Current Alzheimer Research - Volume 11, Issue 6, 2014

Alzheimer’s disease (AD) is a progressive degenerative disorder of the brain and is the most common form of dementia. To-date no simple, inexpensive and minimally invasive procedure is available to confirm with certainty the early diagnosis of AD prior to the manifestations of symptoms characteristic of the disease. Therefore, if population screening of individuals is to be performed, more suitable, easily accessible tissues would need to be used for a diagnostic test that would identify those who exhibit cellular pathology indicative of mild cognitive impairment (MCI) and AD risk so that they can be prioritized for primary prevention. This need for minimally invasive tests could be achieved by targeting surrogate tissues, since it is now well recognized that AD is not only a disorder restricted to pathology and biomarkers within the brain. Human buccal cells for instance are accessible in a minimally invasive manner, and exhibit cytological and nuclear morphologies that may be indicative of accelerated ageing or neurodegenerative disorders such as AD. However, to our knowledge there is no review available in the literature covering the biology of buccal cells and their applications in AD biomarker research. Therefore, the aim of this review is to summarize some of the main findings of biomarkers reported for AD in peripheral tissues, with a further focus on the rationale for the use of the buccal mucosa (BM) for biomarkers of AD and the evidence to date of changes exhibited in buccal cells with AD.

Abstract: Objective: To determine the effects of rivastigmine patch associated with physical exercise versus rivastigmine patch alone in quality of life (QOL), cognition, activities of daily living (ADL) and functional mobility in Alzheimer's disease (AD)subjects. Methods: A randomized, controlled, single-blinded trial was conducted in 40 patients with mild to moderate stages of AD. All patients were daily treated with rivastigmine transdermal patch at a stable dose of 4.6 mg and randomized into two groups: physical exercises or control. The exercise program consisted of aerobic, flexibility, strength and balance movements, twice a week for 6 months. Main outcomes were Quality of Life in Alzheimer's disease scale (QOL), Activities of Daily Living Questionnaire (ADL), Mini-Mental State Examination (MMSE) and “Time Up and Go Test”. Results: Thirty-four patients completed the study. After 6 months, there was a significant improvement in QOL of patients randomized to physical exercise group (P< 0.05). In both groups, there was an improvement on caregivers QOL (P>0.05). When considering cognitive functions, there was no difference between groups. The ability to perform ADL worsened in the group enrolled to RTP alone. There was an improvement in functional mobility in the group treated with RTP. Conclusion: Our results suggest that the association between physical exercises and RTP improves QOL in patients with AD. Cognition remained unchanged in both groups. Regarding the effect of physical exercises in ADL, further trials are necessary to confirm these results.

Background: Most persons with dementia live at home and are treated in the primary care. However, the ambulatory health care system in Germany contains a lot of “interface problems” and is not optimized for the future challenges. Innovative concepts like regional networks in dementia care exist on a project level and need to be tested for efficacy to encourage implementation. The goal of the study is the scientific evaluation of an already existing regional dementia network. Methods: Prospective randomized controlled trial of 235 community-living elderly with dementia and their family caregivers of network treatment (n=117) compared to usual care (n=118) in a predominantly rural region. The allocation to intervention or control group was based on network membership of their General Practitioner. Intervention patients received diagnostic evaluation and subsequent treatment according to network guidelines. Main outcome measures were the early contact with a neurologic or psychiatric specialist and dementia-specific medication as well as quality of life of the patients, and as secondary outcomes caregiver burden and caregiver health-related quality of life. Results: Network patients were more likely to receive antidementive drugs (50.5 % vs. 35.8 %; p=0.035) and had more often contact to a neurologist (18.6 % vs. 2.8 %; p< 0.001). No group differences were found on patient’s quality of life nor overall effects or treatment by time effects. Intervention caregivers reported no significant improvements in health related quality of life measured by SF-36 and EQ-5D. Conclusion: The management of dementia patients in an interdisciplinary regional network solelyprovides measurable advantages with respect to the provision of dementia-specific medication and utilization of medical treatment i.e. referral rates to specialists. Further evaluation research is needed to identify relevant mechanismsof collaborative processes with respect to their impact on patient and caregiver related outcomes.

