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A new method for predicting dementia has over 80% accuracy and works up to nine years before a diagnosis. Researchers at Queen Mary University of London report. They say the new method provides a more accurate way to predict dementia than memory tests or measurements of brain shrinkage, two commonly used methods for diagnosing this condition. It’s estimated that over 55 million people suffer from dementia worldwide. Early, accurate diagnosis has long been a challenge.

“Predicting who is going to get dementia in the future will be vital for developing treatments that can prevent the irreversible loss of brain cells that causes the symptoms of dementia,” said Charles Marshall, Professor and Honorary Consultant Neurologist, who led the research team within the Centre for Preventive Neurology at Queen Mary’s Wolfson Institute of Population Health. 

Their work appears in Nature Mental Health today. The first author is Sam Ereira, of Queen Mary’s Center for Preventive Neurology.

The team developed the test by analyzing functional MRI (fMRI) scans for changes in the brain’s “default mode network (DMN).” The DMN connects regions of the brain to perform specific cognitive functions and is the first neural network to be affected by Alzheimer’s disease. 

They had fMRI scans from over 1,100 volunteers from the UK Biobank, a large-scale biomedical database and research resource containing genetic and health information from half a million U.K. participants, to estimate the effective connectivity between ten regions of the brain that constitute the default mode network. 

The researchers assigned each patient with a “probability of dementia value” based on the extent to which their effective connectivity pattern conforms to a pattern indicating dementia. They compared these predictions to the medical data of each patient, on record with the UK Biobank. 

They found the model accurately predicted onset of dementia up to nine years before an official diagnosis was made, and with greater than 80% accuracy. Where participants went on to develop dementia, the model could also predict, within a two-year margin of error, how long it would take that diagnosis to be made. 

The researchers also examined whether changes to the DMN might be caused by known risk factors for dementia. They found that genetic risk for Alzheimer’s disease was strongly associated with connectivity changes in the DMN, supporting the idea that these changes are specific to Alzheimer’s disease. They also found that social isolation was likely to increase risk of dementia through its effect on connectivity in the DMN. 

“Although we are getting better at detecting the proteins in the brain that can cause Alzheimer’s disease, many people live for decades with these proteins in their brain without developing symptoms of dementia. We hope that the measure of brain function that we have developed will allow us to be much more precise about whether someone is actually going to develop dementia, and how soon, so that we can identify whether they might benefit from future treatments,” said Marshall.

“Enormous potential exists to apply these methods to different brain networks and populations, to help us better understand the interplays between environment, neurobiology and illness, both in dementia and possibly other neurodegenerative diseases,” said Ereira, academic foundation program doctor at the Center for Preventive Neurology, Wolfson Institute of Population Health. “fMRI is a non-invasive medical imaging tool, and it takes about six minutes to collect the necessary data on an MRI scanner, so it could be integrated into existing diagnostic pathways, particularly where MRI is already used.”

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