A five-minute brain scan has been developed that could detect early signs of dementia.
The researchers used arterial spin labeling (ASL), a technique that measures brain perfusion, or penetration of blood into the tissue.
Detecting the signs of the disease early is important because treatments for Alzheimer's disease, the most common type of dementia, are most effective in this phase.
The study's participants included 148 healthy elderly participants and 65 people with mild cognitive impairment (MCI).
Brain magnetic resonance imaging (MRI) and a neuropsychological assessment were performed on the subjects - a common battery of tests used to determine cognitive ability.
It was discovered that individuals who had deteriorated by the time of an 18 month clinical follow-up had shown reduced perfusion at their baseline ASL MRI exams.
This decline was particularly noticeable in the posterior cingulate cortex - an area in the middle of the brain that is associated with the default mode network, the neural network that is active when the brain is not concentrating on a specific task.
Declines in this network are common in MCI patients and are more pronounced in those with Alzheimer's disease.
The researchers found that the pattern of reduced perfusion in the brains of healthy individuals who went on to develop cognitive deficits was similar to that of patients with MCI.
"There is a known close link between neural activity and brain perfusion in the posterior cingulate cortex," Dr Haller said. "Less perfusion indicates decreased neural activity."
Mobilising cognitive reserves could be one way in which people with decreased perfusion detected with ASL MRI could temporarily maintain their cognitive status. However, they will eventually develop subtle cognitive defects.
ASL MRI could be used as a standalone test or combined with another technique known as positron emission tomography, which reduced metabolism in the same area of the brain where the perfusion abnormalities were found.
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