Treating the full spectrum of dementia with memantine

Neurotransmitter release progressively desynchronizes in induced human neurons during synapse maturation and aging

Rapid release of neurotransmitters in synchrony with action potentials is considered a key hardwired property of synapses. Here, in glutamatergic synapses formed between induced human neurons, we show that action potential-dependent neurotransmitter release becomes progressively desynchronized as synapses mature and age. In this solely excitatory network, the emergence of NMDAR-mediated transmission elicits endoplasmic reticulum (ER) stress leading to downregulation of key presynaptic molecules, synaptotagmin-1 and cysteine string protein α, that synchronize neurotransmitter release. The emergence of asynchronous release with neuronal maturity and subsequent aging is maintained by the high-affinity Ca2+ sensor synaptotagmin-7 and suppressed by the introduction of GABAergic transmission into the network, inhibition of NMDARs, and ER stress. These results suggest that long-term disruption of excitation-inhibition balance affects the synchrony of excitatory neurotransmission in human synapses.

Current management decisions in mild cognitive impairment

Efforts toward early detection of Alzheimer disease (AD) have focused on refinement and identification of diagnostic markers, with the goal of preventing or delaying disease progression. Mild cognitive impairment (MCI) has emerged as a potential precursor to dementia. Though not without controversy, MCI has been associated with an increased risk for conversion to AD. In this article, with emphasis on meta-analyses, randomized controlled trials, and extant literature reviews, considerations and recommendations for optimal clinical management of MCI are offered. Given the substantial heterogeneity of this patient population and inconsistent research methodologies, the need for informed, clinical judgment is critical.

Treatment practices of mild cognitive impairment in California Alzheimer's Disease Centers

OBJECTIVES

To examine "real world" treatments for patients with mild cognitive impairment (MCI).

DESIGN

Cross-sectional.

SETTING

California Department of Public Health Alzheimer's Disease (AD) Research Centers of California.

PARTICIPANTS

Five hundred seventy-eight patients diagnosed with MCI.

MEASUREMENTS

All patients underwent comprehensive neurological and neuropsychological evaluations. Logistic regression models were used to determine patient characteristics associated with use of anti-AD medications, statins, antioxidants, and folic acid.

RESULTS

One hundred sixty-six patients (28.7%) were taking anti-AD medications; use was associated with greater functional impairment, higher education, MCI subtype, and older age (P<.05 for all). Two hundred fifty-two patients (43.6%) were taking statins; use was associated with diabetes mellitus, hypertension, myocardial infarct, male sex, and MCI subtype (P<.05 for all). One hundred fifteen patients (19.9%) were taking antioxidants; use was associated with higher education and diabetes mellitus and varied according to site (P<.05 for all). Thirty-seven patients (6.4%) were taking folic acid; use was associated with nonwhite race, male sex, and greater functional impairment (P<.05 for all).

CONCLUSION

This study suggests that patients with MCI are frequently being treated with "off label" cholinesterase inhibitors and memantine, as well as other possible cognition-enhancing drugs. Further investigation of the effect of treatment patterns on the clinical course of MCI is needed.

Oxidative stress and neurodegenerative diseases: a review of upstream and downstream antioxidant therapeutic options

Free radicals are common outcome of normal aerobic cellular metabolism. In-built antioxidant system of body plays its decisive role in prevention of any loss due to free radicals. However, imbalanced defense mechanism of antioxidants, overproduction or incorporation of free radicals from environment to living system leads to serious penalty leading to neuro-degeneration. Neural cells suffer functional or sensory loss in neurodegenerative diseases. Apart from several other environmental or genetic factors, oxidative stress (OS) leading to free radical attack on neural cells contributes calamitous role to neuro-degeneration. Though, oxygen is imperative for life, imbalanced metabolism and excess reactive oxygen species (ROS) generation end into a range of disorders such as Alzheimer's disease, Parkinson's disease, aging and many other neural disorders. Toxicity of free radicals contributes to proteins and DNA injury, inflammation, tissue damage and subsequent cellular apoptosis. Antioxidants are now being looked upon as persuasive therapeutic against solemn neuronal loss, as they have capability to combat by neutralizing free radicals. Diet is major source of antioxidants, as well as medicinal herbs are catching attention to be commercial source of antioxidants at present. Recognition of upstream and downstream antioxidant therapy to oxidative stress has been proved an effective tool in alteration of any neuronal damage as well as free radical scavenging. Antioxidants have a wide scope to sequester metal ions involved in neuronal plaque formation to prevent oxidative stress. In addition, antioxidant therapy is vital in scavenging free radicals and ROS preventing neuronal degeneration in post-oxidative stress scenario.

