The prognosis of mild cognitive impairment in the elderly

Aggressive behavior and prognosis in patients with mild cognitive impairment

The diagnosis of mild cognitive impairment (MCI) is associated with an increased risk of developing dementia. When evaluating the further prognosis of MCI, the occurrence of neuropsychiatric symptoms, particularly aggressive and impulsive behavior, may play an important role.

Objective

The aim of this study was to evaluate the relationship between aggressive behavior and cognitive dysfunction in patients diagnosed with MCI.

Methods

The results are based on a 7-year prospective study. At the time of inclusion in the study, participants, recruited from an outpatient clinic, were assessed with Mini-Mental State Examination (MMSE) and the Cohen-Mansfield Agitation Inventory (CMAI). A reassessment was performed after 1 year using the MMSE scale in all patients. The time of next MMSE administration was depended on the clinical condition of patients took place at the end of follow-up, that is, at the time of diagnosis of the dementia or after 7 years from inclusion when the criteria for dementia were not met.

Results

Of the 193 patients enrolled in the study, 75 were included in the final analysis. Patients who converted to dementia during the observation period exhibited a greater severity of symptoms in each of the assessed CMAI categories. Moreover, there was a significant correlation between the global result of CMAI and the results of the physical nonaggressive and verbal aggressive subscales with cognitive decline during the first year of observation.

Conclusions

Despite several limitations to the study, aggressive and impulsive behaviors seem to be an unfavorable prognostic factor in the course of MCI.

Brain amyloid accumulation possibly exacerbates concurrent mild cognitive impairment with subthreshold depression in older adults: A 1-year follow-up study

BACKGROUND

This study aimed to investigate the 1-year changes in neuropsychological test results in older adults with concomitant late-life depression (LLD) and mild cognitive impairment (MCI) according to the presence or absence of brain amyloidopathy.

METHODS

All subjects underwent ¹⁸F-florbetaben-positron emission tomography and a standardized neuropsychological battery. The subjects were divided based on brain amyloidopathy and severity of depressive symptoms into the following groups: LLD-MCI-A(+), subthreshold depression (STD)-MCI-A(+), major depressive disorder (MDD)-MCI-A(+), LLD-MCI-A(-), STD-MCI-A(-), and MDD-MCI-A(-). After one year, follow-up neurocognitive tests were conducted. Fifty-nine participants completed both the baseline and 1-year follow-up neurocognitive tests.

RESULTS

In the LLD-MCI-A(+) group, the word list recall and word list recognition scores decreased during the follow-up period. The STD-MCI-A(+) group also showed a significant decrease in word list recall score and the score/Z-score of word list recognition. On the other hand, the word list recall Z-score improved at the 1-year follow-up in the LLD-MCI-A(-) group. In particular, the MDD-MCI-A(-) group showed significant increases in word list memory score/Z-score and word list recall Z-score during the follow-up period.

LIMITATIONS

Considering that AD progresses slowly, a longer follow-up period may be required.

CONCLUSIONS

Our findings showed differences in the extent of change of neuropsychological test results depending on the severity of depressive symptoms and presence or absence of brain amyloidopathy. Our results suggest that clinicians might explore the underlying neuropathology when assessing older adults with concomitant depression and cognitive impairment, even if the symptoms of depression are not severe.

The Comparative Efficacy of Multiple Interventions for Mild Cognitive Impairment in Alzheimer's Disease: A Bayesian Network Meta-Analysis

Background: Mild cognitive impairment (MCI) is the early phase of Alzheimer's disease (AD). The aim of early intervention for MCI is to decrease the rate of conversion from MCI to AD. However, the efficacy of multiple interventions in MCI, and the optimal methods of delivery, remain controversial. We aimed to compare and rank the treatment methods for MCI in AD, in order to find an optimal intervention for MCI and a way to prevent or delay the occurrence of AD. Methods: Pair-wise and network meta-analysis were conducted to integrate the treatment effectiveness through direct and indirect evidence. Four English databases and three Chinese databases were searched for international registers of eligible published, single or double blind, randomized controlled trials up to September 31st 2019. We included nine comparative interventions: pharmacological therapies which incorporated cholinesterase inhibitors (ChEI), ginkgo, nimodipine, and Chinese medicine; non-pharmacological therapies comprising of acupuncture, music therapy, exercise therapy, and nutrition therapy; and a placebo group. The primary outcome was the Mini-Mental State Examination (MMSE) score. The secondary outcome was the AD Assessment Scale-cognitive subscale (ADAS-cog). Results: Twenty-eight trials were eligible, including 6,863 participants. In the direct meta-analysis, as for the Mini-Mental State Examination scale, the ChEIs (MD: -0.38; 95% CI: -0.74, -0.01), Chinese medicine (MD: -0.31; 95% CI: -0.75, 0.13), exercise therapy (MD: -0.50; 95% CI: -0.65, -0.35), music therapy (MD: -1.71; 95% CI: -4.49, 1.07), were statistically more efficient than placebo. For AD Assessment Scalecognitive subscale outcome, ChEIs (MD: 1.20; 95% CI: 0.73, 1.68), Acupuncture (MD: 1.36; 95% CI: 1.28, 1.44), Chinese medicine (MD: 0.61; 95% CI: 0.49, 0.73) and exercise (MD: 0.61; 95% CI: 0.49, 0.73) were better than placebo. In the network meta-analysis, the MMSE outcome ranked music therapy (59%) as the best and Acupuncture (26%) as second. Nutrition and Ginkgo treatment had the lowest rank among all interventions. For ADAS-cog outcome, acupuncture (52) ranked the best. Conclusion: Among the nine treatments studied, music therapy appears to be the best treatment for MCI, followed by acupuncture. Our study provides new insights into potential clinical treatments for MCI due to AD, and may aid the development of guidelines for MCI in AD.

Prediction of Cognitive Decline in Temporal Lobe Epilepsy and Mild Cognitive Impairment by EEG, MRI, and Neuropsychology

Cognitive decline is a severe concern of patients with mild cognitive impairment. Also, in patients with temporal lobe epilepsy, memory problems are a frequently encountered problem with potential progression. On the background of a unifying hypothesis for cognitive decline, we merged knowledge from dementia and epilepsy research in order to identify biomarkers with a high predictive value for cognitive decline across and beyond these groups that can be fed into intelligent systems. We prospectively assessed patients with temporal lobe epilepsy (N = 9), mild cognitive impairment (N = 19), and subjective cognitive complaints (N = 4) and healthy controls (N = 18). All had structural cerebral MRI, EEG at rest and during declarative verbal memory performance, and a neuropsychological assessment which was repeated after 18 months. Cognitive decline was defined as significant change on neuropsychological subscales. We extracted volumetric and shape features from MRI and brain network measures from EEG and fed these features alongside a baseline testing in neuropsychology into a machine learning framework with feature subset selection and 5-fold cross validation. Out of 50 patients, 27 had a decline over time in executive functions, 23 in visual-verbal memory, 23 in divided attention, and 7 patients had an increase in depression scores. The best sensitivity/specificity for decline was 72%/82% for executive functions based on a feature combination from MRI volumetry and EEG partial coherence during recall of memories; 95%/74% for visual-verbal memory by combination of MRI-wavelet features and neuropsychology; 84%/76% for divided attention by combination of MRI-wavelet features and neuropsychology; and 81%/90% for increase of depression by combination of EEG partial directed coherence factor at rest and neuropsychology. Combining information from EEG, MRI, and neuropsychology in order to predict neuropsychological changes in a heterogeneous population could create a more general model of cognitive performance decline.

