They also performed better performance in verbal fluency test – where they were asked to give as many examples as possible of a certain topic such as “animals”, within a limited time.
Moreover, they spent less time connecting digits in different colours sequentially under the trail-making test (TMT).
Writing in Nutrients, researchers from BYHEALTH Institute of Nutrition & Health and Academy of Nutrition and Health, Hubei Province Key Laboratory of Occupational Hazard Identification and Control at Wuhan University of Science and Technology, said that the study was first of its kind among Chinese older adults.
A total of 1,006 adults 55 years old and above took part in the cross-sectional study in 2021.
They were recruited through the Health Commission of Hubei Province’s Scientific Research Project and Nutrient Levels of Cognitive Impairment Study.
As part of the study, their whole-blood magnesium concentration was measured using dry blood spot.
To assess their cognitive performance, they had to undergo several examinations, such as the trail-making test B (TMT-B), auditory verbal learning test (AVLT), digit symbol substitution test (DSST), and verbal fluency test.
Low magnesium, high MCI risk
Findings showed that a significantly lower concentration of magnesium was found in participants with MCI as compared to those without MCI.
Mean magnesium concentration was 34.7 ± 9.8 mg/L in the MCI group while that of the non-MCI group was higher at 36.7 ± 9.7 mg/L.
In fact, there was a significant dose-response relationship – which means that the lower the magnesium concentration, the higher the odds of MCI.
“High magnesium concentration was a protective factor for mild cognitive impairment,” said the researchers.
Notably, the protective effect of magnesium was only significant in adults over 60 years old.
“The results were analysed after age stratification, and it was found that high concentrations of magnesium had a protective effect on the general population and people over 60 years old in preventing mild cognitive impairment using the fully adjusted models,” said the researchers.
Low magnesium, poorer cognitive task scores
On the other hand, higher levels of magnesium were associated with better performance in cognitive tasks.
For example, subjects with a higher level of magnesium had better verbal fluency test and digit symbol substitution test scores. The latter test shows the test subjects a symbol that corresponds to digit one to nine, and they were asked to match as many symbols to numbers as possible on a coding table for 90 seconds. Higher scores indicate a better cognitive function.
“Our study revealed the relationship between magnesium and MCI and different domains of cognitive function, suggesting that a higher magnesium concentration is associated with better cognitive function.”
The researchers explained that magnesium deficiency could lead to inflammation, in turn, leading to higher rates of neurodegeneration.
“Magnesium deficiency stimulates the secretion of inflammatory mediators such as interleukin-a, tumor necrosis factor-a, and nitric oxide, leading to higher rates of neurodegeneration and stimulating, thereby increasing the risk of dementia.
“Magnesium has been shown to inhibit the production of excessive amyloid β-protein and prevent this inflammatory cascade,” they said.
On the other hand, the researchers also found that the educational level, economic ability, and physical activity of the MCI group was lower than the non-MCI group.
In the MCI group, 35.4 per cent of the subjects did not finish middle school, while the proportion was 5.9 per cent in the non-MCI group.
In addition, only 16.2 per cent of the MCI group had an average annual income of more than CNY 4000, while that of the non-MCI group was 31.4 per cent.
As for physical activity, 65.1 per cent of the non-MCI group met physical activity recommendations, while only 50.9 per cent of the MCI group met the recommendations, and the difference was statistically significant.
The study was funded by the Health Commission of Hubei Province’s Scientific Research Project and the Study on Nutrient Levels of Cognitive Impairment by BYHEALTH.
Relationship between Whole-Blood Magnesium and Cognitive Performance among Chinese Adults
Authors: Lu, Z.; He, R.; Zhang, Y.; Li, B.; Li, F.; Fu, Y.; Rong, S.