Delivery of peptide and protein drugs over the blood-brain barrier

Peptide and protein (P/P) drugs have been identified as showing great promises for the treatment of various neurodegenerative diseases. A major challenge in this regard, however, is the delivery of P/P drugs over the blood-brain barrier (BBB). Intense research over the last 25 years has enabled a better understanding of the cellular and molecular transport mechanisms at the BBB, and several strategies for enhanced P/P drug delivery over the BBB have been developed and tested in preclinical and clinical-experimental research. Among them, technology-based approaches (comprising functionalized nanocarriers and liposomes) and pharmacological strategies (such as the use of carrier systems and chimeric peptide technology) appear to be the most promising ones. This review combines a comprehensive overview on the current understanding of the transport mechanisms at the BBB with promising selected strategies published so far that can be applied to facilitate enhanced P/P drug delivery over the BBB.

Added therapeutic value of memantine in the treatment of moderate to severe Alzheimer's disease

When evaluating the added therapeutic value of a drug, evidence of greater overall benefit or at least an add-on benefit is increasingly being required. Therefore, cost-effectiveness in addition to clinical efficacy is an important consideration. The efficacy of a drug must be examined on the basis of clinical trials by measuring specific parameters that are affected by the drug (for example blood pressure with antihypertensive treatment). Today not only efficacy but also patient-relevant changes (patient benefits) must be demonstrated for a drug, often by measuring quality of life. In order to evaluate the benefit of monotherapy with the N-methyl-D-aspartate antagonist memantine in the management of moderate to severe Alzheimer's disease, a systematic literature review was conducted. The results showed a benefit for memantine in comparison with placebo in terms of a decrease in nursing care, a delay in care dependency and a delay in admission to nursing homes. In addition, an increase in quality of life has been observed.

Memantine: a review of its use in Alzheimer's disease

Memantine (Ebixa, Axura, Namenda, Akatinol) is a moderate-affinity, uncompetitive, voltage-dependent, NMDA-receptor antagonist with fast on/off kinetics that inhibits excessive calcium influx induced by chronic overstimulation of the NMDA receptor. Memantine is approved in the US and the EU for the treatment of patients with moderate to severe dementia of the Alzheimer's type. In well designed clinical trials, oral memantine, as monotherapy or in addition to a stable dose of acetylcholinesterase inhibitors, was well tolerated during the treatment of mild to severe Alzheimer's disease for up to 52 weeks. Memantine generally modified the progressive symptomatic decline in global status, cognition, function and behaviour exhibited by patients with moderate to severe Alzheimer's disease in four 12- to 28-week trials. In patients with mild to moderate Alzheimer's disease, data from three 24-week trials are equivocal, although meta-analyses indicate beneficial effects on global status and cognition. Memantine is an effective pharmacotherapeutic agent, and currently the only approved option, for the treatment of moderate to severe Alzheimer's disease.

La lunga attesa: towards a molecular approach to neuroimaging and therapeutics in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are Aβ amyloid plaques, neurofibrillary tangles (NFT), synaptic loss and reactive gliosis. Current diagnosis of AD is made by clinical, neuropsychologic, and neuroimaging assessments. Routine structural neuroimaging evaluation with computed tomography (CT) and magnetic resonance imaging (MRI) is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of AD. Functional neuroimaging techniques such as functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET) and single photon emission computed tomography (SPECT), possibly in conjuction with other related Aβ biomarkers in plasma and CSF, could prove to be valuable in the differential diagnosis of AD, as well as in assessing prognosis. With the advent of new therapeutic strategies aimed at reducing the Aβ amyloid burden in the brain, there is increasing interest in the development of MRI contrast agents and PET and SPECT radioligands that will permit the assessment of Aβ amyloid burden in vivo. - ma dov'è / la lenta processione di stagioni / che fu un'alba infinita e senza strade, / dov'è la lunga attesa e qual è il nome / del vuoto che ci invade. - Eugenio Montale.

