Milacemide: a placebo-controlled study in senile dementia of the Alzheimer type

MAO-B inhibitors: multiple roles in the therapy of neurodegenerative disorders?

Monoamine oxidases play a central role in catecholamine catabolism in the central nervous system. The biochemical and pharmacological properties of inhibitors of the monoamine oxidase type B are reviewed. The evidence for biochemical activities distinct from their ability to inhibit MAO-B is discussed, including possible antioxidative and antiapoptotic activities of these agents. The significance of these properties for the pharmacological management of Parkinson's disease and the evidence for a neuroprotective effect of one such agent (selegiline) is also discussed.

Therapeutic approaches to age-associated neurocognitive disorders

The United Nations projects that the number of individuals with dementia in developed countries alone will be approximately 36,7 million by the year 2050. International recognition of the significant emotional and economic burden of Alzheimer's disease has been matched by a dramatic increase in the development of pharmacological and nonpharmacological approaches to this illness in the past decade. Changing demographics have underscored the necessity to develop similar approaches for the remediation of the cognitive impairment associated with more benign syndromes, such as mild cognitive impairment (MCI) and age-associated cognitive decline (AACD). The present article aims to provide an overview of the most current therapeutic approaches to age-associated neurocognitive disorders. Additionally, it discusses the conceptual and methodological issues that surround the design, implementation, and interpretation of such approaches.

Combination therapy for Alzheimer's disease

Alzheimer's disease (AD) is a progressive, degenerative brain disease. The mainstay of current management of patients with AD involves drugs that provide symptomatic therapy. Two classes of medications have been approved by the US FDA for the treatment of AD: the cholinesterase inhibitors (ChEIs), which include galantamine and rivastigmine (both approved for use in mild to moderate AD) and donepezil (approved for use in mild to severe AD); and the non-competitive NMDA receptor antagonist memantine (approved for use in moderate to severe AD). The European and Asian regulatory bodies have also approved ChEIs as monotherapy in mild to moderate AD. Future research directions are mostly focusing on disease modification and prevention. This review covers key studies of the efficacy, safety and tolerability of combination therapy in AD, defined as a combination of the NMDA receptor antagonist memantine with any of the ChEIs (donepezil, galantamine or rivastigmine) for the treatment of AD. Relevant studies were identified via a PubMed search. This review shows that combination therapy for AD seems to be safe, well tolerated and may represent the current gold standard for treatment of moderate to severe AD and possibly mild to moderate AD as well.

Pharmacological study on Alzheimer's drugs targeting calcium/calmodulin-dependent protein kinase II

In the brain of Alzheimer's disease patients, down-regulation of both cholinergic and glutamatergic systems have been found and is thought to play an important role in impairment of cognition, learning, and memory. Nefiracetam is a pyrrolidine-related nootropic drug exhibiting various pharmacological actions such as a cognitive-enhancing effect. The present study was undertaken to elucidate mechanisms underlying the action of nefiracetam on glutamatergic receptors and intracellular protein kinases. N-Methyl-D-aspartate (NMDA)-evoked currents were recorded from rat cortical neurons in long-term cultured primary neurons using the whole-cell patch-clamp technique. NMDA-evoked currents were greatly and reversibly potentiated by bath application of nefiracetam, resulting in a bell-shaped dose-response curve. The maximum potentiation of 170% relative to the control was produced at 10 nM. Treatment with an inhibitor of the glycine binding site of the NMDA receptor, 7-chlorokynurenic acid, at 1 µM prevented augmentation of NMDA-evoked currents by nefiracetam. In rat hippocampal CA1 slices, field excitatory postsynaptic potentials were recorded by stimulation of Schaffer collateral/commissural pathways. Nefiracetam treatment significantly enhanced long-term potentiation (LTP) with the same bell-shaped dose-response curve. Furthermore, nefiracetam-induced LTP enhancement was closely associated with calcium/calmodulin-dependent protein kinase II (CaMKII) activation with concomitant increase in phosphorylation of AMPA-type glutamate receptor subunit 1 (GluA1) (Ser-831) as a postsynaptic CaMKII substrate. In conclusion, nefiracetam enhances NMDA-receptor function through stimulation of its glycine binding site and nefiracetam-induced CaMKII activation likely contributes to improvement of cognition, learning, and memory.

