Figure 7. Model of the correlation among periphery Mg²⁺, brain Mg²⁺, synapse density, and memory.

In the normal condition, RBC [Mg²⁺]_i is regulated by exogenous dietary Mg²⁺ intake and urine Mg²⁺ excretion. RBC [Mg²⁺]_i represents the status of blood Mg²⁺. Mg²⁺ is exchanged between the blood and other tissue in periphery and between the blood and brain ECF through the blood brain barrier (BBB). The brain ECF [Mg²⁺] regulates synapse density in the Hip and PFC, further modulating memory function. During aging, abnormal metabolism of Mg²⁺ between the body and the external environment leads to a decline in RBC [Mg²⁺]_i, which influences ECF [Mg²⁺] and further impairs memory. Enhancing Mg²⁺ intake through diet and/or drugs could affect the metabolic balance of body Mg²⁺ and rescue the degeneration of memory function.