Anosognosia in very mild Alzheimer's disease but not in mild cognitive impairment

OBJECTIVE: To study awareness of cognitive dysfunction in patients with very mild Alzheimer's disease (AD) and subjects with mild cognitive impairment (MCI). METHODS: A complaint interview covering 13 cognitive domains was administered to 82 AD and 79 MCI patients and their caregivers. The patient groups were comparable according to age and education, and Mini Mental State Examination (MMSE) scores were > or =24 in all cases. The discrepancy between the patients' and caregivers' estimations of impairments was taken as a measure of anosognosia. RESULTS: Self-reports of cognitive difficulties were comparable for AD and MCI patients. However, while in comparison to caregivers MCI patients reported significantly more cognitive impairment (p < 0.05), AD patients complained significantly less cognitive dysfunctions (p < 0.001). CONCLUSIONS: While most MCI patients tend to overestimate cognitive deficits when compared to their caregiver's assessment, AD patients in early stages of disease underestimate cognitive dysfunctions. Anosognosia can thus be regarded as a characteristic symptom at a stage of very mild AD (MMSE > or =24) but not MCI. Accordingly, medical history even in mildly affected patients should always include information from both patient and caregiver.     

Awareness of deficits in mild cognitive impairment and Alzheimer's disease: do MCI patients have impaired insight?

In this study we investigated impaired awareness of cognitive deficits in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Very few studies have addressed this topic, and methodological inconsistencies make the comparison of previous studies difficult. From a prospective research program 36 consecutive patients with mild AD (MMSE above 19), 30 with amnesic MCI and 33 matched controls were examined. Using three methods for awareness assessment we found no significant differences in the level of awareness between MCI and AD. Both groups had impaired awareness and significant heterogeneity in the clinical presentation of awareness. The results demonstrate that subjective memory problems should not be a mandatory prerequisite in suspected dementia or MCI, which makes reports from informants together with thorough clinical interview and observation central when assessing suspected dementia disorders.     

Cholinergic plasticity in hippocampus of individuals with mild cognitive impairment: correlation with Alzheimer's neuropathology

Several recent studies indicate that activity of cholinergic enzymes in the cortex of people with mild cognitive impairment (MCI) and early Alzheimer's disease (AD) are preserved. We correlated levels of hippocampal choline acetyltransferase (ChAT) activity with the extent of AD lesions in subjects from the Religious Order Study, including cases with no cognitive impairment (NCI), MCI, and with mild to moderate AD. Hippocampal ChAT activity levels were also determined in a group of end-stage AD patients who were enrolled in the University of Pittsburgh Alzheimer's Disease Research Center. MCI subjects were characterized with increased hippocampal ChAT activity. This elevation was no longer present in mild AD cases, which were not different from NCI subjects. Severe AD cases showed markedly depleted hippocampal ChAT levels. In NCI, MCI, and mild-moderate AD, there was a positive correlation between hippocampal ChAT activity levels and progression of neuritic plaque pathology in entorhinal cortex and hippocampus. A significant elevation of hippocampal ChAT in the MCI group was found selectively in the limbic (i.e., entorhinal-hippocampal, III/IV) Braak stages. We hypothesize that cholinergic changes in the hippocampus of MCI subjects reflect a compensatory response to the progressive denervation of the hippocampus by lost entorhinal cortex input. Moreover, the present findings suggest that the short-term memory loss observed in MCI is not caused by cholinergic deficits; it more likely relates to disrupted entorhinal-hippocampal connectivity.     

