Frontotemporal dementia to Alzheimer's disease

Shadowing Behavior May Be Associated with an Inability to Recognize the External World: A Case Report of Shadowing in a Patient with Posterior Cortical Atrophy

Although shadowing behavior- when one individual closely follows another- is routinely documented among patients with dementia, its mechanisms have yet to be elucidated. In particular, there have been no detailed descriptions of patients with shadowing behavior. To propose its potential backgrounds, we describe a patient with posterior cortical atrophy who exhibited prominent shadowing behavior. He also experienced severe difficulties recognizing external stimuli, including visuospatial dysfunction, several types of agnosia, difficulties in verbal comprehension, disorientation, and its associated depression. This shadowing behavior may be adaptive relative to his extreme difficulty with recognizing the world around him.

Performance of the intracerebroventricularly injected streptozotocin Alzheimer's disease model in a translationally relevant, aged and experienced rat population

The intracerebroventricularly (icv) injected streptozotocin (STZ) induced brain state is a widely used model of sporadic Alzheimer-disease (AD). However, data have been generated in young, naive albino rats. We postulate that the translationally most relevant animal population of an AD model should be that of aged rats with substantial learning history. The objective of the study was thus to probe the model in old rats with knowledge in various cognitive domains. Long-Evans rats of 23 and 10 months age with acquired knowledge in five-choice serial reaction time task (5-CSRTT), a cooperation task, Morris water-maze (MWM) and "pot-jumping" exercise were treated with 3 × 1.5 mg/kg icv. STZ and their performance were followed for 3 months in the above and additional behavioral assays. Both STZ-treated age groups showed significant impairment in the MWM (spatial learning) and novel object recognition test (recognition memory) but not in passive avoidance and fear conditioning paradigms (fear memory). In young STZ treated rats, significant differences were also found in the 5CSRTT (attention) and pot jumping test (procedural learning) while in old rats a significant increase in hippocampal phospho-tau/tau protein ratio was observed. No significant difference was found in the cooperation (social cognition) and pairwise discrimination (visual memory) assays and hippocampal β-amyloid levels. STZ treated old animals showed impulsivity-like behavior in several tests. Our results partly coincide with partly deviate from those published on young, albino, unexperienced rats. Beside the age, strain and experience level of the animals differences can also be attributed to the increased dose of STZ, and the applied food restriction regime. The observed cognitive and non-cognitive activity pattern of icv. STZ in aged experienced rats call for more extensive studies with the STZ model to further strengthen and specify its translational validity.

Clinical Utility of Plasma Lipid Peroxidation Biomarkers in Alzheimer's Disease Differential Diagnosis

BACKGROUND

Differential diagnosis of Alzheimer's disease (AD) is a complex task due to the clinical similarity among neurodegenerative diseases. Previous studies showed the role of lipid peroxidation in early AD development. However, the clinical validation of potential specific biomarkers in minimally invasive samples constitutes a great challenge in early AD diagnosis.

METHODS

Plasma samples from participants classified into AD (n = 138), non-AD (including MCI and other dementias not due to AD) (n = 70) and healthy (n = 50) were analysed. Lipid peroxidation compounds (isoprostanes, isofurans, neuroprostanes, neurofurans) were determined by ultra-performance liquid chromatography coupled with tandem mass spectrometry. Statistical analysis for biomarkers' clinical validation was based on Elastic Net.

RESULTS

A two-step diagnosis model was developed from plasma lipid peroxidation products to diagnose early AD specifically, and a bootstrap validated AUC of 0.74 was obtained.

CONCLUSION

A promising AD differential diagnosis model was developed. It was clinically validated as a screening test. However, further external validation is required before clinical application.

What to make of equivocal amyloid imaging results

INTRODUCTION

Six patients with equivocal amyloid-PET results are discussed.

METHODS

Patients underwent clinical/neuropsychological assessment, MRI, and amyloid-PET. Equivocal amyloid-PET was defined as cortical ligand binding with SUVR < 1.40. Follow-up for up to 5 years is presented.

RESULTS

6 patients (4 males, 2 females, mean age 71.8 +/- 2.5 years) with equivocal amyloid-PET were included from 136 patients who underwent amyloid-PET (4.4% of cases). Patients had variable language, behavioral, and cognitive deficits. Progression varied from no deterioration to residential care within 3 years.

DISCUSSION

Equivocal amyloid-PET should be interpreted cautiously. Improved biomarkers of AD and other neurodegenerative diseases are needed.

