The neuropsychological profile of Alzheimer disease

Fibrillar Amyloid-β Accumulation Triggers an Inflammatory Mechanism Leading to Hyperphosphorylation of the Carboxyl-Terminal End of Tau Polypeptide in the Hippocampal Formation of the 3×Tg-AD Transgenic Mouse

Alzheimer's disease (AD) is a degenerative and irreversible disorder whose progressiveness is dependent on age. It is histopathologically characterized by the massive accumulation of insoluble forms of tau and amyloid-β (Aβ) asneurofibrillary tangles and neuritic plaques, respectively. Many studies have documented that these two polypeptides suffer several posttranslational modifications employing postmortem tissue sections from brains of patients with AD. In order to elucidate the molecular mechanisms underlying the posttranslational modifications of key players in this disease, including Aβ and tau, several transgenic mouse models have been developed. One of these models is the 3×Tg-AD transgenic mouse, carrying three transgenes encoding APPSWE, S1M146V, and TauP301L proteins. To further characterize this transgenicmouse, we determined the accumulation of fibrillar Aβ as a function of age in relation to the hyperphosphorylation patterns of TauP301L at both its N- and C-terminus in the hippocampal formation by immunofluorescence and confocal microscopy. Moreover, we searched for the expression of activated protein kinases and mediators of inflammation by western blot of wholeprotein extracts from hippocampal tissue sections since 3 to 28 months as well. Our results indicate that the presence of fibrillar Aβ deposits correlates with a significant activation of astrocytes and microglia in subiculum and CA1 regions of hippocampus. Accordingly, we also observed a significant increase in the expression of TNF-α associated to neuritic plaques and glial cells. Importantly, there is an overexpression of the stress activated protein kinases SAPK/JNK and Cdk-5 in pyramidal neurons, which might phosphorylate several residues at the C-terminus of TauP301L. Therefore, the accumulation of Aβ oligomers results in an inflammatory environment that upregulates kinases involved in hyperphosphorylation of TauP301L polypeptide.

Cognitive Profile and its Association with Neuroimaging Markers of Non-Demented Cerebral Amyloid Angiopathy Patients in a Stroke Unit

BACKGROUND

Cerebral amyloid angiopathy (CAA) is increasingly recognized as a cause of cognitive impairment in the elderly, but the cognitive profile in patients with the disease has not been well characterized.

OBJECTIVE

To characterize the neuropsychological profile of CAA patients without dementia and to determine the association between cognitive performance in different domains and neuroimaging lesions characteristic of CAA.

METHODS

Fifty-eight non-demented CAA patients were compared to 138 cognitively normal subjects using a standard neuropsychological test battery. Total brain volume (TBV), white matter hyperintensities, number of lobar cerebral microbleeds, hippocampal volume, and cortical superficial siderosis in all CAA patients were assessed. The association between these neuroimaging markers and neuropsychological performance in different cognitive domains in the CAA group were analyzed.

RESULTS

Patients with CAA had significantly worse performance on all individual neuropsychological domains tested, when compared to the cognitive normal group. The cognitive decline of CAA patients was most noticeable in tests for processing speed with a Z score of -1.92±1.56 (mean±SD), then followed by executive function (-0.93±1.01), episodic memory (-0.87±1.29), semantic fluency (-0.73±1.06), and attention (-0.42±0.98). TBV of the CAA patients was correlated with processing speed (β= 0.335, p = 0.03) and executive function (β= 0.394, p = 0.01).

CONCLUSIONS

Non-demented patients with CAA had cognitive deficits in multiple areas. Lower TBV was related to slower processing speed and worse executive function.

Mechanism of 2,3,4',5-Tetrahydroxystilbene 2-O-β-D-Glucoside-Induced Upregulation of Glutamate Transporter 1 Protein Expression in Mouse Primary Astrocytes

Glutamate transporter-1 (GLT-1), a major glutamate transporter expressed in astrocytes, takes up excess glutamate from the micro-environment in order to prevent excitotoxicity. Drugs that increase GLT-1 expression may have therapeutic effects in disorders associated with neuronal excitotoxicity. 2,3,4',5-tetrahydroxystilbene 2-O-β-D-glucoside (TSG), a monomer of stilbene from polygonummultiflorum, exerts neuroprotection in a range of experimental models such as Alzheimer's disease and brain ischemia. In this study, we evaluated the effect of TSG on GLT-1 protein expression in mouse primary-cultured astrocytes. Results showed that TSG markedly increased the GLT-1 protein expression level in mouse primary-cultured astrocytes in a dose- and time-dependent manner, and this increase was mediated by the activation of protein kinase B (Akt) but not by the activation of extracellular signal-regulated protein kinase 1/2. Furthermore, inhibition of cAMP response element-binding protein, but not nuclear factor kappa B, abolished the TSG-mediated increase in GLT-1 protein expression in cultured astrocytes. Collectively, these findings may provide novel insights into the mechanism for TSG in neuroprotection, and would help search new agents targeting neurodegenerative disorders associated with impaired astrocytic glutamate transporters.

Evaluating Recall and Recognition Memory Using the Montreal Cognitive Assessment: Applicability for Alzheimer's and Huntington's Diseases

We sought to investigate whether the Montreal Cognitive Assessment (MoCA) could provide a brief assessment of recall and recognition using Huntington disease (HD) and Alzheimer disease (AD) as disorders characterized by different memory deficits. This study included 80 participants with HD, 64 participants with AD, and 183 community-dwelling control participants. Random-effects hierarchical logistic regressions were performed to assess the relative performance of the normal control (NC), participants with HD, and participants with AD on verbal free recall, cued recall, and multiple-choice recognition on the MoCA. The NC participants performed significantly better than participants with AD at all the 3 levels of assessment. No difference existed between participants with HD and NC for cued recall, but NC participants performed significantly better than participants with HD on free recall and recognition. The participants with HD performed significantly better than participants with AD at all the 3 levels of assessment. The MoCA appears to be a valuable, brief cognitive assessment capable of identifying specific memory deficits consistent with known differences in memory profiles.

Trends on the application of serious games to neuropsychological evaluation: A scoping review

BACKGROUND

The dramatic technological advances witnessed in recent years have resulted in a great opportunity for changing the way neuropsychological evaluations may be performed in clinical practice. Particularly, serious games have been posed as the cornerstone of this still incipient paradigm-shift, as they have characteristics that make them especially advantageous in trying to overcome limitations associated with traditional pen-and-paper based neuropsychological tests: they can be easily administered and they can feature complex environments for the evaluation of neuropsychological constructs that are difficult to evaluate through traditional tests. The objective of this study was to conduct a scoping literature review in order to map rapidly the key concepts underpinning this research area during the last 25years on the use of serious games for neuropsychological evaluation.

METHODS

MEDLINE, PsycINFO, Scopus and IEEE Xplore databases were systematically searched. The main eligibility criteria were to select studies published in a peer-reviewed journal; written in English; published in the last 25years; focused on the human population, and classified in the neuropsychological field. Moreover, to avoid risk of bias, studies were selected by consensus of experts, focusing primarily in psychometric properties. Therefore, selected studies were analyzed in accordance with a set of dimensions of analysis commonly used for evaluating neuropsychological tests.

RESULTS

After applying the selected search strategy, 57 studies -including 54 serious games- met our selection criteria. The selected studies deal with visuospatial capabilities, memory, attention, executive functions, and complex neuropsychological constructs such as Mild Cognitive Impairment (MCI). Results show that the implementation of serious games for neuropsychological evaluation is tackled in several different ways in the selected studies, and that studies have so far been mainly exploratory, just aiming at testing the feasibility of the proposed approaches.

