A new form of the traditional MRI (magnetic resonance imaging) technique can detect signs of cognitive decline before symptoms begin to appear. Researchers from the University of Geneva in Switzerland used arterial spin labeling (ASL), which has the potential to identify Alzheimer’s or dementia very early-on, leading to faster interventions and increased chances of preventing further cognitive decline.
ASL is a non-invasive MRI technique that uses arterial water as a tracer to measure cerebral blood flow (CBF) as well as perfusion. CBF is the blood supply that goes to the brain in a given amount of time, and it is known to correlate with brain function. Perfusion is the penetration of blood into the tissue. Low blood flow and perfusion in the brain would not provide the necessary nutrients to tissue, resulting in lower cognitive functioning.
The participants, including 148 healthy, older men and women, as well as 65 people with mild cognitive impairment (MCI), were given an array of tests, an MRI and a neuropsychiatric assessment to determine their cognitive abilities. At 18-months clinical follow-up, 75 of the 148 healthy participants remained stable. The other 73, who had shown reduced perfusion in their initial ASL MRI exams, showed cognitive decline in the follow-up. Interestingly, the area of the brain that saw reduced blood flow and perfusion was the same area of the brain that is typically affected in MCI and Alzheimer’s.
Why doesn’t reduced perfusion display symptoms right away? The answer is simple: cognitive reserve. When one area of brain function declines over time, other areas of the brain pick up the slack. However, cognitive reserve does not last forever, and eventually other brain areas can’t compensate for the weakened area, which is usually when symptoms appear. Engaging in a cognitively active lifestyle is important in building cognitive reserve and protecting against symptoms of cognitive disorders.
Although more research is needed before an ASL MRI can be used regularly to detect potential for Alzheimer’s and dementia, the promise is strong. ASL doesn’t require an injection of a radioactive contrast agent, while positron emission tomography (PET), the most commonly used brain metabolism imaging, does expose the patient to radiation. ASL is simple, readily available and relatively inexpensive, without the need for special equipment. It could be a convenient process to help prevent cognitive decline.
The University of Geneva researchers are already planning follow-up studies to learn more about the long-term cognitive changes and any other predictions made by ASL in the group of individuals they studied.