Search

Background: In Alzheimer's disease, neurodegenerative atrophy progresses from the entorhinal cortex (ERC) to the hippocampus (HP), limbic system and neocortex. The significance of very mild atrophy of the ERC and HP on MRI scans among elderly subjects is unknown., Methods: A validated visual rating system on coronal MRI scans was used to identify no atrophy of the HP or ERC (HP(0); ERC(0)), or minimal atrophy of the HP or ERC (HP(ma); ERC(ma)), among 414 participants. Subjects fell into the following groups: (1) ERC(0)/HP(0), (2) ERC(ma)/HP(0), (3) ERC(0)/HP(ma), and (4) ERC(ma)/HP(ma). HP volume was independently measured using volumetric methods., Results: In comparison to ERC(0)/HP(0) subjects, those with ERC(0)/HP(ma) had impairment on 1 memory test, ERC(ma)/HP(0) subjects had impairment on 2 memory tests and the Mini Mental State Examination (MMSE), while ERC(ma)/HP(ma) subjects had impairment on 3 memory tests, the MMSE and Clinical Dementia Rating. Progression rates of cognitive and functional impairment were significantly greater among subjects with ERC(ma)., Conclusion: Minimal atrophy of the ERC results in greater impairment than minimal atrophy of the HP, and the combination is additive when measured by cognitive and functional tests. Rates of progression to greater impairment were higher among ERC(ma) subjects., (Copyright © 2011 S. Karger AG, Basel.)

Background/aims: To investigate the longitudinal stability and progression of different subtypes of mild cognitive impairment (MCI) in older adults., Methods: We classified 217 individuals with no cognitive impairment (NCI), amnestic MCI (aMCI) based on a single test (aMCI-1) or multiple tests (aMCI-2+), nonamnestic MCI (naMCI) based on a single test (naMCI-1) or multiple tests (naMCI-2+), or amnestic + nonamnestic MCI (a+naMCI), using their baseline neuropsychological test scores, and performed annual follow-up evaluations for up to 3 years., Results: None of the subjects with aMCI-2+ reverted to normal during follow-up, with 50% of these subjects remaining stable and 50% worsening over time. Similarly, less than 20% of subjects with aMCI-2+ and a+naMCI reverted to NCI during the follow-up period, whereas 50% of aMCI-1 and 37% with naMCI-1 reverted to NCI during this same period., Conclusion: Reversion to NCI occurs much more frequently when the diagnosis of MCI is based on the results of a single neuropsychological test than when it is based on the results of more memory tests. In epidemiological studies and clinical trials the diagnosis of MCI will likely be more stable if impairment on more than one test is required for amnestic and/or nonamnestic domains.

There is evidence that vulnerability to proactive semantic interference may be an early manifestation of early Alzheimer's disease and other neurodegenerative disorders. At present, there is a paucity of data regarding the extent to which such deficits relate to the progression of cognitive deficits and to clinically significant endpoints such as dementia. In this study, we followed 76 older adults, initially diagnosed with mild cognitive impairment, for a period of up to 3 years. Twenty-seven of these individuals (35.5%) progressed from mild cognitive impairment to dementia. An examination of baseline neuropsychological performance indicated lower baseline scores for object memory among those progressing to dementia. However, baseline Mini-Mental State Examination scores, delayed memory for passages, delayed visual memory, letter fluency, category fluency, Trails B and Block Design did not differ among study groups. In contrast, the Semantic Interference Test, a measure susceptible to vulnerability to proactive semantic interference showed the greatest baseline differentiation between those who progressed and those who did not progress to dementia. Further, scores on this measure predicted future progression to dementia with high accuracy. Vulnerability to proactive interference may be an early manifestation of an early dementing process and may have utility in predicting future progression to dementia., (Copyright (c) 2007 S. Karger AG, Basel.)

There has been increasing interest in delineating different cognitive subtypes of mild cognitive impairment (MCI). It remains unclear, however, the extent to which neuropsychological impairment associated with amnestic, nonamnestic, and amnestic+ subtypes of MCI remains stable over time. In this study, 70 persons meeting the criteria for MCI and 38 cognitively normal elderly subjects received a baseline neuropsychological evaluation and were reevaluated 1 year later. Our results indicated that 84.6% of the persons initially classified as amnestic, 75% of those classified as nonamnestic, and 80% of the persons classified as MCI+ evidenced stable or more pronounced neuropsychological impairment across the follow-up period. Less than 7% of the amnestic and amnestic+ cases had nonimpaired neuropsychological profiles at their reevaluation at 12 months, and 16.7% of the nonamnestic cases had nonimpaired neuropsychological test profiles at follow-up. Approximately 87% of the cognitively normal subjects at baseline continued to have unimpaired neuropsychological performance at follow-up. These results indicate that the presence of neuropsychological impairment is relatively stable over a 12-month follow-up period among different cognitive subtypes of MCI, although 15-25% of the cases did not exhibit the specific cognitive deficits that characterized their performance at baseline., (Copyright (c) 2007 S. Karger AG, Basel.)

There has been increasing interest in determining whether amnestic, nonamnestic and multiple-domain subtypes of mild cognitive impairment (MCI) reflect different disease etiologies. In this study, we examined the extent to which cognitive profiles of nondemented patients with MCI diagnosed with prodromal Alzheimer's disease (AD) differed from those MCI patients diagnosed with vascular disease. We also compared these diagnostic groups to mildly demented patients diagnosed with AD and normal elderly controls. Results indicate that a majority of both MCI-AD and MCI-vascular patients experienced amnestic features and that multiple-domain was the most common presentation. MCI-AD and MCI-vascular groups did not differ on neuropsychological measures tapping memory, language, visuospatial skills/praxis or executive function. Further both MCI groups could be distinguished from dementia patients with regards to performance on measures of memory but not on non-memory measures. Considerable variability was observed in the degree of memory impairment among MCI patients with scores as much as 6 standard deviations below expected mean values. MCI-AD and MCI-vascular patients frequently exhibit both common and overlapping amnestic and nonamnestic features. The implication of these findings for future clinical research is discussed., (Copyright (c) 2006 S. Karger AG, Basel.)