NSAIDs and cognition in Alzheimer's disease

Mean Daily Dosage of Aspirin and the Risk of Incident Alzheimer's Dementia in Patients with Type 2 Diabetes Mellitus: A Nationwide Retrospective Cohort Study in Taiwan

Background. Type 2 diabetes mellitus patients are known to have higher risk of developing dementia while aspirin use has been shown to prevent incident dementia. This study was conducted to evaluate the potential benefits of aspirin use on dementia in patients with type 2 diabetes mellitus and identify the appropriate dosage of aspirin that provides the most benefit. Method. A Taiwan nationwide, population-based retrospective 8-year study was employed to analyze the association between the use of aspirin and incidence of dementia including Alzheimer's disease and non-Alzheimer's dementia using multivariate Cox-proportional hazards regression model and adjusting for several potential confounders. Results. Regular aspirin use in mean daily dosage of within 40 mg was associated with a decreased risk of developing incident Alzheimer's dementia in patients with type 2 diabetes mellitus (adjusted HR of 0.51 with 95% CI of 0.27-0.97, p value 0.041). Conclusion. A mean daily dosage of aspirin use within 40 mg might decrease the risk of developing Alzheimer's disease in patients with type 2 diabetes mellitus.

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.

Cytokines and cognition--the case for a head-to-toe inflammatory paradigm

The brain is not only immunologically active of its own accord, but also has complex peripheral immune interactions. Given the central role of cytokines in neuroimmmunoendocrine processes, it is hypothesized that these molecules influence cognition via diverse mechanisms. Peripheral cytokines penetrate the blood-brain barrier directly via active transport mechanisms or indirectly via vagal nerve stimulation. Peripheral administration of certain cytokines as biological response modifiers produces adverse cognitive effects in animals and humans. There is abundant evidence that inflammatory mechanisms within the central nervous system (CNS) contribute to cognitive impairment via cytokine-mediated interactions between neurons and glial cells. Cytokines mediate cellular mechanisms subserving cognition (e.g., cholinergic and dopaminergic pathways) and can modulate neuronal and glial cell function to facilitate neuronal regeneration or neurodegeneration. As such, there is a growing appreciation of the role of cytokine-mediated inflammatory processes in neurodegenerative diseases such as Alzheimer's disease and vascular dementia. Consistent with their involvement as mediators of bidirectional communication between the CNS and the peripheral immune system, cytokines play a key role in the hypothalamic-pituitary-adrenal axis activation seen in stress and depression. In addition, complex cognitive systems such as those that underlie religious beliefs, can modulate the effects of stress on the immune system. Indirect means by which peripheral or central cytokine dysregulation could affect cognition include impaired sleep regulation, micronutrient deficiency induced by appetite suppression, and an array of endocrine interactions. Given the multiple levels at which cytokines are capable of influencing cognition it is plausible that peripheral cytokine dysregulation with advancing age interacts with cognitive aging.

The Alzheimer's Disease Assessment Scale: evaluation of psychometric properties and patterns of cognitive decline in multicenter clinical trials of mild to moderate Alzheimer's disease

PURPOSE

To evaluate the psychometric properties and patterns of decline on the total score and item scores of the cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-Cog) in patients with Alzheimer Disease (AD).

METHODS

We analyzed data from 536 AD outpatients randomized to the placebo group in two identical 26-week multicenter drug trials.

RESULTS

Mean deterioration at week 26 on the ADAS-Cog total score for subjects with moderate dementia was 84% greater than that for those with milder severity ( p < 0.001). After adjusting for this effect, age ( p = 0.015) and educational level ( p = 0.01) also predicted cognitive decline. In a model, absolute change for most individual ADAS items was less than 10% of the possible change, and it was generally smaller than one-third of the standard deviation of the measure. Measurement error variability was greatest for word recognition and the "placebo" effect was greatest for word recall. Variability increased with trial duration in a model.

CONCLUSIONS

There is a relationship between baseline severity and magnitude of cognitive decline. In 6-month trials, measurement error makes a substantial contribution to the variance in ADAS-Cog change scores. Sensitivity to intervention effects will therefore depend both on the variability and magnitude of change. Such data must be considered when designing future trials to minimize measurement error variability and increase sensitivity for specific populations.

[Non-steroidal anti-inflammatory agents with selective inhibitory activity on cyclooxygenase-2. Interest and future prospects]

INTRODUCTION

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit the production of primary prostanoids by blocking the access of arachidonic acid to the active site of the cyclooxygenases (COXs). Because the prostanoids produced by COX-1 appear to play a physiological role (protection of the gastric mucosa, platelet aggregation, vascular homeostasis, maintenance of renal sodium-water balance) while those produced by COX-2 seem mainly to intervene in the inflammatory response and in certain processes associated with cell proliferation, the hypothesis has been put forward that the NSAIDs that are selective COX-2 inhibitors should theoretically be capable of maintaining NSAID therapeutic properties but also have fewer adverse side effects due to the maintenance of prostaglandin production at normal physiological levels.

