This theory didn’t age well.
A popular supplement commonly marketed for improving longevity failed to show meaningful benefits for people with early-stage Parkinson’s disease in a new study.
The findings dash hopes that the vitamin B3 derivative could slow the disease’s progression — with symptoms actually worsening for some patients.
Parkinson’s develops when nerve cells in the brain become damaged and die, reducing levels of dopamine, a chemical messenger that helps coordinate movement.
As the disease progresses, patients can develop tremors, stiff muscles, slowed movements and problems with balance.
It can also cause non-motor symptoms, including depression, anxiety, sleep disturbances, digestive problems, speech changes, bladder issues and sudden drops in blood pressure when standing.
The study authors recruited 410 adults aged 35 and older from 11 centers across Norway who had been diagnosed with early-stage Parkinson’s within the prior two years.
Before the trial, all had been taking levodopa alongside carbidopa or benserazide three times a day, plus 10 milligrams of selegiline daily. They stuck with their usual medications throughout the study unless it was clinically necessary.
At the start, researchers assessed each of the participants using the MDS-UPDRS scale, a standard measurement of Parkinson’s severity. The worse the symptoms, the higher the score.
The participants were then randomly split into two groups. One took a 500-milligram tablet of nicotinamide riboside (NR) twice daily for a year, while the other received a placebo.
NR is a form of vitamin B3 that the body converts into nicotinamide adenine dinucleotide, or NAD+.
NAD+ plays a role in several essential processes, including converting food into energy, repairing damaged DNA, maintaining cellular defenses and regulating the body’s internal clock.
Levels of NAD+ naturally decline as people get older, and changes in the molecule have been linked to aging and several chronic conditions, including heart disease, Alzheimer’s disease and vision loss.
NR has become a $2 billion global market, as celebrities from Kendall Jenner to Joe Rogan and Jennifer Aniston have touted the benefits of NAD+.
Earlier laboratory studies and small clinical trials had raised hopes that boosting NAD+ levels could protect the nerve cells damaged by Parkinson’s.
But when researchers put the theory to a larger test, the results fell short.
After one year, participants taking NR saw their scores worsen by an average of 2.45 points on the MDS-UPDRS scale. In the placebo group, scores improved by 0.27 points.
The 2.72-point difference between the groups was statistically significant and favored the placebo, but it was too small to be considered clinically meaningful, the study authors noted.
The team also assessed non-motor symptoms, including mood and sleep problems, which worsened more among those taking NR than those given the placebo.
Imaging tests showed no evidence that NR slowed or accelerated changes in the brain’s dopamine system. The overall rate of adverse events was also similar in both groups.
“NR clearly increased NAD metabolism, but this did not translate into clinical improvement,” study leader Charalampos Tzoulis, a professor at Haukeland University Hospital and the University of Bergen, said in a press release. “Our results therefore do not support NR as a treatment to slow Parkinson’s disease.”
Based on the findings, the researchers advised against using NR or other NAD-boosting products to treat Parkinson’s outside controlled clinical trials.
However, they noted that the results don’t rule out the possibility that treatments targeting NAD+ could help with other diseases.
“Although the results were not what we had hoped for, their contribution has answered an important medical question and provided valuable guidance for future research,” Tzoulis said.
The findings mark the latest development in the ongoing search for better Parkinson’s treatments, a disease that affects more than 10 million people worldwide, including about 1.1 million in the US, according to the Parkinson’s Foundation.
Each year, around 90,000 Americans are diagnosed with the progressive disorder, which is more common among men and older adults.
The exact cause remains a mystery for most patients, though researchers believe a combination of genetics, environmental factors and aging plays a role.
There is currently no cure for Parkinson’s, but medications, supportive therapies and procedures such as deep brain stimulation can help manage symptoms and improve quality of life.