CaM kinase II and protein kinase C activations mediate enhancement of long-term potentiation by nefiracetam in the rat hippocampal CA1 region

Nefiracetam is a pyrrolidine-related nootropic drug exhibiting various pharmacological actions such as cognitive-enhancing effect. We previously showed that nefiracetam potentiates NMDA-induced currents in cultured rat cortical neurons. To address questions whether nefiracetam affects NMDA receptor-dependent synaptic plasticity in the hippocampus, we assessed effects of nefiracetam on NMDA receptor-dependent long-term potentiation (LTP) by electrophysiology and LTP-induced phosphorylation of synaptic proteins by immunoblotting analysis. Nefiracetam treatment at 1-1000 nM increased the slope of fEPSPs in a dose-dependent manner. The enhancement was associated with increased phosphorylation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor through activation of calcium/calmodulin-dependent protein kinase II (CaMKII) without affecting synapsin I phosphorylation. In addition, nefiracetam treatment increased PKCalpha activity in a bell-shaped dose-response curve which peaked at 10 nM, thereby increasing phosphorylation of myristoylated alanine-rich protein kinase C substrate and NMDA receptor. Nefiracetam treatment did not affect protein kinase A activity. Consistent with the bell-shaped PKCalpha activation, nefiracetam treatment enhanced LTP in the rat hippocampal CA1 region with the same bell-shaped dose-response curve. Furthermore, nefiracetam-induced LTP enhancement was closely associated with CaMKII and PKCalpha activation with concomitant increases in phosphorylation of their endogenous substrates except for synapsin I. These results suggest that nefiracetam potentiates AMPA receptor-mediated fEPSPs through CaMKII activation and enhances NMDA receptor-dependent LTP through potentiation of the post-synaptic CaMKII and protein kinase C activities. Together with potentiation of nicotinic acetylcholine receptor function, nefiracetam-enhanced AMPA and NMDA receptor functions likely contribute to improvement of cognitive function.

Efficacy and tolerability of memantine in the treatment of dementia

BACKGROUND

Until recently, acetylcholinesterase inhibitors were the only approved agents for the treatment of Alzheimer's disease (AD). These medications have also been used in the treatment of vascular dementia (VD). Memantine, the first N-methyl-D-aspartate (NMDA)-receptor antagonist to be well tolerated, has been approved for the treatment of moderate to severe AD.

OBJECTIVE

The aim of this study was to review the current literature on the efficacy and tolerability of memantine in the treatment of AD and VD.

METHODS

A MEDLINE search of the English-language literature from January 1970 to March 2004 was conducted to identify randomized, double-blind, placebo-controlled, parallel-group trials in which memantine was administered to patients with VD or AD. The search terms were memantine, NMDA inhibitor, and NMDA antagonist.

RESULTS

Excessive glutamate, the brain's major excitatory neurotransmitter, can cause excitotoxicity by allowing too much calcium to enter neuronal cells. Moderate-affinity NMDA-receptor antagonists such as memantine block pathologic activity of glutamate while allowing physiologic activity. Use of memantine has been associated with significant improvements in measures of cognition, function, and behavior in both VD and AD. Adverse events associated with memantine have been comparable to those with placebo, with the exception of an increased incidence of dizziness, constipation, cataracts, nausea, dyspnea, confusion, headache, and urinary incontinence.

CONCLUSIONS

Memantine seems to be promising and well tolerated in the treatment of moderate to severe VD or AD, either as monotherapy or in combination with donepezil. It appears to be particularly effective in improving cognitive, functional, and global outcomes in moderate to severe AD and in improving cognitive end points in mild to moderate VD. More research is needed on important clinical questions, including whether memantine can prolong patients' ability to provide self-care and delay institutional placement.

Mechanism of Action of Galantamine onN-Methyl-d-Aspartate Receptors in Rat Cortical Neurons

Galantamine, a new Alzheimer's drug approved in the United States, is known to inhibit acetylcholinesterase and potentiate acetylcholine-induced currents in brain neurons. However, because both cholinergic and N-methyl-D-aspartate (NMDA) systems are down-regulated in the brain of Alzheimer's patients, we studied the effects of galantamine on NMDA receptors. NMDA-induced whole-cell currents were recorded from the rat multipolar cortical neurons in primary culture. NMDA currents recorded in Mg2+-free media without addition of glycine were reversibly potentiated by bath and U-tube applications of galantamine at 10 to 10,000 nM, showing a bell-shaped dose-response relationship. However, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate currents were not affected by galantamine. The maximum potentiation of NMDA currents to approximately 130% of the control was obtained at 1 microM galantamine. The potentiation was due to a shift of the NMDA dose-response curve in the direction of lower NMDA concentrations. Glycine at 1 to 3000 nM enhanced NMDA currents, and potentiation by 1 microM galantamine and 1 to 300 nM glycine was additive. The glycine site antagonist 7-chlorokynurenic acid did not prevent the galantamine action. These results suggested that galantamine did not interact with the glycine binding site. Experiments with various concentrations of Mg2+ indicated that galantamine did not affect the Mg2+ blocking site of the NMDA receptor. PKC was involved in galantamine potentiation of NMDA currents, but protein kinase A, Gi/Go proteins, and Gs proteins were not involved. Potentiation of the activity of NMDA receptors is deemed partially responsible for the improvement of cognition, learning, and memory in Alzheimer's patients.