DISCUSSION

It may be argued that the limited number of databases used might compromise this study. However, we think that the finally included sample is representative, in spite of how difficult is to achieve an optimum and maximum scope. Indeed, this review identifies other research issues related to the development of serious games beyond their reliability and validity. The main conclusion of this review is that there is a great interest in the research community in the use of serious games for neuropsychological evaluation. This scoping review is pertinent, in accordance with the increasing number of studies published in the last three years, they demonstrate its potential as a serious alternative to classic neuropsychological tests. Nevertheless, more research is needed in order to implement serious games that are reliable, valid, and ready to be used in the everyday clinical practice.

Commonly prescribed drugs associate with cognitive function: a cross-sectional study in UK Biobank

OBJECTIVE

To investigate medications associated with cognitive function.

DESIGN

Population-based cross-sectional cohort study.

SETTING

UK Biobank.

PARTICIPANTS

UK Biobank participants aged 37-73 years who completed cognitive tests at the baseline visit in 2006-2010.

MAIN OUTCOME MEASURES

Cognitive test outcomes on verbal-numerical reasoning test (n=165 493), memory test (n=482 766) and reaction time test (n=496 813).

RESULTS

Most drugs (262 of 368) were not associated with any cognitive tests after adjusting for age, gender, education, household income, smoking, alcohol status, psychostimulant/nootropic medication use, assessment centre, and concurrent diagnoses and medications. Drugs used for nervous system disorders were associated with poorer cognitive performance (antiepileptics, eg, topiramate breasoning(score) -0.65 (95% CI -1.05 to -0.24), bmemory(score) -1.41 (-1.79 to -1.04); antipsychotics, eg, risperidone breaction time(ms) -33 (-46 to -20), negative values indicate poor cognitive performance and vice versa). Drugs used for non-nervous system conditions also showed significant negative association with cognitive score, including those where such an association might have been predicted (antihypertensives, eg, amlodipine breasoning -0.1 (-0.15 to -0.06), bmemory -0.08 (-0.13 to -0.03), breaction time -3 (-5 to -2); antidiabetics, eg, insulin breaction time -13 (-17 to -10)) and others where such an association was a surprising observation (proton pump inhibitors, eg, omeprazole breasoning -0.11 (-0.15 to -0.06), bmemory -0.08 (-0.12 to -0.04), breaction time -5 (-6 to -3); laxatives, eg, contact laxatives breaction time -13 (-19 to -8)). Finally, only a few medications and health supplements showed association towards a positive effect on cognitive function (anti-inflammatory agents, eg, ibuprofen breasoning 0.05 (0.02 to 0.08), breaction time 4 (3, 5); glucosamine breasoning 0.09 (0.03 to 0.14), breaction time 5 (3 to 6)).

CONCLUSIONS

In this large volunteer study, some commonly prescribed medications were associated with poor cognitive performance. Some associations may reflect underlying diseases for which the medications were prescribed, although the analysis controlled for the possible effect of diagnosis. Other drugs, whose association cannot be linked to the effect of any disease, may need vigilance for their implications in clinical practice.

Transient Epileptic Amnesia over twenty years: Long-term follow-up of a case series with three detailed reports

Purpose

Transient Epileptic Amnesia (TEA) is a form of adult onset temporal lobe epilepsy characterised by ictal amnesia. The amnesic seizures are often accompanied by interical memory disturbance, involving autobiographical amnesia and accelerated long-term forgetting. Short-term follow-up studies suggest a relatively stable cognitive profile once treated, but recent case reports raise concerns regarding the risk of developing Alzheimer’s Disease (AD). The current study reports clinical and cognitive outcome in TEA patients over a 20-year period.

Methods

A cohort of ten TEA patients first reported in 1998 were followed up at two time intervals, each 10 years apart. Information regarding clinical outcomes and subjective reports of memory functioning was gained via GP records and clinical interview. Objective memory function was determined at each time point via a comprehensive neuropsychological assessment, where possible.

Results

Information was obtained for nine of the original 10 participants. Over the 20-year period, 4 participants died, with no indication of dementia prior to death. One participant was diagnosed with Vascular Dementia. Seizures were generally well controlled. Subjective reports of memory varied, including no concerns, stable memory difficulties, and worsening memory. Neuropsychological assessment at 10 years showed stable performances across most measures. At the 20-year follow up, there was no evidence of a general cognitive decline. Participants showed stability on some measures, with reductions on others. Performance was not consistent with AD.

Conclusions

No elevated risk of dementia was evident from this TEA series. Although memory difficulties persist over time, the prognosis of TEA appears generally benign.

A comparison of theoretical and statistically derived indices for predicting cognitive decline

INTRODUCTION

Both theoretical and statistically derived approaches have been used in research settings for predicting cognitive decline.

METHODS

Fifty-eight cognitively normal (NC) and 71 mild cognitive impairment (MCI) subjects completed a comprehensive cognitive battery for up to 5 years of follow-up. Composite indices of cognitive function were derived using a classic theoretical approach and exploratory factor analysis (EFA). Cognitive variables comprising each factor were averaged to form the EFA composite indices. Logistic regression was used to investigate whether these cognitive composites can reliably predict cognitive outcomes.

RESULTS

Neither method predicted decline in NC. The theoretical memory, executive, attention, and language composites and the EFA-derived "attention/executive" and "verbal memory" composites were significant predictors of decline in MCI. The best models achieved an area under the curve of 0.94 in MCI.

CONCLUSIONS

The theoretical and the statistically derived cognitive composite approaches are useful in predicting decline in MCI but not in NC.

Neuronal Pentraxin 2 predicts medial temporal atrophy and memory decline across the Alzheimer's disease spectrum

Chronic neuroinflammation is thought to potentiate medial temporal lobe (MTL) atrophy and memory decline in Alzheimer's disease (AD). It has become increasingly important to find novel immunological biomarkers of neuroinflammation or other processes that can track AD development and progression. Our study explored which pro- or anti-inflammatory cerebrospinal fluid (CSF) biomarkers best predicted AD neuropathology over 24months. Using Alzheimer's Disease Neuroimaging Initiative data (N=285), CSF inflammatory biomarkers from mass spectrometry and multiplex panels were screened using stepwise regression, followed up with 50%/50% model retests for validation. Neuronal Pentraxin 2 (NPTX2) and Chitinase-3-like-protein-1 (C3LP1), biomarkers of glutamatergic synaptic plasticity and microglial activation respectively, were the only consistently significant biomarkers selected. Once these biomarkers were selected, linear mixed models were used to analyze their baseline and longitudinal associations with bilateral MTL volume, memory decline, global cognition, and established AD biomarkers including CSF amyloid and tau. Higher baseline NPTX2 levels corresponded to less MTL atrophy [R2=0.287, p<0.001] and substantially less memory decline [R2=0.560, p<0.001] by month 24. Conversely, higher C3LP1 modestly predicted more MTL atrophy [R2=0.083, p<0.001], yet did not significantly track memory decline over time. In conclusion, NPTX2 is a novel pro-inflammatory cytokine that predicts AD-related outcomes better than any immunological biomarker to date, substantially accounting for brain atrophy and especially memory decline. C3LP1 as the microglial biomarker, by contrast, performed modestly and did not predict longitudinal memory decline. This research may advance the current understanding of AD etiopathogenesis, while expanding early diagnostic techniques through the use of novel pro-inflammatory biomarkers, such as NPTX2. Future studies should also see if NPTX2 causally affects MTL morphometry and memory performance.

Cognitive impairment and BDNF serum levels

BACKGROUND/AIMS

To investigate the alterations of brain-derived neurotrophic factor (BNDF) serum levels in subjects with different intensity of cognitive impairment and different neurodegenerative processes.

MATERIAL AND METHODS

Serum BDNF levels were analyzed by ELISA kit in 378 subjects: 134 Alzheimer's disease (AD) patients, 115 amnestic mild cognitive impairment (MCI) patients, and 129 controls divided into two groups: neurodegenerative control group (ND), consisting of 49 Parkinson's disease patients without any cognitive complaints, and cognitively normal control group (CN), consisting of 80 subjects without any neurological disorders.

