Effects of Peroral Omega-3 Fatty Acid Supplementation on Cerebrospinal Fluid Biomarkers in Patients with Alzheimer's Disease: A Randomized Controlled Trial-The OmegAD Study.

BACKGROUND: Studies have suggested a connection between a decrease in the levels of polyunsaturated fatty acids (PUFAs) and Alzheimer's disease (AD). We aimed to assess the effect of supplementation with omega-3 fatty acids (n-3 FAs) on biomarkers analyzed in the cerebrospinal fluid (CSF) of patients diagnosed with AD. OBJECTIVE: To investigate the effects of daily supplementation with 2.3 g of PUFAs in AD patients on the biomarkers in CSF described below. We also explored the possible correlation between these biomarkers and the performance in the cognitive test Mini-Mental State Examination (MMSE). METHODS: Thirty-three patients diagnosed with AD were randomized to either treatment with a daily intake of 2.3 g of n-3 FAs (n  =  18) or placebo (n  =  15). CSF samples were collected at baseline and after six months of treatment, and the following biomarkers were analyzed: Aß 38, Aß 40, Aß 42, t-tau, p-tau, neurofilament light (NfL), chitinase-3-like protein 1 (YKL-40), acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), soluble IL-1 receptor type II (sIL-1RII), and IL-6. RESULTS: There were no significant differences between the groups concerning the level of the different biomarkers in the CSF at baseline. Within the treatment group, there was a small but significant increase in both YKL-40 (p = 0.04) and NfL (p = 0.03), while the other CSF biomarkers remained stable. CONCLUSION: Supplementation with n-3 FAs had a statistically significant effect on NfL and YKL-40, resulting in an increase of both biomarkers, indicating a possible increase of inflammatory response and axonal damage. This increase in biomarkers did not correlate with MMSE score.

Elevated soluble amyloid beta protofibrils in Down syndrome and Alzheimer's disease.

Down syndrome (DS) is caused by trisomy of chromosome 21, which leads to a propensity to develop amyloid ß (Aß) brain pathology in early adulthood followed later by cognitive and behavioral deterioration. Characterization of the Aß pathology is important to better understand the clinical deterioration of DS individuals and to identify interventive strategies. Brain samples from people with DS and Alzheimer's disease (AD), as well as non-demented controls (NDC), were analyzed with respect to different Aß species. Immunohistochemical staining using antibodies towards Aß was also performed. Elevated levels of soluble Aß protofibrils and insoluble Aßx-40 and Aßx-42 in formic acid brain extracts, and elevated immunohistochemical staining of Aß deposits were demonstrated with the antibody BAN2401 (lecanemab) in DS and AD compared with NDC. These data and the promising data in a large phase 2 CE clinical trial with lecanemab suggest that lecanemab may have the potential to preserve cognitive capacity in DS. Lecanemab is currently in a phase 3 CE clinical trial.

Characterization of monomeric and soluble aggregated Aß in Down's syndrome and Alzheimer's disease brains.

The major characteristics of Alzheimer's disease (AD) are amyloid plaques, consisting of aggregated beta amyloid (Aß) peptides, together with tau pathology (tangles, neuropil treads and dystrophic neurites surrounding the plaques), in the brain. Down's syndrome (DS) individuals are at increased risk to develop AD-type pathology; most DS individuals have developed substantial pathology already at the age of 40. DS individuals have an extra copy of chromosome 21, harbouring the amyloid precursor protein gene (APP). Our aim was to investigate the Aß peptide pattern in DS and AD brains to investigate differences in their amyloid deposition and aggregation, respectively. Cortical tissue from patients with DS (with amyloid pathology), sporadic AD and controls were homogenized and fractionated into TBS (water soluble) and formic acid (water insoluble) fractions. Immunoprecipitation (IP) was performed using a variety of antibodies targeting different Aß species including oligomeric Aß. Mass spectrometry was then used to evaluate the presence of Aß species in the different patient groups. A large number of Aß peptides were identified including Aß1-X, 2-X, 3-X, 4-X, 5-X, 11-X, and Aß peptides extended N terminally of the BACE1 cleavage site and ending at amino 15 in the Aß sequence APP/Aß(-X to 15), as well as peptides post-translationally modified by pyroglutamate formation. Most Aß peptides had higher abundance in AD and DS compared to controls, except the APP/Aß(-X to 15) peptides which were most abundant in DS followed by controls and AD. Furthermore, the abundancies of AßX-40 and AßX-34 were increased in DS compared with AD. Aß1-40, Aß1-42, and Aß4-42 were identified as the main constitutes of protofibrils (IP'd using mAb158) and higher relative Aß1-42 signals were obtained compared with samples IP'd with 6E10 + 4G8, indicating that the protofibrils/oligomers were enriched with peptides ending at amino acid 42. All Aß peptides found in AD were also present in DS indicating similar pathways of Aß peptide production, degradation and accumulation, except for APP/Aß(-X to 15). Likewise, the Aß peptides forming protofibrils/oligomers in both AD and DS were similar, implying the possibility that treatment with clinical benefit in sporadic AD might also be beneficial for subjects with DS.

