✓ Also buy if…- You're an aging adult worried about NMDA-receptor decline (50+)
- You want the only BBB-crossing magnesium form with trial backing
✗ Also skip if…- You expect same-day cognitive sharpening — effects are subtle and slow (4-12 weeks)
- You can only afford one magnesium bottle and don't have cognition as the specific need
Life Extension Neuro-Mag is the only magnesium bottle on this list that targets a different use case from the rest. While bisglycinate, citrate, and oxide variants all act on peripheral magnesium needs (sleep, cramps, cardiovascular), Magtein L-Threonate is the one form that meaningfully crosses the blood-brain barrier — the Slutsky 2010 MIT paper that anchored this category showed measurable brain-magnesium increases only with threonate. If your goal is cognition, memory, or synaptic plasticity (not sleep), this is the right magnesium. At $28/month for the trial-dose protocol, it's positioned as a specialty pick — not a sleep-stack default, but the right add-on for the right user.