The importance of Alzheimer disease assessment scale-cognitive part in predicting progress for amnestic mild cognitive impairment to Alzheimer disease

Predicting Alzheimer's disease based on survival data and longitudinally measured performance on cognitive and functional scales

This study assessed how well longitudinally taken cognitive and functional scales from people with mild cognitive impairment (MCI) predict conversion to Alzheimer's disease (AD). Participants were individuals with baseline MCI from the Alzheimer's Disease Neuroimaging Initiative. Scales included the Alzheimer Disease Assessment Scale-Cognitive (ADAS-Cog) 11 and 13, the Mini Mental State Examination (MMSE), and the Functional Assessment Questionnaire (FAQ). A joint modelling approach compared performance on the four scales for dynamic prediction of risk for AD. The goodness of fit measures included log likelihood, the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). The area under the curve (AUC) of the receiver operating characteristic assessed predictive accuracy. The parameter α in the ADAS-Cog11, ADAS-Cog13, MMSE, and FAQ joint models was statistically significant. Joint MMSE and FAQ models had better goodness of fit. FAQ had the best predictive accuracy. Cognitive and functional impairment assessment scales are strong screening predictors when repeated measures are available. They could be useful for predicting risk for AD in primary healthcare.

Altered Low-Frequency EEG Connectivity in Mild Cognitive Impairment as a Sign of Clinical Progression

BACKGROUND

Mild cognitive impairment (MCI) is associated with clinical progression to Alzheimer's disease (AD) but not all patients with MCI convert to AD. However, it is important to have methods that can differentiate between patients with MCI who progress (pMCI) and those who remain stable (sMCI), i.e., for timely administration of disease-modifying drugs.

OBJECTIVE

In the current study, we wanted to investigate whether quantitative EEG coherence and imaginary part of coherency (iCoh) could be used to differentiate between pMCI and sMCI.

METHODS

17 patients with AD, 27 patients with MCI, and 38 older healthy controls were recruited and followed for three years and 2nd year was used to determine progression. EEGs were recorded at baseline and coherence and iCoh were calculated after thorough preprocessing.

RESULTS

Between pMCI and sMCI, the largest difference in total coherence was found in the theta and delta bands. Here, the significant differences for coherence and iCoh were found in the lower frequency bands involving the temporal-frontal connections for coherence and parietal-frontal connections for iCoh. Furthermore, we found a significant negative correlation between theta coherence and the Addenbrooke's Cognitive Examination (ACE) (p = 0.0378; rho = -0.2388).

CONCLUSION

These findings suggest that low frequency coherence and iCoh can be used to determine, which patients with MCI will progress to AD and is associated with the ACE score. Low-frequency coherence has previously been associated with increased hippocampal atrophy and degeneration of the cholinergic system and may be an early marker of AD pathology.

Electroencephalographic Cross-Frequency Coupling as a Sign of Disease Progression in Patients With Mild Cognitive Impairment: A Pilot Study

Mild cognitive impairment (MCI) refers to mild objective cognitive deficits and is associated with the later development of Alzheimer’s disease (AD). However, not all patients with MCI convert to AD. EEG spectral power has shown promise as a marker of progression, but brain oscillations in different frequencies are not isolated entities. Coupling between different frequency bands, so-called cross-frequency coupling (CFC), has been associated with memory function and may further contribute to our understanding of what characterizes patients with MCI who progress to AD. In the current study, we wanted to investigate the changes in gamma/theta CFC in patients with AD and MCI compared to HC and in patients with pMCI compared to patients with sMCI. Furthermore, we wanted to investigate the association with cognitive test scores. EEGs were included at baseline for 15 patients with AD, 25 patients with MCI, and 36 older HC, and the participants were followed for up to 3 years. To investigate CFC, we calculated the modulation index (MI), which has been shown to be less affected by noisy data compared to other techniques. We found that patients with pMCI showed a significantly lower global gamma/theta CFC compared to patients with sMCI. In addition, global gamma/theta CFC was significantly correlated with Addenbrooke’s Cognitive Examination (ACE) score (p-value = 0.030, rho = 0.527). Although not significant, patients with AD and MCI showed a lower gamma/theta CFC compared to HC. These findings suggest that gamma/theta CFC is important for proper cognitive functioning and that a decrease in gamma/theta CFC in patients with MCI may be a sign of progression. Gamma/theta CFC may therefore serve as a progression marker in MCI, but larger studies are needed to validate these findings.