[Alzheimer's disease - the most common cause of dementia]. / Alzheimers sjukdom ­ diagnostik och behandling i dag och i framtiden.

Alzheimer's disease is the most common cause of dementia. As many as 250,000 people in Sweden will have a dementia disease in 2050. The ¼amyloid cascade hypothesis« is a common model which explains how ß-amyloid affects the function of the nerve cells. Alzheimer's disease has a long-lasting course and can present in typical and atypical forms. CSF analyses for ¼core AD CSF biomarkers« and synaptic proteins have been available for clinical diagnostics. PET scanning can detect either ß-amyloid or tau aggregates in the brain of living humans. Current Alzheimer's disease therapy is based on two classes of cognition-enhancing drugs: acetylcholinesterase inhibitor and NMDA-receptor antagonist, which delays cognitive decline in most patients. The latest clinical development of potential therapy for Alzheimer's is active or passive immunotherapy against brain ß-amyloid and tau, where several studies have shown varying but promising treatment effects. Non-pharmacological interventions in patients with AD aim to delay the loss of mental abilities, helping people to be independent in everyday life for as long as possible, and to increase their well-being and quality of life.

Homocysteine Status Modifies the Treatment Effect of Omega-3 Fatty Acids on Cognition in a Randomized Clinical Trial in Mild to Moderate Alzheimer's Disease: The OmegAD Study.

BACKGROUND: Trials of supplementation with omega-3 fatty acids (ω3-FAs) in patients with mild cognitive impairment or Alzheimer's disease (AD) have produced inconsistent effects on cognitive decline. There is evidence of an interaction between B vitamin status and ω3-FAs in relation to brain atrophy and cognitive decline. OBJECTIVE: We investigated whether baseline levels of plasma total homocysteine (tHcy), a marker of B vitamin status, modify the effects of ω3-FAs supplementation on cognitive performance in moderate AD. METHODS: This post hoc analysis of the OmegAD trial included 171 community-based patients with AD (MMSE≥15): 88 patients received daily doses of 1.7 g docosahexaenoic acid and 0.6 g eicosapentaenoic acid for 6 months. Treatment outcome on cognition was analyzed according to baseline levels of tHcy using a general linear model and ANCOVA. RESULTS: We found significant interactions between ω3-FA supplementation and tHcy on cognition and clinical stage assessed by MMSE (p = 0.040), global CDR (p = 0.059), and CDRsob (p = 0.023), but not on ADAS-cog (p = 0.649). In patients with tHcy levels <11.7µmol/L, ω3-FA supplementation improved cognitive performance as measured by MMSE (+7.1%, 95% CI: 0.59 to 13.7%, p = 0.033) and clinical status as measured by CDRsob (-22.3%, 95% CI: -5.8 to -38.7%, p = 0.009) compared with placebo. CONCLUSION: The effect of ω3-FA supplementation on MMSE and CDR appears to be influenced by baseline tHcy, suggesting that adequate B vitamin status is required to obtain beneficial effects of ω3-FA on cognition.

Rapid amyloid-ß oligomer and protofibril accumulation in traumatic brain injury.

