A 10-minute brain scan could detect dementia several years before people develop noticeable symptoms, a study suggests.
Scientists used a scan of ‘resting’ brain activity to determine whether people would develop dementia, with an estimated accuracy of 80% up to nine years before people received a diagnosis. If the findings were confirmed in a larger cohort, 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 develop symptoms of dementia,” said Prof. Charles Marshall, who led the research at Queen Mary University of London. “This could help us to identify these changes more accurately using an MRI scan that you could do on any NHS scanner.”
The research comes at a time when a new generation of Alzheimer’s drugs is on the way. The UK Medicines and Healthcare products Regulatory Agency (MHRA) is reviewing lecanemab, made by Eisai and Biogen, and donanemab, made by Eli Lilly, and both drugs are widely expected to be licensed this year.
“Predicting who will develop dementia in the future will be critical to developing treatments that can prevent the irreversible loss of brain cells that cause the symptoms of dementia,” Marshall said.
The researchers used functional MRI (fMRI) scans of 1,100 British 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 does not perform a 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 in the DMN that were most characteristic of those at risk, with the aim of being able to classify people as ‘at risk’ or healthy. The resulting model could 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 in brain connectivity have also been associated with known risk factors, including genetic risk of Alzheimer’s disease and social isolation.
The team said a simple brain scan, which would take about ten minutes, could be used alongside recently developed blood tests that target proteins in the brain that cause 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 required further research.
Walsh pointed out that of 100 people who developed dementia, the average time from scan to diagnosis was 3.7 years. Given the slow diagnosis times in the UK, some of these participants may already have had cognitive impairment 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 the scan and the onset of cognitive problems.” symptoms,” he said.
Dr. Richard Oakley, deputy director of research and innovation at the Alzheimer’s Society, 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 roll out early diagnostic scans, given the shortage of scanners and specialist staff to operate them. “We urgently need to invest in the NHS to improve the diagnosis of dementia,” Oakley said.