Background: The role of magnesium in the pathogenesis of dementia and other degenerative disorders has focused attention in recent years. There have been several studies reporting favorable effects of magnesium in the treatment of various degenerative illnesses. In contrast, other research found that both low and high serum magnesium levels were associated with an increased risk of Alzheimer’s disease and mixed dementia. These contrasting results render the role of magnesium levels in dementia unclear. Our objective was to investigate the possible association between dementia and hypomagnesaemia.

Methods: We conducted a systematic review and meta-analysis of all articles, in any language, reporting on serum magnesium concentrations either in plasma or serum of patients with dementia, compared to patients without dementia. Studies reporting on proportion of hypomagnesaemia patients and not mean levels were excluded.

Results: Seven studies were accepted for the meta-analysis, reporting on 2932 dementia cases and 42920 controls. All types of dementia were reported. There was a significant heterogeneity in the results, and the difference in Mg2+ concentrations between patients with dementia and controls was not significant (mean difference -10.68 micromole/L (95% confidence interval -30.62 and +9.27). There were no significant differences in the measured levels of the different types of dementia.

Conclusions: Our study, based on large numbers of dementia patients and controls, suggests that low serum magnesium concentrations are not associated with increased risk of dementia. This may be explained by poor correlation between serum and tissue distribution of magnesium and by the fact that less than one percent of total body magnesium circulates in the blood.