Deposition of amyloid-ß (Aß) is central to Alzheimer's disease (AD) pathogenesis and associated with progressive neurodegeneration in traumatic brain injury (TBI). We analyzed predisposing factors for Aß deposition including monomeric Aß40, Aß42 and Aß oligomers/protofibrils, Aß species with pronounced neurotoxic properties, following human TBI. Highly selective ELISAs were used to analyze N-terminally intact and truncated Aß40 and Aß42, as well as Aß oligomers/protofibrils, in human brain tissue, surgically resected from severe TBI patients (n = 12; mean age 49.5 ± 19 years) due to life-threatening brain swelling/hemorrhage within one week post-injury. The TBI tissues were compared to post-mortem AD brains (n = 5), to post-mortem tissue of neurologically intact (NI) subjects (n = 4) and to cortical biopsies obtained at surgery for idiopathic normal pressure hydrocephalus patients (iNPH; n = 4). The levels of Aß40 and Aß42 were not elevated by TBI. The levels of Aß oligomers/protofibrils in TBI were similar to those in the significantly older AD patients and increased compared to NI and iNPH controls (P < 0.05). Moreover, TBI patients carrying the AD risk genotype Apolipoprotein E epsilon3/4 (APOE ε3/4; n = 4) had increased levels of Aß oligomers/protofibrils (P < 0.05) and of both N-terminally intact and truncated Aß42 (P < 0.05) compared to APOE ε3/4-negative TBI patients (n = 8). Neuropathological analysis showed insoluble Aß aggregates (commonly referred to as Aß plaques) in three TBI patients, all of whom were APOE ε3/4 carriers. We conclude that soluble intermediary Aß aggregates form rapidly after TBI, especially among APOE ε3/4 carriers. Further research is needed to determine whether these aggregates aggravate the clinical short- and long-term outcome in TBI.

Does Fatty Acid Composition in Subcutaneous Adipose Tissue Differ between Patients with Alzheimer's Disease and Cohabiting Proxies?

Low tissue levels of the major marine ω3 fatty acids (FAs) DHA and EPA are found in Alzheimer's disease (AD). We investigated if healthy proxies to AD patients have higher levels of these ω3 FAs. We observed lower levels of EPA and DHA in subcutaneous adipose tissue biopsies from 64 AD patients compared with 16 cognitively healthy proxies. No significant difference was observed when pairwise comparisons were made between a subset of 16 AD patients and their co-habiting proxies. Larger studies are needed to replicate these findings and to determine if they could depend on FA intake or differences in metabolism.

DHA-rich n-3 fatty acid supplementation decreases DNA methylation in blood leukocytes: the OmegAD study.

Background: Dietary fish oils, rich in long-chain n-3 (ω-3) fatty acids (FAs) [e.g., docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3)], modulate inflammatory reactions through various mechanisms, including gene expression, which is measured as messenger RNA concentration. However, the effects of long-term treatment of humans with DHA and EPA on various epigenetic factors-such as DNA methylation, which controls messenger RNA generation-are poorly described.Objective: We wanted to determine the effects of 6 mo of dietary supplementation with an n-3 FA preparation rich in DHA on global DNA methylation of peripheral blood leukocytes (PBLs) and the relation to plasma EPA and DHA concentrations in Alzheimer disease (AD) patients.Design: In the present study, DNA methylation in four 5'-cytosine-phosphate-guanine-3' (CpG) sites of long interspersed nuclear element-1 repetitive sequences was assessed in a group of 63 patients (30 given the n-3 FA preparation and 33 given placebo) as an estimation of the global DNA methylation in blood cells. Patients originated from the randomized, double-blind, placebo-controlled OmegAD study, in which 174 AD patients received either 1.7 g DHA and 0.6 g EPA (the n-3 FA group) or placebo daily for 6 mo.Results: At 6 mo, the n-3 FA group displayed marked increases in DHA and EPA plasma concentrations (2.6- and 3.5-fold), as well as decreased methylation in 2 out of 4 CpG sites (P < 0.05 for all), respectively. This hypomethylation in CpG2 and CpG4 sites showed a reverse correlation to changes in plasma EPA concentration (r = -0.25, P = 0.045; and r = -0.26, P = 0.041, respectively), but not to changes in plasma DHA concentration, and were not related to apolipoprotein E-4 allele frequency.Conclusion: Supplementation with n-3 FA for 6 mo was associated with global DNA hypomethylation in PBLs. Our data may be of importance in measuring various effects of marine oils, including gene expression, in patients with AD and in other patients taking n-3 FA supplements. This trial was registered at clinicaltrials.gov as NCT00211159.

