Martens · Alzheimer's & dementia : the journal of the Alzheimer's Association 2026 · randomized controlled trial · n=42

A phase-II randomized controlled pilot study of nicotinamide riboside supplementation in older adults with amnestic mild cognitive impairment.

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Level 2 - randomized trial

Individual randomized controlled trial

PubMed 42478598 · doi:10.1002/alz.71605 · record verified 2026-08-29

What was done

A 12-week double-blind, randomized, placebo-controlled phase-II pilot study evaluated the safety, tolerability, and preliminary efficacy of nicotinamide riboside (NR) supplementation in older adults with amnestic mild cognitive impairment (aMCI). Outcomes included cognitive function (primary), total and regional cerebral blood flow (CBF), blood pressure, and blood NAD+ levels.

What was found

42 participants completed the study (NR = 22, placebo = 20). Blood NAD+ increased twofold in the NR group. There were no improvements in cognitive function, total CBF, or blood pressure. Exploratory analyses showed potential increases in regional CBF, particularly in the hippocampus. No serious adverse effects were reported, and adherence was similar between groups. Exact test statistics and confidence intervals were not reported in the abstract.

Why it matters

While oral NR effectively raises circulating NAD+ in people with aMCI, this biochemical increase did not translate to detectable cognitive or hemodynamic benefits over a 12-week period.

Limits

The trial had a small sample size (n = 42 completers) and a short duration (12 weeks). Numerical values, variance, dosage, and p-values for cognitive and CBF measures were omitted in the abstract, and regional CBF findings were exploratory.

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