CERAD test performances in amnestic mild cognitive impairment and Alzheimer's disease

Learning and memory in amnestic mild cognitive impairment: contribution of working memory

In addition to deficits in delayed recall, recent research suggests that participants with amnestic mild cognitive impairment (aMCI) demonstrate diminished use of strategic encoding strategies during learning. Few studies have explored the cognitive mechanisms underlying this deficit. The aim of this study was to investigate in aMCI whether components of working memory (executive attention--attention set-shifting, dividing and focusing attention; and episodic buffer functions--strategic retrieval and manipulation of information) predict strategic encoding strategies during learning (semantic clustering). Thirty-three participants with aMCI and 33 healthy older adults (HOA) were administered neuropsychological tests assessing word-list learning and working memory. The aMCI group demonstrated significant impairment in acquisition, retrieval of information, and decreased use of semantic clustering strategies. Use of semantic clustering in the aMCI group was not predicted by measures of executive attention or phonemic verbal fluency, but was predicted by semantic verbal fluency performance. In the HOA group, semantic clustering was strongly related to semantic verbal fluency. These findings suggest that in aMCI, diminished strategic encoding strategies during learning (semantic clustering) is selectively related to the strategic function of the episodic buffer, but only when in interaction with the manipulation and retrieval of semantic associations.

Learning and forgetting new names and objects in MCI and AD

We studied how subjects with mild cognitive impairment (MCI), early Alzheimer's disease (AD) and age-matched controls learned and maintained the names of unfamiliar objects that were trained with or without semantic support (object definitions). Naming performance, phonological cueing, incidental learning of the definitions and recognition of the objects were tested during follow-up. We found that word learning was significantly impaired in MCI and AD patients, whereas forgetting patterns were similar across groups. Semantic support showed a beneficial effect on object name retrieval in the MCI group 8 weeks after training, suggesting that the MCI patients' preserved semantic memory can compensate for impaired episodic memory. The MCI group performed equally well as the controls in the tasks measuring incidental learning and recognition memory, whereas the AD group showed impairment in this respect. Both the MCI and the AD group benefited less from phonological cueing than the controls. Our findings indicate that word learning is compromised in both MCI and AD, whereas long-term retention of newly learned words is not affected to the same extent. Incidental learning and recognition memory seem to be well preserved in MCI.

Screening for mild cognitive impairment: a systematic review

OBJECTIVE

Patients with mild cognitive impairment account for a significant number of referrals to old age psychiatry services and specialist memory clinics. The cognitive evaluation of such patients is commonly restricted to brief dementia screens, with no consideration to their suitability for assessing MCI. Here, we review the utility of such cognitive screens for MCI and provide an overview of validated instruments.

METHODS

We identified papers published after Petersen and colleagues 1999 MCI criteria (Petersen et al., 1999) and examining face-to-face cognitive screening for MCI from publication databases using combinations of the search terms 'mild cognitive impairment' and 'cognitive screening'. We also combined the former search with the names of 39 screening tests recently identified in a relevant review (Cullen et al., 2007).

RESULTS

Fifteen cognitive screening instruments were identified, 11 cover a restricted range of cognitive domains. High sensitivity and specificity for MCI relative to healthy controls were reported for two comprehensive and two noncomprehensive screening instruments, adequate test-retest and inter-rater reliability for only one of these. With the exception of three studies, sample sizes were universally small (i.e. n </= 100), and prognostic values were reported for only two of the identified 15 screening measures. Sensitivities of the full domain measures were universally high, but information about their specificity against psychiatric and non-progressive neurological conditions and predictive validity is lacking.

CONCLUSION

Several cognitive screening instruments afford the clinician the ability to detect MCI, early AD, and in some cases non-AD dementia, but they cannot currently be used to make reliable inferences about the course and eventual outcome of MCI.

The effect of age on attentional modulation in Dichotic listening

The right-ear advantage (REA) in Dichotic listening (DL) reflects stimulus-driven bottom-up asymmetry in speech processing. The REA can be modified by top-down attentional control. We investigated attentional control in DL task as a function of age. A total of 186 participants between the ages of 5 and 79 years were tested. The youngest children demonstrated a REA that was not modified by attention, suggesting that bottom-up functional asymmetry was present. The 10-11-year-olds began to show ability to voluntarily modify DL, but only young adults were fully capable of doing so. In 59-79-year-olds, this top-down attentional control was lost again.

