From Washington University School of Medicine
Mild cognitive impairment appears to be Alzheimer’s disease
St. Louis, March 14, 2001 — Researchers at Washington University School of Medicine in St. Louis have found that most of the people diagnosed with mild cognitive impairment (MCI) by the school’s Memory and Aging Project (MAP) develop Alzheimer’s disease in the following years. The results suggest that MCI, characterized by minor memory loss, is an early stage of Alzheimer’s disease rather than a separate disorder.
"We were surprised to find that an unexplained memory deficit that is currently called MCI almost always turns out to be early Alzheimer’s," says John C. Morris, M.D.
Morris is the Harvey A. and Dorismae Hacker Friedman Professor of Neurology, director of MAP and co-director of the Alzheimer’s Disease Research Center. He is first author of the paper, which appears in the March issue of Archives of Neurology.
The researchers examined 404 people who had either mild memory loss or no memory problems and who volunteered for annual memory assessments at MAP between July 1990 and June 1997. The 227 individuals with MCI were placed into one of three categories: fairly confident, suspicious and uncertain. The categories reflected the researchers’ degree of confidence that the subtle signs of memory loss might indicate the onset of Alzheimer’s disease.
The volunteers were reassessed annually for up to 9.5 years. After five years, Alzheimer symptoms had developed in 6.8 percent of the healthy volunteers, 19.9 percent of the individuals in the uncertain MCI group, 35.7 percent of those in the suspicious group and 60.5 percent of those in the fairly confident group. By 9.5 years, all the volunteers with the most severe form of MCI had developed the clinical symptoms of Alzheimer’s.
Forty-two participants died before the end of the study and donated their brains for postmortem analysis, the only way to diagnose Alzheimer’s disease with 100 percent accuracy. Autopsy of 25 volunteers who originally were diagnosed with MCI confirmed that 21 had Alzheimer’s disease.
Morris points out that these results are based on a select group of individuals who volunteered for memory research. "Even with that caveat, the findings are impressive," he says. "Any change from normal is, apparently, suspicious. Once physicians recognize this, they will begin to diagnose Alzheimer’s disease much earlier than they do now."
Earlier diagnosis, Morris explains, will reveal that more people suffer from the disease than the current estimate of 4 million Americans. It also will help scientists develop more effective therapies for early intervention.
Morris JC, Storandt M, Miller JP, McKeel DW, Price JL, Rubin EH, Berg L. Mild cognitive impairment represents early-stage Alzheimer’s disease. Archives of Neurology, 58, 392-397, March 14, 2001.
Funding from the National Institute on Aging supported this research.
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