Most people taking magnesium are taking the wrong form for cognitive purposes. Magnesium L-Threonate is the only commercially available magnesium compound with documented ability to meaningfully raise brain magnesium concentrations — addressing the NMDA receptor gating mechanism that determines synaptic plasticity efficiency. The Liu et al. trial reversed approximately 9 years of age-related cognitive decline in 12 weeks. This complete guide covers the mechanism, the MIT Neuron publication, the Magtein® quality distinction, and why evening timing is mechanistically optimal.