A report published Online First in Archives of Neurology, one of the JAMA/Archives journals, shows that under the revised criteria for diagnosing Alzheimer's disease, many patients who are currently diagnosed with very mild or mild Alzheimer disease dementia could potentially be reclassified as having mild cognitive impairment (MCI).
According to John C. Morris, M.D., of Washington University School of Medicine in St. Louis, the revised criteria for MCI that was decided during a work group convention of The National Institute on Aging and the Alzheimer's Association, offers "considerable latitude" regarding the definition of functional independence. For instance, 'mild problems' in terms of carrying out daily activities like shopping, paying bills and cooking are permitted, as well as depending on help or assistance to complete these tasks.
Researchers examined the functional rating from a total of 17,535 patients with normal cognition, MCI or AD dementia who met eligibility requirements and were aged 74.6 years on average, who were listed at federally funded Alzheimer's Disease Centers and whose clinical and cognitive data was maintained by the National Alzheimer's Coordinating Center.
According to the findings, under the revised criteria 99.8% of patients currently diagnosed with very mild AD dementia and 92.7% of those diagnosed with mild AD dementia could be reclassified as having MCI.
Morris declares that whilst the difference between MCI and AD dementia in its earliest symptomatic stages used to be largely based on whether cognitive impairment disrupts the activities of daily living, the new revised criteria "now obscures this distinction."
"The elimination of the functional boundary between MCI and AD dementia means that their distinction will be based solely on the individual judgment of clinicians, resulting in nonstandard and ultimately arbitrary diagnostic approaches to MCI. This recalibration of MCI moves its focus away from the earliest stages of cognitive decline, confounds clinical trials of individuals with MCI where progression to AD dementia is an outcome, and complicates diagnostic decisions and research comparisons with legacy data."
According to Morris, the revised criteria for MCI "laudably recommend" a diagnosis based on cause or origin of the condition, whilst "MCI due to AD" means that a physician makes the judgment that AD is responsible for an individual's cognitive dysfunction.
"The diagnostic overlap for MCI with milder cases of AD dementia is considerable and suggests that any distinction is artificial and arbitrary. Already, many individuals with MCI are treated with pharmacological agents approved for symptomatic AD, indicating that clinicians often do not distinguish the two conditions when faced with issues of medical management. It now is time to advance AD patient care and research by accepting that 'MCI due to AD' is more appropriately recognized as the earliest symptomatic stage of AD."
Written by Petra Rattue