Environment/Climate Change
Association Between Long-Term Methylmercury Exposure from Fish Consumption and Frailty and Cognition in Older Women Edwin van Wijngaarden* EDWIN VAN WIJNGAARDEN Gary Myers Matthew Rand Conrad Shamlaye Emelyn Shroff JJ Strain Alison Yeates Emeir McSorley Maria Mulhern Sally Thurston
Background: Methylmercury (MeHg) exposure from fish consumption has been associated with neurotoxic effects, yet its long-term impact on physical and cognitive function in older adults is unclear. We examined the relationship between MeHg and measures of frailty and cognition in a cohort of middle-aged to older women in a high fish-eating population.
Methods: This study included 609 women (mean age: 58 years, range: 45-77 years), originally recruited in 1990 as part of the Seychelles Child Development Study and re-enrolled in 2013 and 2021. In 2021, frailty was assessed using the Short Physical Performance Battery (SPPB) and hand grip strength (using dynamometry), while cognition was measured with the St. Louis University Mental Status (SLUMS) exam. MeHg exposure was determined as total Hg in hair samples. Fish consumption data was collected in 2013 and 2021. Mean hair Hg (averaged over all three time points) was examined in relation to frailty and cognition outcomes using linear regression adjusted for age, education, occupational status, smoking, alcohol use, waist to hip ratio, parity, marital status, KBIT (a measure of intelligence), and fish intake (averaged over the two time points). We also examined the interaction between fish intake and categories of estimated average Hg, fatty fish percent, and maternal age.
Results: Mean hair Hg concentrations were 6.8 ppm (1990), 6.7 ppm (2013), and 7.3 ppm (2021). Mean fish consumption was 10.3 and 9.8 fish dishes/week in 2013 and 2021, respectively. Hair Hg was not associated with SPPB scores (β = 0.002, 95% CI: -0.032, 0.036), hand grip strength (β = -0.012, 95% CI: -0.149, 0.125), or SLUMS scores (β = -0.026, 95% CI: -0.136, 0.084). Fish intake was not associated with frailty and cognition measures, and the fish intake associations were not significantly different across average Hg, fatty fish, or age categories.
Discussion: These findings suggest that dietary MeHg exposure at observed levels does not affect frailty or cognition in older women. Further cohort follow-up is needed to confirm this. Future research should explore potential modifiers such as dietary nutrient intake or genetic susceptibility.