Rofecoxib: no effect on Alzheimer's disease in a 1-year, randomized, blinded, controlled study

The Cache County Study on Memory in Aging: factors affecting risk of Alzheimer's disease and its progression after onset

The Cache County Study on Memory in Aging is a longitudinal, population-based study of Alzheimer's disease (AD) and other dementias. Initiated in 1995 and extending to 2013, the study has followed over 5,000 elderly residents of Cache County, Utah (USA) for over twelve years. Achieving a 90% participation rate at enrolment, and spawning two ancillary projects, the study has contributed to the literature on genetic, psychosocial and environmental risk factors for AD, late-life cognitive decline, and the clinical progression of dementia after its onset. This paper describes the major study contributions to the literature on AD and dementia.

The amyloid cascade-inflammatory hypothesis of Alzheimer disease: implications for therapy

The amyloid cascade hypothesis is widely accepted as the centerpiece of Alzheimer disease (AD) pathogenesis. It proposes that abnormal production of beta amyloid protein (Abeta) is the cause of AD and that the neurotoxicity is due to Abeta itself or its oligomeric forms. We suggest that this, in itself, cannot be the cause of AD because demonstrating such toxicity requires micromolar concentrations of these Abeta forms, while their levels in brain are a million times lower in the picomolar range. AD probably results from the inflammatory response induced by extracellular Abeta deposits, which later become enhanced by aggregates of tau. The inflammatory response, which is driven by activated microglia, increases over time as the disease progresses. Disease-modifying therapeutic attempts to date have failed and may continue to do so as long as the central role of inflammation is not taken into account. Multiple epidemiological and animal model studies show that NSAIDs, the most widely used antiinflammatory agents, have a substantial sparing effect on AD. These studies provide a proof of concept regarding the anti-inflammatory approach to disease modification. Biomarker studies have indicated that early intervention may be necessary. They have established that disease onset occurs more than a decade before it becomes clinically evident. By combining biomarker and pathological data, it is possible to define six phases of disease development, each separated by about 5 years. Phase one can be identified by decreases in Abeta in the CSF, phase 2 by increases of tau in the CSF plus clear evidence of Abeta brain deposits by PET scanning, phase 3 by slight decreases in brain metabolic rate by PET-FDG scanning, phase 4 by slight decreases in brain volume by MRI scanning plus minimal cognitive impairment, phase 5 by increased scanning abnormalities plus clinical diagnosis of AD, and phase 6 by advanced AD requiring institutional care. Utilization of antiinflammatory agents early in the disease process remains an overlooked therapeutic opportunity. Such agents, while not preventative, have the advantage of being able to inhibit the consequences of both Abeta and tau aggregation. Since there is more than a decade between disease onset and cognitive decline, a window of opportunity exists to introduce truly effective disease-modifying regimens. Taking advantage of this opportunity is the challenge for the future.

Are inflammatory profiles the key to personalized Alzheimer's treatment?

There is currently no disease-modifying treatment for Alzheimer's disease (AD) and the need is great as the number of people diagnosed with AD is predicted to steadily increase. Inflammation is associated with AD, and is predictive of more advanced disease pathology and cognitive impairment. Moreover, preventing inflammation reduces the risk of developing AD. However, clinical trials with anti-inflammatory treatment have not been successful. One reason may be that there is diversity in the immune response and reducing immune activity with anti-inflammatories is not appropriate in all conditions. Recently, we have begun to apply categorizations, used to characterize the peripheral immune response, to the immune processes of the brain. When we do this, we are able to describe an individual's inflammatory profile within this spectrum. We have observed that patients with early AD are distributed across two broad categories of immune activation. If we recognize the diversity within this cohort of individuals with early AD and use information about immune phenotypes to guide the choice of treatment, then we may expect better clinical outcomes.

Therapeutics of Alzheimer's disease: Past, present and future

Alzheimer's disease (AD) is the most common cause of dementia worldwide. The etiology is multifactorial, and pathophysiology of the disease is complex. Data indicate an exponential rise in the number of cases of AD, emphasizing the need for developing an effective treatment. AD also imposes tremendous emotional and financial burden to the patient's family and community. The disease has been studied over a century, but acetylcholinesterase inhibitors and memantine are the only drugs currently approved for its management. These drugs provide symptomatic improvement alone but do less to modify the disease process. The extensive insight into the molecular and cellular pathomechanism in AD over the past few decades has provided us significant progress in the understanding of the disease. A number of novel strategies that seek to modify the disease process have been developed. The major developments in this direction are the amyloid and tau based therapeutics, which could hold the key to treatment of AD in the near future. Several putative drugs have been thoroughly investigated in preclinical studies, but many of them have failed to produce results in the clinical scenario; therefore it is only prudent that lessons be learnt from the past mistakes. The current rationales and targets evaluated for therapeutic benefit in AD are reviewed in this article. This article is part of the Special Issue entitled 'The Synaptic Basis of Neurodegenerative Disorders'.

Molecular links between Alzheimer's disease and diabetes mellitus

Substantial epidemiological evidence shows an increased risk for developing Alzheimer's disease (AD) in people with diabetes. Yet the underlying molecular mechanisms still remain to be elucidated. This article reviews the current studies on common pathological processes of Alzheimer's disease and diabetes with particular focus on potential mechanisms through which diabetes affects the initiation and progression of Alzheimer's disease. Impairment of insulin signaling, inflammation, oxidative stress, mitochondrial dysfunction, advanced glycation end products, APOEε4 and cholesterol appear to be important mediators and are likely to act synergistically in promoting AD pathology.

Inflammation in Alzheimer disease-a brief review of the basic science and clinical literature

Biochemical and neuropathological studies of brains from individuals with Alzheimer disease (AD) provide clear evidence for an activation of inflammatory pathways, and long-term use of anti-inflammatory drugs is linked with reduced risk to develop the disease. As cause and effect relationships between inflammation and AD are being worked out, there is a realization that some components of this complex molecular and cellular machinery are most likely promoting pathological processes leading to AD, whereas other components serve to do the opposite. The challenge will be to find ways of fine tuning inflammation to delay, prevent, or treat AD.

Results of a follow-up study to the randomized Alzheimer's Disease Anti-inflammatory Prevention Trial (ADAPT)

OBJECTIVES

The Alzheimer's Disease Anti-inflammatory Prevention Trial Follow-up Study (ADAPT-FS) was designed to evaluate the efficacy of naproxen and celecoxib for the primary prevention of Alzheimer's disease (AD) several years after cessation of treatment in ADAPT.