This study investigated the possible role of the ApoE receptors Lrp1 and Apoer2 in mediating the pathological effects of ApoE4 in ApoE-targeted-replacement mice expressing either the human ApoE3 or ApoE4 allele. In this study we show that activation of the amyloid cascade by inhibition of the Aβ-degrading enzyme neprilysin results in upregulation of the ApoE receptor Lrp1 in the CA1 hippocampal neurons of 4-month-old ApoE4 mice, but not in the corresponding ApoE3 or ApoE-deficient (KO) mice. These results are in accordance with the previous findings that activation of the amyloid cascade induces Aβ accumulation in the CA1 neurons of ApoE4 mice, but not in ApoE3 or ApoE-KO mice. This suggests that the apoE4-driven elevation of Lrp1 is mediated via a gain of function mechanism and may play a role in mediating the effects of ApoE4 on Aβ. In contrast, no changes were observed in the levels of the corresponding Apoer2 receptor following the neprilysin inhibition. The ApoE receptors of naive ApoE4 mice were also affected differentially and isoform specifically by ApoE4. However, under these conditions, the effect was an ApoE4-driven reduction in the levels of Apoer2 in CA1 and CA3 pyramidal neurons, whereas the levels of Lrp1 were not affected. RT-PCR measurements revealed that the levels of Apoer2 and Lrp1 mRNA in the hippocampus of naïve and neprilysin-inhibited mice were not affected by ApoE4, suggesting that the observed effects of ApoE4 on the levels of these receptors is posttranscriptional. In conclusion, this study shows that the levels of hippocampal ApoE receptors Lrp1 and Apoer2 in vivo are affected isoform specifically by ApoE4 and that the type of receptor affected is context dependent.

Background: Sortilin-related receptor, Sorl1, is a neuronal receptor that interacts with the amyloid precursor protein to regulate amyloidogenesis. Variants in the gene encoding Sorl1 are associated with Alzheimer’s disease (AD), as well as its neuroimaging markers. Objectives: To investigate the relationship between SORL1 gene variants with ADrelated brain morphologies and AD, testing for sex-specific effects. Methods: The sample comprised 292 individuals aged ≥ 75 years participating in the longitudinal Sydney Older Persons Study. A sub-sample also underwent a brain MRI scan (n=102, 53 males; 49 females). The relationships of three SORL1 single nucleotide polymorphisms (SNPs): rs4935774, rs2298813, rs1133174 with brain MRI measures, and AD were determined. Results: Significant associations of SORL1 variants with cross-sectional brain MRI measures and AD were observed only when the sample was stratified by sex. The most common haplotype (H1), comprising rs4935774-T, rs2298813-G, and rs1133174-G alleles (T/G/G) was associated with whole brain atrophy in both males and females (p=0.012 & p=0.013; respectively). Only SNP rs1133174 was individually associated with hippocampal atrophy in males (p= 0.039) and females (p=0.025). Of the 292 participants, 111 had either probable or possible AD. A significant association of H1 with AD (p = 0.017) was observed in females. A nominally significant association of SNP rs1133174 with AD (p = 0.051) was also observed in the whole cohort. Conclusion: The results provide evidence that the association of polymophisms in the sortilin-related receptor gene (SORL1) with AD and its MRI biomarkers of brain and hippocampal atrophy are moderated by sex.

Alzheimer’s disease (AD) is associated with insulin resistance and specific regional declines in cerebral metabolism. The effects of a novel mTOT modulating insulin sensitizer (MSDC-0160) were explored in non-diabetic patients with mild AD to determine whether treatment would impact glucose metabolism measured by FDG-PET in regions that decline in AD. MSDC-0160 (150 mg once daily; N=16) compared to placebo (N=13) for 12 weeks did not result in a significant difference in glucose metabolism in pre-defined regions when referenced to the pons or whole brain. However, glucose metabolism referenced to cerebellum was maintained in MSDC-0160 treated participants while it significantly declined for placebo patients in anterior and posterior cingulate, and parietal, lateral temporal, medial temporal cortices. Voxel-based analyses showed additional differences in FDG-PET related to MSDC-0160 treatment. These exploratory results suggest central effects of MSDC-0160 and provide a basis for further investigation of mTOT modulating insulin sensitizers in AD patients.

Background/Objectives: During the next decades a rapid increase is expected in the number of patients with dementia suffering from pain who often take less medication compared to normal elderly, due to several diagnostic barriers. Comorbid mood disorders result in great difficulties in pain assessment and further treatment. Design: Twenty five patients with Alzheimer’s disease, comorbid mood disorders, and chronic musculoskeletal pain (experimental group) and thirty one patients with Alzheimer’s disease and chronic musculoskeletal pain without comorbid mood disorders (control group) were examined. The assessment tools used were Geriatric Pain Measure, Patient Health Questionnaire, Pain Assessment in Advanced Dementia, Mini Mental State Examination and Pain Anxiety Symptom Scale. Statistical analysis was performed by SPSS v17.0, using the Pearson correlation and the multiple linear regression analysis. Results: The correlation between mood disorders and levels of pain intensity in the experimental group was found to be statistically higher than that in the control group (p< .001). Among all quantitative variables, highly significant correlation (p< .001) was observed between stress and depression symptomatology (r =.550, p<.001) in the experimental group. Normal regression analysis was used to assess possible differences between demographic data and PASS scores. Scores in fearful thinking and physiological responses scales of PASS were higher in female than male (p=.014), whereas scores in the cognitive anxiety scale of PASS have shown a highly significant positive correlation with years of education (p< .001). Discussion: It seems that depression and anxiety are associated with chronic musculoskeletal pain intensity in dementia, thus need to be taken into consideration by health professionals for patient’s management.