Trajectories of cognitive function in late life in the United States: demographic and socioeconomic predictors

This study used mixed-effects modeling of data from a national sample of 6,476 US adults born before 1924, who were tested 5 times between 1993 and 2002 on word recall, serial 7's, and other mental status items to determine demographic and socioeconomic predictors of trajectories of cognitive function in older Americans. Mean decline with aging in total cognition score (range, 0-35; standard deviation, 6.00) was 4.1 (0.68 standard deviations) per decade (95% confidence interval: 3.8, 4.4) and in recall score (range, 0-20; standard deviation, 3.84) was 2.3 (0.60 standard deviations) per decade (95% confidence interval: 2.1, 2.5). Older cohorts (compared with younger cohorts), women (compared with men), widows/widowers, and those never married (both compared with married individuals) declined faster, and non-Hispanic blacks (compared with non-Hispanic whites) and those in the bottom income quintile (compared with the top quintile) declined slower. Race and income differences in rates of decline were not sufficient to offset larger differences in baseline cognition scores. Educational level was not associated with rate of decline in cognition scores. The authors concluded that ethnic and socioeconomic disparities in cognitive function in older Americans arise primarily from differences in peak cognitive performance achieved earlier in the life course and less from declines in later life.

Differential memory test sensitivity for diagnosing amnestic mild cognitive impairment and predicting conversion to Alzheimer's disease

Episodic memory is the first and most severely affected cognitive domain in Alzheimer's disease (AD), and it is also the key early marker in prodromal stages including amnestic mild cognitive impairment (MCI). The relative ability of memory tests to discriminate between MCI and normal aging has not been well characterized. We compared the classification value of widely used verbal memory tests in distinguishing healthy older adults (n = 51) from those with MCI (n = 38). Univariate logistic regression indicated that the total learning score from the California Verbal Learning Test-II (CVLT-II) ranked highest in terms of distinguishing MCI from normal aging (sensitivity = 90.2; specificity = 84.2). Inclusion of the delayed recall condition of a story memory task (i.e., WMS-III Logical Memory, Story A) enhanced the overall accuracy of classification (sensitivity = 92.2; specificity = 94.7). Combining Logical Memory recognition and CVLT-II long delay best predicted progression from MCI to AD over a 4-year period (accurate classification = 87.5%). Learning across multiple trials may provide the most sensitive index for initial diagnosis of MCI, but inclusion of additional variables may enhance overall accuracy and may represent the optimal strategy for identifying individuals most likely to progress to dementia.

Diagnostic utility of the NAB List Learning test in Alzheimer's disease and amnestic mild cognitive impairment

Measures of episodic memory are often used to identify Alzheimer's disease (AD) and mild cognitive impairment (MCI). The Neuropsychological Assessment Battery (NAB) List Learning test is a promising tool for the memory assessment of older adults due to its simplicity of administration, good psychometric properties, equivalent forms, and extensive normative data. This study examined the diagnostic utility of the NAB List Learning test for differentiating cognitively healthy, MCI, and AD groups. One hundred fifty-three participants (age: range, 57-94 years; M = 74 years; SD, 8 years; sex: 61% women) were diagnosed by a multidisciplinary consensus team as cognitively normal, amnestic MCI (aMCI; single and multiple domain), or AD, independent of NAB List Learning performance. In univariate analyses, receiver operating characteristics curve analyses were conducted for four demographically-corrected NAB List Learning variables. Additionally, multivariate ordinal logistic regression and fivefold cross-validation was used to create and validate a predictive model based on demographic variables and NAB List Learning test raw scores. At optimal cutoff scores, univariate sensitivity values ranged from .58 to .92 and univariate specificity values ranged from .52 to .97. Multivariate ordinal regression produced a model that classified individuals with 80% accuracy and good predictive power. (JINS, 2009, 15, 121-129.).

Language performance in Alzheimer's disease and mild cognitive impairment: a comparative review

Mild cognitive impairment (MCI) manifests as memory impairment in the absence of dementia and progresses to Alzheimer's disease (AD) at a rate of around 15% per annum, versus 1-2% in the general population. It thus constitutes a primary target for investigation of early markers of AD. Language deficits occur early in AD, and performance on verbal tasks is an important diagnostic criterion for both AD and MCI. We review language performance in MCI, compare these findings to those seen in AD, and identify the primary issues in understanding language performance in MCI and selecting tasks with diagnostic and prognostic value.

Consortium to Establish a Registry for Alzheimer's Disease (CERAD): the first twenty years

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) was funded by the National Institute on Aging in 1986 to develop standardized, validated measures for the assessment of Alzheimer's disease (AD). The present report describes the measures that CERAD developed during its first decade and their continued use in their original and translated forms. These measures include clinical, neuropsychological, neuropathologic, and behavioral assessments of AD and also assessment of family history and parkinsonism in AD. An approach to evaluating neuroimages did not meet the standards desired. Further evaluations that could not be completed because of lack of funding (but where some materials are available) include evaluation of very severe AD and of service use and need by patient and caregiver. The information that was developed in the U.S. and abroad permits standardized assessment of AD in clinical practice, facilitates epidemiologic studies, and provides information valuable for individual and public health planning. CERAD materials and data remain available for those wishing to use them.

Screening for dementia: a review of self- and informant-assessment instruments

BACKGROUND

The objective of this study was to review available dementia screening instruments that could be recommended for self-administration, particularly in electronic format. Owing to the gradual loss of insight associated with the progression of dementia, a broad definition of self-administration including self-administration by concerned informants (family, friends, carers) was used.

