Nonsteroidal anti-inflammatory drugs for the prevention of Alzheimer's disease: a systematic review

Inflammation and the redox-sensitive AGE-RAGE pathway as a therapeutic target in Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia. Neuritic amyloid plaques and concomitant chronic inflammation are prominent pathological features of AD. beta-amyloid peptide (Abeta), the major component of plaques, and advanced glycation end products (AGEs), post-translational protein modifications, are key activators of plaque-associated inflammation. Abeta, AGEs, S100b, and amphoterin bind to the receptor for AGEs (RAGE), which transmits the signal from RAGE via redox-sensitive pathways to nuclear factor kappa-B (NF-kappaB)-regulated cytokines. RAGE-mediated inflammation caused by glial cells and subsequent changes in neuronal glucose metabolism are likely to be important contributors to neurodegeneration in AD. As long as the neuronal damage is reversible, drugs interfering with the Abeta and AGE-RAGE pathways might be interesting novel therapeutics for the treatment of AD.

Update on nonsteriodal anti-inflammatory drugs

PURPOSE OF REVIEW

This review addresses recent concerns about the cardiovascular safety of nonsteroidal anti-inflammatory drugs, the disease-modifying role of these drugs in ankylosing spondylitis, and their use in the understudied pediatric population.

RECENT FINDINGS

Several recent observational and controlled studies highlight the cardiovascular toxicity of rofecoxib, celecoxib, parecoxib, valdecoxib and naproxen. Concerns about cardiovascular safety raise questions about the chronic use of nonsteroidal anti-inflammatory drugs in patients with rheumatic diseases, including children. The risks of these drugs in the pediatric population are not well known and this review addresses the limited data available concerning nonsteroidal anti-inflammatory drug use in children. A recent trial in ankylosing spondylitis patients demonstrated continuous nonsteroidal anti-inflammatory drug use reduced the rate of syndesmophyte formation, suggesting that they may have a disease-modifying role in these patients.

SUMMARY

Nonsteroidal anti-inflammatory drugs have been in the spotlight this year. While preliminary evidence has supported novel roles for these drugs in ankylosing spondylitis and in cancer prevention, accumulating evidence shows that some cyclooxygenase-2 and perhaps all nonsteroidal anti-inflammatory drugs are associated with cardiovascular toxicity. Further research is needed to understand the magnitude and mechanism of this risk. Clinicians are compelled to weigh carefully the benefits and risks of therapy. Concerns about safety are balanced by optimism about their potential role in delaying the progression of ankylosing spondylitis.

The Worldwide Challenge of the Dementias: A Role for B Vitamins and Homocysteine?

Dementia has reached epidemic proportions, with an estimated 4.6 million new cases worldwide each year. With an aging world population, the prevalence of dementia will increase dramatically in the next few decades. Of the predicted 114 million who will have dementia in 2050, about three-quarters will live in less developed regions. Although strongly age-related, dementia is not an inevitable part of aging but is a true disease, caused by exposure to several genetic and nongenetic risk factors. Prevention will be possible when the nongenetic risk factors have been identified. Apart from age, more than 20 nongenetic risk factors have been postulated, but very few have been established by randomized intervention studies. Elevated blood concentrations of total homocysteine and low-normal concentrations of B vitamins (folate, vitamin B12, and vitamin B6) are candidate risk factors for both Alzheimer's disease and vascular dementia. Seventy-seven cross-sectional studies on more than 34,000 subjects and 33 prospective studies on more than 12,000 subjects have shown associations between cognitive deficit or dementia and homocysteine and/or B vitamins. Biologically plausible mechanisms have been proposed to account for these associations, including atrophy of the cerebral cortex, but a definite causal pathway has yet to be shown. Raised plasma total homocysteine is a strong prognostic marker of future cognitive decline, and is common in world populations. Low-normal concentrations of the B vitamins, the main determinant of homocysteine concentrations, are also common and occur in particularly vulnerable sections of the population, such as infants and elderly. Large-scale randomized trials of homocysteine-lowering vitamins are needed to see if a proportion of dementia in the world can be prevented.

Toll-like receptor 4-dependent upregulation of cytokines in a transgenic mouse model of Alzheimer's disease

BACKGROUND

Abeta deposits in the brains of patients with Alzheimer's disease (AD) are closely associated with innate immune responses such as activated microglia and increased cytokines. Accumulating evidence supports the hypothesis that innate immune/inflammatory responses play a pivotal role in the pathogenesis of AD: either beneficial or harmful effects on the AD progression. The molecular mechanisms by which the innate immune system modulates the AD progression are not well understood. Toll-like receptors (TLRs) are first-line molecules for initiating the innate immune responses. When activated through TLR signaling, microglia respond to pathogens and damaged host cells by secreting chemokines and cytokines and express the co-stimulatory molecules needed for protective immune responses to pathogens and efficient clearance of damaged tissues. We previously demonstrated that an AD mouse model homozygous for a destructive mutation of TLR4 has increases in diffuse and fibrillar Abeta deposits as well as buffer-soluble and insoluble Abeta in the brain as compared with a TLR4 wild-type AD mouse model. Here, we investigated the roles of TLR4 in Abeta-induced upregulation of cytokines and chemokines, Abeta-induced activation of microglia and astrocytes and Abeta-induced immigration of leukocytes.

METHODS

Using the same model, levels of cytokines and chemokines in the brain were determined by multiplex cytokine/chemokine array. Activation of microglia and astrocytes and immigration of leukocytes were determined by immunoblotting and immunohistochemistry followed by densitometry and morphometry, respectively.

RESULTS

Levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-10 and IL-17 in the brains of TLR4 wild-type AD mice were significantly higher than those in TLR4 wild-type non-transgenic littermates. Such increases in cytokines were not found in TLR4 mutant AD mice as compared with TLR4 mutant non-transgenic littermates. Although expression levels of CD11b (a microglia marker) and GFAP (a reactive astrocyte marker) in the brains of TLR4 mutant AD mice were higher than those in TLR4 wild type AD mice, no difference was found in levels of CD45 (common leukocyte antigen).

CONCLUSION

This is the first demonstration of TLR4-dependent upregulation of cytokines in an AD mouse model. Our results suggest that TLR4 signaling is involved in AD progression and that TLR4 signaling can be a new therapeutic target for AD.

No advantage of A beta 42-lowering NSAIDs for prevention of Alzheimer dementia in six pooled cohort studies

INTRODUCTION

Observational studies show reduced incidence of Alzheimer dementia (AD) in users of nonsteroidal anti-inflammatory drugs (NSAIDs). One hypothesis holds that the subset of NSAIDs known as selective A beta(42)-lowering agents (SALAs) is responsible for this apparent reduction in AD risk.

METHODS

We pooled individual-level data from six prospective studies to obtain a sufficient sample to examine AD risk in users of SALA vs non-SALA NSAIDs.

RESULTS

Of 13,499 initially dementia-free participants (70,863 person-years), 820 developed incident AD. Users of NSAIDs (29.6%) showed reduced risk of AD (adjusted hazard ratio [aHR] 0.77, 95% CI 0.65-0.91). The point estimates were similar for SALAs (aHR 0.87, CI 0.72-1.04) and non-SALAs (aHR 0.75, CI 0.56-1.01). Because 573 NSAID users (14.5%) reported taking both a SALA and non-SALA, we examined their use alone and in combination. Resulting aHRs were 0.82 (CI 0.67-0.99) for SALA only, 0.60 (CI 0.40-0.90) for non-SALA only, and 0.87 (CI 0.57-1.33) for both NSAIDs (Wald test for differences, p = 0.32). The 40.7% of participants who used aspirin also showed reduced risk of AD, even when they used no other NSAIDs (aHR 0.78, CI 0.66-0.92). By contrast, there was no association with use of acetaminophen (aHR 0.93, CI 0.76-1.13).