Predicting Cognitive Decline across Four Decades in Mutation Carriers and Non-carriers in Autosomal-Dominant Alzheimer's Disease.

OBJECTIVES: The aim of this study was to investigate cognitive performance including preclinical and clinical disease course in carriers and non-carriers of autosomal-dominant Alzheimer's disease (adAD) in relation to multiple predictors, that is, linear and non-linear estimates of years to expected clinical onset of disease, years of education and age. METHODS: Participants from five families with early-onset autosomal-dominant mutations (Swedish and Arctic APP, PSEN1 M146V, H163Y, and I143T) included 35 carriers (28 without dementia and 7 with) and 44 non-carriers. All participants underwent a comprehensive clinical evaluation, including neuropsychological assessment at the Memory Clinic, Karolinska University Hospital at Huddinge, Stockholm, Sweden. The time span of disease course covered four decades of the preclinical and clinical stages of dementia. Neuropsychological tests were used to assess premorbid and current global cognition, verbal and visuospatial functions, short-term and episodic memory, attention, and executive function. RESULTS: In carriers, the time-related curvilinear trajectory of cognitive function across disease stages was best fitted to a formulae with three predictors: years to expected clinical onset (linear and curvilinear components), and years of education. In non-carriers, the change was minimal and best predicted by two predictors: education and age. The trajectories for carriers and non-carriers began to diverge approximately 10 years before the expected clinical onset in episodic memory, executive function, and visuospatial function. CONCLUSIONS: The curvilinear trajectory of cognitive functions across disease stages was mimicked by three predictors in carriers. In episodic memory, executive and visuospatial functions, the point of diverging trajectories occurred approximately 10 years ahead of the clinical onset compared to non-carriers. (JINS, 2017, 23, 195-203).

High tau levels in cerebrospinal fluid predict nursing home placement and rapid progression in Alzheimer's disease.

BACKGROUND: Increased concentrations of cerebrospinal fluid (CSF) total tau (t-tau) and phosphorylated tau, as well as decreased amyloid-ß 42 peptide, are biomarkers of Alzheimer's disease (AD) pathology, but few studies have shown an association with AD progression rate. We hypothesized that high CSF tau, as a marker of ongoing neurodegeneration, would predict a more aggressive course of AD, using time to nursing home placement (NHP) as the main outcome. METHODS: Our sample inlcuded 234 patients with mild cognitive impairment (MCI) due to AD (n = 134) or mild to moderate AD (n = 100) who underwent lumbar puncture at a memory clinic and were followed for 2-11 years (median 4.9 years). RESULTS: Individuals with CSF t-tau in the highest quartile (≥900 ng/L) had a higher ratio of NHP, both in the total cohort and in patients with MCI only (adjusted HR 2.17 [95% CI 1.24-3.80]; HR 2.37 [95% CI 1.10-5.09], respectively), than the lowest quartile. The association between high t-tau levels and future steep deterioration was confirmed in analyses with conversion to moderate dementia (HR 1.66; 95% CI 1.08-2.56), rapid decline in Mini Mental State Examination score (≥4-point drop/12 months), and dying in severe dementia as outcomes. CONCLUSIONS: To our knowledge, this is the first study to show that high CSF t-tau levels predict early NHP and conversion to moderate dementia in an AD cohort. Selecting patients with high CSF t-tau, indicating more aggressive neurodegeneration and steeper decline, for AD immunotherapy trials might increase the possibility of showing contrast between active treatment and placebo.

Safety and tolerability of BAN2401--a clinical study in Alzheimer's disease with a protofibril selective Aß antibody.

