A 10-minute brain scan can detect dementia several years before people develop noticeable symptoms, a study suggests.
Scientists used a scan of “resting” brain activity to identify whether people went on to develop dementia, with an estimated 80% accuracy up to nine years before people received a diagnosis. If the findings are confirmed in a larger group, the scan could become a routine procedure in memory clinics, scientists said.
“We have known for a long time that the function of the brain starts to change many years before you get dementia symptoms,” says Prof Charles Marshall, who led the work at Queen Mary University of London. “This can help us be more precise in identifying those changes using an MRI scan which you can do on any NHS scanner.”
The research comes as a new generation of Alzheimer’s drugs is on the horizon. The United Kingdom’s Medicines and Healthcare Products Regulatory Agency (MHRA) is assessing lecanemab, made by Eisai and Biogen, and donanemab, made by Eli Lilly, and both drugs are expected to be licensed this year.
“Predicting who will develop dementia in the future will be essential to developing treatments that can prevent the irreversible loss of brain cells that causes the symptoms of dementia,” Marshall said.
The researchers used functional MRI (fMRI) scans of 1,100 UK Biobank volunteers to detect changes in the brain’s “default mode network” (DMN). The scan measures correlations in brain activity between different regions while the volunteer lies still and performs no specific task. The network, which reflects how effectively different regions communicate with each other, is known to be particularly vulnerable to Alzheimer’s disease.
Of the volunteers, 81 developed dementia after the UK Biobank scan. The researchers used AI algorithms to identify changes to the DMN that were most characteristic of those at risk with the goal of being able to classify people as “at risk” or healthy. The resulting model can identify those at risk with 80% accuracy up to nine years before diagnosis, according to the study published in Nature Mental Health.
In the cases where the volunteers developed dementia, the team was able to predict within a margin of error of two years exactly how long it would take for that diagnosis to be made. Changes to brain connectivity have also been associated with known risk factors, including the genetic risk for Alzheimer’s disease and social isolation.
The team said a simple brain scan, which would take about 10 minutes, could be used alongside recently developed blood tests that target proteins in the brain which causes Alzheimer’s disease.
Dr Sebastian Walsh, who studies public health approaches to dementia prevention at the University of Cambridge, said the results were “potentially exciting”, but added that several factors needed further investigation.
Walsh pointed out that of the 100 people who developed dementia, the average time between scan and diagnosis was 3.7 years. Given the slow diagnostic times in the UK, some of these participants may already have had cognitive impairments at the time of the scan. “Before we can be truly confident that this technology can predict the onset of dementia rather than just being an early indicator that it is present, it will be very important to see these findings demonstrated in larger samples with ‘ a much longer delay between scan and onset of cognitive symptoms,” he said.
Dr Richard Oakley, an associate director of research and innovation at the Alzheimer’s Association, said the new technique could pave the way for early and accurate diagnosis of dementia. But, he added, the NHS does not yet have the capacity to carry out early diagnostic scans, given the shortage of scanners and specialized staff to operate them. “We need to see urgent investment in the NHS to improve dementia diagnosis,” Oakley said.