Novel Behavioural Characteristics of Male Human P301S Mutant Tau Transgenic Mice - A Model for Tauopathy

Alzheimer's disease (AD) is a neurodegenerative disease characterised by progressive cognitive decline and the accumulation of two hallmark proteins, amyloid-beta (Aβ) and tau. Traditionally, transgenic mouse models for AD have generally focused on Aβ pathology, however, in recent years a number of tauopathy transgenic mouse models have been developed, including the TAU58/2 mouse model. These mice develop tau pathology and neurofibrillary tangles from 2 months of age and show motor impairments and alterations in the behavioural response to elevated plus maze (EPM) testing. The cognitive and social phenotype of this model has not yet been assessed comprehensively. Furthermore, the behavioural changes seen in the EPM have previously been linked to both anxiety and disinhibitory phenotypes. Thus, this study assessed 4-month-old TAU58/2 males comprehensively for disinhibitory and social behaviours, social recognition memory, and sensorimotor gating. TAU58/2 males demonstrated reduced exploration and anxiety-like behaviours but no changes to disinhibitory behaviours, reduced sociability in the social preference test and impaired acoustic startle and prepulse inhibition. Aggressive and socio-positive behaviours were not affected except a reduction in the occurrence of nosing and anogenital sniffing. Our study identified new phenotypic characteristics of young adult male TAU58/2 transgenic mice and clarified the nature of changes detected in the behavioural response of these mice to EPM testing. Social withdrawal and inappropriate social behaviours are common symptoms in both AD and FTD patients and impaired sensorimotor gating is seen in moderate-late stage AD, emphasising the relevance of the TAU58/2 model to these diseases.

Uncoupling protein 4 (UCP4) gene variability in neurodegenerative disorders: further evidence of association in Frontotemporal dementia

Ongoing research suggests that mitochondrial dysfunction is a common hallmark in neurodegenerative diseases, pointing to mitochondrial uncoupling process as a critical player. We recently reported that rs9472817-C/G, an intronic variant of neuronal mitochondrial uncoupling protein-4 (UCP4/SLC25A27) gene affects the risk of late onset Alzheimer's disease (LOAD), and that the variant's effect is strongly dependent on APOE-ε4 status. Here, we extended our analysis to a cohort of 751 subjects including late-onset familial and sporadic cases of frontotemporal dementia (FTD; 213), Parkinson disease (PD;96), and 442 healthy controls. In all subgroups, carriers of APOE-ε4 allele were at higher risk of disease. Regarding the rs9472817, no association was detected in familial FTD and both subgroups of PD patients. In sporadic FTD, as in LOAD, we found that the C allele increased the risk of disease of about 1.51-fold in a dose-dependent manner (p=0.013) independently from that conferred by APOE-ε4. Expression quantitative trait loci (eQTL) data of different brain regions suggest that rs9472817 likely exerts its effect by a cis-regulatory mechanism involving modulation of UCP4. If validated, the involvement of UCP4 in both FTD and LOAD might indicate interesting shared etiological factors which might give future therapeutic clues.

Cerebrospinal fluid biomarkers and cognitive status in differential diagnosis of frontotemporal dementia and Alzheimer's disease

Objective

This study aimed to determine the most appropriate cognitive and cerebrospinal fluid (CSF) biomarker setting to distinguish frontotemporal dementia (FTD) from Alzheimer’s disease (AD).

Method

Patients with FTD, those with AD, and those without dementia were enrolled in this study. CSF amyloid-ß 42 (Aß42), total (t)-tau, and phosphorylated (p)-tau concentrations were determined by enzyme-linked immunosorbent assays. Cognition was evaluated by the Mini-Mental State Examination (MMSE) and its domain scores. The associations of CSF biomarkers with cognitive measures were examined using regression models and the diagnostic value of CSF biomarkers was determined by receiver operating characteristics curves.

Results

CSF Aß42 levels were lower, whereas t-tau/Aß42 and p-tau/Aß42 ratios were higher in patients with AD compared with those with FTD. Some MMSE domain scores were different in FTD and AD, but they did not improve the ability to distinguish between the two pathologies. Poor temporal orientation scores were associated with low Aß42 levels only in patients with FTD. The p-tau/Aß42 ratio reached sufficient levels of sensitivity and specificity to discriminate FTD with primary progressive aphasia from AD.

Conclusions

The ratio of CSF p-tau/Aß42 is a sensitive and specific biomarker for discriminating patients with primary progressive aphasia from those with AD.