RESULTS

AD patients had significantly lower (p<0.001) BDNF serum levels compared to MCI, CN and ND controls. Age and education had significant influence on BDNF serum levels regardless the diagnosis or group assignment. We have found no influence of depression on BDNF serum levels either in our group as a whole, or in each group assessed separately. We found significant correlation between BDNF serum levels and cognitive impairments. After multiple comparisons between the groups, we found that, after adjustment for confounding factors (age, gender, education, depression, cognitive impairment), BDNF serum levels were the lowest in AD group (p=0.05).

CONCLUSIONS

Advanced age and low educational level are associated with decreased BDNF serum levels. Decreased BDNF serum levels correspond to the severity of cognitive impairment. There is no correlation between BDNF serum levels and depressive symptoms.

The Primacy Effect in Amnestic Mild Cognitive Impairment: Associations with Hippocampal Functional Connectivity

Background: The “primacy effect,” i.e., increased memory recall for the first items of a series compared to the following items, is reduced in amnestic mild cognitive impairment (aMCI). Memory task-fMRI studies demonstrated that primacy recall is associated with higher activation of the hippocampus and temporo-parietal and frontal cortical regions in healthy subjects. Functional magnetic resonance imaging (fMRI) at resting state revealed that hippocampus functional connectivity (FC) with neocortical brain areas, including regions of the default mode network (DMN), is altered in aMCI. The present study aimed to investigate whether resting state fMRI FC between the hippocampus and cortical brain regions, especially the DMN, is associated with primacy recall performance in aMCI.

Methods: A number of 87 aMCI patients underwent resting state fMRI and verbal episodic memory assessment. FC between the left or right hippocampus, respectively, and all other voxels in gray matter was mapped voxel-wise and used in whole-brain regression analyses, testing whether FC values predicted delayed primacy recall score. The delayed primacy score was defined as the number of the first four words recalled on the California Verbal Learning Test. Additionally, a partial least squares (PLS) analysis was performed, using DMN regions as seeds to identify the association of their functional interactions with delayed primacy recall.

Results: Voxel-based analyses indicated that delayed primacy recall was mainly (positively) associated with higher FC between the left and right hippocampus. Additionally, significant associations were found for higher FC between the left hippocampus and bilateral temporal cortex, frontal cortical regions, and for higher FC between the right hippocampus and right temporal cortex, right frontal cortical regions, left medial frontal cortex and right amygdala (p < 0.01, uncorr.). PLS analysis revealed positive associations of delayed primacy recall with FC between regions of the DMN, including the left and right hippocampus, as well as middle cingulate cortex and thalamus (p < 0.04). In conclusion, in the light of decreased hippocampus function in aMCI, inter-hemispheric hippocampus FC and hippocampal FC with brain regions predominantly included in the DMN may contribute to residual primacy recall in aMCI.

The suppression effect in visuospatial and verbal working memory span tasks in patients with Alzheimer's disease: a 2-year follow-up study

This study adapted a new task to assess visuospatial and verbal working memory impairments in patients with Alzheimer Disease (AD), including an executive strategy of information suppression. The aim was to examine the visuospatial and verbal difficulties, and additionally to explore the average sex differences, during a 2-year follow-up study. The results indicated that patients with AD showed a significantly lower performance, compared with healthy elderly controls, especially with the suppression of information required in this new task. However, suppression did not lead to a significantly greater decline in the performance of patients when compared with the control group.

Alzheimer's Disease: Prototype of Cognitive Deterioration, Valuable Lessons to Understand Human Cognition

It is important for neurologists to become more familiar with neuropsychological evaluation for Alzheimer disease. The growth of this method in research, as an available, inexpensive, and noninvasive diagnostic approach, which can be administered even by non-specialist-trained examiners, makes this knowledge more necessary than ever. Such knowledge has a basic role in planning national programs in primary health care systems for prevention and early detection of Alzheimer disease. This is more crucial in developing countries, which have higher rates of dementia prevalence along with cardiovascular risk factors, lack of public knowledge about dementia, and limited social support. In addition compared to the neurological hard signs which are tangible and measurable, the concept of cognition seems to be more difficult for the neurologists to evaluate and for the students to understand. Dementia in general and Alzheimer's disease as the prototype of cognitive disorders specifically, play an important role to explore all domains of human cognition through its symptomatology and neuropsychological deficits.

Rule induction performance in amnestic mild cognitive impairment and Alzheimer's dementia: examining the role of simple and biconditional rule learning processes

INTRODUCTION

Rule induction tests such as the Wisconsin Card Sorting Test require executive control processes, but also the learning and memorization of simple stimulus-response rules. In this study, we examined the contribution of diminished learning and memorization of simple rules to complex rule induction test performance in patients with amnestic mild cognitive impairment (aMCI) or Alzheimer's dementia (AD).

METHOD

Twenty-six aMCI patients, 39 AD patients, and 32 control participants were included. A task was used in which the memory load and the complexity of the rules were independently manipulated. This task consisted of three conditions: a simple two-rule learning condition (Condition 1), a simple four-rule learning condition (inducing an increase in memory load, Condition 2), and a complex biconditional four-rule learning condition-inducing an increase in complexity and, hence, executive control load (Condition 3).

RESULTS

Performance of AD patients declined disproportionately when the number of simple rules that had to be memorized increased (from Condition 1 to 2). An additional increment in complexity (from Condition 2 to 3) did not, however, disproportionately affect performance of the patients. Performance of the aMCI patients did not differ from that of the control participants. In the patient group, correlation analysis showed that memory performance correlated with Condition 1 performance, whereas executive task performance correlated with Condition 2 performance.

CONCLUSIONS

These results indicate that the reduced learning and memorization of underlying task rules explains a significant part of the diminished complex rule induction performance commonly reported in AD, although results from the correlation analysis suggest involvement of executive control functions as well. Taken together, these findings suggest that care is needed when interpreting rule induction task performance in terms of executive function deficits in these patients.

Reference Data of the Spanish Memory Binding Test in a Midlife Population from the ALFA STUDY (Alzheimer's and Family)

BACKGROUND

The Memory Binding Test (MBT) is a novel test based on the learning of two lists of words, developed to detect early memory impairment suggestive of Alzheimer's disease (AD).

OBJECTIVE

To present and provide reference data of the Spanish MBT in a midlife population of mainly first-degree descendants of AD patients.

METHODS

472 cognitively unimpaired subjects, aged 45 to 65 and participants of the ALFA STUDY, were included. Raw scores were transformed to scaled scores on which multivariate regression analysis was applied adjusting by age, gender, and education level. A standard linear regression was employed to derive the scaled score adjusted. Sociodemographic corrections were applied and an adjustment table was constructed.

RESULTS

Performance was heterogeneously influenced by sociodemographic factors. Age negatively influenced free recall. Education tends to have an influence in the results showing lower performance with lower education level. Women tend to outperform men in the learning of the first list and total recall. Only a few variables were unaffected by sociodemographic factors such as those related to semantic proactive interference (SPI) and to the retention of learned material. Our results point out that some vulnerability to SPI is expectable in cognitively healthy subjects. Close to 100% of the learned material was maintained across the delay interval.

CONCLUSION

This study contributes with reference data for the MBT providing the necessary adjustments for sociodemographic characteristics. Our data may prove to be useful for detecting asymptomatic at-risk candidates for secondary prevention studies of AD.

