New study suggests rethink of dementia causes

May 12, 2016

University of Adelaide researchers have developed a new theory for the causes of dementia and other neurodegenerative diseases, involving an out-of-control immune system.

Published in the journal Frontiers in Neuroscience, the researchers have assembled strong evidence that the neurological decline common to these diseases is caused by 'auto-inflammation', where the body's own immune system develops a persistent inflammatory response and causes brain cells to die.

"Dementia, including the most common form Alzheimer's Disease, and related neurodegenerative conditions are dramatically rising in frequency as people live longer and our population ages," says study lead Professor Robert Richards, from the University of Adelaide's School of Biological Sciences. "Australia is predicting that by 2050 there will be almost double the number of people with dementia, and the United States similarly says there will be twice as many.

"Currently we have no effective treatments to assist the millions of affected people, and these diseases are an enormous burden on families and the public health care system."

Previously, researchers have focused on the role of protein deposits called amyloid plaques that lodge in the brain of Alzheimer's affected people. But it is now clear that this is an inadequate explanation for Alzheimer's Disease.

There are many distinct forms of neurodegeneration including Alzheimer's, Parkinson's and Huntington's Diseases. These conditions are distinguished by the different types of brain nerve cells that are first affected and by the symptoms that first appear. However, as all of these diseases progress, they become more similar.

Professor Richards believes that instead of many different mechanisms, each disease has the same underlying mechanism, and common pathway of nerve cell loss.

"Our interest in the body's own (innate) immune system as the culprit began when we discovered that immune system agents become activated in a laboratory model of Huntington's Disease," he says. "Remarkably, researchers from other laboratories were at the same time reporting similar features in other neurodegenerative diseases. When we pulled the evidence together, it made a very strong case that uncontrolled innate immunity is indeed the common cause."

The innate immune system is the first line of defense in cells, and normally distinguishes molecules that belong to the body from foreign, disease-causing, molecules. It is an alarm and response system with a self-destruct mechanism to contain and eliminate invaders or abnormal cells, like cancer.

Malfunctions can occur because of various triggers including genetic mutations, infection, toxins or physical injury, all of which have been linked with different forms of neurodegeneration. Initially the innate immune system protects the tissue against these triggers, but prolonged activation becomes self-perpetuating, causing brain cell death to occur.

"We hope this new way of understanding neurodegeneration will lead to new treatments," Professor Richards says. "We now need to further investigate the immune signaling molecules, to identify new drug targets that will delay the onset and/or halt the progression of these devastating diseases."
-end-
Media Contact:

Professor Rob Richards, (currently in Washington DC, USA). Mobile: +61 (0)422 007 867, Skype: robrichards1.35, robert.richards@adelaide.edu.au

Dani Fornarino (in Adelaide), Phone: +61 (8) 8313 7557, Mobile: +61 (0)430 137 322, danielle.fornarino@adelaide.edu.au

David Ellis, Media Officer. Phone: +61 8 8313 5414, Mobile: +61 (0)421 612 762, david.ellis@adelaide.edu.au

University of Adelaide

Related Immune System Articles from Brightsurf:

How the immune system remembers viruses
For a person to acquire immunity to a disease, T cells must develop into memory cells after contact with the pathogen.

How does the immune system develop in the first days of life?
Researchers highlight the anti-inflammatory response taking place after birth and designed to shield the newborn from infection.

Memory training for the immune system
The immune system will memorize the pathogen after an infection and can therefore react promptly after reinfection with the same pathogen.

Immune system may have another job -- combatting depression
An inflammatory autoimmune response within the central nervous system similar to one linked to neurodegenerative diseases such as multiple sclerosis (MS) has also been found in the spinal fluid of healthy people, according to a new Yale-led study comparing immune system cells in the spinal fluid of MS patients and healthy subjects.

COVID-19: Immune system derails
Contrary to what has been generally assumed so far, a severe course of COVID-19 does not solely result in a strong immune reaction - rather, the immune response is caught in a continuous loop of activation and inhibition.

Immune cell steroids help tumours suppress the immune system, offering new drug targets
Tumours found to evade the immune system by telling immune cells to produce immunosuppressive steroids.

Immune system -- Knocked off balance
Instead of protecting us, the immune system can sometimes go awry, as in the case of autoimmune diseases and allergies.

Too much salt weakens the immune system
A high-salt diet is not only bad for one's blood pressure, but also for the immune system.

Parkinson's and the immune system
Mutations in the Parkin gene are a common cause of hereditary forms of Parkinson's disease.

How an immune system regulator shifts the balance of immune cells
Researchers have provided new insight on the role of cyclic AMP (cAMP) in regulating the immune response.

Read More: Immune System News and Immune System Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.