Functional deficits in patients with mild cognitive impairment: prediction of AD

OBJECTIVE: To evaluate the predictive utility of self-reported and informant-reported functional deficits in patients with mild cognitive impairment (MCI) for the follow-up diagnosis of probable AD. METHODS: The Pfeffer Functional Activities Questionnaire (FAQ) and Lawton Instrumental Activities of Daily Living (IADL) Scale were administered at baseline. Patients were followed at 6-month intervals, and matched normal control subjects (NC) were followed annually. RESULTS: Self-reported deficits were higher for patients with MCI than for NC. At baseline, self- and informant-reported functional deficits were significantly greater for patients who converted to AD on follow-up evaluation than for patients who did not convert, even after controlling for age, education, and modified Mini-Mental State Examination scores. While converters showed significantly more informant- than self-reported deficits at baseline, nonconverters showed the reverse pattern. Survival analyses further revealed that informant-reported deficits (but not self-reported deficits) and a discrepancy score indicating greater informant- than self-reported functional deficits significantly predicted the development of AD. The discrepancy index showed high specificity and sensitivity for progression to AD within 2 years. CONCLUSIONS: These findings indicate that in patients with MCI, the patient's lack of awareness of functional deficits identified by informants strongly predicts a future diagnosis of AD. If replicated, these findings suggest that clinicians evaluating MCI patients should obtain both self-reports and informant reports of functional deficits to help in prediction of long-term outcome.     

Neuropsychological prediction of conversion to Alzheimer disease in patients with mild cognitive impairment

CONTEXT: The likelihood of conversion to Alzheimer disease (AD) in mild cognitive impairment (MCI) and the "optimal" early markers of conversion need to be established. OBJECTIVES: To evaluate conversion rates to AD in subtypes of MCI and to identify neuropsychological measures most predictive of the time to conversion. DESIGN: Patients were followed up semiannually and controls annually. Subtypes of MCI were determined by using demographically adjusted regression norms on neuropsychological tests. Survival analysis was used to identify the most predictive neuropsychological measures. SETTING: Memory disorders clinic. PARTICIPANTS: One hundred forty-eight patients reporting memory problems and 63 group-matched controls. MAIN OUTCOME MEASURE: A consensus diagnosis of probable AD. RESULTS: At baseline, 108 patients met criteria for amnestic MCI: 87 had memory plus other cognitive domain deficits and 21 had pure memory deficits. The mean duration of follow-up for the 148 patients was 46.6 +/- 24.6 months. In 3 years, 32 (50.0%) of 64 amnestic-"plus" and 2 (10.0%) of 20 "pure" amnestic patients converted to AD (P = .001). In 148 patients, of 5 a priori predictors, the percent savings from immediate to delayed recall on the Selective Reminding Test and the Wechsler Adult Intelligence Scale-Revised Digit Symbol Test were the strongest predictors of time to conversion. From the entire neuropsychological test battery, a stepwise selection procedure retained 2 measures in the final model: total immediate recall on the Selective Reminding Test (odds ratio per 1-point decrease, 1.10; 95% confidence interval, 1.05-1.14; P < .0001) and Digit Symbol Test coding (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P = .01). The combined predictive accuracy of these 2 measures for conversion by 3 years was 86%. CONCLUSIONS: Mild cognitively impaired patients with memory plus other cognitive domain deficits, rather than those with pure amnestic MCI, constituted the high-risk group. Deficits in verbal memory and psychomotor speed/executive function abilities strongly predicted conversion to AD.     

Morphological cerebral correlates of CERAD test performance in mild cognitive impairment and Alzheimer's disease

The objective of this study was to investigate the association between structural cerebral changes and neuropsychological deficits in mild cognitive impairment (MCI) and Alzheimer's disease (AD). Sixty patients with MCI, 34 patients with mild to moderate AD, and 32 healthy controls underwent both extensive neuropsychological assessment (CERAD test battery) and high-resolution structural magnetic resonance imaging. We used optimized voxel based morphometry to investigate (i) differences in gray matter density between the three aforementioned groups and (ii) the putative relations of CERAD test performance with atrophic brain changes. When compared to the healthy controls, the AD patients and, to a lesser extent, patients with MCI showed significant density losses predominantly in the medial temporal lobe. Deficits in verbal fluency and word finding were significantly correlated with left fronto-temporal and left temporal (including hippocampal) changes, respectively. Decreased scores in immediate and delayed recall and in delayed recognition were associated with several cortical and subcortical sites including the parahippocampal and posterior cinguli gyri, the right thalamus, and the right hippocampus, whereas deficits in constructional praxis and constructional praxis recall referred to sites in the left thalamus and cerebellum, and the temporal cortices (bilaterally), respectively. Our findings lend further support for medial temporal lobe degeneration in MCI and AD and demonstrate that cognitive deficits as assessed on the CERAD do not simply refer to specific changes in discrete cerebral sites but rather reflect morphological alterations in widespread networks.     