Current concepts in therapeutic strategies targeting cognitive decline and disease modification in Alzheimer's disease

Alzheimer's disease is a progressive neurodegenerative disorder and the leading cause of dementia in the Western world. Postmortem, it is characterized neuropathologically by the presence of amyloid plaques, neurofibrillary tangles, and a profound gray matter loss. Neurofibrillary tangles are composed of an abnormally hyperphosphorylated intracellular protein called tau, tightly wound into paired helical filaments and thought to impact microtubule assembly and protein trafficking, resulting in the eventual demise of neuronal viability. The extracellular amyloid plaque deposits are composed of a proteinacious core of insoluble aggregated amyloid-beta (Abeta) peptide and have led to the foundation of the amyloid hypothesis. This hypothesis postulates that Abeta is one of the principal causative factors of neuronal death in the brains of Alzheimer's patients. With multiple drugs now moving through clinical development for the treatment of Alzheimer's disease, we will review current and future treatment strategies aimed at improving both the cognitive deficits associated with the disease, as well as more novel approaches that may potentially slow or halt the deadly neurodegenerative progression of the disease.

Cognitive function in adult cardiothoracic transplant candidates and recipients

Innovative surgical and medical techniques have prolonged the life span of cardiothoracic (CT) transplant recipients and made transplantation an option for many older patients. Cognitive function is a key determinant of the CT transplant recipient's ability to manage the complex treatment regimen and experience optimum benefit of the procedure. As the CT population ages, risk of cognitive dysfunction due to normal aging is compounded by the physical and mental changes associated with end-stage organ disease, comorbid conditions, and transplant-related complications. Cognitive abilities consist of (a) receptive functions (ability to select, acquire, classify, and integrate information); (b) memory and learning (ability to store and retrieve information); (c) thinking (ability to mentally organize and reorganize information; and (d) expressive functions (ability to communicate or act upon information). Although each of these functions represents a distinct type of behavior, they are interdependent. The purpose of this article is to (a) discuss the literature regarding cognitive function before and after adult heart, lung, and heart-lung transplantation; (b) identify methodological problems associated with the studies done to date; and (c) make recommendations for future research in this area.

Prevalence, resource utilization and costs of vascular dementia compared to Alzheimer's dementia in a population setting

OBJECTIVES

To determine the prevalence of dementia and to measure the monetary impact and health resources utilization of vascular dementia (VD) compared to Alzheimer's dementia (AD) in persons aged over 64 years in a population setting.

METHODS

Retrospective, cross-sectional study. In the initial phase, information was obtained on specific clinical characteristics from the subjects with an active diagnosis of dementia. The second phase consisted of a clinical evaluation and validation of the cases. Mini-Mental State Examination was used to assess cognitive impairment. Dementia and its subtypes were determined using established diagnostic criteria. Information was obtained on the use of health care resources (direct costs) and the number of hours devoted by the primary caregiver (indirect costs) for patients with a documented diagnosis of AD or VD within the last 6 months prior to the interview. A multiple logistic regression analysis was performed to correct the model.

RESULTS

A total of 6,004 subjects were analyzed, 258 with diagnosis of dementia (overall prevalence: 4.3%). An evaluation was made of 224 patients, and gross prevalence of AD and VD was 2.4 and 1.0%, respectively. Cost per patient per semester was EUR 8,086 for AD and EUR 11,039 for VD (p = 0.016). 85.5% of the cost was attributable to primary caregiver time in AD and 84.4% in VD.

CONCLUSIONS

The prevalence of AD and VD increases with age. No sociodemographic differences were seen between AD and VD. Costs associated with health care resource and primary caregiver utilization were high, being higher in VD than in AD.

Neurodegenerative diseases and oxidative stress

Oxidative stress has been implicated in the progression of Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Oxygen is vital for life but is also potentially dangerous, and a complex system of checks and balances exists for utilizing this essential element. Oxidative stress is the result of an imbalance in pro-oxidant/antioxidant homeostasis that leads to the generation of toxic reactive oxygen species. The systems in place to cope with the biochemistry of oxygen are complex, and many questions about the mechanisms of oxygen regulation remain unanswered. However, this same complexity provides a number of therapeutic targets, and different strategies, including novel metal-protein attenuating compounds, aimed at a variety of targets have shown promise in clinical studies.