Have we been getting it all wrong about dementia? Scientists discover new trigger for devastating brain diseases

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Scientists have identified a new cause of devastating neurological conditions such as Alzheimer's disease and Parkinson's.

They believe an out-of-control immune system may be to blame and say there is strong 
evidence the mental decline common to these diseases is caused by 'auto-inflammation',

This is where the body's own immune system develops a persistent inflammatory response - and over time, this inflammation causes brain cells to die. 

Previously, researchers have focused on the role of protein deposits called amyloid plaques that lodge in the brain of Alzheimer's patients. 

'But it is now clear that this is an inadequate explanation for Alzheimer's disease,' claim the researchers, from the University of Adelaide. 

Scientists believe an out-of-control immune system may be to blame for devastating neurological conditions such as Alzheimer's disease and Parkinson's

There are many distinct forms of neurodegeneration including Alzheimer's, Parkinson's and Huntington's disease. 

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.

Study leader, Professor Robert 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 immune system as the culprit began when we discovered immune system agents become activated in a lab y model of Huntington's disease,' he said

'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.'

Previously, researchers have focused on the role of protein deposits called amyloid plaques that lodge in the brain of Alzheimer's patients. But it is now clear that this is an inadequate explanation for Alzheimer's disease,' claim the researchers, from the University of Adelaide

The innate immune system is the first line of defence 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 from various triggers, including genetic mutations, infection, toxins or physical injury.

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 added.

'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.'

'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.'

The research was published in the journal Frontiers in Neuroscience.