METHODS

ADAPT was a randomized, double-masked, multicenter clinical trial of naproxen or celecoxib vs placebo (1:1:1.5 assignment ratio) at six U.S.-based clinics. The trial enrolled 2528 people between 2001 and 2004. Treatments were discontinued in December 2004 and participants were monitored regularly until 2007. In 2010 and 2011, ADAPT-FS screened 1537 participants by telephone and, if indicated, examined them in person using standardized clinical assessments. The primary outcome was time to diagnosis of AD. Death index searches were performed for participants not located.

RESULTS

Eighty-nine additional AD events were identified (24 celecoxib, 25 naproxen, and 40 placebo) yielding a total of 161 events (48 [6.6% of randomized participants] celecoxib, 43 [6.0%] naproxen, and 70 [6.5%] placebo) across ADAPT and ADAPT-FS. Adjusted hazard ratios (HRs) comparing each treatment with placebo showed no overall reduction in risk of AD: HR celecoxib vs placebo, 1.03 (95% confidence interval [CI], 0.72-1.50; P = .86); HR naproxen vs placebo, 0.92 (95% CI, 0.62-1.35; P = .66). There were 349 deaths (110 [15.2%] celecoxib, 96 [13.4%] naproxen, and 143 [13.2%] placebo). Risk of death was similar for the naproxen- and placebo-assigned groups (HR, 0.99; 95% CI, 0.76-1.28; P = .93) and slightly higher for celecoxib compared with the placebo-assigned group (HR, 1.15; 95% CI, 0.90-1.48; P = .27).

CONCLUSIONS

These results acquired during a follow-up of approximately 7 years (which included a median of less than 1.5 years of treatment) do not support the hypothesis that celecoxib or naproxen prevent AD in adults with a family history of dementia.

The role of peripheral inflammatory markers in dementia and Alzheimer's disease: a meta-analysis

BACKGROUND

Studies that have investigated the association between markers of inflammation and risk of dementia are conflicting. Therefore, the researchers conducted a systematic review and meta-analysis of observational studies with the hypothesis that an increased level of peripheral proinflammatory markers would be associated with risk of all-cause dementia or Alzheimer's disease (AD).

METHODS

The researchers conducted a literature search of observational studies indexed in the PubMed and PsycInfo databases. Selected studies included those with at least one peripheral inflammatory biomarker and its association with risk of all-cause dementia or AD. Random effects models were used to generate pooled hazard ratios (HRs) comparing the top versus bottom quantile of inflammatory marker level. Heterogeneity was assessed using the I (2) statistic.

RESULTS

Seven studies were identified, combining for a total 5,717 participants, 746 cases of all-cause dementia and 565 cases of AD. An increased level of C-reactive protein was associated with a 45% increased risk of all-cause dementia (HR: 1.45; 95% CI: 1.10, 1.91). Similarly, a higher level of interleukin-6 was associated with a 32% increased risk (HR: 1.32; 95% CI: 1.06, 1.64) of all-cause dementia. For AD alone, the association with C-reactive protein was less pronounced (HR: 1.21; 95% CI: 1.03, 1.42) and interleukin-6 was not associated with risk of AD (HR: 1.06; 95% CI: 0.83, 1.35). No significant heterogeneity was found in any of the meta-analyses (I (2) = 0%-40%, p ≥ .16).

CONCLUSIONS

An increased peripheral level of inflammatory markers is associated with a modest increase in risk of all-cause dementia. Evidence for an association with risk of AD alone is limited.

New and emerging treatments for Alzheimer's disease

Alzheimer's disease (AD) and other dementias represent a significant and increasing clinical challenge. This review highlights current treatment options for AD and the main focusses of therapies currently being evaluated in clinical trials and for future therapeutic development. Existing treatments slow the progression of symptoms of the disease, but their efficacy does not extend to all people with AD, and benefits are not conveyed beyond an average of 6 months. Despite the substantial economic cost and healthcare burden of AD, which is increasing as populations age, there are currently only three therapies being investigated in Phase III clinical trials. This emphasises the substantial caution and underinvestment in treatment development in this area and why it is critical to address the current lack of effective treatments to target the underlying pathology and disease process in Alzheimer's disease.

Nonsteroidal anti-inflammatory drug use and the risk of cognitive impairment and Alzheimer's disease

BACKGROUND

Some observational studies have established an association between exposure to nonsteroidal anti-inflammatory drugs (NSAIDs) and a decreased risk of subsequently developing Alzheimer's disease (AD). Mild cognitive impairment or cognitive impairment, not dementia (CIND) is more likely to convert to AD, and no specific preventive method is currently available. The objective of this study was to determine the association of NSAID use in 5276 cognitively normal subjects of the Canadian Study of Health and Aging, a 10-year population-based cohort study, with the incidence of CIND, AD, and all-cause dementia.

METHODS

Hazard ratios were calculated from Cox proportional hazards models with age as the time scale according to three study samples including 824 cases of dementia (563 cases of AD), 630 cases of dementia (435 cases of AD), and 883 cases of CIND, respectively. Adjustments were made for gender, education, lifestyle factors, comorbid diseases, and vascular risk factors.

RESULTS

Lower risks for AD and all-cause dementia were significantly associated with the use of any NSAIDs and the salicylates without barbiturates subgroup in the study sample including subjects with CIND at baseline. There was a weak association between any NSAIDs and the risk of CIND (hazard ratio, 0.87; 95% confidence interval, 0.76-1.00).

CONCLUSION

These results suggest that there is an association between NSAID use and a lower incidence of AD and, to a lesser extent, of CIND.

Effects of non-steroidal anti-inflammatory drug treatments on cognitive decline vary by phase of pre-clinical Alzheimer disease: findings from the randomized controlled Alzheimer's Disease Anti-inflammatory Prevention Trial

OBJECTIVE

We examined the effects of non-steroidal anti-inflammatory drugs on cognitive decline as a function of phase of pre-clinical Alzheimer disease.

METHODS

Given recent findings that cognitive decline accelerates as clinical diagnosis is approached, we used rate of decline as a proxy for phase of pre-clinical Alzheimer disease. We fit growth mixture models of Modified Mini-Mental State (3MS) Examination trajectories with data from 2388 participants in the Alzheimer's Disease Anti-inflammatory Prevention Trial and included class-specific effects of naproxen and celecoxib.

RESULTS

We identified three classes: "no decline", "slow decline", and "fast decline", and examined the effects of celecoxib and naproxen on linear slope and rate of change by class. Inclusion of quadratic terms improved fit of the model (-2 log likelihood difference: 369.23; p < 0.001) but resulted in reversal of effects over time. Over 4 years, participants in the slow-decline class on placebo typically lost 6.6 3MS points, whereas those on naproxen lost 3.1 points (p-value for difference: 0.19). Participants in the fast-decline class on placebo typically lost 11.2 points, but those on celecoxib first declined and then gained points (p-value for difference from placebo: 0.04), whereas those on naproxen showed a typical decline of 24.9 points (p-value for difference from placebo: <0.0001).

