A yearlong trial just poured cold water on an NAD+ booster for Parkinson's

One of the most rigorous tests yet of the NAD+ longevity story just delivered a sobering result. The NOPARK trial — 410 people with early Parkinson's disease across 11 Norwegian centers — found that a full year of nicotinamide riboside (NR), a popular supplement that raises cellular NAD+ levels, did not slow the disease. Published in JAMA, the trial is the kind of large, careful study that can settle an argument — and this one settled against NR.

What the 410-person trial showed

Led by professor Charalampos Tzoulis at Haukeland University Hospital and the University of Bergen, NOPARK randomly assigned participants to NR or matching placebo for one year, with neither patients nor study teams knowing who got what. The biological rationale was strong: NAD is essential for cellular energy metabolism, DNA repair, and inflammation control, and smaller earlier studies had produced encouraging signals.

But the yearlong data were unambiguous. On the MDS-UPDRS scale — where higher scores mean more pronounced symptoms — the NR group worsened by an average of 2.45 points while the placebo group remained essentially unchanged. The adjusted difference of 2.72 points favored placebo: statistically significant, but below the commonly used threshold for a clinically important difference. Brain imaging showed no evidence that NR either slowed or accelerated changes in the dopamine system.

What it does — and doesn't — mean

The researchers were blunt about the takeaway: NR clearly increased NAD metabolism, but that did not translate into clinical improvement. They do not recommend that people with Parkinson's use NR or other NAD-boosting supplements outside controlled clinical studies.

What the result does not do is close the book on NAD+ biology. The findings do not rule out benefits in other diseases — effects may differ between conditions and need separate trials. And this is about a specific therapeutic claim (slowing Parkinson's), not the general wellness use of NAD+ precursors. But it is a useful reminder of the gap between a compelling mitochondrial mechanism and a proven treatment — exactly the gap this desk exists to patrol.

Where the evidence stands

• Established: NOPARK: 410 people with early Parkinson's at 11 Norwegian centers, randomized to 500 mg nicotinamide riboside twice daily or placebo for one year, measured on the MDS-UPDRS scale.
• Established: After 52 weeks the NR group had worsened by 2.45 points while placebo stayed essentially unchanged — an adjusted difference of 2.72 points favoring placebo, statistically significant but below the threshold for a clinically important difference; brain imaging showed no dopamine-system effect; adverse events were similar.
• Absent: Any clinical benefit of NR for Parkinson's disease; the researchers do not recommend NR for Parkinson's outside controlled studies. The result says nothing about NAD+ boosters for other conditions.