A widely promoted supplement aimed at improving longevity has failed to demonstrate benefits for individuals with early-stage Parkinson's disease in a significant clinical trial. The study revealed that the vitamin B3 derivative, known as nicotinamide riboside (NR), not only showed no improvement in the condition but also led to a worsening of symptoms in some participants.
Parkinson's disease is a progressive neurodegenerative disorder characterized by the damage and death of dopamine-producing nerve cells in the brain. This reduction in dopamine impairs motor control, leading to symptoms such as tremors, muscle stiffness, and slowed movement. The disease also encompasses non-motor symptoms, including depression, sleep disturbances, and digestive issues.
The trial involved 410 adults diagnosed with early-stage Parkinson's within the two years prior to the study. All participants were already on standard Parkinson's medications, including levodopa, carbidopa or benserazide, and selegiline. Researchers assessed the severity of their Parkinson's symptoms using the MDS-UPDRS scale at the trial's outset.
Participants were randomly assigned to receive either 500 milligrams of nicotinamide riboside twice daily or a placebo for one year. NR is a precursor to nicotinamide adenine dinucleotide (NAD+), a molecule crucial for energy production, DNA repair, and cellular defense, with levels naturally declining with age. The growing popularity of NR has been fueled by celebrity endorsements and its association with anti-aging effects, making it a multi-billion dollar global market.
Previous laboratory research and smaller clinical trials had suggested that boosting NAD+ levels might offer neuroprotective benefits for Parkinson's patients. However, this larger-scale study failed to validate those hopes.
After a year, participants taking NR experienced an average increase of 2.45 points on the MDS-UPDRS scale, indicating symptom progression. In contrast, the placebo group showed a slight improvement of 0.27 points. While the 2.72-point difference between the groups was statistically significant, the study authors concluded it was too small to be clinically meaningful. Furthermore, non-motor symptoms, such as mood and sleep problems, were observed to worsen more frequently in the NR group compared to the placebo group.
Brain imaging did not reveal any positive effects of NR on the brain's dopamine system, and the incidence of adverse events was comparable between both groups. Charalampos Tzoulis, the study's lead investigator and professor at Haukeland University Hospital and the University of Bergen, stated that while NR increased NAD metabolism, this did not translate into clinical improvement. He advised against using NR or similar NAD-boosting products for Parkinson's treatment outside of clinical trials.
The findings, published in JAMA, suggest that NR is not a viable treatment for slowing the progression of Parkinson's disease. However, the researchers noted that these results do not preclude the potential of NAD+-targeting treatments for other conditions.
Parkinson's disease affects over 10 million people globally, with approximately 1.1 million in the United States. The disease is diagnosed in about 90,000 Americans annually. While its exact cause remains unclear, factors such as genetics, environmental influences, and aging are believed to contribute. Currently, there is no cure for Parkinson's, but various treatments exist to manage symptoms and enhance patient quality of life.