Characterizing cognitive performance in a large longitudinal study of aging with computerized semantic indices of verbal fluency

A computational approach for estimating several indices of performance on the animal category verbal fluency task was validated, and examined in a large longitudinal study of aging. The performance indices included the traditional verbal fluency score, size of semantic clusters, density of repeated words, as well as measures of semantic and lexical diversity. Change over time in these measures was modeled using mixed effects regression in several groups of participants, including those that remained cognitively normal throughout the study (CN) and those that were diagnosed with mild cognitive impairment (MCI) or Alzheimer's disease (AD) dementia at some point subsequent to the baseline visit. The results of the study show that, with the exception of mean cluster size, the indices showed significantly greater declines in the MCI and AD dementia groups as compared to CN participants. Examination of associations between the indices and cognitive domains of memory, attention and visuospatial functioning showed that the traditional verbal fluency scores were associated with declines in all three domains, whereas semantic and lexical diversity measures were associated with declines only in the visuospatial domain. Baseline repetition density was associated with declines in memory and visuospatial domains. Examination of lexical and semantic diversity measures in subgroups with high vs. low attention scores (but normal functioning in other domains) showed that the performance of individuals with low attention was influenced more by word frequency rather than strength of semantic relatedness between words. These findings suggest that various automatically semantic indices may be used to examine various aspects of cognitive performance affected by dementia.

Serum high-density lipoprotein is associated with better cognitive function in a cross-sectional study of aging women

Purpose/Aim of the study: Poor cardiovascular health, including obesity and altered lipid profiles at mid-life, are linked to increased risk of Alzheimer's disease (AD). The biological mechanisms linking cardiovascular health and cognitive function are unclear though are likely to be multifactorial. This study examined the association between various lipoproteins and cognitive functioning in ageing women.

MATERIALS AND METHODS

We investigated the relationship between readily available biomarkers (i.e. serum lipoprotein) and cognitive decline in domains associated with increased risk of AD (e.g. episodic verbal memory performance and subjective memory complaint). We report cross-sectional data investigating the relationship between serum total cholesterol, triglycerides, high-density lipoprotein (HDL-C) and low-density lipoprotein with verbal memory and learning ability in 130 women with and without memory complaints (n = 71 and 59, respectively) drawn from a study investigating cognitively healthy Western Australians (average age 62.5 years old).

RESULTS

After statistical modelling that controlled for the effects of age, depression and apolipoprotein E genotype, HDL-C was significantly associated with better verbal learning and memory performance, specifically short and long delay-free recalls (F = 3.062; p < .05 and F = 3.2670; p < .05, respectively).

CONCLUSION

Our cross-sectional findings suggest that the positive effect of HDL-C on verbal memory may be present much earlier than previously reported and provide further support for the role of HDL-C in healthy brain ageing. Further exploration of the protective effect of HDL-C on cognitive function in ageing is warranted through follow-up, longitudinal studies.

Prevalence of below-criterion Reliable Digit Span scores in a clinical sample of older adults

OBJECTIVE

The Reliable Digit Span (RDS) is a well-validated embedded indicator of performance validity. An RDS score of ≤7 is commonly referenced as indicative of invalid performance; however, few studies have examined the classification accuracy of the RDS among individuals suspected for dementia. The current study evaluated performance of the RDS in a clinical sample of 934 non-litigating individuals presenting to an outpatient memory disorders clinic for assessment of dementia.

METHOD

The RDS was calculated for each participant in the context of a comprehensive neuropsychological assessment completed as part of routine clinical care. Score distributions were examined to establish the base rate of below criterion performance for RDS cutoffs of ≤7, ≤6, and ≤5. One-way ANOVA was used to compare performance on a cognitive screening measure and informant reports of functional independence of those falling below and above cutoffs.

RESULTS

A cutoff score of ≤7 resulted in a high prevalence of below-criterion performance (29.7%), though an RDS of ≤6 was associated with fewer below-criterion scores (12.8%) and prevalence of an RDS of ≤5 was infrequent (4.3%). Those scoring below cutoffs performed worse on cognitive measures compared with those falling above cutoffs.

CONCLUSIONS

Using the RDS as a measure of performance validity among individuals presenting with a possibility of dementia increases the risk of misinterpreting genuine cognitive impairment as invalid performance when higher cutoffs are used; lower cutoffs may be useful when interpreted in conjunction with other measures of performance validity.

Redefining Amnestic Mild Cognitive Impairment as an Early Form of Alzheimer's Disease Based on Assessment of Memory Systems

BACKGROUND

It has been suggested that mild cognitive impairment (MCI) can be used to identify patients at risk of developing clinical stages of Alzheimer's disease (AD).

OBJECTIVE

The aim of this study was to describe the characteristics of amnesic syndrome of dementia of the Alzheimer's type (DAT) as a continuous degenerative process from normality to amnesic syndrome and provide a classification of the degrees of amnesia.

METHODS

Of 3,800 new incidental cases at the Memory Clinic, 747 were classified as non-demented patients. A 96-month follow-up study was conducted. We described and compared longitudinal outcomes from normality to amnesic syndrome based on immediate memory, verbal learning, free recall, and recognition using the memory scale from the Basic Neuropsychological Battery, version D (BNB-D) and created a new classification of memory impairment.

RESULTS

Based on differences observed in this longitudinal study, we classified patients in four memory stages: M1, Normal episodic memory; M2, mild impairment in learning and/or free recall; M3, clear impairment in learning and/or free recall; and M4, complete amnesic syndrome. With this new amnesia classification, we studied the chronological progression of all patients diagnosed without dementia from baseline to DAT conversion using the Kaplan-Meier estimator of survival probability (Log Rank/Mantel Cox comparison. χ2  = 171.84, p = 0.001).

CONCLUSION

This new classification of memory impairment can help increase the prediction certainty of conversion from amnestic MCI to AD and improve research on AD biomarkers and their relationship with memory as the principal manifestation of AD.

Impact of AP@LZ in the daily life of three persons with Alzheimer's disease: long-term use and further exploration of its effectiveness

AP@LZ is an electronic organiser that was designed to support the day-to-day activities of persons with Alzheimer's disease. To assess the potential of this technology, three participants (NI, JB, RD) were approached to take part in the study. They benefited from a structured cognitive intervention to learn how to operate AP@LZ; the intervention included the following learning stages: Acquisition, Application and Adaptation. Pre- and post-intervention measures were collected. NI, for whom a longitudinal study was conducted, still continued to use AP@LZ 24 months post-intervention. JB and RD also showed a gradual improvement in their performance throughout the intervention phase (sessions 1 to 19 for JB: performance increased from 50 to 100%; sessions 1 to 25 for RD: from 56 to 89%). The results of the use of AP@LZ in activities of daily living suggest that the application was beneficial for three persons with Alzheimer's disease whose profiles differed notably (age, cognitive and social profiles). Thus, results indicate that they were all able to learn how to operate AP@LZ's functions and to use them in their activities of daily living. Cognitive intervention appears to play an important role for the promotion of learning and adoption of such technology.

Identification of proteins that are differentially expressed in brains with Alzheimer's disease using iTRAQ labeling and tandem mass spectrometry

Alzheimer's disease is one of the leading causes of dementia in the elderly. It is considered the result of complex events involving both genetic and environmental factors. To gain further insights into this complexity, we quantitatively analyzed the proteome of cortex region of brains from patients diagnosed with Alzheimer's disease, using a bottom-up proteomics approach. We identified 721 isobaric-tagged polypeptides. From this universe, 61 were found overexpressed and 69 subexpressed in three brains with Alzheimer's disease in comparison to a normal brain. We determined that the most affected processes involving the overexpressed polypeptides corresponded to ROS and stress responses. For the subexpressed polypeptides, the main processes affected were oxidative phosphorylation, organellar acidification and cytoskeleton. We used Drosophila to validate some of the hits, particularly those non-previously described as connected with the disease, such as Sideroflexin and Phosphoglucomutase-1. We manipulated their homolog genes in Drosophila models of Aβ- and Tau-induced pathology. We found proteins that can either modify Aβ toxicity, Tau toxicity or both, suggesting specific interactions with different pathways. This approach illustrates the potential of Drosophila to validate hits after MS studies and suggest that model organisms should be included in the pipeline to identify relevant targets for Alzheimer's disease.

