Mild cognitive impairment--difficulty with thinking, learning and memory--is increasingly recognized as a neurologic transition stage between normal cognitive function and Alzheimer's disease, according to background information in both articles. Older adults with mild cognitive impairment, especially those with a variety known as amnestic (memory-related) mild cognitive impairment, are thought to have a higher risk of progressing to clinical Alzheimer's disease. Little is known about how this condition affects the physical structures of the brain.
In the first study, Ronald C. Petersen, Ph.D., M.D., Mayo Clinic College of Medicine, Rochester, Minn., and colleagues compared the findings in autopsy tissue of brains of 15 individuals who at the time of their death had amnestic mild cognitive impairment (average age 88.9 years) to those of 28 individuals who were clinically healthy at the time of their death and 23 patients who were believed to have Alzheimer's disease at death and had undergone autopsy. The patients with mild cognitive impairment were examined every year before their death, which occurred between Sept. 1, 1986, and Dec. 31, 2004.
Most of the patients did not meet the requirements for a post-death diagnosis of Alzheimer's disease. However, the changes to their brains as compared to those of individuals without cognitive difficulties were more similar to those of patients with Alzheimer's disease. For instance, the patients had begun developing neurofibrillary tangles, or tangles in the cell bodies of neurons. The number of tangles correlated with the severity
Contact: Lisa Lucier
JAMA and Archives Journals