Oxidative stress and mitochondrial dysfunction appear early and contribute to the disease progression in Alzheimer’s disease (AD), which can be detected extensively in AD patients brains as well as in transgenic AD mice brains. Thus, treatments that result in attenuation of oxidative stress and mitochondrial dysfunction may hold potential for AD treatment. Geniposide, a pharmacologically active component purified from gardenia fruit, exhibits anti-oxidative, antiinflammatory and other important therapeutic properties. However, whether geniposide has any protective effect on oxidative stress and mitochondrial dysfunction in AD transgenic mouse model has not yet been reported. Here, we demonstrate that intragastric administration of geniposide significantly reduces oxidative stress and mitochondrial dysfunction in addition to improving learning and memory in APP/PS1 mice. Geniposide exerts protective effects on mitochondrial dysfunction in APP/PS1 mice through suppressing the mitochondrial oxidative damage and increasing the mitochondrial membrane potential and activity of cytochrome c oxidase. These studies indicate that geniposide may attenuate memory deficits through the suppression of mitochondrial oxidative stress. Thus, geniposide may be a potential therapeutic reagent for halting and preventing AD progress.

Protein folding is a spontaneous self-assembly process, which occurs in the biological system. Understanding this complex process not only helps in deciphering the mechanism involved in protein misfolding diseases but also helps in modeling in vitro and in vivo systems for testing the therapeutic strategies developed for the disease. Among the protein misfolding diseases, much emphasis has been given to Alzheimer’s disease because of its prevalence among elderly individuals and propensity to cause external damage to neurons, an effective cure for which is yet to be designed. Though amyloid fibrils are the major cause of neurotoxicity in Alzheimer’s disease, their mechanism of self-assembly during pathological conditions is still under active investigation. This review aims to understand the basic mechanism of amyloid fibril formation and how it can be characterized in different stages by various techniques. With this information, it is possible to design both in vitro and in vivo systems, which not only serves as model systems for understanding the mechanism of amyloid fibril formation but also helps to test new therapeutic strategies against the disease. This review also highlights the pros and cons of currently available in vitro and in vivo systems, which can aid the readers to select a suitable system for their further studies.

Increasing evidence suggests that elevated production and/or reduced clearance of amyloid-β peptide (Aβ) drives the early pathogenesis of Alzheimer’s disease (AD). Aβ soluble oligomers trigger a neurotoxic cascade that leads to neuronal dysfunction, neurodegeneration and, ultimately, clinical dementia. Inflammation, both within brain and systemically, together with a deficiency in the neurotransmitter acetylcholine (ACh) that underpinned the development of anticholinesterases for AD symptomatic treatment, are invariable hallmarks of the disease. The inter-relation between Aβ, inflammation and cholinergic signaling is complex, with each feeding back onto the others to drive disease progression. To elucidate these interactions plasma samples and peripheral blood mononuclear cells (PBMCs) were evaluated from healthy controls (HC) and AD patients. Plasma levels of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and Aβ were significantly elevated in AD vs. HC subjects, and ACh showed a trend towards reduced levels. Aβ challenge of PBMCs induced a greater release of inflammatory cytokines interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-α) from AD vs. HC subjects, with IL-10 being similarly affected. THP-1 monocytic cells, a cell culture counterpart of PBMCs and brain microglial cells, responded similarly to Aβ as well as to phytohaemagglutinin (PHA) challenge, to allow preliminary analysis of the cellular and molecular pathways underpinning Aβ-induced changes in cytokine expression. As amyloid-β precursor protein expression, and hence Aβ, has been reported regulated by particular cytokines and anticholinesterases, the latter were evaluated on Aβ- and PHA-induced chemocytokine expression. Co-incubation with selective AChE/BuChE inhibitors, (-)-phenserine (AChE) and (-)-cymserine analogues (BuChE), mitigated the rise in cytokine levels and suggest that augmentation of the cholinergic anti-inflammatory pathway may prove valuable in AD.