Detection of mild cognitive impairment in a community‐dwelling population using quantitative,multiparametric MRI‐based classification

Early and accurate mild cognitive impairment (MCI) detection within a heterogeneous, nonclinical population is needed to improve care for persons at risk of developing dementia. Magnetic resonance imaging (MRI)‐based classification may aid early diagnosis of MCI, but has only been applied within clinical cohorts. We aimed to determine the generalizability of MRI‐based classification probability scores to detect MCI on an individual basis within a general population. To determine classification probability scores, an AD, mild‐AD, and moderate‐AD detection model were created with anatomical and diffusion MRI measures calculated from a clinical Alzheimer's Disease (AD) cohort and subsequently applied to a population‐based cohort with 48 MCI and 617 normal aging subjects. Each model's ability to detect MCI was quantified using area under the receiver operating characteristic curve (AUC) and compared with an MCI detection model trained and applied to the population‐based cohort. The AD‐model and mild‐AD identified MCI from controls better than chance level (AUC = 0.600, p = 0.025; AUC = 0.619, p = 0.008). In contrast, the moderate‐AD‐model was not able to separate MCI from normal aging (AUC = 0.567, p = 0.147). The MCI‐model was able to separate MCI from controls better than chance (p = 0.014) with mean AUC values comparable with the AD‐model (AUC = 0.611, p = 1.0). Within our population‐based cohort, classification models detected MCI better than chance. Nevertheless, classification performance rates were moderate and may be insufficient to facilitate robust MRI‐based MCI detection on an individual basis. Our data indicate that multiparametric MRI‐based classification algorithms, that are effective in clinical cohorts, may not straightforwardly translate to applications in a general population.     

Upregulation of choline acetyltransferase activity in hippocampus and frontal cortex of elderly subjects with mild cognitive impairment

In Alzheimer's disease (AD), loss of cortical and hippocampal choline acetyltransferase (ChAT) activity has been correlated with dementia severity and disease duration, and it forms the basis for current therapies. However, the extent to which reductions in ChAT activity are associated with early cognitive decline has not been well established. We quantified ChAT activity in the hippocampus and four cortical regions (superior frontal, inferior parietal, superior temporal, and anterior cingulate) of 58 individuals diagnosed with no cognitive impairment (NCI; n = 26; mean age 81.4 +/- 7.3 years), mild cognitive impairment (MCI; n = 18; mean age 84.5 +/- 5.7), or mild AD (n =14; mean age 86.3 +/- 6.6). Inferior parietal cortex ChAT activity was also assessed in 12 subjects with end-stage AD (mean age 81.4 +/- 4.3 years) and compared to inferior parietal cortex ChAT levels of the other three groups. Only the end-stage AD group had ChAT levels reduced below normal. In individuals with MCI and mild AD, ChAT activity was unchanged in the inferior parietal, superior temporal, and anterior cingulate cortices compared to NCI. In contrast, ChAT activity in the superior frontal cortex was significantly elevated above normal controls in MCI subjects, whereas the mild AD group was not different from NCI or MCI. Hippocampal ChAT activity was significantly higher in MCI subjects than in either NCI or AD. Our results suggest that cognitive deficits in MCI and early AD are not associated with the loss of ChAT and occur despite regionally specific upregulation. Thus, the earliest cognitive deficits in AD involve brain changes other than simply cholinergic system loss. Of importance, the cholinergic system is capable of compensatory responses during the early stage of dementia. The upregulation in frontal cortex and hippocampal ChAT activity could be an important factor in preventing the transition of MCI subjects to AD.     