CONCLUSIONS

Our results appeared statistically robust but provided some unexpected contrasts in effects of different treatments at different times. Naproxen may attenuate cognitive decline in slow decliners while accelerating decline in fast decliners. Celecoxib appeared to have similar effects at first but then attenuated change in fast decliners.

A review: inflammatory process in Alzheimer's disease, role of cytokines

Alzheimer's disease (AD) is the most common neurodegenerative disorder to date. Neuropathological hallmarks are β-amyloid (Aβ) plaques and neurofibrillary tangles, but the inflammatory process has a fundamental role in the pathogenesis of AD. Inflammatory components related to AD neuroinflammation include brain cells such as microglia and astrocytes, the complement system, as well as cytokines and chemokines. Cytokines play a key role in inflammatory and anti-inflammatory processes in AD. An important factor in the onset of inflammatory process is the overexpression of interleukin (IL)-1, which produces many reactions in a vicious circle that cause dysfunction and neuronal death. Other important cytokines in neuroinflammation are IL-6 and tumor necrosis factor (TNF)-α. By contrast, other cytokines such as IL-1 receptor antagonist (IL-1ra), IL-4, IL-10, and transforming growth factor (TGF)-β can suppress both proinflammatory cytokine production and their action, subsequently protecting the brain. It has been observed in epidemiological studies that treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) decreases the risk for developing AD. Unfortunately, clinical trials of NSAIDs in AD patients have not been very fruitful. Proinflammatory responses may be countered through polyphenols. Supplementation of these natural compounds may provide a new therapeutic line of approach to this brain disorder.

Who fans the flames of Alzheimer's disease brains? Misfolded tau on the crossroad of neurodegenerative and inflammatory pathways

Neurodegeneration, induced by misfolded tau protein, and neuroinflammation, driven by glial cells, represent the salient features of Alzheimer's disease (AD) and related human tauopathies. While tau neurodegeneration significantly correlates with disease progression, brain inflammation seems to be an important factor in regulating the resistance or susceptibility to AD neurodegeneration. Previously, it has been shown that there is a reciprocal relationship between the local inflammatory response and neurofibrillary lesions. Numerous independent studies have reported that inflammatory responses may contribute to the development of tau pathology and thus accelerate the course of disease. It has been shown that various cytokines can significantly affect the functional and structural properties of intracellular tau. Notwithstanding, anti-inflammatory approaches have not unequivocally demonstrated that inhibition of the brain immune response can lead to reduction of neurofibrillary lesions. On the other hand, our recent data show that misfolded tau could represent a trigger for microglial activation, suggesting the dual role of misfolded tau in the Alzheimer's disease inflammatory cascade. On the basis of current knowledge, we can conclude that misfolded tau is located at the crossroad of the neurodegenerative and neuroinflammatory pathways. Thus disease-modified tau represents an important target for potential therapeutic strategies for patients with Alzheimer's disease.

Alzheimer's disease: pathological mechanisms and the beneficial role of melatonin

Alzheimer's disease (AD) is a highly complex neurodegenerative disorder of the aged that has multiple factors which contribute to its etiology in terms of initiation and progression. This review summarizes these diverse aspects of this form of dementia. Several hypotheses, often with overlapping features, have been formulated to explain this debilitating condition. Perhaps the best-known hypothesis to explain AD is that which involves the role of the accumulation of amyloid-β peptide in the brain. Other theories that have been invoked to explain AD and summarized in this review include the cholinergic hypothesis, the role of neuroinflammation, the calcium hypothesis, the insulin resistance hypothesis, and the association of AD with peroxidation of brain lipids. In addition to summarizing each of the theories that have been used to explain the structural neural changes and the pathophysiology of AD, the potential role of melatonin in influencing each of the theoretical processes involved is discussed. Melatonin is an endogenously produced and multifunctioning molecule that could theoretically intervene at any of a number of sites to abate the changes associated with the development of AD. Production of this indoleamine diminishes with increasing age, coincident with the onset of AD. In addition to its potent antioxidant and anti-inflammatory activities, melatonin has a multitude of other functions that could assist in explaining each of the hypotheses summarized above. The intent of this review is to stimulate interest in melatonin as a potentially useful agent in attenuating and/or delaying AD.

Aspirin, steroidal and non-steroidal anti-inflammatory drugs for the treatment of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is the most common form of dementia. The incidence of AD rises exponentially with age and its prevalence will increase significantly worldwide in the next few decades. Inflammatory processes have been suspected in the pathogenesis of the disease.

OBJECTIVES

To review the efficacy and side effects of aspirin, steroidal and non-steroidal anti-inflammatory drugs (NSAIDs) in the treatment of AD, compared to placebo.

SEARCH METHODS

We searched ALOIS: the Cochrane Dementia and Cognitive Improvement Group's Specialized Register on 12 April 2011 using the terms: aspirin OR "cyclooxygenase 2 inhibitor" OR aceclofenac OR acemetacin OR betamethasone OR celecoxib OR cortisone OR deflazacort OR dexamethasone OR dexibruprofen OR dexketoprofen OR diclofenac sodium OR diflunisal OR diflusinal OR etodolac OR etoricoxib OR fenbufen OR fenoprofen OR flurbiprofen OR hydrocortisone OR ibuprofen OR indometacin OR indomethacin OR ketoprofen OR lumiracoxib OR mefenamic OR meloxicam OR methylprednisolone OR nabumetone OR naproxen OR nimesulide OR "anti-inflammatory" OR prednisone OR piroxicam OR sulindac OR tenoxicam OR tiaprofenic acid OR triamcinolone OR NSAIDS OR NSAID. ALOIS contains records of clinical trials identified from monthly searches of a number of major healthcare databases (including MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS), numerous trial registries (including national, international and pharmacuetical registries) and grey literature sources.

SELECTION CRITERIA

All randomised controlled trials assessing the efficacy of aspirin, steroidal and non-steroidal anti-inflammatory drugs in AD.

DATA COLLECTION AND ANALYSIS

One author assessed risk of bias of each study and extracted data. A second author verified data selection.

MAIN RESULTS

Our search identified 604 potentially relevant studies. Of these, 14 studies (15 interventions) were RCTs and met our inclusion criteria. The numbers of participants were 352, 138 and 1745 for aspirin, steroid and NSAIDs groups, respectively. One selected study comprised two separate interventions. Interventions assessed in these studies were grouped into four categories: aspirin (three interventions), steroids (one intervention), traditional NSAIDs (six interventions), and selective cyclooxygenase-2 (COX-2) inhibitors (five interventions). All studies were evaluated for internal validity using a risk of bias assessment tool. The risk of bias was low for five studies, high for seven studies, and unclear for two studies.There was no significant improvement in cognitive decline for aspirin, steroid, traditional NSAIDs and selective COX-2 inhibitors. Compared to controls, patients receiving aspirin experienced more bleeding while patients receiving steroid experienced more hyperglycaemia, abnormal lab results and face edema. Patients receiving NSAIDs experienced nausea, vomiting, elevated creatinine, elevated LFT and hypertension. A trend towards higher death rates was observed among patients treated with NSAIDS compared with placebo and this was somewhat higher for selective COX-2 inhibitors than for traditional NSAIDs.

