May 10, 2007
Brain scans of people with mild cognitive impairment (MCI), a form of memory loss that sometimes progresses to Alzheimer's disease, show brain defects similar to those of early Alzheimer's disease. The findings offer hope that brain defects that lead to Alzheimer's may one day be identified at a very early stage, when medicines to treat Alzheimer's may be most effective. The findings were published in Neurology, the scientific journal of the American Academy of Neurology.
In the study, doctors performed PET scans, a form of advanced brain imaging, on the brains of 13 elderly men and women with mild cognitive impairment (MCI). These were compared with PET scans from 14 elderly people with healthy memories. The scans were used to measure uptake of PIB, which is an imaging agent that allows doctors to see abnormal protein inside the brain. The technique can be used to measure the accumulation of abnormal proteins, or beta-amyloid plaque, in the brain. The buildup of such plaque is a hallmark of Alzheimer's disease.
The study found that people with mild cognitive impairment had as much as 39 percent more PIB uptake in parts of the brain than people without MCI. What's more, about half of the seniors with MCI had PIB uptake patterns similar to those in people with Alzheimer's disease.
"This pattern of increased PIB in patients with MCI resembles what's seen in Alzheimer's disease and is suggestive of an early Alzheimer's disease process," said study author Juha O. Rinne, MD, PhD, with the University of Turku in Finland. "Our findings are similar to what's seen in post-mortem studies in which abnormal protein aggregation deposits are found in people who had been diagnosed with probable Alzheimer's disease."
Rinne says larger studies and extended follow-up is needed, since identifying people with mild cognitive impairment who have abnormal protein aggregation deposits could provide clues as to who will ultimately develop Alzheimer's disease. New medicines, currently under development, may be most effective at the earliest stages of Alzheimer's disease, before damage to the memory and other cognitive centers of the brain become extensive.
The study adds to a growing body of research that aims to diagnose Alzheimer's disease at an early stage, in some cases even before memory loss and other troubling symptoms impair quality of life. Currently, Alzheimer's disease is diagnosed definitively only after a person dies, when an autopsy can be performed.
The Fisher Center for Alzheimer's Research Foundation continues to fund critical research into the underlying causes and disease processes that underlie Alzheimer's, an ailment that afflicts more than five million Americans. To learn more, visit www.ALZinfo.org.
N.M. Kemppainen, MD, Phd; S. Aaalto, MSc; I.A. Wilson, PHD, et al: "PET amyloid ligand [11C]PIB uptake is increased in mild cognitive impairment." Neurology, May 8, 2007, Volume 68, pages 1603-1606. American Academy of Neurology.