BIOLOGICAL SIGNIFICANCE

We report a set of differentially expressed proteins in three Alzheimer's disease brains in comparison to a normal brain. Our analyses allowed us to identify that the main affected pathways were ROS and stress responses, oxidative phosphorylation, organellar acidification and cytoskeleton. We validated some identified proteins using genetic models of Amyloid-β and Tau-induced pathology in Drosophila melanogaster. With this approach, Sideroflexin and Phosphoglucomutase-1 were identified as novel proteins connected with Alzheimer's disease.

Memory retrieval by activating engram cells in mouse models of early Alzheimer's disease

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by progressive memory decline and subsequent loss of broader cognitive functions¹. Memory decline in early stages of Alzheimer’s is mostly limited to episodic memory, for which the hippocampus (HPC) plays a crucial role². However, it has been uncertain whether the observed amnesia in early stages of Alzheimer’s is due to disrupted encoding and consolidation of episodic information, or an impairment in the retrieval of stored memory information. Here we show that in transgenic mouse models of early Alzheimer’s, direct optogenetic activation of hippocampal memory engram cells results in memory retrieval despite the fact that these mice are amnesic in long-term memory tests when natural recall cues are utilized, revealing a retrieval, rather than a storage impairment. Prior to amyloid plaque deposition, the amnesia in these mice is age-dependent^3–5, which correlates with a progressive reduction of spine density of hippocampal dentate gyrus (DG) engram cells. We show that optogenetic induction of long-term potentiation (LTP) at perforant path (PP) synapses of DG engram cells restores both spine density and long-term memory. We also demonstrate that an ablation of DG engram cells containing restored spine density prevents the rescue of long-term memory. Thus, selective rescue of spine density in engram cells may lead to an effective strategy for treating memory loss in early stages of Alzheimer’s disease.

Small scale homelike special care units and traditional special care units: effects on cognition in dementia; a longitudinal controlled intervention study

BACKGROUND

Evidence shows that living in small scale homelike Special Care Units (SCU) has positive effects on behavioural and psychological symptoms of patients with dementia. Effects on cognitive functioning in relation to care facilities, however, are scarcely investigated. The purpose of this study is to gain more insight into the effects of living in small scale homelike Special Care Units, compared to regular SCU's, on the course of cognitive functioning in dementia.

METHODS

A group of 67 patients with dementia who moved from a regular SCU to a small scale homelike SCU and a group of 48 patients with dementia who stayed in a regular SCU participated in the study. Cognitive and behavioural functioning was assessed by means of a neuropsychological test battery and observation scales one month before (baseline), as well as 3 (post) and 6 months (follow-up) after relocation.

RESULTS

Comparing the post and follow-up measurement with the baseline measurement, no significant differences on separate measures of cognitive functioning between both groups were found. Additional analyses, however, on 'domain clusters' revealed that global cognitive functioning of the small scale homelike SCU group showed significantly less cognitive decline three months after the transfer (p < 0.05). Effect sizes (95% CI) show a tendency for better aspects of cognition in favour of the homelike small scaled SCU group, i.e., visual memory, picture recognition, cognitive decline as observed by representatives and the clustered domains episodic memory and global cognitive functioning.

CONCLUSIONS

While there is no significant longitudinal effect on the progression of cognitive decline comparing small scaled homelike SCU's with regular SCU's for patients with dementia, analyses on the domain clusters and effect sizes cautiously suggest differences in favour of the small scaled homelike SCU for different aspects of cognition.

Alzheimer's Disease Assessment Scale-Cognitive subscale variants in mild cognitive impairment and mild Alzheimer's disease: change over time and the effect of enrichment strategies

Background

Development of new treatments for Alzheimer’s disease (AD) has broadened into early interventions in individuals with modest cognitive impairment and a slow decline. The 11-item version of the Alzheimer’s Disease Assessment Scale–Cognitive subscale (ADAS-Cog) was originally developed to measure cognition in patients with mild to moderate AD. Attempts to improve its properties for early AD by removing items prone to ceiling and/or by adding cognitive measures known to be impaired early have yielded a number of ADAS-Cog variants. Using Alzheimer’s Disease Neuroimaging Initiative data, we compared the performance of the 3-, 5-, 11- and 13-item ADAS-Cog variants in subjects with early AD. Given the interest in enrichment strategies, we also examined this aspect with a focus on cerebrospinal fluid (CSF) markers.

Methods

Subjects with mild cognitive impairment (MCI) and mild AD with available ADAS-Cog 13 and CSF data were analysed. The decline over time was defined by change from baseline. Direct cross-comparison of the ADAS-Cog variants was performed using the signal-to-noise ratio (SNR), with higher values reflecting increased sensitivity to detect change over time.

Results

The decline over time on any of the ADAS-Cog variants was minimal in subjects with MCI. Approximately half of subjects with MCI fulfilled enrichment criteria for positive AD pathology. The impact of enrichment was detectable but subtle in MCI. The annual decline in mild AD was more pronounced but still modest. More than 90 % of subjects with mild AD had positive AD pathology. SNRs were low in MCI but greater in mild AD. The numerically largest SNRs were seen for the ADAS-Cog 5 in MCI and for both the 5- and 13-item ADAS-Cog variants in mild AD, although associated confidence intervals were large.

Conclusions

The possible value of ADAS-Cog expansion or reduction is less than compelling, particularly in MCI. In mild AD, adding items known to be impaired at early stages seems to provide more benefit than removing items on which subjects score close to ceiling.

Electronic supplementary material

The online version of this article (doi:10.1186/s13195-016-0170-5) contains supplementary material, which is available to authorized users.

A Comprehensive Behavioral Test Battery to Assess Learning and Memory in 129S6/Tg2576 Mice

Transgenic Tg2576 mice overexpressing human amyloid precursor protein (hAPP) are a widely used Alzheimer's disease (AD) mouse model to evaluate treatment effects on amyloid beta (Aβ) pathology and cognition. Tg2576 mice on a B6;SJL background strain carry a recessive rd1 mutation that leads to early retinal degeneration and visual impairment in homozygous carriers. This can impair performance in behavioral tests that rely on visual cues, and thus, affect study results. Therefore, B6;SJL/Tg2576 mice were systematically backcrossed with 129S6/SvEvTac mice resulting in 129S6/Tg2576 mice that lack the rd1 mutation. 129S6/Tg2576 mice do not develop retinal degeneration but still show Aβ accumulation in the brain that is comparable to the original B6;SJL/Tg2576 mouse. However, comprehensive studies on cognitive decline in 129S6/Tg2576 mice are limited. In this study, we used two dementia mouse models on a 129S6 background--scopolamine-treated 129S6/SvEvTac mice (3-5 month-old) and transgenic 129S6/Tg2576 mice (11-13 month-old)-to establish a behavioral test battery for assessing learning and memory. The test battery consisted of five tests to evaluate different aspects of cognitive impairment: a Y-Maze forced alternation task, a novel object recognition test, the Morris water maze, the radial arm water maze, and a Y-maze spontaneous alternation task. We first established this behavioral test battery with the scopolamine-induced dementia model using 129S6/SvEvTac mice and then evaluated 129S6/Tg2576 mice using the same testing protocol. Both models showed distinctive patterns of cognitive impairment. Together, the non-invasive behavioral test battery presented here allows detecting cognitive impairment in scopolamine-treated 129S6/SvEvTac mice and in transgenic 129S6/Tg2576 mice. Due to the modular nature of this test battery, more behavioral tests, e.g. invasive assays to gain additional cognitive information, can easily be added.

Memory Test Performance on Analogous Verbal and Nonverbal Memory Tests in Patients with Frontotemporal Dementia and Alzheimer's Disease

BACKGROUND

Patients with frontotemporal dementia (FTD) typically have initial deficits in language or changes in personality, while the defining characteristic of Alzheimer's disease (AD) is memory impairment. Neuropsychological findings in the two diseases tend to differ, but can be confounded by verbal impairment in FTD impacting performance on memory tests in these patients.