CONCLUSIONS

In this pooled dataset, nonsteroidal anti-inflammatory drug (NSAID) use reduced the risk of Alzheimer dementia (AD). However, there was no apparent advantage in AD risk reduction for the subset of NSAIDs shown to selectively lower A beta(42), suggesting that all conventional NSAIDs including aspirin have a similar protective effect in humans.

Cognitive function over time in the Alzheimer's Disease Anti-inflammatory Prevention Trial (ADAPT): results of a randomized, controlled trial of naproxen and celecoxib

BACKGROUND

Observational studies have shown reduced risk of Alzheimer dementia in users of nonsteroidal anti-inflammatory drugs.

OBJECTIVE

To evaluate the effects of naproxen sodium and celecoxib on cognitive function in older adults.

DESIGN

Randomized, double-masked chemoprevention trial.

SETTING

Six US memory clinics.

PARTICIPANTS

Men and women aged 70 years and older with a family history of Alzheimer disease; 2117 of 2528 enrolled had follow-up cognitive assessment.

INTERVENTIONS

Celecoxib (200 mg twice daily), naproxen sodium (220 mg twice daily), or placebo, randomly allocated in a ratio of 1:1:1.5, respectively.

MAIN OUTCOME MEASURES

Seven tests of cognitive function and a global summary score measured annually.

RESULTS

Longitudinal analyses showed lower global summary scores over time for naproxen compared with placebo (- 0.05 SDs; P = .02) and lower scores on the Modified Mini-Mental State Examination over time for both treatment groups compared with placebo (- 0.33 points for celecoxib [P = .04] and - 0.36 points for naproxen [P = .02]). Restriction of analyses to measures collected from persons without dementia attenuated the treatment group differences. Analyses limited to measures obtained while participants were being issued study drugs produced results similar to the intention-to-treat analyses.

CONCLUSIONS

Use of naproxen or celecoxib did not improve cognitive function. There was weak evidence for a detrimental effect of naproxen.

Asthma, eczema, rhinitis and the risk for dementia

BACKGROUND

Inflammation is associated with Alzheimer's disease (AD) and dementia. In light of the chronic inflammatory properties of the atopic disorders asthma, eczema and rhinitis, we hypothesized an association with dementia.

METHODS

Self-reported asthma, eczema or rhinitis was assessed (prior to dementia follow-up) through questionnaires in the 1960s or 1970s in twins from the population-based Swedish Twin Registry. Dementia was assessed both longitudinally (n = 22,188), through linkages to two population-based registers, and cross-sectionally (n = 7,800), through telephone cognitive screening followed by a clinical evaluation of suspects of dementia. Risk ratios were estimated with Cox and logistic regression models controlling for vascular disease and genetic confounding.

RESULTS

In the longitudinal study, a history of atopy was positively associated with dementia (HR = 1.16; 1.01-1.33). In the cross-sectional study we found overall lower risks, none of which was statistically significant. Asthma was associated with a shorter survival time following AD onset.

CONCLUSIONS

Atopy is associated with a modestly increased risk of AD and dementia that is not mediated by vascular disease or due to genetic confounding. A history of asthma is associated with shorter life expectancy after AD diagnosis.

Possible mechanisms of action of NSAIDs and related compounds that modulate gamma-secretase cleavage

Genetic and biochemical evidence continues to implicate the production and accumulation of the Abeta42 peptide as the causative factor in Alzheimer's disease (AD). Thus, a variety of strategies have been developed to decrease the production and/or aggregation of this peptide, which may be clinically useful for the treatment of this devastating disorder. Recently, the discovery that some non-steroidal anti-inflammatory drugs (NSAIDs) appear to selectively decrease the production of Abeta42 has opened a novel therapeutic avenue for AD treatment that may circumvent potential toxicity associated with long-term global inhibition of gamma-secretase activity. One drug from this class of compounds, R-flurbiprofen, has advanced to phase 3 clinical trials and may soon provide insight into the viability of this strategy for the prevention or treatment of AD. Delineating the target and mechanism of these compounds is essential for developing new agents with increased potency and optimized pharmacologic properties. The evidence indicating that these chemicals modulate the production of Abeta peptides by directly interacting with the gamma-secretase complex is summarized.

Safety, tolerability, pharmacokinetics, and Abeta levels after short-term administration of R-flurbiprofen in healthy elderly individuals

To evaluate the safety and tolerability and pharmacokinetic properties of R-flurbiprofen (Tarenflurbil) in normal elderly individuals and to determine the effect of the drug on amyloid beta 42 (Abeta42) levels, we conducted a double-blind, placebo-controlled study of 48 healthy subjects aged 55 to 80. Three successive cohorts were randomized to doses of 400, 800, or 1600 mg/d, or placebo, given as 2 divided doses for 21 days. Blood and cerebrospinal fluid were collected for pharmacokinetic studies and measurement of Abeta levels at baseline and on day 21. R-flurbiprofen was well-tolerated at all 3 doses. The compound penetrated the blood-brain barrier in a dose-dependent manner. From baseline to 21 days, comparisons between study groups revealed no significant differences in changes of cerebrospinal fluid Abeta42 levels and no significant differences in changes of plasma Abeta42 levels at the time of trough drug level at 21 days of treatment. Further analysis of drug concentration-response for plasma samples showed that at the time of peak plasma concentration, higher plasma drug concentration was related to lower Abeta42 plasma levels (P=0.016). R-flurbiprofen had an excellent safety profile and showed dose-dependent central nervous system penetration. Exploratory analyses of plasma Abeta and peak drug levels suggested a short-term effect in plasma that warrants independent verification. The safety, tolerability, and pharmacokinetic profile of R-flurbiprofen in these older individuals support the ongoing studies of this compound in patients with Alzheimer disease.

The role of interleukin-1 in neuroinflammation and Alzheimer disease: an evolving perspective

Elevation of the proinflammatory cytokine Interleukin-1 (IL-1) is an integral part of the local tissue reaction to central nervous system (CNS) insult. The discovery of increased IL-1 levels in patients following acute injury and in chronic neurodegenerative disease laid the foundation for two decades of research that has provided important details regarding IL-1's biology and function in the CNS. IL-1 elevation is now recognized as a critical component of the brain's patterned response to insults, termed neuroinflammation, and of leukocyte recruitment to the CNS. These processes are believed to underlie IL-1's function in the setting of acute brain injury, where it has been ascribed potential roles in repair as well as in exacerbation of damage. Explorations of IL-1's role in chronic neurodegenerative disease have mainly focused on Alzheimer disease (AD), where indirect evidence has implicated it in disease pathogenesis. However, recent observations in animal models challenge earlier assumptions that IL-1 elevation and resulting neuroinflammatory processes play a purely detrimental role in AD, and prompt a need for new characterizations of IL-1 function. Potentially adaptive functions of IL-1 elevation in AD warrant further mechanistic studies, and provide evidence that enhancement of these effects may help to alleviate the pathologic burden of disease.

Protecting the synapse: evidence for a rational strategy to treat HIV-1 associated neurologic disease

Loss of synaptic integrity and function appears to underlie neurologic deficits in patients with HIV-1-associated dementia (HAD) and other chronic neurodegenerative diseases. Because synaptic injury often long precedes neuronal death and surviving neurons possess a remarkable capacity for synaptic repair and functional recovery, we hypothesize that therapeutic intervention to protect synapses has great potential to improve neurologic function in HAD and other diseases. We discuss findings from both HAD and Alzheimer's disease to demonstrate that the disruption of synaptic structure and function that can occur during excitotoxic injury and neuroinflammation represents a likely substrate for neurologic deficits. Based on available evidence, we provide a rationale for future studies aimed at identifying molecular targets for synaptic protection in neurodegenerative disease. Whereas patients with HAD beginning antiretroviral therapy have shown reversal of neurologic symptoms that is unique for patients with chronic neurodegenerative conditions, we propose that the potential for such reversal is not unique.