[Mild cognitive impairment: what's next?]

The concept of mild cognitive impairment is one of the promising directions for studying the predementia stages of different diseases. The feasibility of studying this phenomenon is due not only to a high risk of dementia, but also the potential reversibility of cognitive decline in old age. Long-term follow-up of patients shows different trajectories of cognitive decline in aging. The study of risk factors for the progression of moderate cognitive impairment provided an opportunity to highlight new horizons of prevention of dementia of various etiologies. Despite the insufficient effectiveness of drug therapy in patients with moderate cognitive impairment, exploring the opportunities for possible treatment of their subtypes seems promising from the point of view of improving clinical symptoms and a possible reduction in the rate of disease progression.

Evaluating trajectories of episodic memory in normal cognition and mild cognitive impairment: Results from ADNI

BACKGROUND

Memory assessment is a key factor for the diagnosis of cognitive impairment. However, memory performance over time may be quite heterogeneous within diagnostic groups.

METHOD

To identify latent trajectories in memory performance and their associated risk factors, we analyzed data from Alzheimer's Disease Neuroimaging Initiative (ADNI) participants who were classified either as cognitively normal or as Mild Cognitive Impairment (MCI) at baseline and were administered the Rey Auditory Verbal Learning test (RAVLT) for up to 9 years. Group-based trajectory modeling on the 30-minute RAVLT delayed recall score was applied separately to the two baseline diagnostic groups.

RESULTS

There were 219 normal subjects with mean age 75.9 (range from 59.9 to 89.6) and 52.5% male participants, and 372 MCI subjects with mean age 74.8 (range from 55.1 to 89.3) and 63.7% male participants included in the analysis. For normal subjects, six trajectories were identified. Trajectories were classified into three types, determined by the shape, each of which may comprise more than one trajectory: stable (~30% of subjects), curvilinear decline (~ 28%), and linear decline (~ 42%). Notably, none of the normal subjects assigned to the stable stratum progressed to dementia during the study period. In contrast, all trajectories identified for the MCI group tended to decline, although some participants were later re-diagnosed with normal cognition. Age, sex, and education were significantly associated with trajectory membership for both diagnostic groups, while APOE ɛ4 was only significantly associated with trajectories among MCI participants.

CONCLUSION

Memory trajectory is a strong indicator of dementia risk. If likely trajectory of memory performance can be identified early, such work may allow clinicians to monitor or predict progression of individual patient cognition. This work also shows the importance of longitudinal cognitive testing and monitoring.

Mild cognitive impairment in primary care: a clinical review

Dementia is projected to become a global health priority but often not diagnosed in its earlier preclinical stage which is mild cognitive impairment (MCI). MCI is generally referred as a transition state between normal cognition and Alzheimer’s disease. Primary care physicians play an important role in its early diagnosis and identification of patients most likely to progress to Alzheimer’s disease while offering evidenced-based interventions that may reverse or halt the progression to further cognitive impairment. The aim of this review is to introduce the concept of MCI in primary care through a case-based clinical review. We discuss the case of a patient with MCI and provide an evidence-based framework for assessment, early recognition and management of MCI while addressing associated risk factors, neuropsychiatric symptoms and prognosis.

Preliminary evidence for an increased likelihood of a stable trajectory in mild cognitive impairment in individuals with higher motivational abilities

BACKGROUND

Motivational abilities (MA), that describe skills in relation to goal-oriented behavior, have recently been found to be associated with neuropathological aging. Here we examine the impact of MA on the long-term course of mild cognitive impairment (MCI).

METHODS

We followed-up N = 64 individuals diagnosed with MCI (Mage = 73 years, 44% female) for 3 years. MA were assessed by long-term informants of the participants using two scales: motivation and decision regulation [Volitional Components Questionnaires, VCQ, (Kuhl and Fuhrmann, Decomposing self-regulation and self-control: the volitional components inventory, 1998)]. Cognitive abilities were assessed with the Mini Mental State Examination (J Psychiatr Res 12:189-98, 1975). Survival analyses and multilevel modeling (MLM) were applied to determine the predicting effect of informant-rated MA at baseline on the likelihood of MCI stability and on the trajectory of cognitive abilities.

RESULTS

Fifty percent (n = 32) of the MCI participants remained stable, while 32.8% (n = 21) and 17.2% (n = 11) converted to Alzheimer's disease (AD) or dropped-out, respectively. Survival analyses revealed that MCI cases with higher-rated MA at baseline were more likely to exert a stable course in MCI over 3 years (p = 0.036) when controlling for demographic characteristics and executive function. MLM analyses indicated that higher informant-rated MA at baseline were significantly related to higher cognitive abilities, even when controlling for MCI subtype (p = 0.030).

CONCLUSIONS

This study provides preliminary longitudinal evidence for a lower risk of conversion to AD and higher cognitive abilities by higher rated MA at an early stage of MCI.

Can a Resting-State Functional Connectivity Index Identify Patients with Alzheimer's Disease and Mild Cognitive Impairment Across Multiple Sites?

Resting-state functional connectivity is one promising biomarker for Alzheimer's disease (AD) and mild cognitive impairment (MCI). However, it is still not known how accurately network analysis identifies AD and MCI across multiple sites. In this study, we examined whether resting-state functional connectivity data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) could identify patients with AD and MCI at our site. We implemented an index based on the functional connectivity frequency distribution and compared performance for AD and MCI identification with multivoxel pattern analysis. The multivoxel pattern analysis using a connectivity map of the default mode network showed good performance, with an accuracy of 81.9% for AD and MCI identification within the ADNI, but the classification model obtained from the ADNI failed to classify AD, MCI, and healthy elderly adults from our site, with an accuracy of only 43.1%. In contrast, a functional connectivity index of the medial temporal lobe based on the frequency distribution showed moderate performance, with an accuracy of 76.5-80.3% for AD identification within the ADNI. The performance of this index was similar for our data, with an accuracy of 73.9-82.6%. The frequency distribution-based index of functional connectivity could be a good biomarker for AD across multiple sites.

Neuropsychiatric symptoms and faster progression of cognitive impairments as predictors of risk of conversion of mild cognitive impairment to dementia

INTRODUCTION

The aim of this research, based on 7 years of observations, was to assess the relationship between the dynamics of changes in the realm of cognitive functions in the early stages of observations and the presence of neuropsychiatric symptoms as well as further progression of cognitive function impairments in people diagnosed with mild cognitive impairment (MCI).

MATERIAL AND METHODS

One hundred and ninety three individuals were included in the study, all of whom referred themselves to the Mental Health Clinic and were diagnosed with MCI based on the criteria of the Working Group on MCI. It was assumed that these individuals would be subjected to systematic psychiatric and neuropsychological observation until they were diagnosed with dementia. This report concerns a completed 7-year period of these observations. Participants were assessed based on the following scales: MMSE, NPI and GDS.

RESULTS

The obtained results indicate statistically significant differences between groups of subjects at the time of inclusion in the study, regarding the frequency of occurrence and severity of the following categories of impairments: thought impairments (p < 0.001), arousal/aggression (p < 0.001), depression/dysphoria (p < 0.001), disinhibition (p < 0.03), irritability/lability (p < 0.001), abnormal motor behaviors (p < 0.02), as well as sleep and night-time behavior disorders (p < 0.01) Moreover, individuals who developed dementia during observation exhibited greater progression in cognitive function impairment assessed with the MMSE scale in the first year of observation (p < 0.01).

