Research reveals optimal magnesium levels could lower dementia risk

By Dr. Chinta SidharthanReviewed by Susha Cheriyedath, M.Sc.Jul 15 2024

In a recent study published in the journal Advances in Nutrition, scientists in the United States conducted a systematic review of randomized controlled trials and cohort-based studies to examine whether various measures of magnesium levels, such as biomarkers, dietary intake, or supplements, were associated with cognitive health and neurological functioning in adults.

Study: Magnesium and Cognitive Health in Adults: A Systematic Review and Meta-Analysis. Image Credit: Rabizo Anatolii / Shutterstock

Background

Dementia in older adults is responsible for a significant portion of disability-related health burden and mortality as it affects not only memory and behavior but most cognitive abilities, including the capacity to carry out daily activities such as self-care. Over 55 million people across the world have dementia, and the numbers, as well as the economic healthcare burden, are expected to rise significantly in the next decade due to the aging global population.

Modifiable risk factors for dementia, such as stress, depression, vascular health, and lifestyle factors, must be targeted to effectively lower the incidence or slow the progression of dementia and reduce the economic and social burden exerted by the disease. Electrolytes have been found to play an important role in neurological health. Magnesium plays a vital role in cellular function and neuronal health, and its deficiency has been linked to memory impairments and Alzheimer’s disease. However, the findings from longitudinal cohort studies about this association have been inconsistent.

About the study

In the present study, the researchers conducted a systematic review of cohort studies and randomized controlled trials on the role of magnesium in cognitive health. They also performed a meta-analysis to determine how various forms of magnesium, such as from dietary intake, supplements, and biomarkers, were associated with cognitive outcomes.

Although the precise mechanisms remain unclear, magnesium is known to support neuronal health by lowering inflammation and oxidative damage and preserving the integrity of the blood-brain barrier. Magnesium also inhibits the activity of the N-methyl-D-aspartate receptor and lowers calcium influx, reducing excitotoxic damage. It also plays a role in maintaining myelinated axons and myelin sheaths on neurons.

Studies on animal models have also shown that magnesium deficiency is linked to memory impairments associated with hippocampal activity, and oral administration of magnesium has been found to lower neuroinflammation.

The present review included cohort and randomized controlled trial studies conducted among adults above 18 years of age that examined the association between magnesium in the forms of biomarkers, dietary intake or supplements, and cognitive outcomes measured in diagnoses or tests.

The researchers extracted data such as magnesium exposure, participant descriptions, association measures, and cognitive outcomes. Each study obtained the form of magnesium exposure, as well as the units and assessment measures. For the outcomes, the researchers considered factors such as the type of outcomes, the tools used to assess them, baseline status, the validity of the assessment tool, and the number of follow-ups.

Dose-curve responses were created after the cohort studies were analyzed for the type of exposure. Furthermore, the researchers used three models to evaluate the association between magnesium exposures and cognitive outcomes. A linear meta-regression model and a quadratic meta-regression model were used to examine the trend shown by the association, while a meta-analysis was used to determine whether pre-existing reference intervals for magnesium exposure showed a relationship with cognitive outcomes.

Results

The study found that existing randomized control trials and cohort-based studies were only able to provide moderate evidence of a U-shaped association between serum magnesium levels and cognitive impairments and dementia. An optimal serum magnesium level of 0.085 millimoles per liter was linked to the lowest dementia risk.

Furthermore, the association between dietary magnesium intake and dementia risk remained unclear due to inconsistencies in results across various studies and the absence of a clear dose-response relationship.

The findings on associations between other forms of magnesium exposure and cognitive outcomes were also unclear. The review and meta-analysis results indicated a dearth of clear evidence on the impact of various forms of magnesium exposure on cognitive outcomes. Therefore, more randomized controlled trials and longitudinal cohort studies need to be conducted to determine the impact of various sources of magnesium on cognitive outcomes over time.

Conclusions

In summary, the study highlighted the absence of conclusive evidence on the role of various forms of magnesium exposure in improving cognitive outcomes and dementia. More detailed and long-term studies examining the impact of magnesium intake from different sources on cognitive outcomes and the role of magnesium biomarkers in neuronal health are essential.