test of processing speed, attention and executive function (A Quick Test of Cognitive Speed, AQT). Associations with blood cadmium (in quartiles, Q1-Q4) at baseline were analyzed using linear regression and adjusted for confounders and known risk factors for cognitive impairment in 2805 individuals with data on blood cadmium and cognitive screening. Results: The mean total score of MMSE was 28.3 (SD 1.7) points (maximum score 30). The MMSE score was 0.38 points lower (95% CI -0.62, -0.13) among individuals in Q4 (median blood cadmium 1.0 µg/L) compared with those in Q1 (median blood cadmium: 0.13 µg/L). The mean total test time for AQT was 136 (SD 30) seconds. Individuals in Q4 of blood cadmium were on average 7.2 seconds slower (95% CI 2.69, 11.8) than those in Q1. Associations were similar among men and women, and among never, former, or current smokers. Conclusions: Blood cadmium in the highest quartile was associated with worse results in two common cognitive tests in a sample from the general population with cadmium exposure comparable to those of most European countries and the U.S. Our findings strengthen the need for further actions to reduce cadmium exposure in the general population. Keywords: cadmium, cognitive tests, general population