CONCLUSIONS

The accruing of cognitive function impairments and the presence of neuropsychiatric symptoms seem to be important risk factors for the development of dementia.

The Effects of Intellectual, Physical, and Social Activity on Further Prognosis in Mild Cognitive Impairment

Background

Our goal was to specify the relationship between the level of activity (intellectual, physical, and social) in persons diagnosed with mild cognitive impairment (MCI) and the further progression of cognitive dysfunction.

Material/Methods

We examined 193 patients diagnosed with MCI (according to the criteria of the Working Group on Mild Cognitive Impairment) and under treatment at our Mental Disorders Clinic. It was assumed that these persons would remain under systematic psychiatric observation until dementia was diagnosed. The present study results from a seven-year observation period. The mini–mental state examination (MMSE), the Activity Scale (with the intellectual, physical, and social subscales), and the Instrumental Activities of Daily Living (IADL) scale were used to evaluate the participants’ status at baseline. The MMSE was re-administered after one year and again at the end of the observation (either upon diagnosis of dementia or after seven years). At each meeting with the participant, the clinical diagnosis was verified to determine if the patient had dementia or not. Of the 193 people initially qualified for the study, 75 were available for the final analysis.

Results

It was found that there was no statistically significant difference in the baseline MMSE scores between the persons with stable MCI and the persons who had progressed to dementia. However, statistically significant differences in the level of activity at baseline on both the global IADL scale and the Activity Scale between those with stable MCI and those who had progressed to dementia were found. These differences were manifested in the IADL subscales for telephone use, shopping, transportation, and personal finances, and in the physical activity subscale.

Conclusions

An evaluation of intellectual, physical, and social activity can be useful in determining the prognosis for the future course of MCI.

Effects of Transcutaneous Electrical Nerve Stimulation (TENS) on Self-Efficacy and Mood in Elderly with Mild Cognitive Impairment

In previous studies, transcutaneous electrical nerve stimulation (TENS) has been applied to patients with either Alzheimer’s disease (AD) or incipient dementia, resulting in an enhancement in memory and verbal fluency. Moreover, affective behavior was shown to improve. Based on the positive effects of TENS in AD, it was hypothesized that TENS would improve self-efficacy in nondemented elderly with mild cognitive impairment (MCI) who live in a residential home. Four outcome measures, that is, a Dutch translation of the General Self-Efficacy Scale (Algemene Competentie Schaal), the Groninger Activity Restriction Scale, the Philadelphia Geriatric Center Morale Scale, and the Geriatric Depression Scale, were administered. Overall, the results suggest that the experimental group showed a mild improvement in self-efficacy and mood. In contrast, the placebo group showed a considerable reduction in self-efficacy and an increase in depression. Limitations of the present study and suggestions for future research are discussed.

Efficacy and safety of Ginkgo biloba extract EGb 761 in mild cognitive impairment with neuropsychiatric symptoms: a randomized, placebo-controlled, double-blind, multi-center trial

OBJECTIVE

The study was conducted to explore the effects of EGb 761 (Dr. Willmar Schwabe GmbH & Co. KG, Karlsruhe, Germany) on neuropsychiatric symptoms (NPS) and cognition in patients with mild cognitive impairment (MCI).

METHODS

One hundred and sixty patients with MCI who scored at least 6 on the 12-item Neuropsychiatric Inventory (NPI) were enrolled in this double-blind, multi-center trial and randomized to receive 240 mg EGb 761 daily or placebo for a period of 24 weeks. Effects on NPS were assessed using the NPI, the state sub-score of the State-Trait Anxiety Inventory and the Geriatric Depression Scale. Further outcome measures were the Trail-Making Test (A/B) for cognition and global ratings of change. Statistical analyses followed the intention-to-treat principle.

RESULTS

The NPI composite score decreased by 7.0 ± 4.5 (mean, standard deviation) points in the EGb 761-treated group and by 5.5 ± 5.2 in the placebo group (p = 0.001). Improvement by at least 4 points was found in 78.8% of patients treated with EGb 761 and in 55.7% of those receiving placebo (p = 0.002). Superiority of EGb 761 over placebo (p < 0.05) was also found for the State-Trait Anxiety Inventory score, the informants' global impression of change, and both Trail-Making Test scores. There were statistical trends favoring EGb 761 in the Geriatric Depression Scale and the patients' global impression of change. Adverse events (all non-serious) were reported by 37 patients taking EGb 761 and 36 patients receiving placebo.

CONCLUSIONS

EGb 761 improved NPS and cognitive performance in patients with MCI. The drug was safe and well tolerated.

Mild cognitive impairment and mood: a systematic review

This systematic review, with meta-analyses conducted where data were available, aimed to investigate the prevalence of symptoms of depression and anxiety in mild cognitive impairment (MCI), and to establish how symptoms of depression and anxiety relate to the progression from no cognitive impairment to MCI, and from MCI to dementia. Sixty studies were included in the review. Meta-analyses indicated that symptoms of depression and anxiety were more prevalent in people with MCI than in people with normal cognitive function, and increased the risk of progression from no cognitive impairment to MCI. There were mixed results regarding the effect of such symptoms on progression from MCI to dementia. The findings highlight the need for more research in this area, which can inform attempts to slow or halt the progression of cognitive impairment in later life, with resulting benefits for quality of life.

Mild cognitive impairment: an epidemiological perspective

Mild cognitive impairment (MCI) refers to cognitive impairment that is assumed to be due to pathological central nervous system processes, but which interacts with normal aging-related changes. Epidemiological studies conducted in the general population have been able to examine more heterogeneous forms of this disorder than clinical studies, and have also been able to provide early estimations of population incidence and prevalence. Large differences in case identification procedures and sampling methods have led to considerable divergence in the rates of prevalence reported, which ranged from 1% to 29%. Suggested improvements in the definition of MCI have led to an upward adjustment of prevalence rates in most studies, giving between 5% and 29%. Incidence is estimated as 8 to 58 new cases per thousand persons per year, and the probability of conversion from MCI to dementia is estimated at around 15%. The principal risk factors that have been identified so far for MCI using regression models applied to general population data are age, education, race, medicated hypertension, infarcts, white matter lesions, depression, and apolipoprotein E4 (AP0E-4J allele. An etiological model derived from these studies indicates possible intervention points for future therapeutic strategies at the level of both clinical intervention and environmental exposure. There is, however, a clear need for epidemiological studies that take into account a broader range of risk factors than those studied to date, which have focused principally on known risk factors for dementia.

Progression from mild to pronounced MCI is not associated with cerebrospinal fluid biomarker deviations

BACKGROUND/AIM

Detection of cerebrospinal fluid (CSF) biomarker deviations improve prediction of progression from mild cognitive impairment (MCI) to dementia. However, it is not settled whether the same pattern exists in patients progressing from very mild to more pronounced MCI. Given that neurodegenerative processes occur very early in the disease course, we also expected to find biomarker deviations in these patients.

METHODS

A total of 246 memory clinic patients with non-progressive (n = 161), progressive (n = 19), or converting (n = 66) MCI, 67 with stable dementia, and 80 controls were followed for 24 months. At baseline, CSF total tau (T-tau), β-amyloid 1-42 (Aβ42) and the light subunit of neurofilament protein (NFL) were determined.