Decreased Parietal Beta Power as a Sign of Disease Progression in Patients with Mild Cognitive Impairment

BACKGROUND

Electroencephalography (EEG) power has previously been used to compare mild cognitive impairment (MCI) patients who progress to Alzheimer's disease (pMCI) with patients with MCI who remain stable (sMCI) by using beta power. However, the beta band is very broad and smaller frequency bands may improve accuracy.

OBJECTIVE

In the present study, we wanted to investigate whether it was possible to find any differences between pMCI and sMCI using relative power and whether these differences were correlated to cognitive function or neuropathology markers.

METHODS

17 patients with AD, 27 patients with MCI, and 38 older healthy controls were recruited from two memory clinics and followed for three years. EEGs were recorded at baseline for all participants and relative power was calculated. All participants underwent adjusted batteries of standardized cognitive tests and lumbar puncture.

RESULTS

We found that pMCI showed decreased baseline relative power in the parietal electrodes in the beta1 band (13-17.99 Hz). At 2-year follow-up, we found changes in all baseline beta bands but most pronounced in the beta1 band. In addition, we found that qEEG parietal power was correlated with amyloid-β42 and anterograde memory.

CONCLUSION

These findings suggests that relative power in the parietal electrodes in the beta1 band may be a better way to discriminate between pMCI and sMCI at the time of diagnosis than the broad beta band. Similar findings have also been found with resting state fMRI. In addition, we found that anterograde memory was correlated to qEEG parietal beta1 power.

Refining Mild-to-Moderate Alzheimer Disease Screening: A Tool for Clinicians

OBJECTIVES

Recent evidence suggests that a substantial minority of people clinically diagnosed with probable Alzheimer disease (AD) in fact do not fulfill the neuropathological criteria for the disease. A clinical hallmark of these phenocopies of AD is that these individuals tend to remain cognitively stable for extended periods of time, in contrast to their peers with confirmed AD who show a progressive decline. We aimed to examine the prevalence of patients clinically diagnosed with mild-to-moderate AD who do not experience the expected clinically significant cognitive decline and identify markers easily available in routine medical practice predictive of a stable cognitive prognosis in this population.

DESIGN

Data were obtained from two independent, longitudinal, observational multicenter studies in patients with mild-to-moderate AD.

SETTING

The two studies were the European "Impact of Cholinergic Treatment Use" (ICTUS) and the French "REseau sur la maladie d'Alzheimer FRançais" (REAL.FR).

PARTICIPANTS

We used prospective data of 756 patients enrolled in ICTUS and 340 enrolled in REAL.FR.

MEASUREMENTS

A prediction rule of cognitive decline was derived on ICTUS using classification and regression tree analysis and then cross-validated on REAL.FR. A range of demographic, clinical and cognitive variables were tested as predictor variables.

RESULTS

Overall, 27.9% of patients in ICTUS and 20.9% in REAL.FR did not decline over 2 years. We identified optimized cut-points on the verbal memory items of the Alzheimer Disease Assessment Scale-Cognitive Subscale capable of classifying patients at baseline into those who went on to decline and those who remained stable or improved over the duration of the trial.

CONCLUSION

The application of this simple rule would allow the identification of dementia cases where a more detailed differential diagnostic examination (eg, with biomarkers) is warranted. These findings are promising toward the refinement of AD screening in the clinic. For a further optimization of our classification rule, we encourage others to use our methodological approach on other episodic memory assessment tools designed to detect even small cognitive changes in patients with AD.