Elevated microsomal prostaglandin-E synthase-1 in Alzheimer's disease

BACKGROUND

The proinflammatory prostaglandin E(2) (PGE(2)) fluctuates over time in the cerebrospinal fluid of patients with Alzheimer's disease (AD), but the cerebral distribution and expression patterns of microsomal prostaglandin-E synthase (mPGES)-1 have not been compared with those of normal human brains.

METHODS

Middle frontal gyrus tissue from AD and age-matched control brains was analyzed by Western blot, immunofluorescence, and immunohistochemistry with mPGES-1-specific antibodies.

RESULTS

Western blotting revealed that mPGES-1 expression was significantly elevated in AD tissue. Furthermore, immunofluorescence of mPGES-1 was observed in neurons, microglia, and endothelial cells of control and AD tissue. Although mPGES-1 was consistently present in astrocytes of control tissue, it was present in only some astrocytes of AD tissue. Immunohistochemical staining suggested that mPGES-1 was elevated in pyramidal neurons of AD tissue when compared with controls.

CONCLUSIONS

The results suggest that mPGES-1 is normally expressed constitutively in human neurons, microglia, astrocytes, and endothelial cells but is up-regulated in AD.

[Risk factors and protective factors of the insanities]

The Alzheimer's disease (AD) is multifactorial. How to explain this group of very heterogeneous factors? Many of them can be considered as biopsychosocial risk factors. In other words, the risk factors, in link with the physiological functioning and a physiopathology, are difficultly dissociable of contingencies of psychological and/or social nature. The vital lead could be the stress bound to these variables, be it biological or psychosocial. It remains to ask the question of the preventive efficiency of treatments to relieve the impact of the traumatizing events of life that entail a depressive state or a state of posttraumatic stress. The hippocamp has to be the object of a quite particular attention. AD is a disease of the adaptation. This integrative model combines three vulnerabilities: a genetic vulnerability which would be there to dictate the type of lesions, their localization and the age of occurence; a psychobiographic vulnerability corresponding to a personality with inadequate mechanisms of defence, precarious adaptability in front of the adversity, weak impact strength and biography built on events of life during childhood, then during the grown-up life of traumatic nature, with a psychosocial environment insufficiently auxiliary; a neuroendocrinologic vulnerability which would base on a deregulation of the corticotrope axis, acquired during its infantile maturation, hampered by too premature stress. It would lead to a bad biological adaptability in stress later, at the origin of the observable lesions in the insanities.

Prevention of Alzheimer's disease

The already considerable public health burden of Alzheimer's disease will likely worsen as populations around the world age. As a result, there is considerable motivation to develop effective strategies for preventing the disease. A wide variety of such strategies are under investigation and include pharmaceuticals, nutriceuticals, diet, physical activity and cognitive activity. We review here the most promising candidates and the epidemiologic evidence for their efficacy. Although none of these have yet to be definitively shown to prevent Alzheimer's disease, further research should help to clarify what role they may play in reducing the burden of this disease.

NSAID use and dementia risk in the Cardiovascular Health Study: role of APOE and NSAID type

BACKGROUND

Epidemiologic and laboratory studies suggest that nonsteroidal antiinflammatory drugs (NSAIDs) reduce risk of Alzheimer disease (AD). We therefore investigated the association between use of NSAIDs, aspirin, and the non-NSAID analgesic acetaminophen with incidence of dementia and AD.

METHODS

Participants in the Cardiovascular Health Cognition Study included 3,229 individuals aged 65 or older, free of dementia at baseline, with information on medication use. We used Cox proportional hazards regression to estimate the association of medication use with incident all-cause dementia, AD, and vascular dementia (VaD). Additional analyses considered the NSAID-AD relationship as a function of age, presence of at least one epsilon 4 allele at APOE, race, and individual NSAIDs' reported ability to reduce production of the amyloid-beta peptide variant A beta(42).

RESULTS

Use of NSAIDs was associated with a lower risk of dementia (adjusted hazard ratio or aHR 0.76, 95% CI or CI 0.60-0.96) and, in particular, AD (aHR 0.63, CI 0.45-0.88), but not VaD (aHR 0.92, CI 0.65-1.28). No similar trends were observed with acetaminophen (aHR 0.99, CI 0.79-1.24). Closer examination suggested AD risk reduction with NSAIDs only in participants having an APOE epsilon 4 allele (aHR 0.34, CI 0.18-0.65; aHR for others 0.88, CI 0.59-1.32). There was no advantage in AD risk reduction with NSAIDs reported to selectively reduce A beta(42).

CONCLUSIONS

Results were consistent with previous cohort studies showing reduced risk of AD in NSAID users, but this association was found only in those with an APOE epsilon 4 allele, and there was no advantage for A beta(42)-lowering NSAIDs.

Neuroinflammation and regulation of glial glutamate uptake in neurological disorders

Oxidative stress, neuroinflammation, and excitotoxicity are frequently considered distinct but common hallmarks of several neurological disorders, including Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and Alzheimer's disease. Although neuron degeneration and death are the ultimate consequences of these pathological processes, it is now widely accepted that alterations in the function of surrounding glial cells are key features in the progression of these diseases. In response to alteration in their local environment, microglia, commonly considered the resident immune cells of the nervous parenchyma, become activated and release a variety of soluble factors. Among these, proinflammatory cytokines and free radicals actively participate in the degenerative insults. In addition, excitotoxic neuronal damage resulting from excessive glutamate is frequently associated with impaired handling of extracellular glutamate by gliotic astrocytes. Although several research projects have focused on the biochemical mechanisms of the regulation of glial glutamate transporters, a relationship between activation of microglia and modulation of astrocytic glutamate uptake is now suggested. The aim of this review is to summarize and discuss the data showing an influence of inflammatory mediators and related free radicals on the expression and activity of glial glutamate transporters.

Pharmacotherapy of Alzheimer disease

OBJECTIVE

To systematically review published clinical trials of the pharmacotherapy of Alzheimer disease (AD).

METHOD

We searched MEDLINE for published English-language medical literature, using Alzheimer disease and treatment as key words. No other search engine was used. Our review focused on randomized clinical trials (RCTs) and corresponding metaanalyses.

RESULTS

Although there are many RCTs for the treatment of mild cognitive impairment (MCI), none have been successful in their primary analysis. The cholinesterase inhibitors donepezil, rivastigmine, and galantamine have demonstrated efficacy in 3- to 12-month placebo-controlled RCTs assessing cognitive, functional, behavioural, and global outcomes in patients with mildly to moderately severe AD. Recent data from patients with severe stages of AD demonstrate the efficacy of donepezil on cognitive and functional measures but not on behaviour. The N-methyl-D-aspartate receptor antagonist memantine has been demonstrated to be effective in 6-month, placebo-controlled RCTs of 6 months duration assessing cognitive, functional, and global outcomes of inpatients with moderate-to-severe AD (defined as a Mini Mental State Examination score below 20). Post hoc analyses have demonstrated a benefit in regard to agitation and (or) aggression, but this needs to be confirmed in a prospective RCT across Canada. Disease-modifying treatments are being tested in mild stages of AD in 18-month RCTs with cognitive and global outcomes as primary efficacy outcomes, primarily with drugs reducing amyloid synthesis or aggregation. Successful treatment in mild stages of AD could lead to RCTs in MCI and, possibly, in genetically high-risk asymptomatic individuals.

CONCLUSION

The significant advances in the symptomatic pharmacotherapy of AD may be followed by disease-modification treatments.

NSAIDs: small molecules for prevention of Alzheimer's disease or precursors for future drug development?