METHODS

Twenty-seven patients with FTD and 102 patients with AD underwent a neuropsychological assessment before diagnosis. By utilizing analogous versions of a verbal and nonverbal memory test, we demonstrated differences in these two modalities between AD and FTD.

DISCUSSION

Better differentiation between AD and FTD is found in a nonverbal memory test, possibly because it eliminates the confounding variable of language deficits found in patients with FTD. These results highlight the importance of nonverbal learning tests with multiple learning trials in diagnostic testing.

The Association of Specific Executive Functions and Falls Risk in People with Mild Cognitive Impairment and Early-Stage Dementia

BACKGROUND/AIMS

Impairment in executive function is associated with a heightened risk for falls in people with mild cognitive impairment (MCI) and dementia. The purpose of this study was to determine which aspects of executive function are associated with falls risk.

METHODS

Forty-two participants with a mean age of 81.6 years and a diagnosis of MCI or mild dementia completed five different executive function tests from the computerised CANTAB test battery and a comprehensive falls risk assessment.

RESULTS

A hierarchical regression analysis showed that falls risk was significantly associated with spatial memory abilities and inhibition of a pre-potent response.

CONCLUSION

The concept of executive function may be too general to provide meaningful results in a research or clinical context, which should focus on spatial memory and inhibition of a pre-potent response.

The Chronicity of HIV Infection Should Drive the Research Strategy of NeuroHIV Treatment Studies: A Critical Review

HIV infection has become a chronic illness when successfully treated with combined antiretroviral therapy (cART). The long-term health prognosis of aging with controlled HIV infection and HIV-associated neurocognitive disorder (HAND) remains unclear. In this review, we propose that, almost 20 years after the introduction of cART, a change in research focus is needed, with a greater emphasis on chronicity effects driving our research strategy. We argue that pre-emptive documentation of episodes of mild neurocognitive dysfunction is needed to determine their long-term prognosis. This strategy would also seek to optimally represent the entire HAND spectrum in therapeutic trials to assess positive and/or negative treatment effects on brain functions. In the first part of the paper, to improve the standard implementation of the Frascati HAND diagnostic criteria, we provide a brief review of relevant quantitative neuropsychology concepts to clarify their appropriate application for a non-neuropsychological audience working in HIV research and wanting to conduct randomized clinical trials on brain functions. The second part comprises a review of various antiretroviral drug classes and individual agents with respect to their effects on HAND, while also addressing the question of when cART should be initiated to potentially reduce HAND incidence. In each section, we use recent observational studies and randomized controlled trials to illustrate our perspective while also providing relevant statistical comments. We conclude with a discussion of the neuroimaging methods that could be combined with neuropsychological approaches to enhance the validity of HIV neurology (neuroHIV) treatment effect studies.

Discrimination between Alzheimer's Disease and Late Onset Bipolar Disorder Using Multivariate Analysis

Background

Late onset bipolar disorder (LOBD) is often difficult to distinguish from degenerative dementias, such as Alzheimer disease (AD), due to comorbidities and common cognitive symptoms. Moreover, LOBD prevalence in the elder population is not negligible and it is increasing. Both pathologies share pathophysiological neuroinflammation features. Improvements in differential diagnosis of LOBD and AD will help to select the best personalized treatment.

Objective

The aim of this study is to assess the relative significance of clinical observations, neuropsychological tests, and specific blood plasma biomarkers (inflammatory and neurotrophic), separately and combined, in the differential diagnosis of LOBD versus AD. It was carried out evaluating the accuracy achieved by classification-based computer-aided diagnosis (CAD) systems based on these variables.

Materials

A sample of healthy controls (HC) (n = 26), AD patients (n = 37), and LOBD patients (n = 32) was recruited at the Alava University Hospital. Clinical observations, neuropsychological tests, and plasma biomarkers were measured at recruitment time.

Methods

We applied multivariate machine learning classification methods to discriminate subjects from HC, AD, and LOBD populations in the study. We analyzed, for each classification contrast, feature sets combining clinical observations, neuropsychological measures, and biological markers, including inflammation biomarkers. Furthermore, we analyzed reduced feature sets containing variables with significative differences determined by a Welch’s t-test. Furthermore, a battery of classifier architectures were applied, encompassing linear and non-linear Support Vector Machines (SVM), Random Forests (RF), Classification and regression trees (CART), and their performance was evaluated in a leave-one-out (LOO) cross-validation scheme. Post hoc analysis of Gini index in CART classifiers provided a measure of each variable importance.

Results

Welch’s t-test found one biomarker (Malondialdehyde) with significative differences (p < 0.001) in LOBD vs. AD contrast. Classification results with the best features are as follows: discrimination of HC vs. AD patients reaches accuracy 97.21% and AUC 98.17%. Discrimination of LOBD vs. AD patients reaches accuracy 90.26% and AUC 89.57%. Discrimination of HC vs LOBD patients achieves accuracy 95.76% and AUC 88.46%.

Conclusion

It is feasible to build CAD systems for differential diagnosis of LOBD and AD on the basis of a reduced set of clinical variables. Clinical observations provide the greatest discrimination. Neuropsychological tests are improved by the addition of biomarkers, and both contribute significantly to improve the overall predictive performance.

The role of nutrition on cognition and brain health in ageing: a targeted approach

Animal experiments and cross-sectional or prospective longitudinal research in human subjects suggest a role for nutrition in cognitive ageing. However, data from randomised controlled trials (RCT) that seek causal evidence for the impact of nutrients on cognitive ageing in humans often produce null results. Given that RCT test hypotheses in a rigorous fashion, one conclusion could be that the positive effects of nutrition on the aged brain observed in other study designs are spurious. On the other hand, it may be that the design of many clinical trials conducted thus far has been less than optimal. In the present review, we offer a blueprint for a more targeted approach to the design of RCT in nutrition, cognition and brain health in ageing that focuses on three key areas. First, the role of nutrition is more suited for the maintenance of health rather than the treatment of disease. Second, given that cognitive functions and brain regions vary in their susceptibility to ageing, those that especially deteriorate in senescence should be focal points in evaluating the efficacy of an intervention. Third, the outcome measures that assess change due to nutrition, especially in the cognitive domain, should not necessarily be the same neuropsychological tests used to assess gross brain damage or major pathological conditions. By addressing these three areas, we expect that clinical trials of nutrition, cognition and brain health in ageing will align more closely with other research in this field, and aid in revealing the true nature of nutrition's impact on the aged brain.

Neuroprotective effects of multifaceted hybrid agents targeting MAO, cholinesterase, iron and β-amyloid in ageing and Alzheimer's disease

Alzheimer's disease (AD) is accepted nowadays as a complex neurodegenerative disorder with multifaceted cerebral pathologies, including extracellular deposition of amyloid β peptide-containing plaques, intracellular neurofibrillary tangles, progressive loss of cholinergic neurons, metal dyshomeostasis, mitochondrial dysfunction, neuroinflammation, glutamate excitoxicity, oxidative stress and increased MAO enzyme activity. This may explain why it is currently widely accepted that a more effective therapy for AD would result from the use of multifunctional drugs, which may affect more than one brain target involved in the disease pathology. The current review will discuss the potential benefits of novel multimodal neuroprotective, brain permeable drugs, recently developed by Youdim and collaborators, as a valuable therapeutic approach for AD treatment. The pharmacological and neuroprotective properties of these multitarget-directed ligands, which target MAO enzymes, the cholinergic system, iron accumulation and amyloid β peptide generation/aggregation are described, with a special emphasis on their potential therapeutic value for ageing and AD-associated cognitive functions. This review is conceived as a tribute to the broad neuropharmacology work of Professor Moussa Youdim, Professor Emeritus in the Faculty of Medicine and Director of Eve Topf Center of Excellence in Technion-Israel Institute of Technology, and Chief Scientific Officer of ABITAL Pharma Pipeline Ltd., at the occasion of his 75th birthday.