RESULTS

Patients with converting MCI and stable dementia had lower CSF Aβ42 concentrations and higher T-tau concentrations and NFL in comparison with controls and non-progressive/progressive MCI (p < 0.0005). No differences were found between progressive and non-progressive MCI.

CONCLUSION

As expected, biomarker deviations predicted progression from MCI to dementia. Contrary to our hypothesis, progression from very mild MCI to more pronounced MCI was not reflected by biomarker deviations. The results suggest that the measured biomarkers are not early disease markers, or alternatively Alzheimer or vascular pathology is not the underlying cause in this patient group.

Estimation of the risk of conversion of mild cognitive impairment of Alzheimer type to Alzheimer's disease in a south Brazilian population-based elderly cohort: the PALA study

BACKGROUND

Higher mild cognitive impairment (MCI) prognostic variability has been related to sample characteristics (community-based or specialized clinic) and to diverse operationalization criteria. The aim of the study was to evaluate the trajectory of MCI of Alzheimer type in a population-based elderly cohort in Southern Brazil. We also estimated the risk for the development of probable Alzheimer's disease (AD) in comparison with healthy subjects.

METHODS

Data were derived from a population-based cohort (the PALA study). MCI outcomes were sub-classified into three categories: conversion, stabilization, and reconversion. The risk of progression to dementia was compared between MCI and normal participants. The analysis was based on 21 MCI subjects and 220 cognitively intact participants (N = 241).

RESULTS

Of the 21 MCI subjects, 38% developed dementia, 24% remained stable and 38% improved. The MCI annual conversion rate to AD was 8.5%. MCI was associated with significantly higher risk of conversion to AD (HR = 49.83, p = 0.004), after adjustment for age, education, sex and Mini-Mental State Examination score.

CONCLUSIONS

Independent of the heterogeneity of the outcomes, MCI of the Alzheimer type participants showed significantly higher risk of developing probable AD, demonstrating the impact of the use of these MCI criteria that emphasize long-term episodic memory impairment.

Association of ApoE and LRP mRNA levels with dementia and AD neuropathology

Inheritance of the ε4 allele of apolipoprotein E (ApoE) is the only confirmed and consistently replicated risk factor for late onset Alzheimer's disease (AD). ApoE is also a key ligand for low-density lipoprotein (LDL) receptor-related protein (LRP), a major neuronal low-density lipoprotein receptor. Despite the considerable converging evidence that implicates ApoE and LRP in the pathogenesis of AD, the precise mechanism by which ApoE and LRP modulate the risk for AD remains elusive. Moreover, studies investigating expression of ApoE and LRP in AD brain have reported variable and contradictory results. To overcome these inconsistencies, we studied the mRNA expression of ApoE and LRP in the postmortem brain of persons who died at different stages of dementia and AD-associated neuropathology relative to controls by quantitative polymerase chain reaction (qPCR) and Western blotting analyses. Clinical dementia rating scores were used as a measure of dementia severity, whereas, Braak neuropathological staging and neuritic plaque density were used as indexes of the neuropathological progression of AD. ApoE and LRP mRNA expression was significantly elevated in the postmortem inferior temporal gyrus (area 20) and the hippocampus from individuals with dementia compared with those with intact cognition. In addition to their strong association with the progression of cognitive dysfunction, LRP and ApoE mRNA levels were also positively correlated with increasing neuropathological hallmarks of AD. Additionally, Western blot analysis of ApoE protein expression in the hippocampus showed that the differential expression observed at the transcriptional level is also reflected at the protein level. Given the critical role played by LRP and ApoE in amyloid beta (Aβ) and cholesterol trafficking, increased expression of LRP and ApoE may not only disrupt cholesterol homeostasis but may also contribute to some of the neurobiological features of AD, including plaque deposition.

A validity study of the Working Group's Orientation Test for individuals with moderate to severe intellectual disability

BACKGROUND

Decline in orientation skill has been reported as an early indicator of Dementia of Alzheimer's Type (DAT). Orientation subtest of the Working Group's Test Battery was examined whether this test is useful to identify DAT patients among adults with moderate to severe ID.

METHODS

Sixteen DAT patients and 35 non-demented normal controls with moderate to severe ID were followed for a year using Orientation Test. The scores on the baseline evaluation and the longitudinal changes over a 1-year period among the DAT patients and the normal controls were compared. The effects of age and etiologies of ID on the performance of Orientation were also examined.

RESULTS

The DAT group's score was significantly poorer than that of the normal control group on the baseline evaluation. The score changes over the 1-year period were not significantly different between the groups. However, there was a considerable overlap between the score distributions of the two groups. The effects of age and etiologies of ID on the performance of Orientation were not significant.

CONCLUSIONS

Screening DAT patients based only on the score of the Orientation Test of the Working Group's Test Battery may produce a large number of diagnostic errors.

Rate of progression of mild cognitive impairment to dementia--meta-analysis of 41 robust inception cohort studies

OBJECTIVE

To quantify the risk of developing dementia in those with mild cognitive impairment (MCI).

METHOD

Meta-analysis of inception cohort studies.

RESULTS

Forty-one robust cohort studies were identified. To avoid heterogeneity clinical studies, population studies and clinical trials were analysed separately. Using Mayo defined MCI at baseline and adjusting for sample size, the cumulative proportion who progressed to dementia, to Alzheimer's disease (AD) and to vascular dementia (VaD) was 39.2%, 33.6% and 6.2%, respectively in specialist settings and 21.9%, 28.9% and 5.2%, respectively in population studies. The adjusted annual conversion rate (ACR) from Mayo defined MCI to dementia, AD and VaD was 9.6%, 8.1% and 1.9%, respectively in specialist clinical settings and 4.9%, 6.8% and 1.6% in community studies. Figures from non-Mayo defined MCI and clinical trials are also reported.

CONCLUSION

The ACR is approximately 5-10% and most people with MCI will not progress to dementia even after 10 years of follow-up.

White matter damage in Alzheimer disease and mild cognitive impairment: assessment with diffusion-tensor MR imaging and parallel imaging techniques

PURPOSE

To prospectively determine regional differences in fiber tract integrity between elderly patients with Alzheimer disease (AD), those with mild cognitive impairment (MCI), and healthy elderly subjects by using diffusion-tensor imaging with parallel imaging techniques and a new eight-element receiving coil.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. Fifteen patients with AD (seven men, eight women; mean age; 68.8 years), 16 patients with MCI (nine men, seven women; mean age, 68.9 years) and 19 healthy control subjects (eight men, 11 women; mean age, 63.9 years) underwent diffusion-tensor imaging performed with a 1.5-T magnetic resonance system. An echo-planar imaging diffusion sequence was used with an integrated parallel acquisition technique (PAT) and an eight-element head coil. The mean apparent diffusion coefficient (ADC), fractional anisotropy (FA), and relative anisotropy (RA) values of several white matter (WM) regions were determined. The Kruskal-Wallis test was used initially to test for overall equality of median values in each data group. Single posttest comparisons were performed with the Mann-Whitney U test, with an overall statistical significance level of .05.

RESULTS

FA and RA values were significantly (P < .05) decreased, whereas ADC values in the splenium of the corpus callosum were higher in patients with AD than in patients with MCI. Evidence of higher ADC values in the WM of the temporal lobe was observed in patients with AD compared with the ADC values in patients with MCI and in control subjects. ADC values in the parietal WM were significantly (P < .05) elevated in patients with MCI compared with those in control subjects. The images obtained with integrated PAT showed fewer susceptibility artifacts and were less distorted than images acquired without parallel imaging techniques.

