University of Otago researchers have discovered molecules in the blood that could assist with early detection of Alzheimer’s disease. 

The research, published in the journal Alzheimer’s & Dementia, shows the level of small molecules called microRNA, that are found in blood plasma, dynamically change as the symptoms of Alzheimer’s disease get worse.

The research was a collaboration with Lead Author Diane Guévremont and Team Leader Associate Professor Joanna Williams, of the Department of Anatomy and the Otago Brain Health Research Centre, members of Otago’s Departments of Psychology, Biochemistry and Medicine, and colleagues in Melbourne and Perth.

Expansion of this work, to be undertaken by Guévremont and Associate Professor Williams, will allow researchers to firmly establish a biomarker of preclinical Alzheimer’s disease and will bolster the development of a simple blood screening tool to pick up those at risk of developing Alzheimer’s disease.

Alzheimer’s disease is a slow progressing neurodegenerative disorder that begins long before people notice problems with their memory.

There is currently no easy way of early detection, Guévremont says.

“It is possible to quantify levels of toxic molecules in the brain or changes in brain structures, but it is not possible to measure these early changes without repeated use expensive and invasive procedures that are only available in highly specialised centres and not currently suitable for routine screening.

“A blood test, however, can be done simply, and although may not be as precise as positron emission tomography (PET) scans, may be a valuable tool to discover those at risk of developing Alzheimer’s disease,” she says.

This would allow for early intervention with currently therapies such as lifestyle modifications and new drug therapies which are being developed.

“This means we might actually have a real chance of making a real impact on this disease.”

The researchers assessed blood plasma levels of 182 neurodegeneration-related microRNA in three different groups representing different stages of the disease-  a group of people who have tested amyloid positive in PET scans but are cognitively normal, another group of people living with mild cognitive impairment, and one that has been diagnosed with Alzheimer’s disease.

“We found that plasma microRNA are dynamically expressed during the progression of Alzheimer’s disease. Those specific microRNA are altered at specific diseases stages including a group which are correlated with levels of the neurotoxic molecule amyloid-ß.”

Associate Professor Williams says the research  team hopes the findings will allow intervention at a time in the disease where therapies are most likely to be effective.

“Our goal is to use blood as a window into the brain, to find biomarkers that can help us diagnose Alzheimer’s disease early, long before symptoms appear, and the brain is too damaged for interventions to be effective.

“This is now within reach and will give hope that current and novel therapeutics can be delivered at a time during the disease process where there is a greater chance of being effective. Furthermore, such a test will be useful to assess therapy effectiveness,”  she says.

More than 70,000 New Zealanders are affected by Alzheimer’s disease, and this is predicted to increase to 150,000 by 2050, at a cost of more than $1.7 billion a year.

“Our ultimate goal is to contribute to effective healthcare for those at risk of Alzheimer’s disease and reduce the burden of Alzheimer’s disease in New Zealand. To achieve this, we are focused on early detection of the disease prior to the onset of symptoms, to allow early and effective treatment.

“Indeed, a therapy that delays the onset of Alzheimer’s disease by as little as one year will reduce associated costs by $300 million per annum. This will only be possible with early detection of the disease.”

It’s not just about money, though, Associate Professor Williams says.
“Early detection and development of effective therapies to stave off dementia will enhance later life experience of elderly  and the early life experience of newer generations, she says. It is particularly relevant to Māori as this will enhance the ability of kaumatua and kuia to share their stories with whānau. Already, much strength and insight can be gained from understanding the Māori world-view of dementia and how whānau treasure elders with dementia.”