Non-steroidal anti-inflammatory drugs (NSAIDs) have been considered for treatment and prevention of Alzheimer's disease (AD) for more than two decades. Biochemical markers in the brains of individuals with AD suggest that inflammation might be a driving cause of the disease that can be suppressed by drug treatment. In addition, a subgroup of widely used NSAIDs inhibits generation of the pathogenic amyloid-beta(1-42) peptide (Abeta42) independently of the inflammatory cyclooxygenase (COX) pathway. Here, we summarize evidence showing that the efficacy of NSAIDs in AD might be attributable to either anti-inflammatory or anti-amyloidogenic activities, and we acknowledge the possibility that current NSAIDs could be neuroprotective through synergistic mechanisms. Ongoing drug development efforts are concentrating on improvement of the COX-independent Abeta42-lowering activity to prevent amyloid pathology and secondary inflammatory reactions and to avoid the clinical side-effects associated with inhibition of COX.

1-(3′,4′-Dichloro-2-fluoro[1,1′-biphenyl]-4-yl)-cyclopropanecarboxylic Acid (CHF5074), a Novel γ-Secretase Modulator, Reduces Brain β-Amyloid Pathology in a Transgenic Mouse Model of Alzheimer's Disease without Causing Peripheral Toxicity

Some nonsteroidal anti-inflammatory drugs has been shown to allosterically modulate the activity of gamma-secretase, the enzymatic complex responsible for the formation of beta-amyloid (Abeta). 1-(3',4'-Dichloro-2-fluoro[1,1'-biphenyl]-4-yl)-cyclopropanecarboxylic acid (CHF5074) is a new gamma-secretase modulator, devoid of anticyclooxygenase (COX) and Notch-interfering activities in vitro. We evaluated the effects of chronic CHF5074 treatment on brain Abeta pathology in Tg2576 transgenic mice. Twenty-eight animals of 9.5 to 10.5 months of age received CHF5074-medicated diet (375 ppm) or standard diet for 17 weeks. Compared with controls, CHF5074 treatment significantly reduced the area occupied by plaques and the number of plaques in cortex (-52.2 +/- 5.6%, p = 0.0003 and -48.9 +/- 6.6%, p = 0.0004, respectively) and hippocampus (-76.7 +/- 6.4%, p = 0.004 and -66.2 +/- 10.3%, p = 0.037, respectively). Biochemical analysis confirmed the histopathological measures, with CHF5074-treated animals showing reduced total brain Abeta40 (-49.2 +/- 9.2%, p = 0.017) and Abeta42 (-43.5 +/- 9.7%, p = 0.027) levels. In a human neuroglioma cell line expressing Swedish mutated form of amyloid precursor protein (H4swe), CHF5074 reduced Abeta42 and Abeta40 secretion, with an IC50 of 3.6 and 18.4 microM, respectively, values consistent with those measured in the brain of the CHF5074-treated Tg2576 mice (6.4 +/- 0.4 microM). At 5 microM, no effects were observed on Notch intracellular cleavage in human embryonic kidney 293swe cells. CHF5074 was well tolerated by Tg2576 mice. No abnormal findings were observed upon histopathological examination of the gastrointestinal tract, indicating the absence of COX-related toxicity. Semiquantitative histochemical evaluation of goblet cells in the ileum of vehicle- and CHF5074-treated animals yielded similar results, suggesting no effects on Notch pathway. CHF5074 is therefore a promising therapeutic agent for Alzheimer's disease.

Inflammation and hepatic encephalopathy: ibuprofen restores learning ability in rats with portacaval shunts

One of the neurological alterations in patients with minimal or overt hepatic encephalopathy is cognitive impairment. This impairment is reproduced in rats with chronic liver failure due to portacaval shunt (PCS). These rats show decreased ability to learn a conditional discrimination task in a Y-maze, likely due to reduced function of the glutamate-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway in brain. It has been proposed that inflammation exacerbates the neuropsychological alterations induced by hyperammonemia, suggesting that inflammation-associated alterations may contribute to cognitive impairment in hepatic encephalopathy. This study assessed whether treatment with an anti-inflammatory drug, ibuprofen, is able to restore the function of the glutamate-NO-cGMP pathway in cerebral cortex in brain in vivo and/or learning ability in PCS rats. We show that PCS rats have increased levels of interleukin-6 and increased activities of cyclooxygenase and of inducible NO synthase in cerebral cortex, indicating the presence of inflammation. Chronic treatment with ibuprofen normalizes cyclooxygenase and inducible NO synthase activities but not interleukin-6 levels. Moreover, ibuprofen normalizes the function of the glutamate-NO-cGMP pathway in cerebral cortex in vivo and completely restores the ability of rats with chronic liver failure to learn the Y-maze task. This supports that inflammation contributes to the cognitive impairment in hepatic encephalopathy.

CONCLUSION

the results reported point to the possible therapeutic utility of decreasing inflammation in the treatment of the cognitive deficits in patients with minimal or overt hepatic encephalopathy.

Aspirin and cognitive function

Benefit has not yet been shown, but may be due to difficulties in selecting the right outcome measure

Oxidative stress: A bridge between Down's syndrome and Alzheimer's disease

Besides the genetic, biochemical and neuropathological analogies between Down's syndrome (DS) and Alzheimer's disease (AD), there is ample evidence of the involvement of oxidative stress (OS) in the pathogenesis of both disorders. The present paper reviews the publications on DS and AD in the past 10 years in light of the "gene dosage" and "two-hit" hypotheses, with regard to the alterations caused by OS in both the central nervous system and the periphery, and the main pipeline of antioxidant therapeutic strategies. OS occurs decades prior to the signature pathology and manifests as lipid, protein and DNA oxidation, and mitochondrial abnormalities. In clinical settings, the assessment of OS has traditionally been hampered by the use of assays that suffer from inherent problems related to specificity and/or sensitivity, which explains some of the conflicting results presented in this work. For DS, no scientifically proven diet or drug is yet available, and AD trials have not provided a satisfactory approach for the prevention of and therapy against OS, although most of them still need evidence-based confirmation. In the future, a balanced up-regulation of endogenous antioxidants, together with multiple exogenous antioxidant supplementation, may be expected to be one of the most promising treatment methods.

Novel modulators of amyloid-beta precursor protein processing

Proteolytic processing of the amyloid precursor protein (APP) is modulated by the action of enzymes alpha-, beta- and gamma-secretases, with the latter two mediating the amyloidogenic production of amyloid-beta (Abeta). Cellular modulators of APP processing are well known from studies of genetic mutations (such as those found in APP and presenilins) or polymorphisms (such as the apolipoprotein E4 epsilon-allele) that predisposes an individual to early or late-onset Alzheimer's disease. In recent years, several classes of molecule with modulating functions in APP processing and Abeta secretion have emerged. These include the neuronal Munc-18 interacting proteins (Mints)/X11s, members of the reticulon family (RTN-3 and RTN-4/Nogo-B), the Nogo-66 receptor (NgR), the peptidyl-prolyl isomerase Pin1 and the Rho family GTPases and their effectors. Mints and NgR bind to APP directly, while RTN3 and Nogo-B interact with the beta-secretase BACE1. Phosphorylated APP is a Pin1 substrate, which binds to its phosphor-Thr668-Pro motif. These interactions by and large resulted in a reduction of Abeta generation both in vitro and in vivo. Inhibition of Rho and Rho-kinase (ROCK) activity may underlie the ability of non-steroidal anti-inflammatory drugs and statins to reduce Abeta production, a feat which could also be achieved by Rac1 inhibition. Detailed understanding of the underlying mechanisms of action of these novel modulators of APP processing, as well as insights into the molecular neurological basis of how Abeta impairs leaning and memory, will open up multiple avenues for the therapeutic intervention of Alzheimer's disease.