CURRENT KNOWLEDGE AND KEY POINTS

The hypothesis of COX isoenzyme selectivity has led to a proposed classification for COX inhibitors: 1) COX-1 selective inhibitors (low-dosage aspirin); 2) COX non-selective inhibitors (the majority of classified NSAIDs, which when administered over the long term, e.g., in cases of rheumatoid arthritis, cause duodenal ulcers in 20% of cases and gastric hemorrhage in 1-4% of cases/year); 3) COX-2 preferential inhibitors (meloxicam and nimesulide, which have fewer gastric side effects than standard NSAIDs, but which are not risk-free at high doses); 4) COX-2 selective inhibitors (celecoxib and rofecoxib). Preliminary clinical studies have shown that COX-2 selective inhibitors are as efficient as standard NSAIDs and have fewer adverse digestive side effects, thereby confirming the interest of this proposed classification. In the UK, the aforementioned studies have led to the commercialization of rofecoxib for the treatment of pain and osteoarthritis, while celecoxib has been introduced in medical practice in the USA and other countries for the treatment of rheumatoid arthritis and osteoarthritis.

FUTURE PROSPECTS AND PROJECTS

Various epidemiological and laboratory studies have indicated that NSAIDs may be able to reduce the risk of cancer (colorectal cancer in particular) and Alzheimer's disease due to their inhibitory activity on COXs, especially COX-2. The therapeutic contribution of COX-2 specific inhibitors has to be more fully evaluated, particularly as these agents could delay the healing of duodenal ulcers and interfere with several COX-2-induced physiological functions. It is therefore suggested that until further information becomes available, this new class of NSAIDs should be used with caution in certain patient populations.

Mechanisms of cell death in Alzheimer disease--immunopathology

Lesions in such chronic neurodegenerative disorders as Alzheimer disease, Parkinson disease, the parkinsonism dementia complex of Guam and amyotrophic lateral sclerosis have associated with them a variety of proteins known to be involved in inflammatory processes. This is particularly true of Alzheimer disease where inflammatory reactions are thought to be important contributors to the neuronal loss. They include complement proteins, complement inhibitors, acute phase reactants, inflammatory cytokines, proteases and protease inhibitors. Studies of cultured human astrocytes and microglia, obtained from postmortem brain, have established that nearly all of these proteins are produced by one or another of these cell types. Human neurons also produce many inflammatory proteins and their inhibitors, creating complex interactions. Accumulations of amyloid and extracellular tangles apparently act as irritants, causing the activation of complement, the initiation of reactive changes in microglia, and the release of potentially neurotoxic products. Such products include the membrane attack complex, oxygen free radicals and excess glutamate. Twenty epidemiological studies that have been published to data indicate that populations taking antiinflammatory drugs have a significantly reduced prevalence of Alzheimer disease or a slower mental decline. One small clinical trial with indomethacin showed arrest of the disease over a 6 month period. Therapeutic intervention in key inflammatory processes holds great promise for the amelioration of Alzheimer disease and possibly other neurodegenerative disorders.

Frequently missed diagnosis in geriatric psychiatry

Older adults are an important segment of the population that has specific health care needs. Their unique biopsychosocial characteristics impact the presentation, evaluation, and management of psychiatric illnesses. This article describes how common psychiatric disorders present in an aging population. Research in this area is relatively new and much more information is still needed. Close attention should be paid to new knowledge as it emerges about this growing population.

The importance of inflammatory mechanisms in Alzheimer disease

Lesions in such chronic neurodegenerative disorders as Alzheimer disease (AD), Parkinson disease, the parkinsonism dementia complex of Guam, and amyotrophic lateral sclerosis have associated with them a variety of proteins known to be involved in inflammatory processes. This is particularly true of AD, where inflammatory reactions are thought to be important contributors to the neuronal loss. Proteins present include complement proteins, complement inhibitors, acute phase reactants, inflammatory cytokines, proteases, and protease inhibitors. Studies of cultured human astrocytes and microglia, obtained from postmortem brain, have established that nearly all of these proteins are produced by one or another of these cell types. Human neurons also produce many inflammatory proteins and their inhibitors, creating complex interactions. Accumulations of amyloid and extracellular tangles apparently act as irritants, causing the activation of complement, the initiation of reactive changes in microglia, and the release of potentially neurotoxic products. Such products include the membrane attack complex, oxygen free radicals, and excess glutamate. Twenty epidemiological studies that have been published to date indicate that populations taking antiinflammatory drugs have a significantly reduced prevalence of AD or a slower mental decline. One small clinical trial with indomethacin showed arrest of the disease over a six-month period. Therapeutic intervention in key inflammatory processes holds great promise for the amelioration of AD and possibly other neurodegenerative disorders.

Cyclooxygenases and the central nervous system

Prostaglandins (PGs) were first described in the brain by Samuelsson over 30 years ago (Samuelsson, 1964). Since then a large number of studies have shown that PGs are formed in regions of the brain and spinal cord in response to a variety of stimuli. The recent identification of two forms of cyclooxygenase (COX; Kujubu et al., 1991; Xie et al., 1991; Smith and DeWitt, 1996), both of which are expressed in the brain, along with superior tools for mapping COX distribution, has spurred a resurgence of interest in the role of PGs in the central nervous system (CNS). In this review we will describe new data in this area, focusing on the distribution and potential role of the COX isoforms in brain function and disease.