CONCLUSION

Reduced FA and RA values in patients with AD suggest that diffusion-tensor imaging of the brain can be used to confirm clinical manifestation of AD but is less applicable in the detection of MCI.

A preliminary study of the validity of memory tests recommended by the Working Group for individuals with moderate to severe intellectual disability

BACKGROUND

Normal aging and Dementia of Alzheimer's Type (DAT) among higher functioning individuals with intellectual disability (ID) have been relatively well studied using a variety of cognitive tests. However, cognitive studies for lower functioning individuals with ID are scarce in the literature. The Working Group recommended the Test Battery for the Diagnosis of Dementia in Individuals with various level of ID. Few studies have investigated whether the Test Battery is useful to study dementia among individuals with moderate to severe ID. The purpose of this study is to investigate whether the memory subtests of the Test Battery are useful for measuring memory function and studying DAT in individuals with moderate to severe ID.

METHODS

We compared performances on the memory subtests in the Test Battery between 31 normal controls and 13 DAT patients with moderate to severe ID. Performance on the Picture Recognition Test was also compared between five normal controls and five DAT patients. This test was designed by our team to measure memory functions of individuals with moderate to severe ID.

RESULTS

Among the memory subtests of the Test Battery, the Autobiographical Memory and the Orientation were found to be useful for studying normal and abnormal aging among individuals with moderate to severe ID. Preliminary data for the Picture Recognition Test demonstrated that these individuals properly responded to this test and the majority of DAT patients could be differentiated from the normal controls based on their performance.

CONCLUSIONS

Further studies are necessary to improve usefulness of the memory subtests of the Test Battery for lower functioning individuals with ID. While the results suggest that the Picture Recognition Test may be more effective in discriminating individuals with DAT, given the very small sample sizes, a study with larger sample sizes should be undertaken to validate these findings.

Decreased theta event-related synchronization during working memory activation is associated with progressive mild cognitive impairment

BACKGROUND

Among the different quantitative electroencephalographic markers, theta activity is known to reflect neural resources involved in memory processes and directed attention. Previous studies suggested that synchronization likelihood analysis in theta-band frequency might be a sensitive method to identify early alterations of neuronal networks in mild cognitive impairment (MCI).

METHODS

We report here a longitudinal study of 24 MCI patients with theta event-related synchronization (ERS) analysis during the n-back working memory task and neuropsychological follow-up after 1 year. Statistical analysis included analysis of variance and logistic regression to assess the relationship between cognitive decline and theta ERS.

RESULTS

Upon follow-up, 13 MCI patients showed progressive MCI and 11 remained stable. In both groups, the phasic increase in theta amplitude after stimulus presentation did not depend on working memory load and electrode sites. Progressive MCI cases displayed significantly lower theta ERS power over all electrode sites compared to stable MCI cases. Theta ERS was significantly related to the cognitive outcome explaining 15.5% of its variability. In terms of MCI classification, the best combination of sensitivity and specificity was 0.87 and 0.60, respectively, with an area under the corresponding receiver operating characteristic curve reaching 76%.

CONCLUSIONS

The present data indicate that a decrease in the early phasic theta ERS power during working memory activation may predict cognitive decline in MCI. This phenomenon is not related to working memory load but may reflect the presence of early deficits in directed attention-related neural circuits in MCI.

Cognitive Impairment and Carotid Atherosclerosis in a General Italian Midlife and Old Population

The authors describe the design and the general, ultrasonographic, neuropsychological methodology of an observational epidemiological population survey, named REMEMBER (Registry Evaluation Memory in Buttrio e Remanzacco) conducted in the northeast of Italy in a randomized stratified sample of 1,026 subjects (554 F and 472 M) aged 55-98 years. The study was planned as cross-sectional and longitudinal survey of cognitive impairment, cardiovascular risk factors, carotid atherosclerosis in a midlife and older Italian population sample. The objectives of the first phase are to assess the prevalence of the different types of dementia, the cognitive impairment non-dementia, the cardiovascular risk factors, the carotid intima-media thickness and arterial distensibility, and of depression. The conclusions of this study will make it possible to organize preventive and interventional strategies for these epidemic conditions.

Neuropsychological markers of progression from mild cognitive impairment to Alzheimer's disease

To find early clinical markers that may predict a likely progression to Alzheimer's disease (AD), the authors performed neuropsychological tests on 82 mild cognitive impairment (MCI) subjects. After 3 years, 38 patients developed AD while 44 retained the diagnosis of MCI. The cognitive differences between the groups were studied. Patients who developed AD showed significantly lower values than did MCI subjects in some neuropsychological scores (P = .02-.001), with sensitivities and specificities higher than 84% and 64%, respectively, for detecting early-onset AD, with a 7.9-fold increased risk of converting to AD (P < .001). Regarding the logistic regression model, the CAMCOG Memory and Perception cognitive screening items were the optimum independent tools to classify the patients who will progress to AD, showing a relative risk of progression of 10.5 (P = .002), 5.5 (P = .008), and 3.9 times (P = .05), respectively, with a sensibility of of 92.1% and a specificity 72.7%.

A longitudinal study regarding conversion from mild memory impairment to dementia in a Japanese community

OBJECTIVE

To estimate the rate that subjects with Mild Memory Impairment /Not Dementia (MMI/ND) shifted to dementia in a population-based cohort and to establish simple diagnostic methods for identification of high-risk persons for dementia.

METHODS

Subjects in a community-based elderly cohort of MMI/ND were followed longitudinally. Subjects were selected from the participants in the first Nakayama study. MMI/ND was defined as memory deficit with objective memory assessment, without dementia, impairment of general cognitive function, or disability in activities of daily living. The conversion rate was calculated using the person-year method.

RESULTS

At baseline, the sample consisted of 104 subjects (59 female; 45 male) selected from 1,162 community dwellers aged over 65 year. During the five-year follow-up, 14 subjects died, 13 moved to other communities, and six refused to participate further. Eleven (10.6%) subjects were diagnosed with Alzheimer's disease (AD), five (4.8%) were diagnosed with vascular dementia (VaD), and six (5.8%) were diagnosed with dementia of other etiology. The annual conversion rate that MMI/ND shifted to AD is calculated on 8.5% per 100 person-year, and shifted to dementia on 16.1% per 100 person-year in this survey.

CONCLUSIONS

The rate at which subjects with MMI/ND whose conditions shifted to dementia was the same as the rate that subjects with mild cognitive impairment (MCI) shifted to dementia in a previous report. It would be useful to identify groups of high-risk individuals for dementia by simple diagnostic methods.

The Goteborg MCI study: mild cognitive impairment is a heterogeneous condition

BACKGROUND

Mild cognitive impairment (MCI) has been considered a transitional state between normal aging and dementia, characterised by memory impairment but normal general cognitive functioning. Recently other cognitive deficits have been reported. This has led to a modification of MCI criteria.

OBJECTIVE

To examine which neuropsychological tests most clearly distinguish MCI subjects from normal controls.

METHODS

112 consecutive MCI subjects and 35 controls were included in the study. The diagnosis of MCI was based on an objective history of cognitive decline and a neuropsychiatric examination, comprising instruments STEP, I-Flex, MMSE, and CDR. Participants were examined with 21 neuropsychological tests in the cognitive domains speed/attention, memory and learning, visuospatial function, language, and executive function.