Cognition in MCI and Alzheimer’s Disease: Baseline Data from a Longitudinal Study of the NTB

Baseline data are summarized from a study examining the psychometric properties of the Neuropsychological Test Battery (NTB) and its subtests, and correlating the NTB with other cognitive and functional assessments. A multicenter, longitudinal, non-interventional study included mild to moderate Alzheimer’s disease (AD, n = 196), mild cognitive impairment (MCI, n = 70), or normal cognition participants (NC, n = 75). The NTB, other cognitive assessment tools, functional/behavioral questionnaires, and health outcome assessments were administered. At baseline composite NTB, NTB memory, and NTB executive function z-scores were significantly lower for participants with AD compared with MCI, and for participants with MCI compared with NC. The composite NTB z-score had high test–retest reliability between screening and baseline. The results of this study suggest that NTB exhibits good reliability in patients with mild to moderate AD and MCI.     

Volumetric MRI measurements can differentiate Alzheimer's disease,mild cognitive impairment,and normal aging

BACKGROUND: Volumetric magnetic resonance imaging (MRI) has been extensively studied in the last decade as a method to help with the clinical diagnosis of Alzheimer's disease (AD). In recent years, researchers have also started investigating if that technique would be useful to identify individuals with mild cognitive impairment (MCI), differentiating them from AD patients and from normal elderly controls. This research project was planned to assess the accuracy of volumetric MRI to differentiate those groups of individuals. METHOD: The investigation involved 39 patients with diagnosis of mild to moderate dementia in AD, according to the criteria of the NINCDS-ADRDA, DSM-III-R, and ICD-10; 21 subjects with complaints of cognitive decline without other psychiatric disorders (MCI); and 20 normal elderly controls. All the subjects were submitted to a standard protocol, including volumetric MRI evaluations. RESULTS: The results indicated that all regions of interest measured (amygdala, hippocampus, and parahippocampal gyrus) were significantly different (p < .005) in AD patients compared to MCI subjects and controls. The left volumetric measures (amygdala, hippocampus, and parahippocampal gyrus) were also significantly different between the MCI subjects and controls (p < .05). The discriminant function analysis correctly classified 88.14% of the AD patients and controls, 81.67% of AD patients and MCI subjects, and 80.49% of the MCI subjects and controls. CONCLUSIONS: The results suggest that measures of medial temporal lobe regions are useful to identify mild to moderate AD patients and MCI subjects, separating them from normal elderly individuals.     

Visual mismatch negativity highlights abnormal pre-attentive visual processing in mild cognitive impairment and Alzheimer's disease

Alzheimer's disease (AD) and mild cognitive impairment (MCI) are traditionally characterised in relation to abnormalities in higher-level brain function, particularly memory. However, in the study presented here we report significant abnormality in pre-attentive visual processing in both MCI and AD compared to healthy ageing. The functional integrity of the automatic change detection system was determined by measuring the visual mismatch negativity (vMMN) component of the N2 visual event-related potential (ERP) in 8 individuals with amnestic MCI, 10 individuals with AD and 10 healthy older adult controls. Compared to healthy ageing, both the MCI and AD groups displayed a significant abnormally increased vMMN over the 140–250 ms measurement epoch although such effects were not apparent over the later 250–400 ms epoch. These novel findings support the view that deficits in brain function in both AD and MCI are not exclusively high-level and indeed that abnormal output from ‘low level’ or pre-attentive processes (as evinced by the abnormal vMMN) is likely to contribute to the high-level processing deficits so characteristic of these clinical disorders.     