Cognitive reserve moderates the association between functional network anti-correlations and memory in MCI

Cognitive reserve (CR) shows protective effects on cognitive function in older adults. Here, we focused on the effects of CR at the functional network level. We assessed in patients with amnestic mild cognitive impairment (aMCI) whether higher CR moderates the association between low internetwork cross-talk on memory performance. In 2 independent aMCI samples (n = 76 and 93) and healthy controls (HC, n = 36), CR was assessed via years of education and intelligence (IQ). We focused on the anti-correlation between the dorsal attention network (DAN) and an anterior and posterior default mode network (DMN), assessed via sliding time window analysis of resting-state functional magnetic resonance imaging (fMRI). The DMN-DAN anti-correlation was numerically but not significantly lower in aMCI compared to HC. However, in aMCI, lower anterior DMN-DAN anti-correlation was associated with lower memory performance. This association was moderated by CR proxies, where the association between the internetwork anti-correlation and memory performance was alleviated at higher levels of education or IQ. In conclusion, lower DAN-DMN cross-talk is associated with lower memory in aMCI, where such effects are buffered by higher CR.

Psychometric Properties of Alzheimer’s Disease Assessment Scale-Cognitive Subscale for Mild Cognitive Impairment and Mild Alzheimer’s Disease Patients in an Asian Context

Introduction: The purpose of the current study is to assess the psychometric properties of Alzheimer’s Disease Assessment Scale-Cognitive subscale (ADAS-Cog) on patients with mild cognitive impairment (MCI) and mild Alzheimer’s disease (AD) in a multicultural Asian context. Materials and Methods: Sixty-four mild AD patients (mean age ± SD; 72.24 ± 7.88 years), 80 MCI patients (66.44 ± 7.45 years) and 125 healthy controls (HCs) (61.81 ±6.96 years) participated in the study. Participants underwent a clinical interview and serial neuropsychological testing. ADAS-Cog total and subtest scores were compared across the 3 groups. Receiver operating characteristics (ROC) analysis were performed and sensitivity, specificity, positive predictive values (PPVs) and negative predictive values (NPVs) were calculated. Results: Patients with MCI attained significantly worse neuropsychological test scores than healthy controls but significantly better results than patients with mild AD on ADAS-Cog total score, subtest items, and the delayed recall item (P <0.001). The best cutoff score to differentiate between MCI and HC was ≥4 (sensitivity = 0.73, specificity = 0.69, PPV = 0.90, NPV = 0.40), while the best cutoff score to distinguish between MCI and mild AD was ≥12 (sensitivity = 0.86, specificity = 0.89, PPV = 0.99, NPV = 0.32). Evidence of internal consistency of the ADAS-Cog (Cronbach α = 0.85) as well as convergent validity with the Mini-Mental State Examination (MMSE) (ρ = -0.75) and Montreal Cognitive Assessment (MoCA) (ρ = -0.81) (both P <0.001) was also found. Conclusion: The ADAS-Cog which is widely used in clinical trials is applicable to the Asian cohort. It is useful in the detection of MCI and mild AD as well as in distinguishing these 2 conditions. Key words: Dementia, Neuropsychology, Psychometric validation

At risk or not at risk? A meta-analysis of the prognostic accuracy of psychometric interviews for psychosis prediction

An accurate detection of individuals at clinical high risk (CHR) for psychosis is a prerequisite for effective preventive interventions. Several psychometric interviews are available, but their prognostic accuracy is unknown. We conducted a prognostic accuracy meta-analysis of psychometric interviews used to examine referrals to high risk services. The index test was an established CHR psychometric instrument used to identify subjects with and without CHR (CHR+ and CHR-). The reference index was psychosis onset over time in both CHR+ and CHR- subjects. Data were analyzed with MIDAS (STATA13). Area under the curve (AUC), summary receiver operating characteristic curves, quality assessment, likelihood ratios, Fagan's nomogram and probability modified plots were computed. Eleven independent studies were included, with a total of 2,519 help-seeking, predominately adult subjects (CHR+: N=1,359; CHR-: N=1,160) referred to high risk services. The mean follow-up duration was 38 months. The AUC was excellent (0.90; 95% CI: 0.87-0.93), and comparable to other tests in preventive medicine, suggesting clinical utility in subjects referred to high risk services. Meta-regression analyses revealed an effect for exposure to antipsychotics and no effects for type of instrument, age, gender, follow-up time, sample size, quality assessment, proportion of CHR+ subjects in the total sample. Fagan's nomogram indicated a low positive predictive value (5.74%) in the general non-help-seeking population. Albeit the clear need to further improve prediction of psychosis, these findings support the use of psychometric prognostic interviews for CHR as clinical tools for an indicated prevention in subjects seeking help at high risk services worldwide.

