Amnestic mild cognitive impairment (MCI) has been defined as a precursor to Alzheimer's disease (AD), although it is sometimes difficult to identify which persons with MCI will eventually convert to AD. We sought to predict MCI conversion to AD over a two-year follow-up period using baseline demographic and neuropsychological test data from 49 MCI patients. Using a stepwise discriminant function analysis with Dementia Rating Scale (DRS) Initiation/Perseveration and Wechsler Memory Scale, third edition (WMS-III) Visual Reproduction Percent Retention scores, we correctly classified 85.7% of the sample as either AD converters or MCI nonconverters, with 76.9% sensitivity and 88.9% specificity. Adding race, the presence of vascular risk factors, or cholinesterase inhibitor use to the analysis did not greatly change the classification rates obtained with neuropsychological test data. Examining neuropsychological test cutoff scores revealed that DRS Initiation/Perseveration scores below 37 and Visual Reproduction Percent Retention scores below 26% correctly identified AD converters with 76.9% sensitivity and 91.7% specificity. These results demonstrate that commonly administered neuropsychological tests identify persons with MCI at baseline who are at risk for conversion to AD within 1-2 years. Such methods could aid in identifying MCI patients who might benefit from early treatment, in providing prognostic information to patients, and identifying potential clinical trial participants.
"There is also a need to develop valid screening tools that can (1) discriminate between unimpaired individuals and those with MCI and (2) identify those individuals with MCI who are most likely to progress to AD (Feldman et al., 2004). The capacity to accurately determine which individuals with MCI will go on to develop AD from those who will not offers the benefit of allowing the commencement of pharmacological, behavioral, and cognitive therapies at the earliest stages of disease progression, thereby maximizing the potential of slowing disease progression (Griffith et al., 2006). While variation in the rate of conversion to dementia raises questions about the utility of the MCI classification as an indicator of impending dementia, perhaps more striking are reports that a sizable proportion of those classified with MCI fail to demonstrate cognitive impairment at subsequent assessment. "
[Show abstract][Hide abstract] ABSTRACT: Studies of Mild Cognitive Impairment (MCI) show elevated rates of conversion to dementia at the group level. However, previous studies of the trajectory of MCI identify great heterogeneity of outcomes, with a significant proportion of individuals with MCI remaining stable over time, changing MCI subtype classification, or reverting to a normal cognitive state at long-term follow-up.
The present study examined individual outcomes at 20 months in a group of older adults classified according to MCI subtypes. A total of 106 participants, 81 with different subtypes of MCI and 25 healthy controls, undertook longitudinal neuropsychological assessment of visual and verbal memory, attentional processing, executive functions, working memory capacity, and semantic memory.
At 20 months 12.3% of the MCI group progressed to dementia, 62.9% continued to meet MCI criteria, and 24.7% reverted to unimpaired levels of function. A discriminant function analysis predicted outcome at 20 months on the basis of baseline neuropsychological test performance with 86.3% accuracy. The analysis indicated that a pattern of impairments on visual episodic memory, verbal episodic memory, short-term memory, working memory, and attentional processing differentiated between participants who developed dementia, recovered from MCI, or remained in stable MCI.
The results of the present study raise questions regarding the specificity of existing criteria for the subtypes of MCI, with these results indicating a high degree of instability in classification over time. In addition, the results suggest that multidomain MCI is the most reliable precursor stage to the development of AD.
"Shiri-Feshki, 2009; Petersen et al., 1999) and are particularly prone to develop Alzheimer's disease (AD) (Fischer et al., 2007; Griffith et al., 2006; Guarch, Marcos, Salamero, Gasto, & Blesa, 2007; Winblad et al., 2004). As a result, efforts have focused on identifying and characterizing individuals with aMCI early in their course in the hope of developing interventions that will prevent the progression to AD. "
[Show abstract][Hide abstract] ABSTRACT: Individuals with amnestic mild cognitive impairment (aMCI) show deficits on traditional episodic memory tasks and reductions in speed of performance on reaction time tasks. We present results on a novel task, the Cued-Recall Retrieval Speed Task (CRRST), designed to simultaneously measure level and speed of retrieval. A total of 390 older adults (mean age, 80.2 years), learned 16 words based on corresponding categorical cues. In the retrieval phase, we measured accuracy (% correct) and retrieval speed/reaction time (RT; time from cue presentation to voice onset of a correct response) across 6 trials. Compared to healthy elderly adults (HEA, n = 303), those with aMCI (n = 87) exhibited poorer performance in retrieval speed (difference = -0.13; p < .0001) and accuracy on the first trial (difference = -0.19; p < .0001), and their rate of improvement in retrieval speed was slower over subsequent trials. Those with aMCI also had greater within-person variability in processing speed (variance ratio = 1.22; p = .0098) and greater between-person variability in accuracy (variance ratio = 2.08; p = .0001) relative to HEA. Results are discussed in relation to the possibility that computer-based measures of cued-learning and processing speed variability may facilitate early detection of dementia in at-risk older adults.
Journal of the International Neuropsychological Society 03/2012; 18(2):260-8. DOI:10.1017/S1355617711001664 · 2.96 Impact Factor
"). The DRS-2 is a global cognitive scale known to discriminate adequately between patients with dementia and those without, and this instrument is also very sensitive to AD (Griffith et al., 2006; Matteau, Simard, Jean, & Turgeon, 2008; Meiran, Stuss, Guzman, Lafleche, & Willmer, 1996; Shay et al., 1991; Stuss, Meiran, Guzman, Lafleche, & Willmer, 1996). Moreover, a controlled study performed in our laboratory (Matteau et al., 2008) recently showed that MCI-A individuals score significantly lower than controls on the DRS Initiation/Perseveration and Memory subscales. "
[Show abstract][Hide abstract] ABSTRACT: This study aimed to determine the efficacy of cognitive training in a 10-week randomised controlled study involving 22 individuals presenting with mild cognitive impairment of the amnestic type (MCI-A). Participants in the experimental group (n = 11) learned face-name associations using a paradigm combining errorless (EL) learning and spaced retrieval (SR) whereas participants in the control group (n = 11) were trained using an errorful (EF) learning paradigm. Psycho-educational sessions on memory were also provided to all participants. After neuropsychological screening and baseline evaluations, the cognitive training took place in 6 sessions over a 3-week period. The post-training and follow-up evaluations, at one and four weeks respectively, were performed by research assistants blind to the participant's study group. The results showed that regardless of the training condition, all participants improved their capacity to learn face-name associations. A significant amelioration was also observed in participant satisfaction regarding their memory functioning and in the frequency with which the participants used strategies to support memory functions in daily life. The absence of difference between groups on all variables might be partly explained by the high variability of scores within the experimental group. Other studies are needed in order to verify the efficacy of EL learning and SR over EF in MCI-A.
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