AUTHORS' CONCLUSIONS

Based on the studies carried out so far, the efficacy of aspirin, steroid and NSAIDs (traditional NSAIDs and COX-2 inhibitors) is not proven. Therefore, these drugs cannot be recommended for the treatment of AD.

Gene expression profiling and therapeutic interventions in neurodegenerative diseases: a comprehensive study on potentiality and limits

INTRODUCTION

Neurodegenerative diseases are incurable debilitating disorders of the nervous system that affect approximately 30 million people worldwide. Despite profuse efforts attempting to define the molecular mechanisms underlying neurodegeneration, many aspects of these pathologies remain elusive. The novelty of their mechanisms represents a challenge to biology, to their related biomarkers identification and drug discovery. Because of their multifactorial aspects and complexity, gene expression analysis platforms have been extensively used to investigate altered pathways during degeneration and to identify potential biomarkers and drug targets.

AREAS COVERED

This work offers an overview of the gene expression profiling studies carried out on Alzheimer's disease, Huntington's disease, Parkinson's disease and prion disease specimens. Therapeutic approaches are also discussed.

EXPERT OPINION

Although many therapeutic approaches have been tested, some of them acting on several altered cellular pathways, no effective cures for these neurodegenerative diseases have been identified. Microarray technology must be associated with functional proteomics and physiology in an effort to identify specific and selective biomarkers and druggable targets, thus allowing the successful discovery of disease-modifying therapeutic treatments.

Ibuprofen attenuates oxidative damage through NOX2 inhibition in Alzheimer's disease

Considerable evidence points to important roles for inflammation in Alzheimer's disease (AD) pathophysiology. Epidemiological studies have suggested that long-term nonsteroidal anti-inflammatory drug (NSAID) therapy reduces the risk for Alzheimer's disease; however, the mechanism remains unknown. We report that a 9-month treatment of aged R1.40 mice resulted in 90% decrease in plaque burden and a similar reduction in microglial activation. Ibuprofen treatment reduced levels of lipid peroxidation, tyrosine nitration, and protein oxidation, demonstrating a dramatic effect on oxidative damage in vivo. Fibrillar β-amyloid (Aβ) stimulation has previously been demonstrated to induce the assembly and activation of the microglial nicotinamide adenine dinucleotide phosphate (NADPH) oxidase leading to superoxide production through a tyrosine kinase-based signaling cascade. Ibuprofen treatment of microglia or monocytes with racemic or S-ibuprofen inhibited Aβ-stimulated Vav tyrosine phosphorylation, NADPH oxidase assembly, and superoxide production. Interestingly, Aβ-stimulated Vav phosphorylation was not inhibited by COX inhibitors. These findings suggest that ibuprofen acts independently of cyclooxygenase COX inhibition to disrupt signaling cascades leading to microglial NADPH oxidase (NOX2) activation, preventing oxidative damage and enhancing plaque clearance in the brain.

Vitamin A and Alzheimer's disease

The deposition of amyloid β-protein (Aβ) in the brain is an invariant feature of Alzheimer's disease (AD). Vitamin A, which has been traditionally considered an anti-oxidant compound, plays a role in maintaining higher function in the central nervous system. Plasma or cerebrospinal fluid concentrations of vitamin A and β-carotene have been reported to be lower in AD patients, and these vitamins have been clinically shown to slow the progression of dementia. Vitamin A (retinol, retinal and retinoic acid) and β-carotene have been shown in in vitro studies to inhibit the formation, extension and destabilizing effects of β-amyloid fibrils. Recently, the inhibition of the oligomerization of Aβ has been suggested as a possible therapeutic target for the treatment of AD. We have recently shown the inhibitory effects of vitamin A and β-carotene on the oligomerization of Aβ40 and Aβ42 in vitro. In previous in vivo studies, intraperitoneal injections of vitamin A decreased brain Aβ deposition and tau phosphorylation in transgenic mouse models of AD, attenuated neuronal degeneration, and improved spatial learning and memory. Thus, vitamin A and β-carotene could be key molecules for the prevention and therapy of AD.

Promoting transparency in pharmaceutical industry-sponsored research

Strong, evidence-based practice requires that objective, unbiased research be available to inform individual clinical decisions, systematic reviews, meta-analyses, and expert guideline recommendations. Industry has used seeding trials, publication planning, messaging, ghostwriting, and selective publication and reporting of trial outcomes to distort the medical literature and undermine clinical trial research by obscuring information relevant to patients and physicians. Policies that promote transparency in the clinical trial research process, through improved and expanded disclosure of investigator contributions and funding, comprehensive publicly available trial registration, and independent analysis of clinical trial data analysis may address these subversive practices by improving accountability among industry and investigators. Minimizing marketing's impact on clinical trial research and strengthening the science will protect medical literature's integrity and the public's health.

Disease-modifying treatments for Alzheimer's disease

The first drugs developed for Alzheimer's disease (AD), acetylcholinesterase inhibitors (AChEI), increase acetylcholine levels, previously demonstrated to be reduced in AD. To date, four AChEI are approved for the treatment of mild-to-moderate AD. A further therapeutic option available for moderate-to-severe AD is memantine. These treatments are symptomatic, whereas drugs under development are intended to modify the pathological steps leading to AD, thus acting on the evolution of the disease. For this reason they are have been termed 'disease-modifying' drugs. To block the progression of the disease they have to interfere with the pathogenic steps responsible for the clinical symptoms, including the deposition of extracellular amyloid beta (Aβ) plaques and of intracellular neurofibrillary tangles, inflammation, oxidative damage, iron deregulation and cholesterol metabolism. In this review, new perspectives will be discussed. In particular, several approaches will be described, including interference with Aβ deposition by anti-Aβ aggregation agents, vaccination, γ-secretase inhibitors or selective Aβ-lowering agents; interference with tau deposition by methylthioninium chloride; and reduction of inflammation and oxidative damage.

Changing the course of Alzheimer's disease: anti-amyloid disease-modifying treatments on the horizon

OBJECTIVES

To review the amyloid hypothesis as the predominant mechanistic theory of Alzheimer's disease and update the status of new disease-modifying, anti-amyloid treatments in clinical development.