MCI of different etiologies differ on the Cognitive Assessment Battery

OBJECTIVES

The study aims to investigate whether patients with mild cognitive impairment (MCI) who have significant vascular disease (MCI-vas) differ from those with no significant vascular disease (MCI-nov) in terms of cognitive profile when assessed with the cognitive assessment battery (CAB).

MATERIALS AND METHODS

Seventy patients clinically diagnosed with MCI were included in the study, 32 were classified as MCI-vas, and 38 as MCI-nov, together with 40 healthy controls. CAB consists of six short tests measuring speed and attention, memory, visuospatial functions, language, and executive functions.

RESULTS

The healthy controls performed better than both MCI groups on CAB. MCI-vas patients were significantly older and had fewer years of education than MCI-nov patients. When adjusted for age and education, MCI-vas performed significantly worse than MCI-nov on memory, language, and executive tests.

CONCLUSIONS

The results suggest that CAB can differentiate between MCI patients with and without vascular disease and that their cognitive profiles differ. Furthermore, CAB classified the patients as vascular and non-vascular MCI with good sensitivity and specificity.

Cognitive effects of a dietary supplement made from extract of Bacopa monnieri, astaxanthin, phosphatidylserine, and vitamin E in subjects with mild cognitive impairment: a noncomparative, exploratory clinical study

A prospective cohort, noncomparative, multicenter trial was conducted to explore the potential of a phytotherapeutic compound, available as a dietary supplement and containing extracts of Bacopa monnieri and Haematococcus pluvialis (astaxanthin) plus phosphatidylserine and vitamin E, in improving cognition in subjects diagnosed with mild cognitive impairment. Enrolled subjects (n=104) were aged 71.2±9.9 years and had a mini-mental state examination score of 26.0±2.0 (mean ± standard deviation). They underwent the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) test and the clock drawing test at baseline and upon completion of a 60-day period of dietary supplementation with one tablet daily of the tested compound. In 102 assessable subjects, total ADAS-cog scores improved from 13.7±5.8 at baseline to 9.7±4.9 on day 60, and the clock drawing test scores improved from 8.5±2.3 to 9.1±1.9. Both changes were statistically significant (P<0.001). Memory tasks were the individual components of ADAS-cog showing the largest improvements. In a multivariate analysis, larger improvements in total ADAS-cog score were associated with less compromised baseline mini-mental state examination scores. Perceived efficacy was rated as excellent or good by 62% of study subjects. The tested compound was well tolerated; one nonserious adverse event was reported in the overall study population, and perceived tolerability was rated excellent or good by 99% of the subjects. In conclusion, dietary supplementation with the tested compound shows potential for counteracting cognitive impairment in subjects with mild cognitive impairment and warrants further investigation in adequately controlled, longer-term studies.

A systematic review of screening tools for predicting the development of dementia

Early detection of dementia is essential to guide front-line health care practitioners in further clinical evaluations and treatments. There is a paucity of literature assessing the effectiveness of screening tools to predict the development of dementia, thus we conducted a systematic review to fill this gap. The purpose of the systematic review was to make recommendations to health care practitioners on which screening tool best predicts the development of dementia and is most feasible in the primary care setting. Ten databases were searched for relevant articles, yielding 751 papers. Of these, 12 met relevance criteria for inclusion. Screening tools were assessed for test accuracy, cognitive domain coverage, predictive ability, and feasibility. Four screening tools were recommended. Addenbrooke's Cognitive Examination (ACE) was considered to be the ideal tool. A revised version of this tool is now used in clinical practice but the psychometric properties of the ACE-R remain to be established.