BACKGROUND: Several monoclonal antibodies for the treatment of Alzheimer's disease (AD) have been in development over the last decade. BAN2401 is a monoclonal antibody that selectively binds soluble amyloid ß (Aß) protofibrils. METHODS: Here we describe the first clinical study with BAN2401. Safety and tolerability were investigated in mild to moderate AD. A study design was used with staggered parallel single and multiple ascending doses, from 0.1 mg/kg as a single dose to 10 mg/kg biweekly for four months. The presence of amyloid related imaging abnormalities (ARIA, E for edema, H for hemorrhage) was assessed with magnetic resonance imaging (MRI). Cerebrospinal fluid (CSF) and plasma samples were analyzed to investigate pharmacokinetics (PK) and effects on biomarkers. RESULTS: The incidence of ARIA-E/H on MRI was comparable to that of placebo. BAN2401 exposure was approximately dose proportional, with a serum terminal elimination half-life of ~7 days. Only a slight increase of plasma Aß(1-40) was observed but there were no measurable effects of BAN2401 on CSF biomarkers. On the basis of these findings Phase 2b efficacy study has been initiated in early AD. CONCLUSIONS: BAN2401 was well-tolerated across all doses. The PK profile has guided us for selecting dose and dose regimens in the ongoing phase 2b study. There was no clear guidance for an effective dose based on biomarkers. TRIAL REGISTRATION NUMBER: NCT01230853 ClinicalTrials.gov Registered October 27, 2010.

Lithium as a Treatment for Alzheimer's Disease: A Systematic Review and Meta-Analysis.

BACKGROUND: This is the first meta-analysis of randomized placebo-controlled trials testing lithium as a treatment for patients with Alzheimer's disease (AD) and individuals with mild cognitive impairment (MCI). METHODS: The primary outcome measure was efficacy on cognitive performance as measured through the Alzheimer's Disease Assessment Scale cognitive subscale or the Mini-Mental State Examination. Other outcome measures were drug discontinuation rate, individual side effects, and biological markers (phosphorylated tau 181, total tau, and amyloid-ß42) in cerebrospinal fluid (CSF). RESULTS: Three clinical trials including 232 participants that met the study's inclusion criteria were identified. Lithium significantly decreased cognitive decline as compared to placebo (standardized mean difference = -0.41, 95% confidence interval = -0.81 to -0.02, p = 0.04, I2 = 47% , 3 studies, n = 199). There were no significant differences in the rate of attrition, discontinuation due to all causes or adverse events, or CSF biomarkers between treatment groups. CONCLUSIONS: The results indicate that lithium treatment may have beneficial effects on cognitive performance in subjects with MCI and AD dementia.

Plasma Fatty Acid Profiles in Relation to Cognition and Gender in Alzheimer's Disease Patients During Oral Omega-3 Fatty Acid Supplementation: The OmegAD Study.

BACKGROUND: ω3 fatty acids (ω3 FAs) may slow the rate of decline in cognitive performance in mild forms of cognitive impairment and Alzheimer's disease (AD). However, the relationship between changes of plasma ω3 FA levels and cognitive performance, as well as effects of gender, are poorly known. OBJECTIVE: To study the effect of 6-month administration of DHA-rich ω3 FA supplementation on plasma FA profiles in patients with mild to moderate AD in relation to cognitive performance and gender. This investigation is part of the OmegAD Study. METHODS: 174 AD patients (74 ± 9 years) were randomized to a daily intake of 2.3 g ω3 FA or placebo for 6 months; subsequently all received the ω3 FA preparation for the next 6 months. Baseline as well as changes in plasma levels of the main ω3 FAs in 165 patients, while receiving ω3 FA supplementation for 6 months, were analyzed for association to cognitive performance (assessed by ADAS-cog and MMSE scores) as well as to gender. RESULTS: Preservation of cognitive functioning, assessed by ADAS-cog or its sub-items (but not MMSE) scores, was significantly associated to increasing plasma ω3 FA levels over time. Thus, the higher ω3 FA plasma levels rose, the lower was the rate of cognitive deterioration. This effect was not related to gender; since although females displayed higher ω3 FA plasma levels than did males after 6 months of supplementation, this difference disappeared when adjusted for body weight. CONCLUSIONS: Since our study suggests dose-response relationships between plasma levels of ω3 FA and preservation of cognition, future ω3 FA trials in patients with mild AD should consider exploring graded (and body weight adjusted) doses of ω3 FA.

Perspectives on future Alzheimer therapies: amyloid-ß protofibrils - a new target for immunotherapy with BAN2401 in Alzheimer's disease.

