Diagnostic for Early Biomarker of Cognitive Decline

Arterial spin labeling (ASL), a promising magnetic resonance imaging (MRI) technique that doesn't require injection of a contrast agent, can detect signs of cognitive decline in the brain even before symptoms appear, say researchers from the University of Geneva in Switzerland. Sven Haller, MD, and colleagues studied 48 healthy elderly participants and 65 people with mild cognitive impairment (MCI). The participants underwent brain MRI and a neuropsychological assessment, a common battery of tests used to determine cognitive ability. At clinical follow-up 18-months later, of the 148 healthy individuals, 75 remained stable, while 73 deteriorated cognitively. Those who deteriorated had shown reduced perfusion at their baseline ASL MRI exams, particularly 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 seen in patients with mild cognitive impairment (MCI) and are more pronounced in those with Alzheimer's disease. "There is a known close link between neural activity and brain perfusion in the posterior cingulate cortex. Less perfusion indicates decreased neural activity," Dr. Haller said. "ASL MRI is simple to perform, doesn't require special equipment and only adds a few minutes to the exam." The results suggest that the technique has the potential to serve as a biomarker in very early diagnosis of preclinical dementia. Early detection of cognitive decline is vital, as treatments for Alzheimer's disease, the most common type of dementia, are most effective in this early phase.