Among individuals with mild cognitive impairment, often considered a transitional state between normal cognitive function and Alzheimer's dementia, those who have more difficulties performing routine activities appear more likely to progress quickly to dementia, according to a report in the September issue of Archives of Neurology, one of the JAMA/Archives journals.
Mild cognitive impairment is recognized as a risk factor for dementia and an important public health issue, according to background information in the article. "Annual conversion rates [from mild cognitive impairment to dementia] often range from 10 percent to 15 percent in clinic samples. Conversion rates in community-based studies are often substantially lower (i.e., 3.8 percent to 6.3 percent per year)," the authors write. "Clearly patients with mild cognitive impairment compose a heterogeneous group, of whom not all rapidly convert to dementia. As such, it is important to identify risk factors for progressing rapidly among individuals diagnosed with mild cognitive impairment."
Sarah Tomaszewski Farias, Ph.D., of the University of California, Davis, and colleagues studied 111 individuals with mild cognitive impairment. Of these, 46 percent (51) were recruited from patients referred to a university-based memory disorders clinic on suspicion of cognitive decline, and 54 percent (60) were recruited directly through community outreach. All participants underwent annual clinical evaluations, diagnostic imaging, routine laboratory tests and neuropsychological evaluations.
During an average of 2.4 years of follow-up, 28 individuals progressed from mild cognitive impairment to dementia, including 23 from the clinic and five from the community. Annually, 13 percent of the clinic-based group and 3 percent of the community group converted into dementia.
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