Circulating
magnesium has been associated with a lower risk of
dementia, but the physiologic effects by which
magnesium may prevent neurological insults remain unclear. We studied 1466 individuals (mean age 76.2 ± 5.3, 28.8% black, 60.1% female) free of prevalent
stroke, with measured serum
magnesium and with available MRI scans obtained in 2011-2013, participating in the
Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS). Cross-sectional differences in frontal, temporal, parietal, and occipital lobe volume, along with deep grey matter, total brain, and white matter hyperintensity volume across serum
magnesium (categorized into quintiles and per standard deviation increases) were assessed using multiple linear regression. We also examined associations of
magnesium with the prevalence of cortical, subcortical, and
lacunar infarcts using multiple logistic regression. After adjusting for demographics,
biomarkers, medications, and cardiometabolic risk factors, higher circulating
magnesium was associated with greater total brain volume and frontal, temporal, and parietal lobe volumes (volumes 0.14 to 0.19 standard deviations higher comparing Q5 to Q1). Elevated
magnesium was also associated with lower odds of subcortical
infarcts (OR (95%CI): 0.44 (0.25, 0.77) comparing Q5 to Q1) and
lacunar infarcts (OR (95%CI): 0.40 (0.22, 0.71) comparing Q5 to Q1). Elevated serum
magnesium was cross-sectionally associated with greater brain volumes and lower odds of subclinical
cerebrovascular disease, suggesting beneficial effects on pathways related to neurodegeneration and cerebrovascular damage. Further exploration through prospective analyses is needed to assess increasing circulating
magnesium as a potential neuroprotective intervention.