Category fluency in mild cognitive impairment: reduced effect of practice in test-retest conditions

Verbal fluency tests are commonly used in neurocognitive and mental status examinations in patients with suspected dementia. Inflation of test scores as a result of practice effects may yield false-negative results in test-retest and multidisciplinary settings, particularly among patients with mild cognitive deficits. To address this issue, animal naming was administered twice within a 1-week period to a group of individuals referred for suspected dementia who were ultimately diagnosed with mild cognitive impairment (MCI; amnestic form), probable Alzheimer disease (AD), or no dementia. A 2 x 3 repeated-measures analysis of variance revealed a statistically significant interaction between administration time and group. Post hoc analyses indicated that nondemented controls were the only group to demonstrate a significant practice effect, producing an average of approximately three more animal names at time two. Like patients with a diagnosis of AD, subjects with amnestic MCI failed to benefit from repeated exposure to the animal naming test, and only controls showed an average improvement upon retest. This underscores the cognitive similarity between individuals diagnosed with amnestic MCI and AD and suggests that improvement upon retest may be a diagnostically useful finding.     

Different perception of cognitive impairment, behavioral disturbances, and functional disabilities between persons with mild cognitive impairment and mild Alzheimer's disease and their caregivers

Insight in dementia is a multifaceted concept and ability, which includes the persons' perception of their behavioral and cognitive symptoms and functional disability. This ability seems to deteriorate as dementia progresses. The aim of this study was to evaluate the level of insight in the cognitive, behavioral, and functional disorders in a group of persons with mild cognitive impairment (MCI) or mild AD (Alzheimer's disease) and to compare their perception of their illness with that of their caregivers. The study involved a group of 121 persons with MCI and mild AD and their caregivers. The persons with MCI and mild AD were administered the tests Mini-Mental State Examination, Instrumental Activities of Daily Living, Activities of Daily Living, Neuropsychiatric Inventory, Schedule for the Assessment of Insight, Clinical Insight Rating Scale, and a short interview. Major differences were identified between how the persons with MCI or mild AD and their caregivers perceived the persons' cognitive and behavioral disorders. The group with MCI or mild AD underestimated their deficits, which were considered serious and disabling by their caregivers.     

Impact of cognitive impairment on mild dementia patients and mild cognitive impairment patients and their informants

BACKGROUND: The aim of this study was to identify key aspects of the impact of cognitive impairment on patients with mild cognitive impairment (MCI) and mild probable Alzheimer disease (AD) and their informants, and identify overlap and differences between the groups. METHODS: Structured focus group discussions were conducted with MCI patients, AD patients, MCI informants, and AD informants. Participants were recruited from memory clinics in the U.K. and the U.S.A. A total of 20 AD and 20 MCI patients and 16 AD and 11 MCI informants participated. Sessions were content reviewed to identify key impacts of cognitive impairment; results were compared across diagnostic groups and for patients and informants. RESULTS: Seven key themes emerged: uncertainty of diagnosis, skill loss, change in social and family roles, embarrassment and shame, emotionality, insight, and burden. Patients were able to discuss the impact of cognitive impairment on their lives and reported frustration with recognized memory problems, diminished self-confidence, fear of embarrassment, concerns about changing family roles due to cognitive impairment, and anxiety. Informants reported more symptoms and more impairment than did patients and indicated increased dependence on others among patients. CONCLUSION: MCI and mild AD exert substantial burden on patients' lives and the lives of those close to them.     

