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Longitudinal analysis of abnormal domains comprising mild cognitive impairment (MCI) during aging
John Meyer1, Gelin Xu, John Thornby
1Department of Neurology, Baylor College of Medicine, Houston, TX, USA. jmeyer@bcm.tm.edu
Abstract:
Research directed towards early diagnosis and therapy of dementia demands rapid identification of prodromal mild cognitive impairment (MCI). A longitudinal study was designed to clarify whether different domains of cognitive impairment, tested by Mini-Mental State Examination (MMSE), help predict dementia. After 3.74+/-2.94 years of follow-up among 291 cognitively normative volunteers, 73 developed MCI. During the next 3.88+/-3.01 years of MCI follow-up, 47.9% of MCI developed dementia of Alzheimer's type (DAT), 20.5% of MCI developed vascular dementia (VaD) and 31.5% maintained persistent MCI at the time of data analysis. Total MMSE and subtest scores analyzed at MCI onset showed significant differences for serial seven subtest scores between DAT and persistent MCI (P<0.05). Rates of change in subtests of orientation and memory and total MMSE scores predicted DAT (P<0.01). Decreasing orientation and total MMSE scores predicted VaD conversion rates of MCI to DAT at 2 years were 20.06% among single-domain MCI versus 41.7% for multi-domain MCI (P<0.05). Subjects with MCI often have impaired cognitive domains other than memory and show rapid deterioration, which predicts DAT. VaD sometimes mimics DAT with subtle cognitive impairment appearing before onset of dementia.
Insights
Identifying mild cognitive impairment (MCI) early is crucial for dementia therapy. Cognitive domain changes, particularly in orientation and memory, predict Alzheimer's type dementia (DAT) and vascular dementia (VaD) progression.
Area of Science:
- Neurology
- Cognitive Science
- Geriatrics
Background:
- Early identification of prodromal mild cognitive impairment (MCI) is essential for dementia diagnosis and therapy.
- The Mini-Mental State Examination (MMSE) is a common tool for assessing cognitive function.
- Understanding cognitive changes in MCI can help predict the development of different dementia types.
Purpose of the Study:
- To determine if different cognitive impairment domains, assessed by MMSE, can predict dementia development.
- To analyze the predictive value of cognitive domain changes for Alzheimer's type dementia (DAT) and vascular dementia (VaD).
- To compare the progression rates from MCI to DAT based on the number of affected cognitive domains.
Main Methods:
- A longitudinal study followed 291 cognitively normative volunteers.
- Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and its subtests.
- Participants were monitored for the development of MCI, DAT, VaD, or persistent MCI over several years.
Main Results:
- Of 73 participants who developed MCI, 47.9% progressed to DAT, 20.5% to VaD, and 31.5% maintained persistent MCI.
- Differences in serial seven subtest scores were significant between DAT and persistent MCI groups.
- Rates of change in orientation, memory, and total MMSE scores predicted DAT; decreasing scores predicted VaD.
- Two-year conversion rates to DAT were higher for multi-domain MCI (41.7%) compared to single-domain MCI (20.06%).
Conclusions:
- Impaired cognitive domains beyond memory in MCI, coupled with rapid deterioration, predict Alzheimer's type dementia (DAT).
- Vascular dementia (VaD) can present with subtle cognitive impairments mimicking DAT.
- Multi-domain cognitive impairment in MCI is associated with a significantly higher risk of progressing to DAT.