Dementia epidemiology research: it is time to modify the focus of research

The incidence and prevalence of dementia are increasing. There is an urgent need to develop a preventive strategy. The identification of modifiable risk factors must therefore be a high priority. Newer imaging techniques provide an opportunity to identify subclinical manifestations of "dementias" that can be limited to the risk factors and subsequent clinical disease. The contribution of vascular disease to dementia and Alzheimer's disease (AD) should be a high priority as it offers a potential preventive strategy. Study designs need to be modified, including a greater emphasis on geographic variations in AD and dementia based on imaging studies, longitudinal studies of successful aging without cardiovascular disease (CVD) or AD, gene-environment interactions, and studies of unique populations that may be at lower risk because of specific lifestyles. Primary prevention trials for vascular disease should include a dementia component. Most, if not all, studies should include newer imaging studies.

Long-term efficacy and safety of celecoxib in Alzheimer's disease

BACKGROUND/AIMS

Cyclooxygenase-2 (COX-2) may play an important role in the neuropathology of Alzheimer's disease (AD). The efficacy and safety of celecoxib (200 mg bid), a COX-2 selective inhibitor, were assessed in patients > or =50 years with established mild-to-moderate AD to determine whether treatment was effective in retarding deterioration of cognitive function.

METHODS

This was a 52-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study. The primary efficacy end points were the change from baseline to week 52 in the Alzheimer's Disease Assessment Scale-Cognitive Behavior (ADAS-cog) composite score and the week 52 Clinician's Interview-Based Impression of Change Plus (CIBIC+).

RESULTS

At 52 weeks, change in ADAS-cog scores from baseline was similar for placebo and celecoxib 200 mg bid groups (5.00 and 4.39, respectively). CIBIC+ scores were also similar (4.83 and 4.92). Two extension studies were conducted but were terminated early based on these efficacy results. Safety data from all 3 studies indicated that celecoxib was generally well-tolerated.

CONCLUSION

Celecoxib 200 mg bid did not slow the progression of AD in this study, and the occurrence of adverse events was as expected for an elderly population with a complex chronic medical condition.

Disease-modifying therapies in Alzheimer's disease: how far have we come?

Currently, there are no disease-modifying therapies available for Alzheimer's disease (AD). Acetylcholinesterase inhibitors and memantine are licensed for AD and have moderate symptomatic benefits. Epidemiological studies have suggested that NSAIDs, estrogen, HMG-CoA reductase inhibitors (statins) or tocopherol (vitamin E) can prevent AD. However, prospective, randomised studies have not convincingly been able to demonstrate clinical efficacy. Major progress in molecular medicine suggests further drug targets. The metabolism of the amyloid-precursor protein and the aggregation of its Abeta fragment are the focus of current studies. Abeta peptides are produced by the enzymes beta- and gamma-secretase. Inhibition of gamma-secretase has been shown to reduce Abeta production. However, gamma-secretase activity is also involved in other vital physiological pathways. Involvement of gamma-secretase in cell differentiation may preclude complete blockade of gamma-secretase for prolonged times in vivo. Inhibition of beta-secretase seems to be devoid of serious adverse effects according to studies with knockout animals. However, targeting beta-secretase is hampered by the lack of suitable inhibitors to date. Other approaches focus on enzymes that cut inside the Abeta sequence such as alpha-secretase and neprilysin. Stimulation of the expression or activity of alpha-secretase or neprilysin has been shown to enhance Abeta degradation. Furthermore, inhibitors of Abeta aggregation have been described and clinical trials have been initiated. Peroxisome proliferator activated receptor-gamma agonists and selected NSAIDs may be suitable to modulate both Abeta production and inflammatory activation. On the basis of autopsy reports, active immunisation against Abeta in humans seems to have proven its ability to clear amyloid deposits from the brain. However, a first clinical trial with active vaccination against the full length Abeta peptide has been halted because of adverse effects. Further trials with vaccination or passive transfer of antibodies are planned.

The elephant in the room - healthy brains in later life, epidemiology and public health

The increasing age of the population around the world has meant that greater attention is being paid to disorders that mainly affect older people. In particular, work is focusing on ways to preserve the healthy brain and prevent dementia. Preventive studies are complex and must take into account not only simple approaches such as those used in risk and outcome studies, but also stage of life, survival and mortality, and population context before their effect can be assessed. This paper presents questions and areas which must be explored if the potential for prevention of dementia during brain ageing is to be properly understood.

Amyloid-beta vaccination, but not nitro-nonsteroidal anti-inflammatory drug treatment, increases vascular amyloid and microhemorrhage while both reduce parenchymal amyloid

Vaccination with Abeta(1-42) and treatment with NCX-2216, a novel nitric oxide releasing flurbiprofen derivative, have each been shown separately to reduce amyloid deposition in transgenic mice and have been suggested as potential therapies for Alzheimer's disease. In the current study we treated doubly transgenic amyloid precursor protein and presenilin-1 (APP+PS1) mice with Abeta(1-42) vaccination, NCX-2216 or both drugs simultaneously for 9 months. We found that all treatments reduced amyloid deposition, both compact and diffuse, to the same extent while only vaccinated animals, with or without nonsteroidal anti-inflammatory drug (NSAID) treatment, showed increased microglial activation associated with the remaining amyloid deposits. We also found that active Abeta vaccination resulted in significantly increased cerebral amyloid angiopathy and associated microhemorrhages, while NCX-2216 did not, in spite of similar reductions in parenchymal amyloid. Co-administration of NCX-2216 did not attenuate this effect of the vaccine. This is the first report showing that active immunization can result in increased vascular amyloid and microhemorrhage, as has been observed with passive immunization. Co-administration of an NSAID agent with Abeta vaccination does not substantially modify the effects of Abeta immunotherapy. The difference between these treatments with respect to vascular amyloid development may reflect the clearance-promoting actions of the vaccine as opposed to the production-modifying effects proposed for flurbiprofen.

Alzheimer's disease: progress in the development of anti-amyloid disease-modifying therapies

The amyloid hypothesis--the leading mechanistic theory of Alzheimer's disease--states that an imbalance in production or clearance of amyloid beta (Abeta) results in accumulation of Abeta and triggers a cascade of events leading to neurodegeneration and dementia. The number of persons with Alzheimer's disease is expected to triple by mid-century. If steps are not taken to delay the onset or slow the progression of Alzheimer's disease, the economic and personal tolls will be immense. Different classes of potentially disease-modifying treatments that interrupt early pathological events (ie, decreasing production or aggregation of Abeta or increasing its clearance) and potentially prevent downstream events are in phase II or III clinical studies. These include immunotherapies; secretase inhibitors; selective Abeta42-lowering agents; statins; anti-Abeta aggregation agents; peroxisome proliferator-activated receptor-gamma agonists; and others. Safety and serious adverse events have been a concern with immunotherapy and gamma-secretase inhibitors, though both continue in clinical trials. Anti-amyloid disease-modifying drugs that seem promising and have reached phase III clinical trials include those that selectively target Abeta42 production (eg, tarenflurbil), enhance the activity of alpha-secretase (eg, statins), and block Abeta aggregation (eg, transiposate).

Increased isoprostane and prostaglandin are prominent in neurons in Alzheimer disease

BACKGROUND

Inflammation and oxidative stress are both involved in the pathogenesis of Alzheimer disease and have been shown to be reciprocally linked. One group of molecules that have been directly associated with inflammation and the production of free radicals are the prostaglandin 13,14-dihydro 15-keto PGF2alpha and the isoprostane 8-iso-PGF2alpha.

RESULTS

To further delineate the role of inflammatory and oxidative parameters in Alzheimer disease, in this study we evaluated the amount and localization of 13,14-dihydro 15-keto PGF2alpha and 8-iso-PGF2alpha in hippocampal post mortem tissue samples from age-matched Alzheimer disease and control patients. Our results demonstrate increased levels of 13,14-dihydro 15-keto PGF2alpha and 8-iso-PGF2alpha in the hippocampal pyramidal neurons of Alzheimer disease patients when compared to control patients.

