NOPARK: nicotinamide riboside was worse than placebo in early Parkinson disease — what that means for NR marketing

Nicotinamide riboside (NR) is sold as a longevity and "NAD-boosting" supplement. On 8 October 2026, JAMA published NOPARK, the largest randomized trial of NR in early Parkinson disease. Over 52 weeks, people on NR did worse than people on placebo on the trial's main clinical score, and nonmotor symptoms also worsened more with NR.

Nothing in this explainer is medical advice, and it does not offer guidance on treating Parkinson disease. It is about what the largest NR clinical trial found, and what that does and does not say for healthy people who buy NR for aging or energy marketing.

The short answer: among 393 people with early Parkinson disease analyzed in NOPARK, NR 500 mg twice daily for a year was associated with a 2.72-point worse change on the MDS-UPDRS parts I to III than placebo (P = .02), and a 4.22-point worse change on the Non-Motor Symptoms Scale (P = .009). Four of five key secondary outcomes were null. The authors conclude that the findings do not support NR as a disease-modifying treatment for Parkinson disease. That undercuts disease-modifying hype around NR. It does not prove that NR is useless in healthy adults, and it sits beside earlier 2026 evidence that whole-blood NAD does not fall with age in healthy adults.

What NOPARK studied

NOPARK was a phase 3, randomized, double-blind, placebo-controlled trial at 11 centers in Norway, sponsored by Haukeland University Hospital. Of 537 people screened, 410 were randomized between 6 May 2020 and 20 June 2024 to oral NR 500 mg twice daily (n = 206) or matching placebo (n = 204) for 52 weeks. The primary analysis included 393 participants. Mean age was 65.6 years (standard deviation 9.4), and 133 (34%) were female. Eligible participants were aged 35 or older, diagnosed with Parkinson disease within two years, Hoehn and Yahr stage less than 3, with abnormal dopamine transporter imaging confirming nigrostriatal denervation, and on stable dopaminergic treatment before enrolment. Final follow-up was completed on 19 June 2025.

The primary outcome was change from baseline to week 52 in the Movement Disorder Society Unified Parkinson Disease Rating Scale total score for parts I to III (MDS-UPDRS; range 0 to 236, higher worse). The paper states clinically important differences of 6.7 points for improvement and 5.2 points for worsening. The five key secondary outcomes were the individual MDS-UPDRS parts I, II and III, dopamine transporter SPECT imaging, and the Non-Motor Symptoms Scale (NMSS; range 0 to 360, higher worse).

What it found

• Primary outcome: at week 52, MDS-UPDRS parts I to III rose by 2.45 points (95% CI 0.80 to 4.10) with NR and fell by 0.27 points (95% CI −1.95 to 1.40) with placebo. The adjusted mean difference was 2.72 points (95% CI 0.47 to 4.98; P = .02), favoring placebo.
• That between-group difference was statistically significant and below the paper's stated clinically important difference for worsening (5.2 points).
• Of five key secondary outcomes, four showed no significant difference. Nonmotor symptom burden worsened more with NR: NMSS adjusted mean difference 4.22 points (95% CI 1.07 to 7.37; P = .009).
• Serious adverse events occurred in 17 of 205 participants on NR (8.3%) and 29 of 205 on placebo (14.1%) in the safety population.
• The authors' conclusion: among patients with early Parkinson disease, NR for 52 weeks did not improve clinical outcomes and was associated with worse clinical outcomes than placebo. The findings do not support NR as a disease-modifying treatment for Parkinson disease.

The University of Bergen summary states that NR clearly increased NAD metabolism but that this did not translate into clinical improvement, that brain imaging showed no evidence NR slowed or accelerated changes in the brain's dopamine system, and that overall adverse-event rates were similar between groups. ChromaDex Inc, a Niagen Bioscience company, supplied NR and placebo; the summary says the funders had no role in design, conduct, analysis, interpretation, manuscript preparation or the publication decision. JAMA also published an accompanying research summary (doi 10.1001/jama.2026.18859). A Nature Aging research highlight on 6 November 2026, "NAD+ precursor fails in Parkinson's disease," described the same trial: no clinical benefit, with the primary score worse than placebo.

What this means for healthy-person NR marketing

Two claims often travel together in longevity marketing: that NAD falls with age, and that raising NAD with NR (or NMN) will slow disease or aging. NOPARK is a disease trial, not a healthy-aging trial. It does not measure wrinkles, VO2 max or lifespan in people without Parkinson disease. It does show that the largest, longest NR trial yet, in people for whom a disease-modifying effect was the reason for testing, missed its primary clinical endpoint in the wrong direction and worsened nonmotor symptoms more than placebo.

That is a hard stop for "NR modifies Parkinson disease" marketing. It is not proof that every NAD-related claim in healthy adults is false. It does belong next to the 2026 Nature Metabolism work summarized on our blood-NAD page: in healthy adults, whole-blood NAD did not fall with age in the cohorts studied. Together, those findings cut the usual story from both ends. Rising blood NAD with a pill is not the same as a clinical benefit, and a lower NAD with age is not an established fact in healthy blood.

People with Parkinson disease should talk to their neurologist about any supplement, including NR. This page does not recommend starting, stopping or changing any treatment for Parkinson disease.

Safety in the trial

In NOPARK, serious adverse events were less common with NR than with placebo (8.3% versus 14.1%). That does not make NR a treatment. It also does not answer long-term safety in healthy people taking NR for years outside a trial. The University of Bergen summary says the researchers do not recommend that people with Parkinson disease use NR or other NAD-boosting supplements outside controlled clinical studies.

US rules

FDA is not authorized to approve dietary supplements for safety and effectiveness before they are marketed. A product sold as a supplement but represented as treating or preventing a disease is regulated as a drug. Disease-modifying claims about Parkinson disease on an NR label would sit under drug rules, not supplement marketing. Talk to a doctor or pharmacist before using any supplement, especially alongside prescription medicines for Parkinson disease.

FAQ

Did NR help Parkinson disease in NOPARK?

No. The primary MDS-UPDRS parts I to III score was 2.72 points worse with NR than with placebo at 52 weeks (P = .02). Nonmotor symptoms also worsened more with NR. The authors say the findings do not support NR as a disease-modifying treatment for Parkinson disease.

Was the difference clinically important?

The adjusted difference of 2.72 points was statistically significant and below the paper's stated clinically important difference for worsening (5.2 points). It still favored placebo, and nonmotor symptoms moved the wrong way as well.

Does this prove NR does nothing in healthy adults?

No. NOPARK enrolled people with early Parkinson disease, not healthy adults seeking longevity. A failed disease-modifying endpoint is still a serious problem for disease-modifying marketing. Healthy-adult claims need their own trials.

How does this relate to blood NAD and age?

Separately, 2026 Nature Metabolism work found that whole-blood NAD did not fall with age in the healthy cohorts studied. NOPARK shows that raising NAD metabolism with NR did not improve clinical outcomes in early Parkinson disease. Read both together when you see marketing that assumes NAD decline plus NR rescue.

Does FDA approve NR for Parkinson disease?

No. NOPARK was an academic clinical trial, not an FDA approval study for a Parkinson indication. FDA does not approve dietary supplements for treating disease before marketing.