DATA SOURCES

Governmental Web sites and those of professional Alzheimer's disease associations and drug manufacturers were searched for new drugs in development. An English-language search of PubMed (January 2003-January 2006) was conducted using the search terms Alzheimer's disease and amyloid hypothesis and each of the drugs and immunotherapies from the 4 identified classes of anti-amyloid, disease-modifying therapies.

STUDY SELECTION AND DATA EXTRACTION

Studies and reports were selected on the basis of recent publication, adequate methodology, and completeness of data.

DATA SYNTHESIS

Immunotherapy, γ-secretase inhibitors, selective neurotoxic aggregated 42-amino acid peptide subspecies of amyloid β (Aβ₄₂)-lowering agents (tarenflurbil), inhibitors of amyloid aggregation (tramiprosate), and statins show promise in clinical trials. Safety remains an important factor. Disease-modifying drugs that specifically target the amyloid cascade and do not interact with essential biological pathways are expected to possess a lower rate of unintended adverse events.Agents that selectively target Aβ₄₂ production (e.g., tarenflurbil), block Aβ aggregation (e.g., tramiprosate), or enhance alpha-secretase activity (statins) offer hope for disease modification and prevention and do not appear to interfere with other biological pathways.

CONCLUSIONS

Discovery of safe and effective disease-modifying therapies will usher in a new age of Alzheimer's disease treatment.

Non-steroidal anti-inflammatory drugs as disease-modifying agents for Parkinson's disease: evidence from observational studies

BACKGROUND

Neuroinflammation may play a key role in the neurodegeneration associated with Parkinson's disease (PD). Non-steroidal anti-inflammatory drugs (NSAIDs) may be beneficial in the primary and secondary prevention of PD.

OBJECTIVES

1) Do NSAIDs prevent the onset of PD?2) Are NSAIDs neuroprotective in PD - do they slow the progression of disease once PD is established?3) What are the adverse effects of taking NSAIDs in PD?

SEARCH METHODS

We searched electronic databases, including trial registers, complemented with handsearching of conference proceedings and citation searching on key articles. All searching was updated in May 2011. We contacted authors to provide additional information where necessary.

SELECTION CRITERIA

For the primary prevention review, we sought primary prevention trials and observational studies (cohort and case-control studies). Participants were free of PD when exposure to NSAIDs was assessed. For the secondary prevention review, we sought clinical trials in patients with a well-defined definition of PD. Two people independently selected studies for inclusion using predetermined criteria.

DATA COLLECTION AND ANALYSIS

Two review authors abstracted data from the source papers and assessed methodological quality independently. No studies met the inclusion criteria for the secondary prevention review. For the primary prevention review only observational studies were found. We combined data where appropriate using the inverse variance method. We assessed methodological quality using the Newcastle Ottawa Scales and by examining the period of exposure assessed prior to PD onset (or the index date in controls).

MAIN RESULTS

Fourteen observational studies met the inclusion criteria for the primary prevention review (five cohort, nine case-control studies). Exposure to any NSAIDs or aspirin had no effect on the risk of developing PD. Exposure to non-aspirin NSAIDs reduced the risk of developing PD by 13% (effect estimate 0.87 (95% CI 0.73 to 1.04 - random-effects model), but this did not reach statistical significance. We found similar results for the most robust studies. Ibuprofen in isolation was examined in four studies and was associated with a 27% reduction in risk (effect estimate 0.73, 95% CI 0.63 to 0.85). There was a lack of information on adverse effects.

AUTHORS' CONCLUSIONS

There is currently no evidence for the use of NSAIDs in the secondary prevention of PD. Non-aspirin NSAIDs, particularly ibuprofen, may reduce the risk of developing PD. However, little is known of the effects of other individual drugs and at present no recommendations can be made regarding their use in primary prevention.

Non-steroidal anti-inflammatory drugs and cognitive function: are prostaglandins at the heart of cognitive impairment in dementia and delirium?

Studies of non-steroidal anti-inflammatory drugs (NSAIDs) in rheumatoid arthritis imply that inflammation is important in the development of Alzheimer’s disease (AD). However, these drugs have not alleviated the symptoms of AD in those who have already developed dementia. This suggests that the primary mediator targeted by these drugs, PGE2, is not actively suppressing memory function in AD. Amyloid-β oligomers appear to be important for the mild cognitive changes seen in AD transgenic mice, yet amyloid immunotherapy has also proven unsuccessful in clinical trials. Collectively, these findings indicate that NSAIDs may target a prodromal process in mice that has already passed in those diagnosed with AD, and that synaptic and neuronal loss are key determinants of cognitive dysfunction in AD. While the role of inflammation has not yet become clear, inflammatory processes definitely have a negative impact on cognitive function during episodes of delirium during dementia. Delirium is an acute and profound impairment of cognitive function frequently occurring in aged and demented patients exposed to systemic inflammatory insults, which is now recognised to contribute to long-term cognitive decline. Recent work in animal models is beginning to shed light on the interactions between systemic inflammation and CNS pathology in these acute exacerbations of dementia. This review will assess the role of prostaglandin synthesis in the memory impairments observed in dementia and delirium and will examine the relative contribution of amyloid, synaptic and neuronal loss. We will also discuss how understanding the role of inflammatory mediators in delirious episodes will have major implications for ameliorating the rate of decline in the demented population.

Dementia: Alzheimer pathology and vascular factors: from mutually exclusive to interaction

Alzheimer's disease (AD) is the most common type of dementia. Both its incidence and prevalence are expected to increase exponentially as populations' age worldwide. Despite impressive efforts of research worldwide, neither cure nor effective preventive strategy is available for this devastating disease. Currently there are several hypotheses on what causes AD, with the amyloid hypothesis being the most investigated and accepted hypothesis over the past 20 years. However the exact role of amyloid-β in the onset and progression of AD is not yet fully understood, and even the validity of the amyloid hypothesis itself is still being discussed. This debate is fuelled by the vascular hypothesis, as increasing epidemiological, neuroimaging, pathological, pharmacotherapeutic and clinical studies suggest that vascular pathology plays a key role in the onset and progression of AD. We here will discuss arguments in favor and limitations of both hypotheses within the framework of available literature, but also provide arguments for convergence of both hypotheses. Finally we propose approaches that may aid in unraveling the etiology and treatment of AD. This article is part of a Special Issue entitled: Imaging Brain Aging and Neurodegenerative disease.

Progress in Alzheimer's disease

After more than one century from Alois Alzheimer and Gaetano Perusini's first report, progress has been made in understanding the pathogenic steps of Alzheimer's disease (AD), as well as in its early diagnosis. This review discusses recent findings leading to the formulation of novel criteria for diagnosis of the disease even in a preclinical phase, by using biological markers. In addition, treatment options will be discussed, with emphasis on new disease-modifying compounds and future trial design suitable to test these drugs in an early phase of the disease.

