Could a simple dietary supplement treat Alzheimer's?

Alzheimer’s disease has proven to be one of the most difficult neurodegenerative diseases to fight, with Big Pharmas and biotechs alike laboring to find a therapy that sticks. But researchers from Indiana University (IU) School of Medicine say a simple dietary supplement, niacin (or vitamin B3), shows promise.

In a new study released Wednesday in Science Translational Medicine, IU researchers led by Gary Landreth, Ph.D, and Miguel Moutinho, Ph.D., aimed to discover whether niacin had any clinical therapeutic benefit for Alzheimer's. To do this, they tested Niaspan, an FDA-approved version of niacin, in an Alzheimer's mouse model.

The results focused on the role of a specific receptor in the brain, HCAR2, and how its activation—or lackthereof—affected Alzheimer's disease. HCAR2 governs the function of microglial cells, which remove damaged neurons and maintain the health of the central nervous system. 

Among mice that lacked HCAR2 activation, microglial function was decreased and the burdern of amyloid plaques—a biomarker of Alzheimer's—increased. But when mice were given Niaspan, HCAR2 was stimulated, correlating with a reduction in plaque burdens and improved cognition.

The findings indicate that as companies and researchers hunt for potential Alzheimer’s treatments, activation of HCAR2 may be a critical tool for gauging promise. 

“These data support that niacin could potentially be administered after onset of robust amyloid pathology and perhaps even in symptomatic stages of [Alzheimer’s disease],” the authors wrote. 

The findings are the latest to show niacin's potential benefits to the nervous system. One study from February 2020 found that niacin improved the body’s ability to rebuild protective myelin sheaths around neurons, a potential benefit for people with multiple sclerosis. Another showed that niacin stimulated the body’s immune response to fight brain tumors. 

Because of this promise, at least two different niacin trials are underway. The first, run by the U.S. Department of Veterans Affairs (VA) Office of Research and Development, is assessing niacin as a potential treatment for Parkinson’s disease. A previous study from the VA found that niacin was associated with improved motor function. The other, a phase 1/2 trial led by Alberta Health Service, is looking at the impact of niacin when combined with first-line cancer treatment for glioblastoma. 

As for its use in Alzheimer’s, the IU researchers concluded “niacin is a promising therapeutic agent for [Alzheimer’s disease] with a high translational potential for clinical use.” Landreth and Moutinho are collaborating with another colleague to launch a clinical trial to test the effects of niacin on the brain.