UC Irvine scientists are now conducting a clinical trial to determine its effect in humans.
Nicotinamide was found to reduce the levels of a protein called phosphorylated tau that leads to the development of tangles, one of two brain lesions linked with Alzheimer's.
The researchers found that the vitamin also strengthened scaffolding along which information travels in brain cells.
It would not only help in keeping the neurons alive but will further prevent symptoms in mice genetically wired to develop Alzheimer's.
"Nicotinamide has a very robust effect on neurons. Nicotinamide prevents loss of cognition in mice with Alzheimer's disease, and the beauty of it is we already are moving forward with a clinical trial," said Kim Green, UCI scientist and lead author of the study.
Nicotinamide is a water-soluble vitamin sold in health food stores. It belongs to a class of compounds called HDAC inhibitors, which have been shown to protect the central nervous system in rodent models of Parkinson's and Huntington's diseases and amyotrophic lateral sclerosis.
Scientists are conducting clinical trials to learn whether HDAC inhibitors help ALS and Huntington's patients.
In the current study, Green and his colleague, Frank LaFerla, added the vitamin to drinking water fed to mice.
They tested the rodents' short-term and long-term memory over time using water-maze and object-recognition tasks and found that treated Alzheimer's mice performed at the same level as normal mice, while untreated Alzheimer's mice experienced memory loss.
They also found that the nicotinamide led to a slight enhancement in cognitive abilities in normal mice.
"This suggests that not only is it good for Alzheimer's disease, but if normal people take it, some aspects of their memory might improve," said LaFerla, UCI neurobiology and behavior professor.
The results showed that the nicotinamide-treated animals had dramatically lower levels of the tau protein that leads to the Alzheimer's tangle lesion.
The vitamin did not affect levels of the protein beta amyloid, which clumps in the brain to form plaques, the second type of Alzheimer's lesion.
Also, they found that nicotinamide led to an increase in proteins that strengthen microtubules, the scaffolding within brain cells along which information travels.
The brain cells can die in case this scaffolding breaks down. Neuronal death leads to dementia experienced by Alzheimer's patients.
"Microtubules are like highways inside cells. What we're doing with nicotinamide is making a wider, more stable highway. In Alzheimer's disease, this highway breaks down. We are preventing that from happening," said Green.
The study has appeared online in the latest issue of the Journal of Neuroscience.