A comparative study of curcuminoids to measure their effect on inflammatory and apoptotic gene expression in an Aβ plus ibotenic acid-infused rat model of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder, which depicts features of chronic inflammatory conditions resulting in cellular death and has limited therapeutic options. We aimed to explore the effect of a curcuminoid mixture and its individual components on inflammatory and apoptotic genes expression in AD using an Aβ+ibotenic acid-infused rat model. After 5 days of treatment with demethoxycurcumin, hippocampal IL-1β levels were decreased to 118.54 ± 47.48 and 136.67 ± 31.96% respectively at 30 and 10mg/kg, compared with the amyloid treated group (373.99 ± 15.28%). After 5 days of treatment, the curcuminoid mixture and demethoxycurcumin effectively decreased GFAP levels in the hippocampus. When studied for their effect on apoptotic genes expression, the curcuminoid mixture and bisdemethoxycurcumin effectively decreased caspase-3 level in the hippocampus after 20 days of treatment, where bisdemethoxycurcumin showed a maximal rescuing effect (92.35 ± 3.07%) at 3mg/kg. The curcuminoid mixture at 30 mg/kg decreased hippocampal FasL level to 70.56 ± 3.36% after 5 days of treatment and 19.01 ± 2.03% after 20 days. In the case of Fas receptor levels, demethoxycurcumin decreased levels after 5 days of treatment with all three doses showing a maximal effect (189.76 ± 15.01%) at 10mg/kg. Each compound was effective after 20 days in reducing Fas receptor levels in the hippocampus. This study revealed the important effect of curcuminoids on genes expression, showing that, each component of the curcuminoid mixture distinctly affects gene expression, thus highlighting the therapeutic potential of curcuminoids in AD.

Microglia activation mediates fibrillar amyloid-β toxicity in the aged primate cortex

The amyloid-β peptide (Aβ) plays a central role in the pathogenesis of Alzheimer's disease (AD). The fibrillar form of Aβ (fAβ) exerts toxic effects on neurons through mechanisms not well understood. We have shown that the aged primate cortex is selectively vulnerable to fAβ toxicity at low concentrations. In addition to neuronal loss, fAβ induced massive activation of microglia in the aged rhesus cortex. We now demonstrate that inhibition of microglia activation abolishes fAβ toxicity. Injection or pump delivery of macrophage/microglia inhibitory factor (MIF) significantly reduced activation of microglia and the volume of damage caused by fAβ. Microglia isolated from aged rhesus cortex produced substantial reactive oxygen species when stimulated by fAβ, which was inhibited by MIF in a dose-dependent manner. This is the first definitive in vivo demonstration that the fAβ-induced microglia activation and inflammation mediate, at least in part, its toxic effects on neurons. Combined with our earlier observations, these findings suggest that aged primate microglia may display an exaggerated inflammatory response to fAβ when compared with young microglia.

Age-related differences in white matter integrity and cognitive function are related to APOE status

While an extensive literature is now available on age-related differences in white matter integrity measured by diffusion MRI, relatively little is known about the relationships between diffusion and cognitive functions in older adults. Even less is known about whether these relationships are influenced by the apolipoprotein (APOE) ε4 allele, despite growing evidence that ε4 increases cognitive impairment in older adults. The purpose of the present study was to examine these relationships in a group of community-dwelling cognitively normal older adults. Data were obtained from a sample of 126 individuals (ages 52-92) that included 32 ε4 heterozygotes, 6 ε4 homozygotes, and 88 noncarriers. Two measures of diffusion, the apparent diffusion coefficient (ADC) and fractional anisotropy (FA), were obtained from six brain regions-frontal white matter, lateral parietal white matter, the centrum semiovale, the genu and splenium of the corpus callosum, and the temporal stem white matter-and were used to predict composite scores of cognitive function in two domains, executive function and memory function. Results indicated that ADC and FA differed with increasing age in all six brain regions, and these differences were significantly greater for ε4 carriers compared to noncarriers. Importantly, after controlling for age, diffusion measures predicted cognitive function in a region-specific way that was also influenced by ε4 status. Regardless of APOE status, frontal ADC and FA independently predicted executive function scores for all participants, while temporal lobe ADC additionally predicted executive function for ε4 carriers but not noncarriers. Memory scores were predicted by temporal lobe ADC but not frontal diffusion for all participants, and this relationship was significantly stronger in ε4 carriers compared to noncarriers. Taken together, age and temporal lobe ADC accounted for a striking 53% of the variance in memory scores within the ε4 carrier group. The results provide further evidence that APOE ε4 has a significant impact on the trajectory of age-related cognitive functioning in older adults. Possible mechanisms are discussed that could account for the associations between ε4, diffusion, and cognitive function, including the influence of ε4 on neural repair, oxidative stress, and the health of myelin-producing oligodendroglia.

Frontiers in Alzheimer's disease therapeutics

Alzheimer disease (AD) is a progressive neurodegenerative disease which begins with insidious deterioration of higher cognition and progresses to severe dementia. Clinical symptoms typically involve impairment of memory and at least one other cognitive domain. Because of the exponential increase in the incidence of AD with age, the aging population across the world has seen a congruous increase AD, emphasizing the importance of disease altering therapy. Current therapeutics on the market, including cholinesterase inhibitors and N-methyl-D-aspartate receptor antagonists, provide symptomatic relief but do not alter progression of the disease. Therefore, progress in the areas of prevention and disease modification may be of critical interest. In this review, we summarize novel AD therapeutics that are currently being explored, and also mechanisms of action of specific drugs within the context of current knowledge of AD pathologic pathways.

Progress in the development of new drugs in Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disease with a global prevalence estimated at 26.55 million in 2006. During the past decades, several agents have been approved that enhance cognition of AD patients. However, the effectiveness of these treatments are limited or controversial and they do not modify disease progression. Recent advances in understanding AD pathogenesis have led to the development of numerous compounds that might modify the disease process. AD is mainly characterized neuropathologically by the presence of two kinds of protein aggregates: extracellular plaques of Abeta-peptide and intracellular neurofibrillary tangles. Abeta and tau could interfere in an original way contributing to a cascade of events leading to neuronal death and transmitter deficits. Investigation for novel therapeutic approaches targeting the presumed underlying pathogenic mechanisms is major focus of research. Antiamyloid agents targeting production, accumulation, clearance, or toxicity associated with Abeta peptide, are some approaches under investigation to limit extracellular plaques of Abeta-peptide accumulation. We can state as an example: Abeta passive and active immunization, secretases modulation, Abeta degradation enhancement, or antiaggregation and antifibrillization agents. Tau-related therapies are also under clinical investigation but few compounds are available. Another alternative approach under development is neuroprotective agents such as antioxidants, anti-inflammatory drugs, compounds acting against glutamate mediated neurotoxicity. Neurorestorative approaches through neurotrophin or cell therapy also represent a minor avenue in AD research. Finally, statins, receptor for advanced glycation end products inhibitors, thiazolidinediones, insulin, and hormonal therapies are some other ways of research for a therapeutic approach of Alzheimer's disease. Taking into account AD complexity, it becomes clear that polypharmacology with drugs targeting different sites could be the future treatment approach and a majority of the recent drugs under evaluation seems to act on multiple targets. This article exposes general classes of disease-modifying therapies under investigation.