LINKED ARTICLES

This article is part of a themed section on Updating Neuropathology and Neuropharmacology of Monoaminergic Systems. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.13/issuetoc.

Cognitive Effects of Hormone Therapy Continuation or Discontinuation in a Sample of Women at Risk for Alzheimer Disease

OBJECTIVE

Use of estrogen-based hormone therapy (HT) as a protection from cognitive decline and Alzheimer disease (AD) is controversial, although cumulative data support HT use when initiated close to menopause onset with estrogen formulations containing 17β-estradiol preferable to conjugated equine estrogen formulations. Little is known regarding specific populations of women who may derive benefit from HT.

METHODS

Women with heightened risk for AD (aged 49-69), all of whom were taking HT for at least 1 year and most of whom initiated HT close to menopause onset, underwent cognitive assessment followed by randomization to continue or discontinue HT. Assessments were repeated at 2 years after randomization.

RESULTS

Women who continued HT performed better on cognitive domains composed of measures of verbal memory and combined attention, working memory, and processing speed measures. Women who used 17β-estradiol versus conjugated equine estrogen, whether randomized to continue or discontinue HT, showed better verbal memory performance at the 2-year follow-up assessment. An interaction was also found with HT randomization and family history of AD in a first-degree relative. All female offspring of patients with AD declined in verbal memory; however, women who continued HT declined less than women who discontinued HT. Women without a first-degree relative with AD showed verbal memory improvement (likely because of practice effects) with continuance and declined with discontinuance of HT.

CONCLUSION

Continuation of HT use appears to protect cognition in women with heightened risk for AD when initiated close to menopause onset.

Proteomics in Traditional Chinese Medicine with an Emphasis on Alzheimer's Disease

In recent years, there has been an increasing worldwide interest in traditional Chinese medicine (TCM). This increasing demand for TCM needs to be accompanied by a deeper understanding of the mechanisms of action of TCM-based therapy. However, TCM is often described as a concept of Chinese philosophy, which is incomprehensible for Western medical society, thereby creating a gap between TCM and Western medicine (WM). In order to meet this challenge, TCM research has applied proteomics technologies for exploring the mechanisms of action of TCM treatment. Proteomics enables TCM researchers to oversee various pathways that are affected by treatment, as well as the dynamics of their interactions with one another. This review discusses the utility of comparative proteomics to better understand how TCM treatment may be used as a complementary therapy for Alzheimer's disease (AD). Additionally, we review the data from comparative AD-related TCM proteomics studies and establish the relevance of the data with available AD hypotheses, most notably regarding the ubiquitin proteasome system (UPS).

Dissecting Alzheimer disease in Down syndrome using mouse models

Down syndrome (DS) is a common genetic condition caused by the presence of three copies of chromosome 21 (trisomy 21). This greatly increases the risk of Alzheimer disease (AD), but although virtually all people with DS have AD neuropathology by 40 years of age, not all develop dementia. To dissect the genetic contribution of trisomy 21 to DS phenotypes including those relevant to AD, a range of DS mouse models has been generated which are trisomic for chromosome segments syntenic to human chromosome 21. Here, we consider key characteristics of human AD in DS (AD-DS), and our current state of knowledge on related phenotypes in AD and DS mouse models. We go on to review important features needed in future models of AD-DS, to understand this type of dementia and so highlight pathogenic mechanisms relevant to all populations at risk of AD.

Structural brain alterations in heart failure: a review of the literature and implications for risk of Alzheimer's disease

Cardiovascular disease is a recognized contributor to the pathogenesis of Alzheimer's disease (AD). Heart failure (HF) is a cardiovascular subtype that can be used to model the contribution of cardiovascular disease to AD. Neuroimaging research indicates that HF patients exhibit a diverse range of structural brain alterations and epidemiological studies suggest HF may be an important risk factor for AD. The neural alterations observed in HF may overlap with those observed in AD and contribute to increased risk of AD in HF patients. To examine this possibility, we reviewed structural MRI studies in persons with HF. We examined subcortical brain regions affected in the early stages of AD (medial temporal lobes), as well as cortical alterations that typically occur in the later stages of AD. Our review indicates that patients with HF exhibit greater neural atrophy and white matter microstructural alterations of nearly every region of the Papez circuit (e.g., hippocampus, cingulate gyrus, thalamus, mammillary bodies, and fornix), as well-significant alterations in cortical and cerebellar regions. Based on animal research and past work in AD patients, the mechanisms for structural brain changes in HF may stem from reductions in cerebral blood flow subsequent to cardiac deficiency. This review supports the hypothesis that HF may contribute to AD risk via widespread structural brain changes, including many of the same regions affected by AD. Case-controlled prospective neuroimaging studies with long-term follow-ups are needed to clarify the risk of AD in HF and elucidate the neural underpinnings of AD risk in HF.

Relating hippocampus to relational memory processing across domains and delays

The hippocampus has been implicated in a diverse set of cognitive domains and paradigms, including cognitive mapping, long-term memory, and relational memory, at long or short study-test intervals. Despite the diversity of these areas, their association with the hippocampus may rely on an underlying commonality of relational memory processing shared among them. Most studies assess hippocampal memory within just one of these domains, making it difficult to know whether these paradigms all assess a similar underlying cognitive construct tied to the hippocampus. Here we directly tested the commonality among disparate tasks linked to the hippocampus by using PCA on performance from a battery of 12 cognitive tasks that included two traditional, long-delay neuropsychological tests of memory and two laboratory tests of relational memory (one of spatial and one of visual object associations) that imposed only short delays between study and test. Also included were different tests of memory, executive function, and processing speed. Structural MRI scans from a subset of participants were used to quantify the volume of the hippocampus and other subcortical regions. Results revealed that the 12 tasks clustered into four components; critically, the two neuropsychological tasks of long-term verbal memory and the two laboratory tests of relational memory loaded onto one component. Moreover, bilateral hippocampal volume was strongly tied to performance on this component. Taken together, these data emphasize the important contribution the hippocampus makes to relational memory processing across a broad range of tasks that span multiple domains.

A 24-week study to evaluate the effect of rilapladib on cognition and cerebrospinal fluid biomarkers of Alzheimer's disease

Background

The lipoprotein-associated phospholipase A₂ inhibitor (Lp-PLA₂), rilapladib (SB659032), is being evaluated as a potential treatment to slow the progression of Alzheimer's disease (AD).

Methods

One hundred twenty-four subjects with possible mild AD and with neuroimaging evidence of cerebrovascular disease were randomized to placebo or 250-mg rilapladib once daily, for 24 weeks, in addition to stable background acetylcholinesterase inhibitor and/or memantine. The study assessed the safety and tolerability of rilapladib and its effects on cognition, mechanistic, and disease-related biomarkers. Although the overall intent behind the study was to take a broad exploratory view of the data, two primary end points of interest (cerebrospinal fluid [CSF] amyloid beta peptide 1–42 [Aβ_1–42] and CogState executive function/working memory [EF/WM] composite score at week 24) were prespecified in the analysis plan for inferential statistical analysis.

Results

Rilapladib was well tolerated with no significant safety concerns. A significant difference from placebo was observed for rilapladib on change from baseline in EF/WM (effect size, 0.45; P = .026). There was no significant difference between groups on the change from baseline in CSF Aβ_1–42 (P = .133). Preliminary evidence of effects was detected on other mechanistic (albumin quotient) and disease-related biomarkers (tau/P-tau and neurofilament light chain).

Conclusion

These data provide initial evidence supporting Lp-PLA₂ inhibition as a novel treatment for dementia.

Clinical Trial Registration

Clinicaltrials.gov identifier: NCT01428453.

A multi-contrast MRI study of microstructural brain damage in patients with mild cognitive impairment

Objectives

The aim of this study was to investigate pathological mechanisms underlying brain tissue alterations in mild cognitive impairment (MCI) using multi-contrast 3 T magnetic resonance imaging (MRI).