Loss of calculation abilities in patients with mild and moderate Alzheimer disease

BACKGROUND: Calculation deficits are a common early manifestation of Alzheimer disease (AD). OBJECTIVE: To investigate oral and written calculation skills in AD patients using quantitative and qualitative methods. DESIGN: Comparison among controls, patients with mild AD, and patients with moderate AD on measures of arithmetic skill. SETTING: Tertiary care university medical center. PARTICIPANTS: Twenty patients with AD (11 with mild AD, 9 with moderate AD) and 23 elderly controls. MAIN OUTCOME MEASURES: Tests of oral arithmetic (Wechsler Adult Intelligence Scale-Third Edition [WAIS-III] Arithmetic subtest) and written arithmetic (Wide Range Achievement Test-3 [WRAT-3] Arithmetic subtest) were administered, and overall group differences were examined. Errors on selected WRAT-3 problems were qualitatively analyzed across groups using a set of error codes. RESULTS: Patients with mild and moderate AD performed significantly below controls on both oral and written arithmetic tasks (P<.001). Patients with moderate AD performed worse than those with mild AD on written arithmetic (P<.002) but not on oral arithmetic tasks. On selected WRAT-3 problems, single- and multiple-digit addition and subtraction operations and single-digit division operations were preserved in patients with mild AD. In contrast, only single-digit addition was preserved in patients with moderate AD. Errors of operation substitution and number position were the most common error types observed in AD patients. Patients with moderate AD displayed multiple error types and high incidence rates compared with controls, while patients with mild AD exhibited error types and incidence rates intermediate to controls and patients with moderate AD. CONCLUSIONS: A decline in calculation abilities is one of the hallmark cognitive features of AD. Patients with mild AD maintain relative preservation of simple written calculation skills but demonstrate marked impairment as task complexity increases. Patients with moderate AD demonstrate global impairments extending to the simplest arithmetic skills. These findings suggest that loss of calculation abilities in AD is both hierarchical (by arithmetic operation) and a function of disease severity.     

The patient with dementia, the caregiver and the doctor: cognition, depression and quality of life from three perspectives

BACKGROUND: For comprehensive information about the situation of patients with dementia or mild cognitive impairment (MCI), clinicians have to rely on information from different sources, e.g. caregivers or the patients themselves, which may differ from each other. In addition to the assessment of cognitive impairment, the importance of evaluating not only depressive symptoms but also health related quality of life (HRQOL) in clinical research and practice in dementia has increased. OBJECTIVE: To examine about how the ratings of patients, caregivers and clinicians regarding the patients' cognitive impairment, depression and HRQOL relate to each other by comparing these three perspectives by using self- and proxy-rating measures. METHOD: One hundred outpatients with mild to moderate dementia or MCI and their family caregivers participated in this study. Depression and cognitive impairment were examined with self- and proxy-ratings as well as the Mini-Mental Status Examination (MMSE); HRQOL was assessed with the SF-12 Health Survey and the EUROHIS quality of life index. RESULTS: We found high correspondence between caregivers' assessment of cognitive function and MMSE scores, while patients' self-rating did not correlate with MMSE. HRQOL was underestimated by caregivers compared to self-rating. Concerning depression, the patients' assessment was in good accordance with the clinician's evaluation. CONCLUSION: The study suggests that patients with mild to moderate dementia and MCI are important informants of their HRQOL and depressive symptoms, but they underestimate their cognitive deficits. Assessing different perspectives of the patients' HRQOL is relevant in order to obtain a comprehensive understanding of the patients' well-being.     

Mild cognitive impairment: a cross-national comparison

OBJECTIVE: The main aim of this collaborative study was to assess the comparability of the most commonly used criteria for mild cognitive impairment (MCI) by comparing the cognitive performance of patients with MCI from the Mayo Clinic (USA) and the Karolinska Institutet (Sweden). METHODS: Standardised neuropsychological test scores were used to compare the two samples from the two institutions with regard to the number of cognitive domains in which performance was below 1.5 SD. Possible predictors for the conversion from MCI to Alzheimer's disease (AD) were assessed. RESULTS: When the two institutions were considered together in the Cox proportional hazard model, the number of affected cognitive domains below 1.5 SD was a significant predictor of time to AD diagnosis with age, education, and APOE epsilon4 genotype entered into the same model as covariates. The number of affected cognitive areas remained as a significant predictor when the institutions were considered separately. The logistic regression model of conversion to AD showed that only tests assessing learning and retention were predictors of developing AD. CONCLUSIONS: Differences in population as well as in methodology of case ascertainment as well as other aspects may account for the observed variability between samples of patients with MCI. The number of impaired cognitive factors at baseline can predict the progression from MCI to AD. Furthermore, tests assessing learning and retention are the best predictors for progression to AD.     