Inflammation and gliosis in neurological diseases--clinical implications

The inflammatory reaction accompany all acute processes in the central nervous system (CNS), (as stroke or traumatic brain injury) and chronic neurodegenerative processes (as Parkinson's or Alzheimer's disease), and through the stage of cleaning of damage tissue, contribute to recovery and regeneration and eventually to restoration of the function. However many studies showed that inflammation in the CNS may be harmful because of an excessive vulnerability of the nervous tissue or impaired regulation. Manipulation of the inflammation is now one of the approaches in the treatment of the various diseases of the CNS.

Does administration of non-steroidal anti-inflammatory drug determine morphological changes in adrenal cortex: ultrastructural studies

Rofecoxib (Vioxx© made by Merck Sharp & Dohme, the USA) is a non-steroidal anti-inflammatory drug which belongs to the group of selective inhibitors of cyclooxygenasis-2, i.e., coxibs. Rofecoxib was first registered in the USA, in May 1999. Since then the drug was received by millions of patients. Drugs of this group were expected to exhibit increased therapeutic action. Additionally, there were expectations concerning possibilities of their application, at least as auxiliary drugs, in neoplastic therapy due to intensifying of apoptosis. In connection with the withdrawal of Vioxx© (rofecoxib) from pharmaceutical market, attempts were made to conduct electron-microscopic evaluation of cortical part of the adrenal gland in preparations obtained from animals under influence of the drug. Every morning animals from the experimental group (15 rats) received rofecoxib (suspension in physiological saline)--non-steroidal anti-inflammatory drug (Vioxx©, Merck Sharp and Dohme, the USA), through an intragastric tube in the dose of 1.25 mg during 8 weeks. In the evaluated material, there was found a greater number of secretory vacuoles and large, containing cholesterol and other lipids as well as generated glucocorticoids, lipid drops in cytoplasm containing prominent endoplasmic reticulum. There were also found cells with cytoplasm of smaller density--especially in apical and basal parts of cells. Mitochondria occasionally demonstrated features of delicate swelling. The observed changes, which occurred on cellular level with application of large doses of the drug, result from mobilization of adaptation mechanisms of the organism.

How does diabetes accelerate Alzheimer disease pathology?

Diabetes and Alzheimer disease (AD)-two age-related diseases-are both increasing in prevalence, and numerous studies have demonstrated that patients with diabetes have an increased risk of developing AD compared with healthy individuals. The underlying biological mechanisms that link the development of diabetes with AD are not fully understood. Abnormal protein processing, abnormalities in insulin signaling, dysregulated glucose metabolism, oxidative stress, the formation of advanced glycation end products, and the activation of inflammatory pathways are features common to both diseases. Hypercholesterolemia is another factor that has received attention, owing to its potential association with diabetes and AD. This Review summarizes the mechanistic pathways that might link diabetes and AD. An understanding of this complex interaction is necessary for the development of novel drug therapies and lifestyle guidelines aimed at the treatment and/or prevention of these diseases.

NSAIDs may protect against age-related brain atrophy

The use of non-steroidal anti-inflammatory drugs (NSAIDs) in humans is associated with brain differences including decreased number of activated microglia. In animals, NSAIDs are associated with reduced microglia, decreased amyloid burden, and neuronal preservation. Several studies suggest NSAIDs protect brain regions affected in the earliest stages of AD, including hippocampal and parahippocampal regions. In this cross-sectional study, we examined the protective effect of NSAID use on gray matter volume in a group of middle-aged and older NSAID users (n = 25) compared to non-user controls (n = 50). All participants underwent neuropsychological testing and T1-weighted magnetic resonance imaging. Non-user controls showed smaller volume in portions of the left hippocampus compared to NSAID users. Age-related loss of volume differed between groups, with controls showing greater medial temporal lobe volume loss with age compared to NSAID users. These results should be considered preliminary, but support previous reports that NSAIDs may modulate age-related loss of brain volume.

Nonsteroidal anti-inflammatory drugs are associated with increased neuritic plaques

OBJECTIVES

Observational and experimental studies suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) may protect against Alzheimer disease (AD); however, clinical trials and other observational studies, including the Adult Changes in Thought (ACT) study, show no protection or promotion of AD. The objective of this study is to determine the relationship between common dementia-associated pathologies and mid- to late-life NSAID exposure.

METHODS

We examined the association of mid- to late-life NSAID use with neuropathologic findings on 257 autopsies from ACT, a population-based study of brain aging and incident dementia. Cumulative standard daily doses (SDD) of nonselective NSAIDs were determined from ≥10 years of computerized pharmacy dispensing data. Analyses were adjusted for selection bias to broaden generalizability of results to 3,026 eligible participants in the ACT cohort. Seven pathologic indices were evaluated: intermediate or frequent score for neuritic plaques, Braak stages V or VI for neurofibrillary tangles, >2 cerebral microinfarcts, the presence of any neocortical Lewy bodies, any macroscopic infarcts, any amyloid angiopathy, and moderate or severe atherosclerosis.

RESULTS

Of the neuropathologic indices evaluated, only neuritic plaque score was significantly increased in participants with greater use of nonselective NSAIDs (p = 0.065), specifically in those with high levels of cumulative use: 1,000-2,000 SDD (adjusted relative risk [RR] 2.16, 95% confidence interval [CI] 1.02-4.25, compared to light/nonuse [<60 SDD]) and >2,000 SDD (adjusted RR 2.37, 95% CI 1.24-4.67).

CONCLUSIONS

Increased neuritic plaque accumulation may explain the association between heavy use of nonselective NSAIDs and increased risk of dementia among ACT participants.

Adaptive immune regulation of glial homeostasis as an immunization strategy for neurodegenerative diseases

Neurodegenerative diseases, notably Alzheimer's and Parkinson's diseases, are amongst the most devastating disorders afflicting the elderly. Currently, no curative treatments or treatments that interdict disease progression exist. Over the past decade, immunization strategies have been proposed to combat disease progression. Such strategies induce humoral immune responses against misfolded protein aggregates to facilitate their clearance. Robust adaptive immunity against misfolded proteins, however, accelerates disease progression, precipitated by induced effector T cell responses that lead to encephalitis and neuronal death. Since then, mechanisms that attenuate such adaptive neurotoxic immune responses have been sought. We propose that shifting the balance between effector and regulatory T cell activity can attenuate neurotoxic inflammatory events. This review summarizes advances in immune regulation to achieve a homeostatic glial response for therapeutic gain. Promising new ways to optimize immunization schemes and measure their clinical efficacy are also discussed.

