Conversion to Dementia among Two Groups with Cognitive Impairment
A Preliminary ReportLuis C.A. · Barker W.W. · Loewenstein D.A. · Crum T.A. · Rogaeva E. · Kawarai T. · St. George-Hyslop P. · Duara R.
aWien Center for Alzheimer’s Disease and Memory Disorders, Mount Sinai Medical Center, Departments of bPsychiatry and Behavioral Sciences and cMedicine, University of Miami School of Medicine, Miami, Fla., USA; dDepartment of Medicine and Physiology, Center for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Canada
Objective: To determine the conversion rates to dementia in patients diagnosed with mild cognitive impairment (MCI) thought to be caused by incipient Alzheimer’s disease (MCI-AD) or with MCI with features of vascular disease (MCI-Vas). Methods: On the basis of patient history, neurocognitive, neurological and MRI evaluation, 99 patients were diagnosed with MCI-AD and 35 with MCI-Vas. Conversion to dementia over an average of a 2.4 ± 1.8-year period was determined. Results: Over the follow-up period, 44% converted to dementia, 51.5% remained classified as MCI, and 4.5% were reclassified as cognitively normal. The conversion rate to dementia was significantly faster at 3 years for the MCI-AD (50.5%) than for the MCI-Vas group (25.7%). The neuropsychological test found to best differentiate converters from non-converters was the Fuld-OME, a measure of learning and recall. Age, education, gender or APOE ε4 allele frequency did not differentiate converters from non-converters. Conclusions: MCI-AD and MCI-Vas are clinically meaningful subtypes of MCI that may convert to dementia at different rates. Prospective studies on larger subsets of MCI patients are required to confirm these findings.