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Mercury Exposure Cancels Cognitive Benefits of Exercise

Aerobic exercise benefits cognition, but not after high levels of prenatal mercury exposure

TUESDAY, Sept. 27, 2016 (HealthDay News) — In young Faroese adults, aerobic fitness is associated with short-term memory and processing speed, and the correlation is attenuated by prenatal methylmercury exposure, according to a study published online Sept. 9 in Environmental Health Perspectives.

Youssef Oulhote, Ph.D., from the Harvard T.H. Chan School of Public Health in Boston, and colleagues examined the correlation between aerobic fitness and neurocognitive outcomes at young adult age, and assessed the potential moderating effect of prenatal methylmercury exposure. A total of 262 members of a Faroese birth cohort underwent a graded exercise test of aerobic fitness at age 22 years to measure maximal oxygen uptake (VO2Max). Prenatal methylmercury exposure was assessed from the cord blood concentration of mercury.

The researchers observed a correlation for a one standard deviation (SD) increase in VO2Max with better scores on short-term memory and cognitive processing speed (0.21 and 0.28 SD, respectively). A one SD increase in VO2Max correlated with increased cognitive processing scores (0.45 SD) and a slightly lesser benefit in short-term memory in the group with lower prenatal methylmercury exposure. The group with high prenatal methylmercury exposure exhibited no such correlation.

“Higher aerobic capacity was associated with better performance in short-term memory and processing speed,” the authors write. “However, prenatal methylmercury exposure seemed to attenuate these positive associations.”

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