Neuroinflammatory processes in Alzheimer's disease

Generation of neurotoxic amyloid beta peptides and their deposition along with neurofibrillary tangle formation represent key pathological hallmarks in Alzheimer's disease (AD). Recent evidence suggests that inflammation may be a third important component which, once initiated in response to neurodegeneration or dysfunction, may actively contribute to disease progression and chronicity. Various neuroinflammatory mediators including complement activators and inhibitors, chemokines, cytokines, radical oxygen species and inflammatory enzyme systems are expressed and released by microglia, astrocytes and neurons in the AD brain. Degeneration of aminergic brain stem nuclei including the locus ceruleus and the nucleus basalis of Meynert may facilitate the occurrence of inflammation in their projection areas given the antiinflammatory and neuroprotective action of their key transmitters norepinephrine and acetylcholine. While inflammation has been thought to arise secondary to degeneration, recent experiments demonstrated that inflammatory mediators may stimulate amyloid precursor protein processing by various means and therefore can establish a vicious cycle. Despite the fact that some aspects of inflammation may even be protective for bystander neurons, antiinflammatory treatment strategies should therefore be considered. Non-steroidal anti-inflammatory drugs have been shown to reduce the risk and delay the onset to develop AD. While, the precise molecular mechanism underlying this effect is still unknown, a number of possible mechanisms including cyclooxygenase 2 or gamma-secretase inhibition and activation of the peroxisome proliferator activated receptor gamma may alone or, more likely, in concert account for the epidemiologically observed protection.

Neuroinflammation, microglia and implications for anti-inflammatory treatment in Alzheimer's disease

Neuroinflammation has been implicated in the pathology of Alzheimer's disease (AD) for decades. Still it has not been fully understood when and how inflammation arises in the course of AD. Whether inflammation is an underling cause or a resulting condition in AD remains unresolved. Mounting evidence indicates that microglial activation contributes to neuronal damage in neurodegenerative diseases. However, also beneficial aspects of microglial activation have been identified. The purpose of this review is to highlight new insights into the detrimental and beneficial role of neuroinflammation in AD. It is our intention to focus on newer controversies in the field of microglia activation. Precisely, we want to shed light on whether neuroinflammation is associated to brain tissue damage and functional impairment or is there also a damage limiting activity. In regard to this, we discuss the limitations and the advantages of anti-inflammatory treatment options and identify what future implications might result from this underling neuroinflammation for AD therapy.

Non-Steroidal Anti-Inflammatory Drugs in Alzheimer's Disease and Parkinson's Disease: Reconsidering the Role of Neuroinflammation

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative diseases with age as the greatest risk factor. As the general population experiences extended life span, preparation for the prevention and treatment of these and other age-associated neurological diseases are warranted. Since epidemiological studies suggested that non-steroidal anti-inflammatory drug (NSAID) use decreased risk for AD and PD, increasing attention has been devoted to understanding the costs and benefits of the innate neuroinflammatory response to functional recovery following pathology onset. This review will provide a general overview on the role of neuroinflammation in these neurodegenerative diseases and an update on NSAID treatment in recent experimental animal models, epidemiological analyses, and clinical trials.

Microsomal prostaglandin E synthase-2: cellular distribution and expression in Alzheimer's disease

Nonsteroidal anti-inflammatory drugs, such as cyclooxygenase (COX)-2 inhibitors, have been unsuccessful in slowing or reversing Alzheimer's disease (AD). Thus, understanding the expression patterns of the downstream effectors for the regulation of prostaglandin synthesis may be important for understanding the pathological processes involved in AD and formulating more effective pharmacotherapeutics for this disease. In this study, we used immunofluorescence, immunohistochemistry, and Western blot analysis to compare patterns of microsomal prostaglandin E synthase (mPGES)-2 expression in the middle frontal gyrus (MFG) of AD patients and age-matched controls. In control human brain sections, mPGES-2 immunoreactivity was observed in neurons, activated microglia, and endothelium, but not in resting microglia, astrocytes, or smooth muscle cells. Microsomal PGES-2 immunoreactivity was particularly elevated in the pyramidal neurons of brains from three of five sporadic and four of five familial AD patients compared with four of five age-matched control brains that showed minimal immunoreactivity. In contrast, Western blot analysis revealed no difference in mPGES-2 levels between end-stage AD brain tissue and control brain tissue. These results suggest that in human cortex, mPGES-2 is constitutive in neurons and endothelium and induced in activated microglia. Furthermore, the high immunoreactivity of mPGES-2 in pyramidal neurons of AD brains indicates that it might have a potential role in the functional replacement of cytosolic PGES or inactive mPGES-1 in later stages of AD.

Are NSAIDs useful to treat Alzheimer's disease or mild cognitive impairment?

Several epidemiological studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) may protect subjects carrying one or more ε4 allele of the apolipoprotein E (APOE ε4) against the onset of Alzheimer's disease (AD). The biological mechanism of this protection is not completely understood and may involve the anti-inflammatory properties of NSAIDs or their ability of interfering with the β-amyloid (Aβ) cascade. Unfortunately, long-term, placebo-controlled clinical trials with both non-selective and cyclooxygenase-2 (COX-2) selective inhibitors in mild-to-moderate AD patients produced negative results. A secondary prevention study with rofecoxib, a COX-2 selective inhibitor, in patients with mild cognitive impairment was also negative. A primary prevention study (ADAPT trial) of naproxen (a non-selective COX inhibitor) and celecoxib (a COX-2 selective inhibitor) in cognitively normal elderly subjects with a family history of AD was prematurely interrupted for safety reasons after a median period of treatment of 2 years. Although both drugs did not reduce the incidence of dementia after 2 years of treatment, a 4-year follow-up assessment surprisingly revealed that subjects previously exposed to naproxen were protected from the onset of AD by 67% compared to placebo. Thus, it could be hypothesized that the chronic use of NSAIDs may be beneficial only in the very early stages of the AD process in coincidence of initial Aβ deposition, microglia activation and consequent release of pro-inflammatory mediators. When the Aβ deposition process is already started, NSAIDs are no longer effective and may even be detrimental because of their inhibitory activity on chronically activated microglia that on long-term may mediate Aβ clearance. The research community should conduct long-term trials with NSAIDs in cognitively normal APOE ε4 carriers.