Vascular predictors of cognitive decline in patients with mild cognitive impairment

Our aim in this study was to assess the relationship between the state of cerebral vessels and the risk of conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD). We included 117 MCI patients. They underwent an ultrasonographic assessment of common carotid arteries intima-media thickness (IMT) and carotid plaque index. Cerebrovascular reactivity to hypercapnia in the middle cerebral arteries was calculated with the Breath-Holding Index (BHI). After a 12-month follow-up period, neuropsychological examinations demonstrated a progression to dementia in 21 patients. Pathological values of BHI and IMT significantly increased the risk of conversion (BHI: odds ratio, 5.80; 95% confidence interval, 1.83-18.37, p < 0.05; IMT: odds ratio, 3.08; 95% confidence interval, 1.02-9.33; p < 0.05, multinomial logistic regression analysis). Comparison between patients with all normal values and those with the simultaneous alteration of the 2 vascular indexes showed an increase in the risk of conversion from 9% to 33% (ordinal regression analysis). Our findings show that alterations of cerebral vessel functional and anatomic status increase the risk of conversion from MCI to dementia.

Population-based distribution and psychometric properties of a short cognitive performance measure in the population-based Heinz Nixdorf Recall Study

BACKGROUND

Providing a valid and sensitive measure of different domains of cognitive performance in epidemiologic studies of early old-age populations presents a methodological challenge, given the broad range of variability in cognitive functioning in this age group.

OBJECTIVES

(1) To provide data on the distribution of cognitive performance scores in a representative sample of an early old-age population, and (2) to assess psychometric properties of a short cognitive performance measure developed within the framework of a cohort study.

DESIGN

Population-based cohort study.

SETTING AND PARTICIPANTS

As part of the second examination of the Heinz Nixdorf Recall Study, 4,145 participants aged 50-80 years underwent a short cognitive performance assessment composed of 5 subtests with a mean duration of 7.31 min. Additionally, a subsample of 656 participants had a detailed neuropsychological and neurological examination.

METHODS

Age- and education-specific cognitive performance scores in the total sample were calculated. Based on data from the subsample, concurrent validity was examined by comparing findings with a clinically validated neuropsychological assessment.

RESULTS

In the total sample, younger and more highly educated participants had higher scores of cognitive performance. In the subsample, a good accuracy [area under the curve (AUC) = 0.81 (0.74-0.87)] of the short cognitive performance assessment compared with results from a clinically established Alzheimer disease assessment scale and diagnosis of mild cognitive impairment [AUC = 0.82 (0.78-0.82)] was observed.

CONCLUSION

This brief, cognitive performance measure, documenting good psychometric properties, can be useful in future epidemiological investigations exploring different domains and overall cognitive functioning in early old-age populations.

Touch Panel-type Dementia Assessment Scale: a new computer-based rating scale for Alzheimer's disease

BACKGROUND

The Alzheimer's Disease Assessment Scale (ADAS) was designed as a rating scale for the severity of dysfunction in the cognitive and non-cognitive behaviours that are characteristic of persons with Alzheimer's disease. Its subscale, the ADAS-cog, is a cognitive testing instrument most widely used to measure the impact of the disease. However, the ADAS-cog takes more than 45 min to administer and requires a qualified clinical psychologist as the rater. A more comprehensive rating battery is therefore required. In the present study, we developed a computerized test battery named the Touch Panel-type Dementia Assessment Scale (TDAS), which was intended to substitute for the ADAS-Cog, and was specifically designed to rate cognitive dysfunction quickly and without the need of a specialist rater.

METHODS

The hardware for the TDAS comprises a 14-inch touch panel display and computer devices built into one case. The TDAS runs on Windows OS and was bundled with a custom program made with reference to the ADAS-cog. Participants in the present study were 34 patients with Alzheimer's disease. Each participant was administered the ADAS-cog and the TDAS. The test scores for each patient were compared to determine whether the severity of cognitive dysfunction of the patients could be rated equally as well by both tests.