RESULTS

Controls were significantly older. No differences were found in education or general intellectual capacity. Controls performed significantly better than MCI on tests within all five cognitive domains. The clearest differences were seen on language tests, followed by executive function, and learning and memory. Only two subjects (1.8%) were purely amnestic; 17% showed no impairment compared with controls, with a cut off of 1.5 SD below age mean. These subjects were better educated and performed significantly better on measures of general cognitive capacity.

CONCLUSIONS

The results illustrate the heterogeneity of MCI, with a significant degree of impairment in all five cognitive domains. When examined with a comprehensive neuropsychological battery, very few subjects had an isolated memory impairment.

Early Event-Related Potential Changes During Working Memory Activation Predict Rapid Decline in Mild Cognitive Impairment

BACKGROUND

The conversion of mild cognitive impairment (MCI) to Alzheimer's disease is associated with substantial compromise of neocortical circuits subserving rapid cognitive functions such as working memory. Event-related potential (ERP) analysis is a powerful tool to identify early impairment of these circuits, yet research for an electrophysiological marker of cognitive deterioration in MCI is scarce. Using a "2-back" activation paradigm, we recently described an electrophysiological correlate of working memory activation (positive-negative working memory [PN(wm)] component) over parietal electrodes.

METHODS

Ours was a longitudinal study of 24 MCI patients with ERP analysis at inclusion and neuropsychological follow-up after 1 year. We used ERP waveform subtraction analysis between the n-back and control tasks. Analysis of variance (ANOVA) was used to compare electroencephalograph latencies between progressive MCI (PMCI) and stable MCI (SMCI), and univariate regression was used to assess the relationship between neuropsychological measures at baseline and clinical outcome.

RESULTS

Thirteen (54%) MCI patients showed PMCI, and 11 (46%) remained stable (SMCI). In SMCI, a PN(wm) component with significantly larger density compared to baseline was identified when subtracting the detection task for both the 1- and 2-back tasks. In contrast, in PMCI, the PN(wm) component was absent in both 1-back and 2-back conditions. Neuropsychological variables and n-back test performance at inclusion did not predict cognitive deterioration 1 year later.

CONCLUSIONS

In conjunction with recent functional imaging data, the present results support the notion of an early dysfunction of neural generators within the parietal cortex in MCI. They also reveal that the absence of the PN(wm) component may provide an easily applicable qualitative predictive marker of rapid cognitive deterioration in MCI.

Psychiatric aspects of mild cognitive impairment

Mild cognitive impairment in the elderly may represent a transitional phase between normal aging and early Alzheimer's disease (AD). It recently has been recognized as a distinct clinical entity with potentially different cognitive subtypes and etiologies. Like AD, studies have shown that psychiatric symptoms are more common than in the cognitively normal geriatric population. Understanding these symptoms has been recognized as important not only because they may impair patient function and caregiver burden, but also these symptoms may be relevant to understanding the development of AD in general. This article presents current information on psychiatric symptoms in mild cognitive impairment, their suggested role in the pathophysiology of AD and future research considerations on the subject.

Predictors of reversible mild cognitive impairment after stroke: a 2-year follow-up study

Many studies have investigated mild cognitive impairment (MCI) in the context of prodromal dementia, but few have investigated recovery from MCI. The aim of this study was to determine the prevalence of reversible MCI after stroke and to identify factors related to recovery.

METHODS

One hundred and eighteen patients with a first ever cerebral stroke were followed up for 2 years. Neuropsychological assessment was performed at 1, 6, 12, and 24 months poststroke. Possible predictors of reversible MCI were demographic variables, baseline MMSE scores, presence of stroke risk factors, and CT variables. Poststroke MCI was diagnosed when there was a deficit in at least one cognitive domain, without their being demented. Recovery was considered when MCI was no longer present.

RESULTS

Twenty-four (20.3%) patients were classified as having permanent reversible MCI and were compared with patients without recovery. Most patients recovered from MCI between the first and second assessments (19.7% versus 13.1% and 2.0% later on). Higher baseline MMSE scores and female sex were independent predictors of recovery (OR(High MMSE)=9.9; OR(female sex)=2.8). Neither stroke-related risk factors nor CT variables were predictors of favorable outcome.

CONCLUSION

About 20% of patients with poststroke MCI recover from MCI. Higher MMSE scores at baseline and female sex are independent predictors of this recovery.

Similar 1H magnetic resonance spectroscopic metabolic pattern in the medial temporal lobes of patients with mild cognitive impairment and Alzheimer disease

Structures of the medial temporal lobes are recognized to play a central role in memory processing and to be the primary sites of deterioration in Alzheimer disease (AD). Mild cognitive impairment (MCI) represents potentially an intermediate state between normal aging and AD. Proton magnetic resonance spectroscopy (MRS) was used to examine brain metabolic changes in patients with AD and MCI in the medial temporal lobes (MTLs), parietotemporal cortices (PTCs) and prefrontal cortices (PFCs). Fourteen patients with MCI, 14 patients with mild AD and 14 age- and sex-matched control subjects were studied. Patients with AD and MCI demonstrated significant reductions of NAA/H(2)O and Cho/H(2)O in the left MTL relative to control subjects. Patients with AD showed mI/H(2)O increases relative to patients with MCI and control subjects in all six regions investigated, and a statistically significant mI/H(2)O increase was measured in the right PTC. Patients with AD and MCI demonstrated the same metabolic pattern in the left MTL, suggesting a similar pathological process underlying memory impairment. Increased mI signal appears to be a neurochemical abnormality associated mostly with AD and the dementia process. Some interhemispheric metabolite asymmetries were increased in AD patients.

Semantic interference deficits and the detection of mild Alzheimer's disease and mild cognitive impairment without dementia

Impairment in delayed recall has traditionally been considered a hallmark feature of Alzheimer's disease (AD). However, vulnerability to semantic interference may reflect early manifestations of the disorder. In this study, 26 mildly demented AD patients (mild AD), 53 patients with mild cognitive impairment without dementia (MCI), and 53 normal community-dwelling elders were first presented 10 common objects that were recalled over 3 learning trials. Subjects were then presented 10 new semantically related objects followed by recall for the original targets. After controlling for the degree of overall memory impairment, mild AD patients demonstrated greater proactive but equivalent retroactive interference relative to MCI patients. Normal elderly subjects exhibited the least amount of proactive and retroactive interference effects. Recall for targets susceptible to proactive interference correctly classified 81.3% of MCI patients and 81.3% of normal elderly subjects, outperforming measures of delayed recall and rate of forgetting. Adding recognition memory scores to the model enhanced both sensitivity (84.6%) and specificity (88.5%). A combination of proactive and retroactive interference measures yielded sensitivity of 84.6% and specificity of 96.2% in differentiating mild AD patients from normal older adults. Susceptibility to proactive semantic interference may be an early cognitive feature of MCI and AD patients presenting for clinical evaluation.

A critical discussion of the role of neuroimaging in mild cognitive impairment

OBJECTIVE

In this paper, the current neuroimaging literature is reviewed with regard to characteristic findings in mild cognitive impairment (MCI). Particular attention is drawn to the possible value of neuroimaging modalities in the prediction and early diagnosis of Alzheimer's disease (AD).

METHODS

First, the potential contribution of neuroimaging to an early, preclinical diagnosis of degenerative disorders is discussed at the background of our knowledge about the pathogenesis of AD. Second, relevant neuroimaging studies focusing on MCI are explored and summarized. Neuroimaging studies were found through Medline search and by systematically checking through the bibliographies of relevant articles.