The symptomatic drugs currently on the market for Alzheimer's disease (AD) have no effect on disease progression, and this creates a large unmet medical need. The type of drug that has developed most rapidly in the last decade is immunotherapy: vaccines and, especially, passive vaccination with monoclonal antibodies. Antibodies are attractive drugs as they can be made highly specific for their target and often with few side effects. Data from recent clinical AD trials indicate that a treatment effect by immunotherapy is possible, providing hope for a new generation of drugs. The first anti-amyloid-beta (anti-Aß) vaccine developed by Elan, AN1792, was halted in phase 2 because of aseptic meningoencephalitis. However, in a follow-up study, patients with antibody response to the vaccine demonstrated reduced cognitive decline, supporting the hypothesis that Aß immunotherapy may have clinically relevant effects. Bapineuzumab (Elan/Pfizer Inc./Johnson & Johnson), a monoclonal antibody targeting fibrillar Aß, was stopped because the desired clinical effect was not seen. Solanezumab (Eli Lilly and Company) was developed to target soluble, monomeric Aß. In two phase 3 studies, Solanezumab did not meet primary endpoints. When data from the two studies were pooled, a positive pattern emerged, revealing a significant slowing of cognitive decline in the subgroup of mild AD. The Arctic mutation has been shown to specifically increase the formation of soluble Aß protofibrils, an Aß species shown to be toxic to neurons and likely to be present in all cases of AD. A monoclonal antibody, mAb158, was developed to target Aß protofibrils with high selectivity. It has at least a 1,000-fold higher selectivity for protofibrils as compared with monomers of Aß, thus targeting the toxic species of the peptide. A humanized version of mAb158, BAN2401, has now entered a clinical phase 2b trial in a collaboration between BioArctic Neuroscience and Eisai without the safety concerns seen in previous phase 1 and 2a trials. Experiences from the field indicate the importance of initiating treatment early in the course of the disease and of enriching the trial population by improving the diagnostic accuracy. BAN2401 is a promising candidate for Aß immunotherapy in early AD. Other encouraging efforts in immunotherapy as well as in the small-molecule field offer hope for new innovative therapies for AD in the future.

Effects of supplementation with omega-3 fatty acids on oxidative stress and inflammation in patients with Alzheimer's disease: the OmegAD study.

BACKGROUND: Oxidative stress and inflammation are two key mechanisms suggested to be involved in the pathogenesis of Alzheimer's disease (AD). Omega-3 fatty acids (ω-3 FAs) found in fish and fish oil have several biological properties that may be beneficial in AD. However, they may also auto-oxidize and induce in vivo lipid peroxidation. OBJECTIVE: The objective of this study was to evaluate systemic oxidative stress and inflammatory biomarkers following oral supplementation of dietary ω-3 FA. METHODS: Forty patients with moderate AD were randomized to receive 1.7 g DHA (22:6) and 0.6 g EPA (20:5) or placebo for 6 months. Urinary samples were collected before and after supplementation. The levels of the major F2-isoprostane, 8-iso-PGF2α, a consistent in vivo biomarker of oxidative stress, and 15-keto-dihydro-PGF2α, a major metabolite of PGF2α and biomarker of inflammatory response, were measured. RESULTS: F2-isoprostane in urine increased in the placebo group after 6 months, but there was no clear difference in treatment effect between supplemented and non-supplemented patients on the urinary levels of F2-isoprostanes and 15-keto-dihydro-PGF2α. At baseline, the levels of 15-keto-dihydro-PGF2α showed negative correlative relationships to ω-3 FAs, and a positive correlation to linoleic acid. 8-iso-PGF2α correlated negatively to the ω-6 FA arachidonic acid. CONCLUSION: The findings indicate that supplementation of ω-3 FAs to patients with AD for 6 months does not have a clear effect on free radical-mediated formation of F2-isoprostane or cyclooxygenase-mediated formation of prostaglandin F2α. The correlative relationships to FAs indicate a potential role of FAs in immunoregulation.

Performance on a pattern separation task by Alzheimer's patients shows possible links between disrupted dentate gyrus activity and apolipoprotein E ∈4 status and cerebrospinal fluid amyloid-ß42 levels.