CONCLUSION

These data not only support the shared mechanistic involvement of free radical damage and inflammation in Alzheimer disease, but also indicate that multiple pathogenic "hits" are likely necessary for both the development and propagation of Alzheimer disease.

NSAIDs for the chemoprevention of Alzheimer's disease

Epidemiologic and laboratory studies suggest that non-steroidal anti-inflammatory drug (NSAID) use reduces the risk of Alzheimer's disease (AD). Initial reports in the early 1990's indicated that a history of arthritis, a presumed surrogate of NSAID use, was associated with a lower risk of AD. [1] These reports were followed by epidemiologic studies in which NSAID use was assessed directly and the majority of these reports confirmed the inverse association with risk for AD. [2, 3] Postmortem studies in humans [4], studies in animal models of AD [5, 6], and in vitro studies [7, 8] generally support the notion that NSAIDs can reduce the deleterious inflammation which surrounds amyloid beta (Abeta) plaques in the AD brain. In addition, some studies conducted in vitro and in rodents point to a subgroup of NSAIDs that may work by inhibiting amyloidogenic APP metabolism rather than through traditional anti-inflammatory mechanisms. [9-11] This novel property of NSAIDs is currently being explored in epidemiologic studies. Results from randomized clinical trials of NSAIDs and established AD and one trial on secondary prevention have not been promising and there have been no prevention trials completed. The feasibility of using NSAIDs as a chemopreventive agent in AD is discussed.

Autotransplantation of bone marrow-derived stem cells as a therapy for neurodegenerative diseases

Neurodegenerative diseases are characterized by a progressive degeneration of selective neural populations. This selective hallmark pathology and the lack of effective treatment modalities make these diseases appropriate candidates for cell therapy. Bone marrow-derived mesenchymal stem cells (MSCs) are self-renewing precursors that reside in the bone marrow and may further be exploited for autologous transplantation. Autologous transplantation of MSCs entirely circumvents the problem of immune rejection, does not cause the formation of teratomas, and raises very few ethical or political concerns. More than a few studies showed that transplantation of MSCs resulted in clinical improvement. However, the exact mechanisms responsible for the beneficial outcome have yet to be defined. Possible rationalizations include cell replacement, trophic factors delivery, and immunomodulation. Cell replacement theory is based on the idea that replacement of degenerated neural cells with alternative functioning cells induces long-lasting clinical improvement. It is reasoned that the transplanted cells survive, integrate into the endogenous neural network, and lead to functional improvement. Trophic factor delivery presents a more practical short-term approach. According to this approach, MSC effectiveness may be credited to the production of neurotrophic factors that support neuronal cell survival, induce endogenous cell proliferation, and promote nerve fiber regeneration at sites of injury. The third potential mechanism of action is supported by the recent reports claiming that neuroinflammatory mechanisms play an important role in the pathogenesis of neurodegenerative disorders. Thus, inhibiting chronic inflammatory stress might explain the beneficial effects induced by MSC transplantation. Here, we assemble evidence that supports each theory and review the latest studies that have placed MSC transplantation into the spotlight of biomedical research.

Alzheimer's and dementia in the oldest-old: a century of challenges

Alzheimer's disease (AD) is the most common type of dementia in the US and much of the world with rates increasing exponentially from age 65. Increases in life expectancy in the last century have resulted in a large number of people living to old ages and will result in a quadrupling of AD cases by the middle of the century. Preventing or delaying the onset of AD could have a huge impact in the number of cases expected to develop. The oldest-old are the fastest growing segment of the population and are estimated to account for 12% of the population over 65. Establishing accurate estimates of dementia and AD rates in this group is crucial for public health planning. Prevalence and incidence estimates above age 85 are imprecise and inconsistent because of the lack of very old individuals in most studies. Moreover, risk and protective factors in our oldest citizens have been studied little, and clinical-pathological correlations appear to be poor. We introduce The 90+ Study, established to address some of the unanswered questions about AD and dementia in the oldest-old. Our preliminary results show that close to half of demented oldest-old do not have known cerebral pathology to account for their cognitive deficits. Furthermore, the APOE-e4 allele appears to be a risk factor for AD only in the women in our study. In addition to the challenge of preventing and treating AD, the oldest-old will require major investigative energy to better understand the concomitants of longevity, the causes of dementia, and the factors that promote successful aging in oldest citizens.

Cardiovascular and cerebrovascular events in the randomized, controlled Alzheimer's Disease Anti-Inflammatory Prevention Trial (ADAPT)

Objectives:

The Alzheimer's Disease Anti-inflammatory Prevention Trial (ADAPT) was designed to evaluate the conventional NSAID naproxen sodium and the selective COX-2 inhibitor celecoxib for primary prevention of Alzheimer's dementia (AD). On 17 December 2004, after the Adenoma Prevention with Celecoxib (APC) trial reported increased cardiovascular risks with celecoxib, the ADAPT Steering Committee suspended treatment and enrollment. This paper reports on cardiovascular and cerebrovascular events in ADAPT.

Design:

ADAPT is a randomized, placebo-controlled, parallel chemoprevention trial with 1–46 mo of follow-up.

Setting:

The trial was conducted at six field sites in the United States: Baltimore, Maryland; Boston, Massachusetts; Rochester, New York; Seattle, Washington; Sun City, Arizona; and Tampa, Florida.

Participants:

The 2,528 participants were aged 70 y and older with a family history of AD.

Interventions:

Study treatments were celecoxib (200 mg b.i.d.), naproxen sodium (220 mg b.i.d.), and placebo.

Outcome measures:

Outcome measures were deaths, along with nonfatal myocardial infarction (MI), stroke, congestive heart failure (CHF), transient ischemic attack (TIA), and antihypertensive treatment recorded from structured interviews at scheduled intervals. Cox proportional hazards regression was used to analyze these events individually and in several composites.

Results:

Counts (with 3-y incidence) of participants who experienced cardiovascular or cerebrovascular death, MI, stroke, CHF, or TIA in the celecoxib-, naproxen-, and placebo-treated groups were 28/717 (5.54%), 40/713 (8.25%), and 37/1070 (5.68%), respectively. This yielded a hazard ratio (95% confidence interval [CI]) for celecoxib of 1.10 (0.67–1.79) and for naproxen of 1.63 (1.04–2.55). Antihypertensive treatment was initiated in 160/440 (47.43%), 147/427 (45.00%), and 164/644 (34.08%). This yielded hazard ratios (CIs) of 1.56 for celecoxib (1.26–1.94) and 1.40 for naproxen (1.12–1.75).

Conclusions:

For celecoxib, ADAPT data do not show the same level of risk as those of the APC trial. The data for naproxen, although not definitive, are suggestive of increased cardiovascular and cerebrovascular risk.

Background: Evidence from observational studies suggests that people taking certain nonsteroidal anti-inflammatory drugs (NSAIDs) are at lower risk of developing Alzheimer's disease. However, in order to reliably find out whether NSAIDs reduce the risk of Alzheimer's, it is important to perform a properly designed randomized trial. Such a trial, ADAPT, was sponsored by the United States National Institute on Aging, and the study started recruitment in 2001. The trial involved three treatment arms: naproxen (one type of NSAID), celecoxib (another type of NSAID, but one that specifically inhibits an enzyme called COX-2), and placebo, acting as a control. It was planned that 2,625 participants would be recruited and that the primary outcome of interest was incidence of Alzheimer's disease in the three treatment arms; the trial would run for 7 y. However, this trial was terminated early, a decision based in part on information from other studies that demonstrated an increased risk of certain harms, such as heart attacks and strokes, in people taking celecoxib and other types of COX-2 inhibitors. Therefore meaningful data were not available at the time on the study's primary outcome (prevention of Alzheimer's disease). However, data about the chance of these harms are available from the ADAPT results, and these results are presented here.

