Alzheimer’s, Dementia & Mental Health
Alzheimer’s study points finger of blame at immune system
Search for treatment, cure seems headed in new direction today after Duke study
Colorful depection of regions of the human brainApril 15, 2015 – The search for a cure or treatment of Alzheimer’s disease appears to being going in a new direction today. New research points the finger of blame away from “plaques” and “tangles” and toward a failure of the immune system.
A Duke University study published in the Journal of Neuroscience found that cells in the immune system that normally protect the brain from infection will begin to consume a key nutrient, arginine, during the early stages of Alzheimer’s.
The researchers blocked this process in lab mice with a small-molecule drug, difluoromethylornithine (DFMO), which prevented the brain plaques and the loss of memory. This stopped the damage caused by arginase, an enzyme which breaks down arginine.
“Plaques and tangles in the brain are two of the main features of Alzheimer’s disease,” according to the National Institute on Aging. “The third is the loss of connections between nerve cells (neurons) in the brain.
Alzheimer’s is an irreversible, progressive brain disease that slowly destroys memory and thinking skills and, eventually even the ability to carry out the simplest tasks of daily living.
In most people with Alzheimer’s, symptoms first appear after age 65. Alzheimer’s disease is the most common cause of dementia among older people. There are about 5 million cases in the U.S. today.
The mystery is not completely solved, however, as the precise role of the immune system cells is not understood. Still, the study points to a new possible cause of AD, which could open the door to new therapy.
“If indeed arginine consumption is so important to the disease process, maybe we could block it and reverse the disease,” said Carol Colton, professor of neurology at the Duke University School of Medicine, a senior author of the study.
“We see this study opening the doors to thinking about Alzheimer’s in a completely different way, to break the stalemate of ideas in Alzheimer’s disease.”
Research into the brains of Alzheimer’s sufferers has typically focused on plaques and tangles. Plaques are a build-up of sticky proteins known as beta amyloid while tangles are a twisted protein called tau.
By studying a type of mouse created several years ago with a similar type of immune system to a human, researchers found that immune cells called microglia began to divide and change early in the onset of Alzheimer’s.
“All of this suggests to us that if you can block this local process of amino acid deprivation, then you can protect – the mouse, at least – from Alzheimer’s disease,” said Matthew Kan, one of the researchers involved in the study.
The researchers will next test older mice that already have an advanced form of Alzheimer’s.