People with multiple sclerosis (MS) and other neurological diseases have a significantly higher aluminum content in their brains than those with no known neurological impairment and no identifiable neurodegenerative disease, a recent study found.
The research further supports a role of aluminum in the development of these brain conditions, and puts researchers closer to answer the question of how much aluminum is too much in the human brain.
Their study, “Aluminium in human brain tissue from donors without neurodegenerative disease: A comparison with Alzheimer’s disease, multiple sclerosis and autism,” was published in the journal Nature Scientific Reports.
Due to the increasing presence of aluminum in household appliances, cars, airplanes, cellphones, and even in food, medicine, and cosmetics, its presence in the human body is becoming inevitable.
Aluminum is a neurotoxic molecule that is not part of the metals normally found in the human body. But the body can accommodate certain aluminum levels through biochemical reactions that render the molecule inert, with the brain being a target tissue for aluminum accumulation.
This has raised the question of how much aluminum in the brain is too much for it to start causing damage.
To find out, Christopher Exley, PhD, at the Keele University, U.K., and Elizabeth Clarkson, PhD, from the Wichita State University in Kansas, examined the aluminum content in a set of donor brain tissues, identified by a brain bank as potential controls for brains affected with neurological conditions.
The analysis included a total of 191 tissue samples collected from 20 control brains. Donors included five men and 15 women, ages 47 to 105 years old. Tissues were obtained from frontal, occipital, parietal, and temporal lobes and cerebellum from all donors.
Control donors had no signs of neurodegeneration and no diagnosis of a neurodegenerative disease, but some of the older ones had signs of age-related changes in their brains.
Results showed that aluminum content ranged from 0.01 micrograms per gram (mcg/g) of dry weight of tissue to 9.28 mcg/g.
“The aluminum content of 191 tissue samples was invariably low with over 80% of tissues having an aluminum content below 1.0 [mcg]/g dry weight of tissue,” the researchers wrote.
Contrasting with prior studies, aluminum content did not significantly change with age, though the researchers believe this is due to the older age of donors, with only two of 20 donors being younger than 66.
Sex and brain region analyzed also did not affect aluminum concentrations, though the cerebellum showed a trend toward lower aluminium concentrations.
The researchers then compared their findings with data, measured under identical conditions, for donors who died with diagnoses of MS (14 patients), sporadic (60 patients) and familial Alzheimer’s disease (12 patients), and autism spectrum disorder (five patients).
In the case of Alzheimer’s, the group with sporadic Alzheimer’s disease also included control donors, as the “information discriminating between control and sAD [sporadic Alzheimer’s disease] donors was not made available to us,” the researchers wrote.
Notably, aluminum content was significantly higher across all disease groups, including in those with sporadic Alzheimer’s disease, compared to controls. This was true across a range of statistical analysis, and throughout all main lobes of the brain, the researchers noted.
The findings are in line with a recent study conducted by Exley and his team suggesting that people with MS have higher aluminum levels in their brain than those who died of other traumatic diseases and specifically cancer-related conditions.
The data does not directly confirm a role for aluminum in each of these diseases, but “since there is no debate as to the neurotoxicity of aluminum in humans, such data do implicate aluminum in disease aetiology [causes],” the researchers concluded.
Additional studies measuring aluminum content in more brains of patients and controls are now needed to understand if and how aluminum plays a role in neurodegenerative diseases, they added.
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