Year-Long Trial Finds NAD-Boosting Supplement Worsens Early Parkinson Symptoms

The NOPARK trial, a randomized, placebo-controlled study conducted at 11 centers in Norway and published October 8, 2026, in JAMA, enrolled 410 people with Parkinson's disease diagnosed within the prior two years and randomized 393 into the main analysis. Participants averaged 65.6 years old and 34% were female. Half took the supplement twice daily and half took a matching dummy pill for 52 weeks. The primary measure was the Movement Disorder Society Unified Parkinson Disease Rating Scale, a 0-236 point score combining mood, daily function and movement symptoms, where higher numbers mean worse disease. At 52 weeks, that score rose 2.45 points on the supplement and dropped 0.27 points on placebo, a 2.72-point difference favoring placebo. Of five prespecified secondary measures, four showed no real difference between groups, but nonmotor symptom burden, measured on a 0-360 point scale covering sleep, mood and thinking, worsened 4.22 points more on the supplement than placebo. Serious adverse events occurred in 8.3% of the supplement group versus 14.1% of the placebo group.

Nicotinamide riboside is a building block cells use to make NAD+, a molecule involved in energy production and DNA repair inside mitochondria, the cell's energy-generating structures. Researchers proposed that boosting NAD+ could protect the dopamine-producing brain cells that die off in Parkinson's disease, based on earlier lab and small human studies. The authors concluded this trial found no such protection: clinical outcomes did not improve and were measurably worse with the supplement than with placebo, and the findings do not support it as a disease-modifying treatment for Parkinson's.