RESULTS

Structural volumetric magnetic resonance imaging (MRI) and positron emission tomography (PET)/single photon emission tomography (SPECT) are currently the most commonly used neuroimaging modalities in studies focusing on MCI. There were considerable variations in demographical and clinical characteristics across studies. However, significant hippocampal and entorhinal cortex volume reductions were consistently found in subjects with MCI as compared with cognitively unimpaired controls. While hippocampal and entorhinal cortex atrophy in subjects with MCI are also well-established risk factors for the development of AD, these measures cannot be regarded as being of high predictive value in an individual case. Evidence for other typical neuroimaging changes in MCI is still scarce. In PET and SPECT studies, reduced blood flow and/or glucose metabolism in temporoparietal association areas, posterior cingulate and hippocampus were associated with a higher risk of progressive cognitive decline in MCI. In quantitative electroencephalogram (QEEG), low beta, high theta, low alpha and slowed mean frequency were associated with development of dementia.

CONCLUSIONS

Existing studies suggest that neuroimaging measures have the potential to become valuable tools in the early diagnosis of AD. To establish their value in routine use, larger studies, preferably with long prospective follow-up are needed.

Early diagnosis of Alzheimer's disease: contribution of structural neuroimaging

To accurately predict the development of Alzheimer's disease (AD) at its predementia stage would be a major breakthrough from both therapeutic and research standpoints. In this review, our focus is on markers obtained with structural imaging--especially magnetic resonance imaging (MRI)--and on studies of subjects at risk of developing AD. Among the latter, amnestic mild cognitive impairment (MCI) is currently the most commonly accepted reference, and therefore is specially targeted in this review. MCI refers to patients with significant but isolated memory impairment relative to subjects of identical age. Consistent with established histopathological data, structural imaging studies comparing patients with early probable AD to healthy aged subjects have shown that the most specific and sensitive features of AD at this stage are hippocampal and entorhinal cortex atrophy, especially when combined with a reduced volume of the temporal neocortex. MCI patients have significant hippocampal atrophy when compared to aged normal controls. When comparing patients with probable AD to MCI subjects, hippocampal region atrophy significantly extends to the neighboring temporal association neocortex. However, only longitudinal studies of MCI subjects are suited to assess (in a retrospective way) the predictive value of initial atrophy measurements for progression to AD. Few such studies have been published so far and for the most they were based on small samples. Furthermore, the comparison among studies is clouded by differences in both populations studied and MRI methodology used. Nevertheless, comparing the initial MRI data of at-risk subjects who convert to AD at follow-up to those of nonconverters suggests that a reduced association temporal neocortex volume combined with hippocampal or anterior cingulate cortex atrophy may be the best predictor of progression to AD. These data, although still preliminary, are consistent with postmortem studies describing the hierarchical progression of tau lesions in normal aging and early stages of AD, such that damage to the medial temporal lobe and association cortex would account for the memory and nonmemory cognitive impairments, respectively, the combination of which is required to operationally define probable AD. Future research in this field should capitalize on thorough methodology for brain structure delineation, and combine atrophy measurements to cognitive and/or functional imaging data.

Longitudinal analysis of abnormal domains comprising mild cognitive impairment (MCI) during aging

Research directed towards early diagnosis and therapy of dementia demands rapid identification of prodromal mild cognitive impairment (MCI). A longitudinal study was designed to clarify whether different domains of cognitive impairment, tested by Mini-Mental State Examination (MMSE), help predict dementia. After 3.74+/-2.94 years of follow-up among 291 cognitively normative volunteers, 73 developed MCI. During the next 3.88+/-3.01 years of MCI follow-up, 47.9% of MCI developed dementia of Alzheimer's type (DAT), 20.5% of MCI developed vascular dementia (VaD) and 31.5% maintained persistent MCI at the time of data analysis. Total MMSE and subtest scores analyzed at MCI onset showed significant differences for serial seven subtest scores between DAT and persistent MCI (P<0.05). Rates of change in subtests of orientation and memory and total MMSE scores predicted DAT (P<0.01). Decreasing orientation and total MMSE scores predicted VaD conversion rates of MCI to DAT at 2 years were 20.06% among single-domain MCI versus 41.7% for multi-domain MCI (P<0.05). Subjects with MCI often have impaired cognitive domains other than memory and show rapid deterioration, which predicts DAT. VaD sometimes mimics DAT with subtle cognitive impairment appearing before onset of dementia.

Prevalence of mild cognitive impairment: a population-based study in elderly subjects

OBJECTIVES

Mild cognitive impairment (MCI) has been suggested as a term for a boundary area between normal aging and dementia, especially Alzheimer's disease (AD). In follow-up studies, more than 50% of MCI subjects have been converted to dementia in 3-4 years. However, the epidemiology of MCI is not well known. This study was designed to determine the prevalence of MCI in an elderly population.

METHODS

A total of 806 subjects (60-76 years of age) from a population-based random sample of 1150 subjects living in the city of Kuopio in eastern Finland were evaluated. Neuropsychological tests and a structured interview including the modified Clinical Dementia Rating (CDR) were used to apply the diagnostic criteria of MCI as proposed by Mayo Clinic Alzheimer's Disease Research Centre. Thus, subjects having a test score more than 1.5 SDs below the age appropriate mean in memory tests and a CDR score of 0.5 but no dementia, were diagnosed as having MCI.

RESULTS

A total of 43 subjects, 5.3%, met the MCI criteria. MCI was more prevalent in older and less-educated subjects, but no difference was found between men and women. The CDR appeared to be the most important part of the criteria. The memory tests had less impact on prevalence variables.

CONCLUSIONS

The low prevalence of MCI indicate that in a population-based study design its criteria may identify a more homogeneous group of subjects at the lower end of the cognitive continuum as contrasted with various other criteria of cognitive impairment in the elderly population. This is compatible with follow-up studies showing a high probability of dementia in the MCI group. Thus, probable candidates for trials of preventive intervention for dementia can be screened from the elderly population using these diagnostic criteria.

Dementia epidemiology

Determining the incidence and prevalence of dementia is an inexact science. Dementia is difficult to define and detect in the population. Even with the difficulties of determining prevalence and incidence, it is clear that dementia causes a substantial burden on our society. Problems with diagnostic inaccuracy and insidious disease onset influence our ability to observe risk factor associations; factors related to survival may be mistaken for risk/protective factors. Current studies suggest that factors influencing brain development or cognitive reserve may delay the onset of AD, perhaps through a protective mechanism or a delay in diagnosis caused by improved performance on cognitive tests. The recent identification of genes that cause dementia suggests that these genes or their biochemical pathways may be involved in the pathogenesis of nonfamilial cases. The contribution of genes that cause disease in and of themselves may be smaller than that of genes that act to metabolize or potentiate environmental exposures. The interaction between gene and environment should be increasingly well studied in the future. Epidemiology must take advantage of these molecular advances. The tasks of public health and epidemiology should still involve prevention, the nonrandom occurrence of disease, and its environmental context in addition to heredity. The tools to address these tasks should continue to be refined.