What this trial shows: The investigators compared frequency of particular types of harm in the treatment arms: heart attack, stroke, congestive heart failure (CHF), and transient ischemic attack (TIA). For each individual type of event, some were more likely in people treated with celecoxib compared with placebo, but others were not. When considering people taking naproxen, all four types of adverse events were more likely to occur in the treatment group as compared to placebo. The investigators then combined data from all four types of harm together, and here they found that the overall risk in people taking celecoxib was higher than for people taking placebo, but that this was not statistically significant, so it could have been due to chance alone. When considering naproxen as compared with placebo, the researchers saw an approximately 60% increase in risk for all four harms combined, and this result was statistically significant. The death rate in people taking either celecoxib or naproxen was higher than for those taking placebo, but this was not statistically significant, and therefore could have been due to chance.

Strengths and limitations: Strengths of this study include the randomization procedures, which used a distributed computer system to assign patients to treatment arms (minimizing the chance of bias), blinding of patients to their treatment assignment, and blinding of the committee reviewing deaths and safety reports to treatment assignment. One limitation is that although the trial was large and appropriately powered for the main outcome (prevention of Alzheimer's disease), the number of safety events reported here were small and the trial was not primarily designed to examine safety. Further, participants eligible to join this trial were required to have a family history of Alzheimer's disease, so it is possible that their risk factors are slightly different from the general population.

Contribution to the evidence: The cardiovascular safety of NSAID's, including COX-2 inhibitors, is an intensely debated topic. Very few published data exist on the long-term safety of celecoxib as compared with placebo, although there are a number of as-yet-unpublished studies. These data on harms provided by ADAPT provide important results that should be incorporated into future meta-analyses. Such meta-analyses will give a more rigorous and reliable assessment of the safety of the drugs studied here.

Clinical practice with anti-dementia drugs: a consensus statement from British Association for Psychopharmacology

The British Association for Psychopharmacology (BAP) coordinated a meeting of experts to review the evidence on the drug treatment for dementia. The level of evidence (types) was rated using a standard system: Types 1a and 1b (evidence from meta-analysis of randomised controlled trials or at least one controlled trial respectively); types 2a and 2b (one well-designed study or one other type of quasi experimental study respectively); type 3 (non-experimental descriptive studies); and type 4 (expert opinion). There is type 1a evidence for cholinesterase inhibitors (donepezil, rivastigmine and galantamine) for mild to moderate Alzheimer's disease; memantine for moderate to severe Alzheimer's disease; and for the use of bright light therapy and aromatherapy. There is type 1a evidence of no effect of anti inflammatory drugs or statins. There is conflicting evidence regarding oestrogens, with type 2a evidence of a protective effect of oestrogens but 1b evidence of a harmful effect. Type 1a evidence for any effect of B12 and folate will be forthcoming when current trials report. There is type 1b evidence for gingko biloba in producing a modest benefit of cognitive function; cholinesterase inhibitors for the treatment of people with Lewy body disease (particularly neuropsychiatric symptoms); cholinesterase inhibitors and memantine in treatment cognitive impairment associated with vascular dementia; and the effect of metal collating agents (although these should not be prescribed until more data on safety and efficacy are available). There is type 1b evidence to show that neither cholinesterase inhibitors nor vitamin E reduce the risk of developing Alzheimer's disease in people with mild cognitive impairment; and there is no evidence that there is any intervention that can prevent the onset of dementia. There is type 1b evidence for the beneficial effects of adding memantine to cholinesterase inhibitors, and type 2b evidence of positive switching outcomes from one cholinesterase inhibitor to another. There is type 2a evidence for a positive effect of reminiscence therapy, and type 2a evidence that cognitive training does not work. There is type 3 evidence to support the use of psychological interventions in dementia. There is type 2 evidence that a clinical diagnosis of dementia can be made accurately and that brain imaging increases that accuracy. Although the consensus statement dealt largely with medication, the role of dementia care in secondary services (geriatric medicine and old age psychiatry) and primary care, along with health economics, was discussed. There is ample evidence that there are effective treatments for people with dementia, and Alzheimer's disease in particular. Patients, their carers, and clinicians deserve to be optimistic in a field which often attracts therapeutic nihilism.

Role of toll-like receptor signalling in Abeta uptake and clearance

Deposits of amyloid beta-protein (Abeta) in neuritic plaques and cerebral vessels are a pathological hallmark of Alzheimer's disease. Fibrillar Abeta deposits are closely associated with inflammatory responses such as activated microglia in brain with this disease. Increasing lines of evidence support the hypothesis that activated microglia, innate immune cells in the CNS, play a pivotal role in the progression of the disease: either clearing Abeta deposits by phagocytic activity or releasing cytotoxic substances and pro-inflammatory cytokines. Toll-like receptors (TLRs) are a family of pattern-recognition receptors in the innate immune system. Exogenous and endogenous TLR ligands activate microglia. To investigate the role of TLR4 in the amyloidogenesis in vivo, we determined the amounts of cerebral Abeta in Alzheimer's disease mouse models with different genotypes of TLR4 using three distinct methods. We show that mouse models (Mo/Hu APPswe PS1dE9 mice) homozygous for a destructive mutation of TLR4 (Tlr(Lps-d)/Tlr(Lps-d)) had increases in diffuse and fibrillar Abeta deposits by immunocytochemistry, fibrillar Abeta deposits by thioflavine-S staining and buffer-soluble and insoluble Abeta by ELISA in the cerebrum, as compared with TLR4 wild-type mouse models. Although the differences in these parameters were less significant, mouse models heterozygous for the mutation (Tlr(Lps-d)/) showed co-dominant phenotypes. Consistent with these observations in vivo, cultured microglia derived from Tlr(Lps-d)/Tlr(Lps-d) mice failed to show an increase in Abeta uptake after stimulation with a TLR4 ligand but not with a TLR9 ligand in vitro. Furthermore, activation of microglia (BV-2 cell) with a TLR2, TLR4 or TLR9 ligand, markedly boosted ingestion of Abeta in vitro. These results suggest that TLR signalling pathway(s) may be involved in clearance of Abeta-deposits in the brain and that TLRs can be a therapeutic target for Alzheimer's disease.

Toward prevention of Alzheimers disease--potential nutraceutical strategies for suppressing the production of amyloid beta peptides

Alzheimers disease (AD) can be viewed as a vicious cycle in which excess production and deposition of amyloid beta (Abeta) peptides promote microglial activation, and the resultant production of inflammatory mediators further boosts Abeta production while inducing death and dysfunction of neurons. Abeta production is mediated by beta- and gamma-secretase activities; it is prevented by alpha-secretase activity, and insulin-degrading enzyme (IDE) catabolizes Abeta. High cellular cholesterol content increases Abeta synthesis by boosting beta-secretase activity; inhibition of cholesterol syntheses and/or stimulation of cholesterol export thus diminishes Abeta production. PPARgamma activity decreases Abeta production by promoting harmless catabolism of amyloid precursor protein while blocking the up-regulatory impact of cytokines on beta-secretase expression. Nitric oxide produced by the healthy cerebral microvasculature can suppress Abeta production by boosting expression of alpha-secretase while suppressing that of beta-secretase; conversely, cerebral ischemia provokes increased APP expression. Good insulin sensitivity and efficient brain insulin function protect by inhibiting gamma-secretase activity and increasing expression of IDE. The DHA provided by fish oil diminishes cerebral Abeta deposition in rodent AD models, for unclear reasons. Various measures which oppose microglial activation can inhibit up-regulation of beta-secretase and gamma-secretase by oxidants and cytokines, respectively. These considerations suggest that a number of nutraceutical or lifestyle measures may have potential for preventing or slowing AD: policosanol; 9-cis-beta-carotene; isomerized hops extract; DHA; measures which promote efficient endothelial NO generation, such as low-salt/potassium-rich diets, exercise training, high-dose folate, and flavanol-rich cocoa; chromium picolinate and cinnamon extract as aids for insulin sensitivity; and various agents which can oppose microglial activation, including vitamin D, genistein, and sesamin. The impact of these measures on Abeta production in rodent models of AD should be evaluated, with the intent of defining practical strategies for AD prevention.

