(OR32-07-24) Associations of Serum Magnesium With Brain Morphology and Cognitive Function, and Modification by Diabetes and Hypertension in Puerto Rican Adults

Objectives: Magnesium (Mg) plays a key role in normal neuronal functioning, but its association with brain aging is under-studied. We aimed to examine the associations of serum Mg with brain MRI and cognitive measures, and the effect modification by diabetes and hypertension.

Methods: Adults from the Boston Puerto Rican Health Study who had serum Mg measured at the 2^nd visit and underwent MRI scans at the 4^th visit were included in the analyses on brain morphology (n=216). Hypomagnesemia was defined as serum Mg < 0.75 mmol/L. Brain age (z scores) and volumes were estimated based on T1-weighted MRI. Multivariable linear regression was used to estimate β coefficients and 95% CI. Participants who underwent cognitive evaluation using a 7-test neuropsychological battery at baseline, 2^nd and 4^th visits were included in the analyses on serum Mg and cognitive function (n=1113). A global cognitive score was calculated as an average of z scores of all tests. Executive function and memory domains were identified using principal components analysis. Linear mixed effects models were used to evaluate the associations adjusted for confounders. Stratified analyses by diabetes and hypertension status were performed.

Results: In this cohort of Puerto Ricans aged > 45 y and followed for > 10 y, hypomagnesemia was associated with lower gray matter volume [β (95% CI) = -1.52 (-2.87, -0.17)], especially for cerebrum and cerebellum. In participants with diabetes, those with hypomagnesemia had older brain age [β (95% CI) = 0.66 (0.032, 1.28)] and lower volumes of total gray matter, cerebrum (gray matter of frontal, parietal, and temporal lobes; white matter of frontal and temporal lobes), cerebellum (both gray and white matter), and deep gray matter components including hippocampus and amygdala, compared to those with normal serum Mg. These associations were not observed in the group without diabetes. Hypomagnesemia was also associated with lower global cognitive score [β (95% CI) = -0.082 (-0.13, -0.031)] and executive function score [β (95% CI) = -0.20 (-0.30, -0.098)], but the associations were confined to people with diabetes or hypertension.

Conclusions: Hypomagnesemia was associated with reduced brain volumes and cognitive function. Mg status merits more attention for the prevention of neurodegenerative diseases, especially among people with diabetes and hypertension.

Funding Sources: NIH