Methods

Forty-two MCI patients and 77 healthy controls (HC) underwent T1/T2* relaxometry as well as Magnetization Transfer (MT) MRI. Between-groups comparisons in MRI metrics were performed using permutation-based tests. Using MRI data, a generalized linear model (GLM) was computed to predict clinical performance and a support-vector machine (SVM) classification was used to classify MCI and HC subjects.

Results

Multi-parametric MRI data showed microstructural brain alterations in MCI patients vs HC that might be interpreted as: (i) a broad loss of myelin/cellular proteins and tissue microstructure in the hippocampus (p ≤ 0.01) and global white matter (p < 0.05); and (ii) iron accumulation in the pallidus nucleus (p ≤ 0.05). MRI metrics accurately predicted memory and executive performances in patients (p ≤ 0.005). SVM classification reached an accuracy of 75% to separate MCI and HC, and performed best using both volumes and T1/T2*/MT metrics.

Conclusion

Multi-contrast MRI appears to be a promising approach to infer pathophysiological mechanisms leading to brain tissue alterations in MCI. Likewise, parametric MRI data provide powerful correlates of cognitive deficits and improve automatic disease classification based on morphometric features.

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Forty-two MCI patients and 77 HC underwent multi-contrast quantitative MRI.

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MCI patients showed T1/T2* increase and MTR decrease in the hippocampus.

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MCI patients exhibited T1 increase in WM and T2* decrease in the pallidus.

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MRI metrics accurately predicted memory and executive function in patients.

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SVM classified MCI patients with 75% accuracy using volumetric/parametric MRI.

Detecting early egocentric and allocentric impairments deficits in Alzheimer's disease: an experimental study with virtual reality

Several studies have pointed out that egocentric and allocentric spatial impairments are one of the earliest manifestations of Alzheimer's Disease (AD). It is less clear how a break in the continuous interaction between these two representations may be a crucial marker to detect patients who are at risk to develop dementia. The main objective of this study is to compare the performances of participants suffering from amnestic mild cognitive impairment (aMCI group), patients with AD (AD group) and a control group (CG), using a virtual reality (VR)-based procedure for assessing the abilities in encoding, storing and syncing different spatial representations. In the first task, participants were required to indicate on a real map the position of the object they had memorized, while in the second task they were invited to retrieve its position from an empty version of the same virtual room, starting from a different position. The entire procedure was repeated across three different trials, depending on the object location in the encoding phase. Our finding showed that aMCI patients performed significantly more poorly in the third trial of the first task, showing a deficit in the ability to encode and store an allocentric viewpoint independent representation. On the other hand, AD patients performed significantly more poorly when compared to the CG in the second task, indicating a specific impairment in storing an allocentric viewpoint independent representation and then syncing it with the allocentric viewpoint dependent representation. Furthermore, data suggested that these impairments are not a product of generalized cognitive decline or of general decay in spatial abilities, but instead may reflect a selective deficit in the spatial organization Overall, these findings provide an initial insight into the cognitive underpinnings of amnestic impairment in aMCI and AD patient exploiting the potentiality of VR.

Acetylcholine mediates behavioral and neural post-error control

Humans often commit errors when they are distracted by irrelevant information and no longer focus on what is relevant to the task at hand. Adjustments following errors are essential for optimizing goal achievement. The posterior medial frontal cortex (pMFC), a key area for monitoring errors, has been shown to trigger such post-error adjustments by modulating activity in visual cortical areas. However, the mechanisms by which pMFC controls sensory cortices are unknown. We provide evidence for a mechanism based on pMFC-induced recruitment of cholinergic projections to task-relevant sensory areas. Using fMRI in healthy volunteers, we found that error-related pMFC activity predicted subsequent adjustments in task-relevant visual brain areas. In particular, following an error, activity increased in those visual cortical areas involved in processing task-relevant stimulus features, whereas activity decreased in areas representing irrelevant, distracting features. Following treatment with the muscarinic acetylcholine receptor antagonist biperiden, activity in visual areas was no longer under control of error-related pMFC activity. This was paralleled by abolished post-error behavioral adjustments under biperiden. Our results reveal a prominent role of acetylcholine in cognitive control that has not been recognized thus far. Regaining optimal performance after errors critically depends on top-down control of perception driven by the pMFC and mediated by acetylcholine. This may explain the lack of adaptivity in conditions with reduced availability of cortical acetylcholine, such as Alzheimer's disease.

Morphometric and histologic substrates of cingulate integrity in elders with exceptional memory capacity

This human study is based on an established cohort of "SuperAgers," 80+-year-old individuals with episodic memory function at a level equal to, or better than, individuals 20-30 years younger. A preliminary investigation using structural brain imaging revealed a region of anterior cingulate cortex that was thicker in SuperAgers compared with healthy 50- to 65-year-olds. Here, we investigated the in vivo structural features of cingulate cortex in a larger sample of SuperAgers and conducted a histologic analysis of this region in postmortem specimens. A region-of-interest MRI structural analysis found cingulate cortex to be thinner in cognitively average 80+ year olds (n = 21) than in the healthy middle-aged group (n = 18). A region of the anterior cingulate cortex in the right hemisphere displayed greater thickness in SuperAgers (n = 31) compared with cognitively average 80+ year olds and also to the much younger healthy 50-60 year olds (p < 0.01). Postmortem investigations were conducted in the cingulate cortex in five SuperAgers, five cognitively average elderly individuals, and five individuals with amnestic mild cognitive impairment. Compared with other subject groups, SuperAgers showed a lower frequency of Alzheimer-type neurofibrillary tangles (p < 0.05). There were no differences in total neuronal size or count between subject groups. Interestingly, relative to total neuronal packing density, there was a higher density of von Economo neurons (p < 0.05), particularly in anterior cingulate regions of SuperAgers. These findings suggest that reduced vulnerability to the age-related emergence of Alzheimer pathology and higher von Economo neuron density in anterior cingulate cortex may represent biological correlates of high memory capacity in advanced old age.

A Summary Score for the Framingham Heart Study Neuropsychological Battery

OBJECTIVE

To calculate three summary scores of the Framingham Heart Study neuropsychological battery and determine which score best differentiates between subjects classified as having normal cognition, test-based impaired learning and memory, test-based multidomain impairment, and dementia.

METHOD

The final sample included 2,503 participants. Three summary scores were assessed: (a) composite score that provided equal weight to each subtest, (b) composite score that provided equal weight to each cognitive domain assessed by the neuropsychological battery, and (c) abbreviated score comprised of subtests for learning and memory. Receiver operating characteristic analysis was used to determine which summary score best differentiated between the four cognitive states.

RESULTS

The summary score that provided equal weight to each subtest best differentiated between the four cognitive states.

DISCUSSION

A summary score that provides equal weight to each subtest is an efficient way to utilize all of the cognitive data collected by a neuropsychological battery.

Clinical characterization of mild cognitive impairment as a prodrome to dementia with Lewy bodies

Limited information regarding the specificity of mild cognitive impairment (MCI) as it relates to dementia with Lewy bodies (DLB) exists. Here, we summarize the clinical phenotype of MCI in clinically suspect DLB. Ten patients with a primary diagnosis of MCI and secondary diagnoses of DLB were identified. Patients underwent clinical neurological and neuropsychological evaluation that included application of McKeith criteria. We found parkinsonism and gait abnormality in 9 of the 10 patients; fluctuations in 8 of the 10; and hallucinations and dream enactment behavior in 5 of the 10. Of the 10 cases, 4 were classified as nonamnestic MCI and 6 were amnestic MCI. Of the 10 cases, 9 displayed executive and/or visuospatial dysfunction. Of the 10 cases, 6 have progressed to DLB. Progression of MCI to DLB is not dependent on memory impairment. The presence of core clinical features-parkinsonism and cognitive fluctuations-and predominant executive and visuospatial dysfunction ± memory impairment is suggestive of a prodromal DLB presentation.