No Evidence Gadolinium Causes Neurologic Harm

A new study concludes there is no evidence that accumulation in the brain of the element Gadolinium (Gd) speeds cognitive decline.

Researchers at the Mayo Clinic (Rochester, MN, USA) conducted a retrospective study of the Mayo Clinic Study of Aging (MCSA) cohort in order to examine the effects of Gd exposure on neurologic and neurocognitive function. The study included 4,261 cognitively normal participants (mean age 71.9 years) who received one or more gadolinium based contrast agent (GBCA) doses. The mean time from first Gd exposure was 5.6 years. All participants underwent neurologic evaluation and neuropsychological assessment at baseline and at 15-month follow-up intervals.

After adjusting for age, sex, education level, baseline neurocognitive performance, Charlson comorbidity index, and ApoE4 status, the results showed that GBCA exposure was not a major predictor of cognitive decline, diminished neuropsychological performance, or diminished motor performance. Dose-related effects were not observed among these metrics, and Gd exposure was not an independent risk factor in the rate of cognitive decline from normal cognitive status to dementia. The study was presented at the annual meeting of the Radiological Society of North America (RSNA), held during November 2017 in Chicago (IL, USA).

“Gadolinium contrast material is used in 40-50% of MRI scans performed today; it's estimated that approximately 400 million doses of gadolinium have been administered since 1988,” said lead author neuroradiologist Robert McDonald, MD, PhD. “Right now there is concern over the safety of gadolinium-based contrast agents, particularly relating to gadolinium retention in the brain and other tissues. This study provides useful data that at the reasonable doses 95% of the population is likely to receive in their lifetime, there is no evidence at this point that gadolinium retention in the brain is associated with adverse clinical outcomes.”

Gadolinium--a rare earth heavy metal--is used for enhancement during MRI. Neurotoxic effects have been seen in animals and when a GBCA is given intrathecally in humans. On its own, gadolinium can be toxic; therefore, when used in contrast agents, gadolinium is bonded with a molecule called a chelating agent, which controls the distribution of gadolinium within the body. In July 2015, the U.S. Food and Drug Administration (FDA) stated that it was unknown whether gadolinium deposits in the brain were harmful.

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