Preventive Effects of Dairy Products on Dementia and the Underlying Mechanisms

Alongside the rapid population aging occurring worldwide, the prevention of age-related memory decline and dementia has become a high priority. Dairy products have many physiological effects owing to their contents of lactic acid bacteria and the fatty acids and peptides generated during their fermentation. In particular, several recent studies have elucidated the effects of fermented dairy products on cognitive function. Epidemiological and clinical evidence has indicated that fermented dairy products have preventive effects against dementia, including Alzheimer’s disease. Recent preclinical studies have identified individual molecules generated during fermentation that are responsible for those preventive effects. Oleamide and dehydroergosterol have been identified as the agents responsible for reducing microglial inflammatory responses and neurotoxicity. In this review, the protective effects of fermented dairy products and their components on cognitive function, the mechanisms underlying those effects, and the prospects for their future clinical development will be discussed.

Genetic architecture of sporadic frontotemporal dementia and overlap with Alzheimer's and Parkinson's diseases

BACKGROUND

Clinical, pathological and genetic overlap between sporadic frontotemporal dementia (FTD), Alzheimer's disease (AD) and Parkinson's disease (PD) has been suggested; however, the relationship between these disorders is still not well understood. Here we evaluated genetic overlap between FTD, AD and PD to assess shared pathobiology and identify novel genetic variants associated with increased risk for FTD.

METHODS

Summary statistics were obtained from the International FTD Genomics Consortium, International PD Genetics Consortium and International Genomics of AD Project (n>75 000 cases and controls). We used conjunction false discovery rate (FDR) to evaluate genetic pleiotropy and conditional FDR to identify novel FTD-associated SNPs. Relevant variants were further evaluated for expression quantitative loci.

RESULTS

We observed SNPs within the HLA, MAPT and APOE regions jointly contributing to increased risk for FTD and AD or PD. By conditioning on polymorphisms associated with PD and AD, we found 11 loci associated with increased risk for FTD. Meta-analysis across two independent FTD cohorts revealed a genome-wide signal within the APOE region (rs6857, 3'-UTR=PVRL2, p=2.21×10^-12), and a suggestive signal for rs1358071 within the MAPT region (intronic=CRHR1, p=4.91×10^-7) with the effect allele tagging the H1 haplotype. Pleiotropic SNPs at the HLA and MAPT loci associated with expression changes in cis-genes supporting involvement of intracellular vesicular trafficking, immune response and endo/lysosomal processes.

CONCLUSIONS

Our findings demonstrate genetic pleiotropy in these neurodegenerative diseases and indicate that sporadic FTD is a polygenic disorder where multiple pleiotropic loci with small effects contribute to increased disease risk.

Eating Behaviors and Dietary Changes in Patients With Dementia

BACKGROUND

Eating problems and dietary changes have been reported in patients with dementia.

OBJECTIVES

The aim of this article is to explore the generalized problems with nutrition, diet, feeding, and eating reported among patients with dementia.

METHODS

Medline and Google Scholar searches were conducted for relevant articles, chapters, and books published before 2016. Search terms used included behavioral and psychological symptoms of dementia, dementia, dietary changes, eating behavior. Publications found through this indexed search were reviewed for further relevant references.

RESULTS

Abnormal eating behaviors, eating problems, and dietary changes are present in most people with dementia, especially in the later stages of the condition.

CONCLUSION

Individuals with dementia frequently develop serious feeding difficulties and changes in eating and dietary habits. The changes may be secondary to cognitive impairment or apraxia, or the result of insufficient caregiving, or the consequence of metabolic or neurochemical abnormalities occurring as part of the dementing process.

A Systematic Review of Metacognitive Differences Between Alzheimer's Disease and Frontotemporal Dementia

Clinicians often have difficulty distinguishing between various forms of dementia to achieve a correct diagnosis. Little research has been done to examine whether awareness of one's cognitive deficits, or metacognitive monitoring, might differ between dementia diagnoses, thereby providing an additional means of differentiating between dementia subtypes. We review articles examining metacognitive comparisons between two of the most common dementia subtypes: Alzheimer's disease and frontotemporal dementia. Greater monitoring deficits were apparent in frontotemporal dementia than in Alzheimer's disease, and participants with frontotemporal dementia were less likely to utilize task experience to update and improve the accuracy of subsequent monitoring judgments. Results provide evidence for the utility of metacognitive measures as a means of distinguishing between Alzheimer's disease and frontotemporal dementia.