Imaging and in vivo quantitation of beta-amyloid: an exemplary biomarker for Alzheimer's disease?

Alzheimer's disease (AD) is characterized pathologically by the presence of beta-amyloid plaques in the brain. A substantial body of research indicates that the presence of increased beta-amyloid peptide (Abeta) is neurotoxic and may initiate the further pathology observed in AD, including neurofibrillary tangles, synaptic loss and dysfunction, and neurodegeneration. The use of brain imaging in patients with or at risk for AD has increased our understanding of the pathophysiology of the disease and may potentially aid in diagnosis. The development of new therapeutics that reduce Abeta in the brain has also indicated a potential use for amyloid imaging in monitoring response to treatment. This review explores the utility of amyloid as a biomarker and the use of positron emission tomography and magnetic resonance imaging in the diagnosis and treatment of AD.

Anti-inflammatory effect of jeongshintang through suppression of p38 activation in human astrocytoma, U373MG cells

Jeongshintang (JST) is a Korean herbal prescription, which has been successfully used for cerebral diseases. However, the anti-inflammatory effect of JST on Alzheimer's disease (AD) is still not fully understood. In this study, we investigated the effects of JST in attenuating the inflammatory response induced by interleukin (IL)-1beta plus beta-amyloid [1-42] fragment (A beta) in the human astrocyte cell line, U373MG. The production of IL-6, IL-8, and prostaglandin (PG)E2 was significantly increased by IL-1beta plus A beta (1-42) in a time-dependent manner (P < 0.05). JST significantly inhibited the IL-1beta plus A beta (1-42)-induced IL-6, IL-8, and PGE2 production at 24 h (P < 0.05). Maximal inhibition rate of IL-6, IL-8, and PGE2 production by JST was about 54.40%, 56.01%, and 44.06% respectively. JST (0.01-1 mg/ml) also attenuated the expression of cyclooxygenase (COX)-2 and activation of p38 MAPK induced by IL-1beta and A beta (1-42). These results demonstrated that JST has an anti-inflammatory effect, which might explain its beneficial effect in the treatment of various neurodegenerative diseases such as AD.

NSAIDs and Alzheimer disease: epidemiological, animal model and clinical studies

This review reports correlations between four independent fields related to inflammation and Alzheimer disease: fundamental pathology, epidemiology, transgenic animal studies and clinical trials. Activated microglia, along with a spectrum of inflammatory mediators, have been identified in association with the lesions of Alzheimer disease (AD), suggesting that antiinflammatory agents such as NSAIDs should protect against the disease. In multiple epidemiological investigations testing this hypothesis, a significant risk reduction, or a trend towards such a reduction has been observed in long term as opposed to short term users of traditional NSAIDs. In studies where such NSAIDs have been administered to AD transgenic mice, a dose dependent reduction in pathology was observed. The selective C0X-2 inhibitors were ineffective. Results of clinical investigations have so far been disappointing but have nevertheless correlated with fundamental pathological findings and with transgenic mouse results. Four clinical trials using selective COX-2 inhibitors failed which is in keeping with the animal results and is consistent with pathological findings demonstrating that COX-1 and not COX-2 is the appropriate target in activated human microglia. A low dose trial of the traditional NSAID naproxen also failed, but pilot trials using therapeutically established doses of indomethacin and diclofenac/misoprostol showed promise. Further clinical investigations with relatively high doses of traditional NSAIDs might be warranted, although significant side effects should be anticipated.

Deletion of the prostaglandin E2 EP2 receptor reduces oxidative damage and amyloid burden in a model of Alzheimer's disease

Epidemiological studies demonstrate that chronic use of nonsteroidal anti-inflammatory drugs (NSAIDs) in normal aging populations reduces the risk of developing Alzheimer's disease (AD). NSAIDs inhibit the enzymatic activity of cyclooxygenase-1 (COX-1) and inducible COX-2, which catalyze the first committed step in the synthesis of prostaglandins. These studies implicate COX-mediated inflammation as an early and potentially reversible preclinical event; however, the mechanism by which COX activity promotes development of AD has not been determined. Recent studies implicate the prostaglandin E2 (PGE2) E prostanoid subtype 2 (EP2) receptor in the development of the innate immune response in brain. Here, we report that deletion of the PGE2 EP2 receptor in the APPSwe-PS1DeltaE9 model of familial AD results in marked reductions in lipid peroxidation in aging mice. This reduction in oxidative stress is associated with significant decreases in levels of amyloid-beta (Abeta) 40 and 42 peptides and amyloid deposition. Aged APPSwe-PS1DeltaE9 mice lacking the EP2 receptor harbor lower levels of beta C-terminal fragments, the product of beta-site APP cleaving enzyme (BACE1) processing of amyloid precursor protein. Increases in BACE1 processing have been demonstrated in models of aging and AD and after oxidative stress. Our results indicate that PGE2 signaling via the EP2 receptor promotes age-dependent oxidative damage and increased Abeta peptide burden in this model of AD, possibly via effects on BACE1 activity. Our findings identify EP2 receptor signaling as a novel proinflammatory and proamyloidogenic pathway in this model of AD, and suggest a rationale for development of therapeutics targeting the EP2 receptor in neuroinflammatory diseases such as AD.

Novel therapeutic opportunities for Alzheimer's disease: focus on nonsteroidal anti-inflammatory drugs

Alzheimer's disease (AD) is the most common form of neurodegenerative disorder with dementia in the elderly. The AD brain pathology is characterized by deposits of amyloid-beta (Abeta) peptides and neurofibrillary tangles but also (among other aspects) by signs of a chronic inflammatory process. Epidemiological studies have shown that long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) reduces the risk of developing AD and delays its onset. Classical targets of NSAIDs include cycloxygenase, nuclear factor kappaB, and peroxisome proliferator-activated receptors. Modulation of these pathways, all of which have been implicated in AD pathogenesis, could explain the NSAID effect on AD progression. However, recent studies indicate that a subset of NSAIDs such as ibuprofen, indomethacin, and flurbiprofen may have direct Abeta-lowering properties in cell cultures as well as transgenic models of AD-like amyloidosis. A renewed interest in the old and a discovery of new pharmacological properties of these drugs are providing vital insight for future clinical trials. In this review we will summarize how the combination of traditional (anti-inflammatory) and new (anti-amyloidogenic) properties of some NSAIDs is providing unprecedented opportunities for drug discovery and could potentially result in novel therapeutic approaches for the treatment of AD.

Contribution of inflammatory processes to Alzheimer's disease: molecular mechanisms

There is compelling evidence that Alzheimer's disease (AD) amyloid-beta (Abeta) deposition is associated with a local inflammatory response, which is initiated by the activation of microglia and the recruitment of astrocytes. These cells secrete a number of cytokines and neurotoxic products that may contribute to neuronal degeneration and cell death. It has been documented that long-term intake of non-steroidal anti-inflammatory drugs (NSAIDs) decrease the risk for developing AD and delay the onset of the disease. The mechanism behind these NSAIDs is still controversial and several hypotheses have been raised, including changes in the amyloid precursor protein (APP) metabolism, in Abeta aggregation and a decrease in inflammatory mediators. Recently, it was proposed that some NSAIDs might activate the peroxisome proliferator-activated receptor-gamma (PPAR-gamma). PPAR-gamma belongs to a family of nuclear receptors that are able to regulate the transcription of pro-inflammatory molecules, such as iNOS. The activation of PPAR-gamma has been recently reported to reduce Abeta levels in cell culture and AD animal models. The implication of PPAR-gamma in the control of Abeta-induced inflammation suggests a new target for AD therapy and emphasize the contribution of neuroinflammatory mechanisms to the pathogenesis of AD.