Alzheimer's neurofibrillary pathology and the spectrum of cognitive function: findings from the Nun Study

The development of interventions designed to delay the onset of dementia highlights the need to determine the neuropathologic characteristics of individuals whose cognitive function ranges from intact to demented, including those with mild cognitive impairments. We used the Braak method of staging Alzheimer's disease pathology in 130 women ages 76-102 years who were participants in the Nun Study, a longitudinal study of aging and Alzheimer's disease. All participants had complete autopsy data and were free from neuropathologic conditions other than Alzheimer's disease lesions that could affect cognitive function. Findings showed a strong relationship between Braak stage and cognitive state. The presence of memory impairment was associated with more severe Alzheimer's disease pathology and higher incidence of conversion to dementia in the groups classified as having mild or global cognitive impairments. In addition to Braak stage, atrophy of the neocortex was significantly related to the presence of dementia. Our data indicate that Alzheimer's neurofibrillary pathology is one of the neuropathologic substrates of mild cognitive impairments. Additional studies are needed to help explain the variability in neuropathologic findings seen in individuals whose cognitive performance falls between intact function and dementia.

The impact of mild cognitive impairment on functional abilities in the elderly

Mild cognitive impairment (MCI) covers a spectrum of cognitive impairment, bordered by normal cognitive performance on one end and frank dementia on the other. How wide the net for MCI is cast will affect the prevalence and severity of its functional consequences. Many studies suggest that MCI is an early stage of Alzheimer's disease. Therefore, investigation of the functional impact of MCI offers an important opportunity to examine the quality-of-life impact of a prodromal stage of Alzheimer's disease. In this review, the authors examine the nosology of the condition, the subjective experience of having an MCI diagnosis, and cross- sectional and prospective studies that have examined the topic.

Magnetic resonance imaging of the entorhinal cortex and hippocampus in mild cognitive impairment and Alzheimer's disease

OBJECTIVES

To explore volume changes of the entorhinal cortex (ERC) and hippocampus in mild cognitive impairment (MCI) and Alzheimer's disease (AD) compared with normal cognition (NC); to determine the powers of the ERC and the hippocampus for discrimination between these groups.

METHODS

This study included 40 subjects with NC, 36 patients with MCI, and 29 patients with AD. Volumes of the ERC and hippocampus were manually measured based on coronal T1 weighted MR images. Global cerebral changes were assessed using semiautomatic image segmentation.

RESULTS

Both ERC and hippocampal volumes were reduced in MCI (ERC 13%, hippocampus 11%, p<0.05) and AD (ERC 39%, hippocampus 27%, p<0.01) compared with NC. Furthermore, AD showed greater volume losses in the ERC than in the hippocampus (p<0.01). In addition, AD and MCI also had cortical grey matter loss (p< 0.01) and ventricular enlargement (p<0.01) when compared with NC. There was a significant correlation between ERC and hippocampal volumes in MCI and AD (both p<0.001), but not in NC. Using ERC and hippocampus together improved discrimination between AD and CN but did not improve discrimination between MCI and NC. The ERC was better than the hippocampus for distinguishing MCI from AD. In addition, loss of cortical grey matter significantly contributed to the hippocampus for discriminating MCI and AD from NC.

CONCLUSIONS

Volume reductions in the ERC and hippocampus may be early signs of AD pathology that can be measured using MRI.

Natural history of Alzheimer's disease

Alzheimer's disease (AD) is the principal cause of dementia in the elderly, and affects about 15 million people worldwide. The earliest symptom is usually an insidious impairment of memory. As the disease progresses, there is increasing impairment of language and other cognitive functions. Problems occur with naming and word-finding, and later with verbal and written comprehension and expression. Visuospatial, analytic and abstract reasoning abilities, judgment, and insight become affected. Behavioral changes may include delusions, hallucinations, irritability, agitation, verbal or physical aggression, wandering, and disinhibition. Ultimately, there is loss of self-hygiene, eating, dressing, and ambulatory abilities, and incontinence and motor dysfunction. Before diagnosis of AD, individuals may have memory complaints, which represent a period of mild cognitive impairment (MCI). Before MCI, there is a prodromal, ill-defined presymptomatic period of disease ('pre-MCI"). In this review, we particularly focus on these earliest stages. We also discuss the more advanced stages of AD, and address factors that may influence disease course. Understanding the natural history of AD will allow better targeting of the disease-modifying treatments that are on the horizon.

Elevation of LDL receptor-related protein levels via ligand interactions in Alzheimer disease and in vitro

The low-density lipoprotein (LDL) receptor-related protein (LRP) is a multifunctional receptor in the CNS that binds both apolipoprotein E (apoE) and activated alpha2-macroglobulin (alpha2M*); all 3 proteins are genetically associated with Alzheimer disease (AD). In this study we found an 85% increase in LRP levels in human AD brain frontal cortex, along with an increased level of the LRP ligands, apoE, and alpha2M. We speculated that LRP levels might be increased in response to the increased levels of its ligands, apoE, and alpha2M*. To test this hypothesis we examined the effects of alpha2M* on LRP in primary cultures. Treatment of neurons with alpha2M* significantly increased LRP levels (by 92%). This increase was prevented by coculture with receptor-associated protein (RAP), which blocks binding of LRP ligands to LRP Native alpha2M or RAP alone did not change LRP levels in vitro. We also found that alpha2M* stimulated activation of astrocytes in vitro and promoted the levels of LRP by 65%. These data indicate 1) the LRP ligand alpha2M* increases levels of LRP in primary neuronal and astrocytic cultures, 2) alpha2M*-induction of LRP levels in vitro depends on binding to LRP, and 3) LRP levels are increased in AD brain, perhaps in response to the increased levels of alpha2M.

Hippocampal volume discriminates between normal cognition; questionable and mild dementia in the elderly

The sensitivity of MRI volumetric measures to detect cognitive dysfunction is examined in 39 participants of an epidemiological field study (age 75-85, MMSE 19-30). According to Clinical dementia rating (CDR), 17 subjects had normal cognition (CDR 0), 12 had questionable (CDR 0.5) and 10 mild dementia (CDR 1). Discriminant analysis based on four hippocampal measures resulted in a correct classification of 76.9% of all subjects. Left-sided and posterior hippocampal measures were more responsible for group discrimination than right-sided and anterior measures. In CDR 0.5, a significant hippocampal volume reduction of 14.3% vs.11.3% (left vs. right) relative to normal was found. The right hippocampus was significantly greater than the left in CDR 0 and CDR 0.5, but not in CDR 1. The magnitude of non-directional hippocampal asymmetry increased with decreasing cognitive state. We conclude that hippocampal atrophy is sensitive to detect cognitive dysfunction and subjects at risk for Alzheimer's disease in the elderly population.

Age-related cognitive decline, mild cognitive impairment or preclinical Alzheimer's disease?

With the promising development of effective treatment, significant improvement in the very early diagnosis of Alzheimer's disease (AD) is required. There is vast agreement that a decline in memory, especially in verbal episodic memory, is the earliest and perhaps the most sensitive sign of incipient AD at the preclinical stage. However, this review offers evidence that impairment in episodic memory can be observed in normal elderly people as well as in aged subjects with mild cognitive impairment (MCI), a large proportion of whom will, however, not convert to dementia. Quantitative measurement of atrophy and brain activation in the hippocampal-parahippocampal formation by using structural and functional magnetic resonance imaging may help to distinguish the MCI decliners from the nondecliners. Cerebrospinal fluid levels of tau protein and Abet1-42 peptide, together with the presence of an apolipoprotein (apo)E epsilon4 allele may also increase our confidence in the early positive diagnosis of AD. This review concludes, however, that while adequate for constituting groups of patients in a research perspective, the extensive diagnostic procedure based on specific cognitive testing, neuroimaging and biological investigations is still out of reach for the practitioner.