RESULTS

Pearson's correlation coefficient showed a significant correlation between the total scores (r= 0.69, P < 0.01) on the two scales for each patient. The Kendall coefficients of concordance obtained for the three corresponding pairs of tasks (word recognition, orientation, and naming object and fingers) showed the three TDAS tasks can rate symptoms of cognitive decline equally as well as the corresponding items on the ADAS-cog.

CONCLUSIONS

The TDAS appears to be a sensitive and comprehensive assessment battery for rating the symptoms of Alzheimer's disease, and can be substituted for the ADAS-cog.

Predicting conversion from mild cognitive impairment to Alzheimer's disease using neuropsychological tests and multivariate methods

Behavioral markers measured through neuropsychological testing in mild cognitive impairment (MCI) were analyzed and combined in multivariate ways to predict conversion to Alzheimer's disease (AD) in a longitudinal study of 43 MCI patients. The test measures taken at a baseline evaluation were first reduced to underlying components (principal component analysis, PCA), and then the component scores were used in discriminant analysis to classify MCI individuals as likely to convert or not. When empirically weighted and combined, episodic memory, speeded executive functioning, recognition memory (false and true positives), visuospatial memory processing speed, and visuospatial episodic memory were together strong predictors of conversion to AD. These multivariate combinations of the test measures achieved through the PCA were good, statistically significant predictors of MCI conversion to AD (84% accuracy, 86% sensitivity, and 83% specificity). Importantly, the posterior probabilities of group membership that accompanied the binary prediction for each participant indicated the confidence of the prediction. Most of the participants (81%) were in the highly confident probability bins (.70-1.00), where the obtained prediction accuracy was more than 90%. The strength and reliability of this multivariate prediction method were tested by cross-validation and randomized resampling.

An MRI substudy of a donepezil clinical trial in mild cognitive impairment

A magnetic resonance imaging (MRI) study was conducted as part of an intervention study in subjects with amnestic mild cognitive impairment (aMCI) to assess donepezil's treatment effect on brain atrophy. Adults with aMCI were randomly assigned to double-blind treatment with 10 mg/day donepezil hydrochloride or placebo for 48 weeks. Brain MRI scans were acquired at baseline and endpoint. The primary outcome measure was annualized percentage change (APC) in hippocampal volume; the main secondary outcome measure was APC in whole brain volumes. An analysis of variance (ANOVA) model including terms for treatment, site, and age was used to compare the treatment groups. APCs for hippocampal volumes were not significantly different between treatment groups. There were significant differences favoring the donepezil group for total (p = 0.001), ventricular region (p = 0.0002), and cortical region (p = 0.003) whole brain volumes. Although the primary MRI outcome measure was negative, the main secondary MRI outcome measure showed a positive result. These findings suggest a treatment effect of donepezil on brain atrophy in aMCI.

Ibuprofen treatment modifies cortical sources of EEG rhythms in mild Alzheimer's disease

OBJECTIVE

Non-steroidal anti-inflammatory drugs such as ibuprofen have a protective role on risk of Alzheimer's disease (AD). Here we evaluated the hypothesis that long-term ibuprofen treatment affects cortical sources of resting electroencephalographic (EEG) rhythms in mild AD patients.

METHODS

Twenty-three AD patients (13 treated AD IBUPROFEN; 10 untreated AD PLACEBO) were enrolled. Resting EEG data were recorded before and 1 year after the ibuprofen/placebo treatment. EEG rhythms were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). LORETA was used for EEG source analysis.

RESULTS

In the AD PLACEBO group, amplitude of delta sources was globally greater at follow-up than baseline. Instead, amplitude of delta sources remained stable or decreased in the majority of the AD IBUPROFEN patients. Clinical (CDR) but not global cognitive status (MMSE) reflected EEG results.

CONCLUSIONS

These results suggest that in mild AD patients, a long-term ibuprofen treatment slightly slows down the progressive increment of delta rhythms as a sign of contrast against the neurodegenerative processes.

SIGNIFICANCE

They motivate future investigations with larger population and extended neuropsychological testing, to study the relationships among ibuprofen treatment, delta cortical sources, and higher order functions.