Can Hydrogen Water Help Mild Cognitive Impairment? What a 1-Year Trial Found

Mild cognitive impairment often precedes more serious memory conditions, so researchers are actively looking for safe, early interventions. This study combined animal research with a year-long human trial to test hydrogen water specifically for this purpose.

What the research looked at

Published in Current Alzheimer Research in 2018, this study combined a mouse model with a randomized, double-blind, placebo-controlled human trial. In the human portion, 73 people with mild cognitive impairment drank approximately 300 mL per day of hydrogen-rich water or a placebo water for one year. Cognitive performance was measured using the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog), a standard tool for tracking cognitive change.

What they found

Over the full year, there was no statistically significant difference in ADAS-cog scores between the hydrogen water group and the placebo group. In a smaller subgroup analysis, participants who carried the ApoE4 gene variant (a known genetic risk factor for Alzheimer's disease) showed improvement on the total ADAS-cog score and a word recall task — but the authors note this subgroup was small and the finding could be a statistical artifact rather than a real effect. In mice, hydrogen-rich water reduced markers of oxidative stress and slowed memory decline.

What this means in practice

The headline result here is a null one: over a full year, hydrogen water didn't move the needle on cognitive scores in the overall study group. The ApoE4 subgroup finding is intriguing but explicitly flagged by the researchers themselves as possibly not a real effect, given how few people were in that subgroup — it needs a dedicated, larger trial before it means anything clinically. This is a case where the animal data looks more promising than the human data, and mild cognitive impairment should be evaluated and managed with a doctor rather than addressed with hydrogen water alone.