Yes/No Versus Forced-Choice Recognition Memory in Mild Cognitive Impairment and Alzheimer's Disease: Patterns of Impairment and Associations with Dementia Severity

Memory tests are sensitive to early identification of Alzheimer's disease (AD) but less useful as the disease advances. However, assessing particular types of recognition memory may better characterize dementia severity in later stages of AD. We sought to examine patterns of recognition memory deficits in individuals with AD and mild cognitive impairment (MCI). Memory performance and global cognition data were collected from participants with AD (n?=?37), MCI (n?=?37), and cognitively intact older adults (normal controls, NC; n?=?35). One-way analyses of variance (ANOVAs) examined differences between groups on yes/no and forced-choice recognition measures. Individuals with amnestic MCI performed worse than NC and nonamnestic MCI participants on yes/no recognition, but were comparable on forced-choice recognition. AD patients were more impaired across yes/no and forced-choice recognition tasks. Individuals with mild AD (≥120 Dementia Rating Scale, DRS) performed better than those with moderate-to-severe AD (<120 DRS) on forced-choice recognition, but were equally impaired on yes/no recognition. There were differences in the relationships between learning, recall, and recognition performance across groups. Although yes/no recognition testing may be sensitive to MCI, forced-choice procedures may provide utility in assessing severity of anterograde amnesia in later stages of AD. Implications for assessment of insufficient effort and malingering are also discussed.     

Automated Neuropsychological Test Battery (CANTAB) in mild cognitive impairment and in Alzheimer's disease

Neuropsychological deficits, such as poor episodic memory, are consistent features of mild cognitive impairment and also that of early stage of dementia. The aim of the present study was to detect cognitive dysfunction among patients with Alzheimer's disease or with mild cognitive impairment (MCI), which refers to a transitional state between the cognition of normal aeging and mild dementia regarded as a high-risk condition for the development of clinically probable Alzheimer's disease (AD). Computerized tests of memory, attention and executive functions were studied in groups of AD subjects (n=15) and MCI subjects (n=25). On all measures, the performance of the AD group was significantly weaker compared to healthy individuals or to the MCI group. The performance of both the AD and MCI patients in the Paired Associate Learning test was significantly impaired, which may suggest that MCI patients are already in the early stages of the disease.     

Magnetoencephalographic parietal delta dipole density in mild cognitive impairment: preliminary results of a method to estimate the risk of developing Alzheimer disease

BACKGROUND: Subjects with mild cognitive impairment (MCI) are at a higher risk of experiencing Alzheimer disease (AD). Magnetoencephalographic temporoparietal dipole densities of low-frequency activity are good predictors of individuals' cognitive status, and might be a useful tool to investigate the conversion from MCI to AD. OBJECTIVE: To investigate the role of low-frequency dipole densities as predictors of the risk of developing AD. DESIGN: Whole-head magnetoencephalographic recordings were obtained from 19 probable AD patients, 17 MCI patients, and 17 healthy control subjects. The generators of focal magnetic slow waves were located using a single moving dipole model. RESULTS: Left parietal delta dipole density permitted a reliable classification of AD and MCI patients. The MCI patients were divided into 2 groups based on the median left parietal delta dipole density, and were followed up for 2 years. The estimated relative risk of conversion to AD was increased by 350% in those MCI patients with high left parietal delta dipole density scores. CONCLUSIONS: Results confirmed the important role of parietal delta dipole density in the evaluation of AD and MCI. A magnetoencephalographic-based assessment of AD and MCI patients might be considered a useful clinical test in the near future.