Cognitive decline predicted by arterial spin labeling before symptoms appear

Arterial spin labeling (ASL), an MRI technique that doesn’t require contrast, may be able to depict early and subtle alterations in brain perfusion in cognitively normal older patients that can serve as a biomarker of preclinical dementia, according to a study published online in Radiology.

“Since MR imaging is part of the routine work-up of cognitive decline at many centers, ASL is a cost-efficient and operator-independent tool used to assess early cognitive decline, which simply prolongs an already existing assessment for a few minutes,” wrote lead author Aikaterini Xekardaki, MD, of the University of Geneva in Switzerland, and colleagues.

The study included 148 healthy elderly participants and 65 with mild cognitive impairment, all of whom underwent brain MRI and neuropsychological assessment.

Of the healthy participants, 73 were found to have deteriorated cognitively at 18-month follow-up. These participants’ baseline ASL MRI scans had shown reduced perfusion, particularly in the posterior cingulate cortex. This area is associated with the default mode network, and declines in this network are seen in patients with mild cognitive impairment and even more so in those with Alzheimer’s disease. The pattern of reduced perfusion in those who were healthy and then experienced cognitive decline was similar to that of the patient with mild cognitive impairment.

Problems in the brain related to dementia may be present for years, though cognitive reserve may compensate for the deficit, prolonging the onset of symptoms. The results of the current study suggest ASL MRI can spot the decreased perfusion in those who may be maintaining their cognitive status but are on the way to developing deficits.

The researchers noted that studies done with PET imaging in those with Alzheimer’s show reduced metabolism in same areas of the brain where ASL MRI picks up abnormalities, which both supports a link between metabolism and perfusion and suggests ASL can serve as an alternative to PET that doesn’t expose patients to radiation.

“ASL might replace the classic yet unspecific fluordesoxyglucose PET that measures brain metabolism. Instead, PET could be done with the new and specific amyloid PET tracers,” said senior author Sven Haller, MD, in a press release.