Article

Mild Cognitive Impairment: Clinical Characterization and Outcome

Department of Neurology, Mayo Clinic, Rochester, Minn 55905, USA.
JAMA Neurology (Impact Factor: 7.42). 04/1999; 56(3):303-8. DOI: 10.1001/archneur.56.6.760
Source: PubMed

ABSTRACT

Subjects with a mild cognitive impairment (MCI) have a memory impairment beyond that expected for age and education yet are not demented. These subjects are becoming the focus of many prediction studies and early intervention trials.
To characterize clinically subjects with MCI cross-sectionally and longitudinally.
A prospective, longitudinal inception cohort.
General community clinic.
A sample of 76 consecutively evaluated subjects with MCI were compared with 234 healthy control subjects and 106 patients with mild Alzheimer disease (AD), all from a community setting as part of the Mayo Clinic Alzheimer's Disease Center/Alzheimer's Disease Patient Registry, Rochester, Minn.
The 3 groups of individuals were compared on demographic factors and measures of cognitive function including the Mini-Mental State Examination, Wechsler Adult Intelligence Scale-Revised, Wechsler Memory Scale-Revised, Dementia Rating Scale, Free and Cued Selective Reminding Test, and Auditory Verbal Learning Test. Clinical classifications of dementia and AD were determined according to the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition and the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria, respectively.
The primary distinction between control subjects and subjects with MCI was in the area of memory, while other cognitive functions were comparable. However, when the subjects with MCI were compared with the patients with very mild AD, memory performance was similar, but patients with AD were more impaired in other cognitive domains as well. Longitudinal performance demonstrated that the subjects with MCI declined at a rate greater than that of the controls but less rapidly than the patients with mild AD.
Patients who meet the criteria for MCI can be differentiated from healthy control subjects and those with very mild AD. They appear to constitute a clinical entity that can be characterized for treatment interventions.

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    • "As previously discussed, MCI was originally referred to as the transition between normal cognitive function and clinically probable AD, which gained widespread use after the introduction of the Mayo criteria for amnestic MCI in 1991[14]. However, as research on MCI progressed, it had become apparent that MCI is not just a " pre-clinical " state of AD and may not be associated with the development of dementing illness[15]. "
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    ABSTRACT: As the population of the world increases, there will be larger numbers of people with dementia and an emerging need for prompt diagnosis and treatment. Early dementia screening is the process by which a patient who might be in the prodromal phases of a dementing illness is determined as having, or not having, the hallmarks of a neurodegenerative condition. The concepts of mild cognitive impairment, or mild neurocognitive disorder, are useful in analyzing the patient in the prodromal phase of a dementing disease; however, the transformation to dementia may be as low as 10% per annum. The search for early dementia requires a comprehensive clinical evaluation, cognitive assessment, determination of functional status, corroborative history and imaging (including MRI, FDG-PET and maybe amyloid PET), cerebrospinal fluid (CSF) examination assaying Aβ1-42, T-τ and P-τ might also be helpful. Primary care physicians are fundamental in the screening process and are vital in initiating specialist investigation and treatment. Early dementia screening is especially important in an age where there is a search for disease modifying therapies, where there is mounting evidence that treatment, if given early, might influence the natural history-hence the need for cost-effective screening measures for early dementia.
    Preview · Article · Jan 2016
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    • "Several definitions of MCI have been proposed since the 1960s and many terms have been adopted in the literature to describe MCI (Kral, 1962; Reisberg et al., 1982; Flicker et al., 1991; Levy, 1994; Ebly et al., 1995). In 1999, Petersen et al. (1999) investigated MCI as a prodromal condition for Alzheimer's disease (AD), highlighting the importance of memory complaints in incipient AD in nondemented subjects. Subsequent work enlarged the definition of MCI to include other forms of cognitive impairment that cover a range of clinical phenotypes (Winblad et al., 2004). "
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    ABSTRACT: Introduction: To investigate cortical excitability and synaptic plasticity in amnestic mild cognitive impairment (aMCI) using 5 Hz repetitive transcranial magnetic stimulation (5 Hz-rTMS) and to assess whether specific TMS parameters predict conversion time to Alzheimer's disease (AD). Materials and methods: Forty aMCI patients (single- and multi-domain) and 20 healthy controls underwent, at baseline, a neuropsychological examination and 5 Hz-rTMS delivered in trains of 10 stimuli and 120% of resting motor threshold (rMT) intensity over the dominant motor area. The rMT and the ratio between amplitude of the 1st and the 10th motor-evoked potential elicited by the train (X/I-MEP ratio) were calculated as measures of cortical excitability and synaptic plasticity, respectively. Patients were followed up annually over a period of 48 months. Analysis of variance for repeated measures was used to compare TMS parameters in patients with those in controls. Spearman's correlation was performed by considering demographic variables, aMCI subtype, neuropsychological test scores, TMS parameters, and conversion time. Results: Thirty-five aMCI subjects completed the study; 60% of these converted to AD. The baseline rMT and X/I-MEP ratio were significantly lower in patients than in controls (p = 0.04 and p = 0.01). Spearman's analysis showed that conversion time correlated with the rMT (0.40) and X/I-MEP ratio (0.51). Discussion: aMCI patients displayed cortical hyperexcitability and altered synaptic plasticity to 5 Hz-rTMS when compared with healthy subjects. The extent of these changes correlated with conversion time. These alterations, which have previously been observed in AD, are thus present in the early stages of disease and may be considered as potential neurophysiological markers of conversion from aMCI to AD.
    Preview · Article · Jan 2016 · Frontiers in Aging Neuroscience
    • "MCI is defined as a condition of objective cognitive impairment greater than expected for age, but insufficient to warrant a diagnosis of early dementia, with subjective memory complaints preferably corroborated by an informant (Petersen, 2005). The initial diagnostic criteria for MCI specified generally intact everyday functioning (Petersen et al., 1999). Functional abilities refer to a range of self-initiated, multidimensional, everyday skills and activities necessary for independent daily living within the home and community (Gomar, Harvey, Bobes-Bascaran, Davies, & Goldberg, 2011). "
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    ABSTRACT: The objective of this meta-analysis was to improve understanding of the heterogeneity in the relationship between cognition and functional status in individuals with mild cognitive impairment (MCI). Demographic, clinical, and methodological moderators were examined. Cognition explained an average of 23% of the variance in functional outcomes. Executive function measures explained the largest amount of variance (37%), whereas global cognitive status and processing speed measures explained the least (20%). Short- and long-delayed memory measures accounted for more variance (35% and 31%) than immediate memory measures (18%), and the relationship between cognition and functional outcomes was stronger when assessed with informant-report (28%) compared with self-report (21%). Demographics, sample characteristics, and type of everyday functioning measures (i.e., questionnaire, performance-based) explained relatively little variance compared with cognition. Executive functioning, particularly measured by Trails B, was a strong predictor of everyday functioning in individuals with MCI. A large proportion of variance remained unexplained by cognition.
    No preview · Article · Jan 2016 · Archives of Clinical Neuropsychology
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