INTRODUCTION: Emerging evidence suggests that decreased adult hippocampal neurogenesis represents an early critical event in the course of Alzheimer's disease (AD). In mice, adult neurogenesis is reduced by knock-in alleles for human apolipoprotein E (ApoE) ∈4. Decreased dentate gyrus (DG) neural progenitor cells proliferation has been observed in the triple-transgenic mouse model of AD (3xTg-AD); this reduction being directly associated with the presence of amyloid-ß (Aß) plaques and an increase in the number of Aß-containing neurons in the hippocampus. Cognitive tasks involving difficult pattern separations have been shown to reflect DG activity and thus potentially neurogenesis in both animals and man. This study involved the administration of a pattern separation paradigm to Alzheimer's patients to investigate relationships between task performance and both ApoE status and cerebrospinal fluid (CSF) Aß42 levels. METHODS: The CDR System pattern separation task involves the presentation of pictures that must later be discriminated from closely similar pictures. This paper presents pattern separation data from 66 mild to moderate AD patients, of which 50 were genotyped and 65 in whom CSF Aß42 was measured. RESULTS: ApoE ∈4 homozygotes were not compromised on the easy pattern separations compared with the other patients, but they were statistically significantly poorer at the difficult separations. In all patients CSF Aß42 correlated significantly with the ability to make the difficult discriminations, but not easier discriminations. Pattern separation speed correlated negatively with CSF Aß42, and thus the association was not due to increased impulsivity. CONCLUSIONS: These are, to our knowledge, the first human pattern separation data to suggest a possible genetic link to poor hippocampal neurogenesis in AD, as well as a relationship to Aß42. Therapies which target neurogenesis may thus be useful in preventing the early stages of AD, notably in ApoE ∈4 homocygotes.

The Arctic AßPP mutation leads to Alzheimer's disease pathology with highly variable topographic deposition of differentially truncated Aß.

BACKGROUND: The Arctic mutation (p.E693G/p.E22G)fs within the ß-amyloid (Aß) region of the ß-amyloid precursor protein gene causes an autosomal dominant disease with clinical picture of typical Alzheimer's disease. Here we report the special character of Arctic AD neuropathology in four deceased patients. RESULTS: Aß deposition in the brains was wide-spread (Thal phase 5) and profuse. Virtually all parenchymal deposits were composed of non-fibrillar, Congo red negative Aß aggregates. Congo red only stained angiopathic vessels. Mass spectrometric analyses showed that Aß deposits contained variably truncated and modified wild type and mutated Aß species. In three of four Arctic AD brains, most cerebral cortical plaques appeared targetoid with centres containing C-terminally (beyond aa 40) and variably N-terminally truncated Aß surrounded by coronas immunopositive for Aßx-42. In the fourth patient plaque centres contained almost no Aß making the plaques ring-shaped. The architectural pattern of plaques also varied between different anatomic regions. Tau pathology corresponded to Braak stage VI, and appeared mainly as delicate neuropil threads (NT) enriched within Aß plaques. Dystrophic neurites were scarce, while neurofibrillary tangles were relatively common. Neuronal perikarya within the Aß plaques appeared relatively intact. CONCLUSIONS: In Arctic AD brain differentially truncated abundant Aß is deposited in plaques of variable numbers and shapes in different regions of the brain (including exceptional targetoid plaques in neocortex). The extracellular non-fibrillar Aß does not seem to cause overt damage to adjacent neurons or to induce formation of neurofibrillary tangles, supporting the view that intracellular Aß oligomers are more neurotoxic than extracellular Aß deposits. However, the enrichment of NTs within plaques suggests some degree of intra-plaque axonal damage including accumulation of hp-tau, which may impair axoplasmic transport, and thereby contribute to synaptic loss. Finally, similarly as the cotton wool plaques in AD resulting from exon 9 deletion in the presenilin-1 gene, the Arctic plaques induced only modest glial and inflammatory tissue reaction.

Effects on transthyretin in plasma and cerebrospinal fluid by DHA-rich n - 3 fatty acid supplementation in patients with Alzheimer's disease: the OmegAD study.