METHOD

A systematic search of PubMed, PsychINFO, and the Cochrane Library Database was conducted. Only available full-text articles about dementia screening instruments written in English were included. Articles reporting on instruments used in a non-English context were excluded unless a validated English version of the instrument was available. Included instruments were assessed against the precise criteria and characteristics of the Mini-mental State Examination (MMSE), the most widely used screening instrument.

RESULTS

The Concord Informant Dementia Scale (CIDS) and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) were the only instruments meeting all selection criteria. The Memory Impairment Screen (MIS) also met the criteria, although it lacks validation for self-administration. No instrument has been validated for self-administration in electronic format.

CONCLUSIONS

It is recommended that the MIS, the CIDS and the IQCODE be validated for self-administration in electronic format.

The value of the clock drawing test and the mini-mental state examination for identifying vascular cognitive impairment no dementia

OBJECTIVE

To determine the validity of the Clock Drawing Test (CDT) and the Mini-Mental State Examination (MMSE) respectively or in combination for differentiating Vascular Cognitive Impairment No Dementia (V-CIND) from normal subjects.

METHODS

Eighty V-CIND patients and 80 healthy control subjects were blindly evaluated with MMSE, CDT, and additional neuropsychological tests. CDT was scored according to the Rouleau method and AD Cooperative Study method. Sensitivities and specificities of the two CDT measures and MMSE for identifying V-CIND patients were determined. The Areas Under the Receiver Operating Characteristic Curve (AUCs) were compared, and the sensitivity of the combination of CDT with MMSE calculated.

RESULTS

V-CIND group performed worse than controls on both MMSE (p < 0.0001) and the two CDTs (p < 0.0001). In differentiating V-CIND patients from normal subjects, the two CDT measures provided sensitivities of 68.7% and 65.0%, and specificities of 78.7% and 86.2% respectively at optimal cutoff scores, which did no better than MMSE (sensitivity 80%, specificity 70%) (comparison of the AUCs, p = 0.992 and 0.428). The sensitivity of MMSE was marginally higher than that of CDT scored with AD Cooperative Study method (p = 0.053). By combining the two CDT measures with MMSE, the sensitivity was improved to 93.7% and 92.5% respectively.

CONCLUSIONS

Compared with MMSE, CDT is of only similar or even weaker ability for identifying V-CIND. MMSE at a cutoff of 28 may be of some value in detecting V-CIND patients. CDT and MMSE in combination provide a valid instrument for V-CIND screening.

Regional white matter pathology in mild cognitive impairment: differential influence of lesion type on neuropsychological functioning

BACKGROUND AND PURPOSE

Associations between regional white matter lesion pathology and neuropsychological performance across the aging spectrum are not well understood and, to date, research has been largely contradictory and inconclusive. The current study set out to clarify some of the inconsistencies in the literature by relating volumetric analyses of white matter lesions (deep white matter lesions and periventricular lesions) to neuropsychological performance in a large clinical sample of older adults diagnosed with mild cognitive impairment.

METHODS

Seventy older adults with mild cognitive impairment were administered a comprehensive neuropsychological battery. White matter lesions identified on T2-weighted FLAIR images were quantified using a semi-automated volumetric approach (pixel thresholding).

RESULTS

Results showed that, in contrast to performance on memory and naming tasks, total white matter lesions strongly predicted executive impairments, slowed processing speed, and visuospatial/construction difficulties. In addition, separate regression analyses demonstrated that results were primarily accounted for by deep white matter lesions (but not periventricular lesions), most likely due to frontal-subcortical circuitry disruption. Moreover, deep white matter lesions, but not periventricular lesions, significantly predicted overall poorer neuropsychological functioning after controlling for age, education, and level of depression.

CONCLUSIONS

Taken together, findings demonstrate a differential influence of lesion type on cognitive impairment in mild cognitive impairment and implicate deep white matter lesions as being most detrimental in terms of neuropsychological functioning. Clinical, theoretical, and methodological implications of these results are discussed.

Neural correlates of naming newly learned objects in MCI

Our objective was to study the neural correlates of naming of newly learned unfamiliar objects in subjects with mild cognitive impairment (MCI) and in age-matched controls, by using positron emission tomography (PET). Prior to the PET scanning, each subject underwent a 4-day long training period in which 40 names of rare unfamiliar objects were taught. The stimuli consisted of five categories: unfamiliar objects for which both the name and the definition (=semantic support) were given during training, unfamiliar objects with only the name given, unfamiliar objects with no information given, familiar objects and visual noise patterns. The unfamiliar objects mainly represented ancient domestic tools unknown to modern-day people. When naming newly learned objects trained without semantic support, the MCI group showed increased activation in the anterior cingulate when compared with the controls. Our results suggest that the naming of newly learned objects posed additional executive and attentional demands on the patients.