Almost half of the adults in a small Massachusetts General Hospital pilot met the study's definition of ADHD treatment response after taking one unusual form of magnesium for up to 12 weeks. That is a striking headline number. Before you order a bottle, you need to know what the study can and cannot tell us.
The supplement is magnesium L-threonate, sold under the brand name Magtein. The paper calls it L-threonic acid magnesium salt (LTAMS).
Why Threonate Is Different From Other Magnesium Forms
Most magnesium supplements, such as citrate, glycinate and oxide, are mainly judged on how well they raise magnesium in the body overall. Magnesium L-threonate gets attention for a different reason. Preclinical work, notably a 2010 study in Neuron by Slutsky and colleagues, found that it raised magnesium levels in the brains of rodents and was linked to higher synaptic density and better learning and memory.
The study authors cite that kind of preclinical work as the rationale: LTAMS is associated with neurobiological and neurofunctional effects that could plausibly help in ADHD. The "brain-penetrating" label comes from this animal research. Whether the compound meaningfully changes brain magnesium or brain function in people with ADHD is exactly what a controlled human trial would have to show.
It is also worth separating the marketing from the mechanism. Magnesium is involved in neuronal signaling, and a plausible biological story is not proof of clinical benefit.
The MGH Pilot: What Was Actually Done
The study, published in the Journal of Dietary Supplements (2021;18(2):119-131), came from researchers in the Clinical and Research Programs in Pediatric Psychopharmacology and Adult ADHD at Massachusetts General Hospital. Lead author Craig Surman and senior author Joseph Biederman are well-known names in adult ADHD research.
The design was simple:
- 15 adults with ADHD of moderate severity
- Up to 12 weeks of LTAMS, given as two formulations, MMFS302 and MMFS202
- Open-label, meaning everyone knew they were taking the compound
- Approved by an institutional review board and registered at ClinicalTrials.gov (NCT02558790)
The Results: The Number Behind the Buzz
The headline figure: 47% of participants met the response criteria. To count as a responder, a person needed both:
- A Clinical Global Impression-Improvement (CGI-I) score of 2 or lower, meaning "much" or "very much" improved
- At least a 25% reduction in total score on the Adult ADHD Investigator Symptom Rating Scale (AISRS)
Beyond the responder rate, the group showed statistically significant improvement on:
- The AISRS, with average scores falling from roughly 25 to roughly 19, a drop of about 6 points
- The CGI-I
- The shifting subscale of the BRIEF, a measure of executive function related to cognitive flexibility
The authors also reported favorable, significant changes in IQ and WASI-II performance. The supplement was described as well tolerated. Their conclusion was that nearly half of participants met their definition of clinical response.
The Big Caveats (Read These Before You Get Excited)
This was an open-label study with no placebo group. Everyone knew what they were taking, and nobody was compared against a dummy pill.
Only 15 people were enrolled. With a sample this small, a single person moves the responder rate by roughly 7 percentage points. The 47% figure rests on about seven people.
Placebo effects are large in ADHD. Expectation, attention from clinicians and regular check-ins can all improve scores on subjective rating scales. Without a control arm, there is no way to separate the compound's effect from those influences.
The research was funded by Neurocentria, a company founded by the discoverers of magnesium threonate and linked to the Magtein brand. Industry funding does not make results wrong, but it is context you should weigh, and it is another reason independent replication matters.
Improvements in IQ-type scores also deserve caution. Without a control group, practice effects from repeated testing cannot be ruled out.
The authors themselves say the findings "support the need to further evaluate this compound in larger samples under double-blind conditions." That is the honest reading: a signal worth testing, not evidence that it works.
Practical Takeaways
Dosing. The paper's abstract does not spell out consumer dosing, so the following comes from how Magtein is typically sold, not from the study. Common labeled servings run about 1.5-2 g of magnesium L-threonate per day, which supplies roughly 144 mg of elemental magnesium. Elemental magnesium is a small share of the total because the threonate portion makes up much of the compound's weight. Check the product label, since formulations differ and the study used specific MMFS formulations that may not match what's on shelves.
Timing. Many Magtein products split the daily dose, with the last portion taken in the evening. This is a common label convention, and some people report it fits their routine because magnesium products are often associated with relaxation. The pilot study does not test timing, so treat it as a practical preference rather than an evidence-based rule.
Who might consider trying it. Adults curious about a low-risk nootropic who have no kidney problems may reasonably discuss it with a clinician. Magnesium is cleared by the kidneys, so anyone with kidney disease, or taking medications that interact with magnesium, should be especially careful and get medical advice first.
What not to do. Do not replace prescribed ADHD treatment with magnesium L-threonate, and do not stop or change medication without talking to your doctor. Stimulants and other approved therapies have decades of controlled-trial evidence behind them. This compound has one small, uncontrolled pilot.
The Bottom Line
The MGH pilot is an interesting early signal, built on a plausible preclinical rationale, that deserves a proper test. It is not proof that Magtein treats ADHD. Until a randomized, double-blind, placebo-controlled trial reports back, the most accurate summary is: promising, preliminary and unproven.