Transthyretin (TTR) binds amyloid-ß (Aß) and may reduce brain Aß, a pathological feature in Alzheimer's disease (AD). N - 3 fatty acids (FA), docosahexaenoic (DHA), and eicosapentaenoic acid (EPA) may increase TTR transcription in rat hippocampus. We studied effects of n - 3 FA supplementation on TTR-levels in patients with AD. Outpatients were randomized to receive 1.7 g DHA and 0.6 g EPA (n - 3/n - 3 group) or placebo (placebo/n - 3 group) during 6 months. After 6 months, all patients received n - 3 FA for another 6 months. TTR and FA were measured in plasma in all subjects, whereas TTR in cerebrospinal fluid (CSF) was measured in a subgroup. The study was completed by 89 patients in the n - 3/n - 3 group (75 y, 57% w) and 85 in the placebo/n - 3 group (75 y, 46% w). Baseline plasma-TTR was within normal range in both groups. After 6 months, plasma-TTR decreased in the placebo/n - 3 group (p < 0.001 within and p < 0.015 between the groups). No changes were observed in CSF TTR. From 6 to 12 months when both groups were supplemented, plasma-TTR increased significantly in both groups. Repeated measures ANOVA indicated an increase in TTR over time (p = 0.04) in those receiving n - 3 FA for 12 months. By linear regression analyses, n - 3 FA treatment was independently associated with increased plasma-TTR at 6 months (ß = -0.172, p = 0.028). Thus, n - 3 FA treatment appeared to increase plasma-TTR in patients with AD. Since TTR may influence Aß deposition in the brain, the results warrant further exploration.

Omega-3 fatty acids enhance phagocytosis of Alzheimer's disease-related amyloid-ß42 by human microglia and decrease inflammatory markers.

The use of supplements with omega-3 (ω3) fatty acids (FAs) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) is widespread due to proposed beneficial effects on the nervous and cardiovascular systems. Many effects of ω3 FAs are believed to be caused by down-regulation and resolution of inflammation. Alzheimer's disease (AD) is associated with inflammation mediated by microglia and astrocytes, and ω3 FAs have been proposed as potential treatments for AD. The focus of the present study is on the effects of DHA and EPA on microglial phagocytosis of the AD pathogen amyloid-ß (Aß), on secreted and cellular markers of immune activity, and on production of brain-derived neurotrophic factor (BDNF). Human CHME3 microglial cells were exposed to DHA or EPA, with or without the presence of Aß42. Phagocytosis of Aß42 was analyzed by flow cytometry in conjunction with immunocytochemistry using antibodies to cellular proteins. Secreted proteins were analyzed by ELISA. Both DHA and EPA were found to stimulate microglial phagocytosis of Aß42. Phagocytosis of Aß42 was performed by microglia with a predominance of M2 markers. EPA increased the levels of BDNF in the culture medium. The levels of TNF-α were decreased by DHA. Both DHA and EPA decreased the pro-inflammatory M1 markers CD40 and CD86, and DHA had a stimulatory effect on the anti-inflammatory M2 marker CD206. DHA and EPA can be beneficial in AD by enhancing removal of Aß42, increasing neurotrophin production, decreasing pro-inflammatory cytokine production, and by inducing a shift in phenotype away from pro-inflammatory M1 activation.

Microglial markers are elevated in the prodromal phase of Alzheimer's disease and vascular dementia.

Microglia manage immunosurveillance and mediate inflammation, both suggested to be important in Alzheimer's disease (AD). The aim of this study was to investigate if microglial markers could differentiate, firstly between AD and controls, and secondly between stable mild cognitive impairment (MCI) and those progressing to AD and vascular dementia (VaD). Furthermore, we investigated if these markers were sufficiently stable to be used in clinical trials. We quantified YKL-40 and sCD14 in cerebrospinal fluid (CSF) from 96 AD patients, 65 healthy controls, and 170 patients with MCI from baseline and over 5.7 years. For the stability analysis, two CSF samples were collected from 52 AD patients with a six-month interval in between. YKL-40, but not sCD14, was significantly elevated in AD compared with healthy controls (p = 0.003). Furthermore, YKL-40 and sCD14 were increased in MCI patients who converted to VaD (p = 0.029 and p = 0.008), but not to AD according to NINCDS-ADRDA. However, when stratified according to CSF levels of tau and Aß42, YKL-40 was elevated in those with an AD-indicative profile compared with stable MCI with a normal profile (p = 0.037). In addition, YKL-40 and sCD14 were very stable in AD patients with good correlation between time-points (r = 0.94, p = 3.4 × 10-25; r = 0.77, p = 2.0 × 10-11) and the cortical damage marker T-tau. Thus, microglial markers are stable and may be used as safety markers for monitoring CNS inflammation and microglia activation in clinical trials. Moreover, YKL-40 differentiates between AD and controls and between stable MCI to AD and those that convert to AD and VaD.