Unique mechanism of action of Alzheimer's drugs on brain nicotinic acetylcholine receptors and NMDA receptors

While a variety of hypotheses have been proposed for the cause of Alzheimer's disease, our knowledge is far from complete to explain the disease making it difficult to develop the methods for treatment. In the brain of Alzheimer's patients, both neuronal nicotinic acetylcholine (nACh) receptors and NMDA receptors are known to be down-regulated. Thus four anticholinesterases have been developed and approved for the treatment in the U.S.A. However, these are not ideal drugs considering their side effects and limited effectiveness. Nefiracetam is being developed for the treatment of Alzheimer's and other patients with dementia, and has unique actions in potentiating the activity of both nACh and NMDA receptors as demonstrated by in vitro patch clamp experiments using rat cortical neurons in primary culture. Nefiracetam potentiated alpha4beta2-like ACh- and NMDA-induced currents at nanomolar concentrations forming bell-shaped dose-response curves with the maximum potentiation occurring at 1 and 10 nM, respectively. Nefiracetam potentiated nACh receptor currents via G(s) proteins, but not G(i)/G(o) proteins, PKA or PKC. Nefiracetam potentiation of NMDA currents occurred via interactions with the glycine binding site of the NMDA receptor. The nefiracetam potentiation of both nACh and NMDA receptors in a potent and efficacious manner is deemed responsible for its cognitive enhancing action.

Mechanisms of Action of Cognitive Enhancers on Neuroreceptors

No strategies for curing Alzheimer's disease have been developed yet as we do not know the exact cause of the disease. The only therapy that is available for patients is symptomatic treatment. Since Alzheimer's disease is associated with downregulation of the cholinergic system in the brain, its stimulation is expected to improve the patients' cognition, learning, and memory. Four anticholinesterases have been approved in the U.S.A. for the treatment of Alzheimer's disease patients. However, because of the inhibition of cholinesterases, these drugs have side effects and their effectiveness does not last long. Thus new approaches are needed. One approach is to stimulate directly nicotinic acetylcholine (nACh) receptors in the brain, and another is to stimulate NMDA receptors which are also known to be downregulated in Alzheimer's patients. Nefiracetam has been shown to potentiate ACh currents in the alpha4beta2 receptor of rat cortical neurons with a bell-shaped dose-response relationship and the maximum effect at 1 nM. This effect was exerted via G(s) proteins. The alpha7 receptor was almost unaffected by nefiracetam. Nefiracetam also potentiated NMDA currents with the maximum effect at 10 nM via interaction with the glycine-binding site of the receptor. Galantamine had a moderate potentiating effect on the alpha4beta2 receptor and potentiated NMDA currents with the maximum effect at 1 microM. However, galantamine did not interact with the glycine-binding site. Donepezil, a potent anticholinesterase, also potentiated NMDA currents at 1-10000 nM. In conclusion, these three drugs potentiate the activity not only of the cholinergic system but also of the NMDA system, thereby stimulating the downregulated nACh receptors and NMDA receptors to improve patients' learning, cognition, and memory.

Potentiation of N-methyl-D-aspartate-induced currents by the nootropic drug nefiracetam in rat cortical neurons

Nefiracetam is a new pyrrolidone nootropic drug being developed for the treatment of Alzheimer's type and post-stroke vascular-type dementia. In the brain of Alzheimer's disease patients, down-regulation of both cholinergic and glutamatergic systems has been found and is thought to play an important role in impairment of cognition, learning and memory. We have previously shown that the activity of neuronal nicotinic acetylcholine receptors is potently augmented by nefiracetam. The present study was undertaken to elucidate the mechanism of action of nefiracetam on glutamatergic receptors. Currents were recorded from rat cortical neurons in long-term primary culture using the whole-cell patch-clamp technique at a holding potential of -70 mV in Mg2+-free solutions. N-Methyl-D-aspartate (NMDA)-evoked currents were greatly and reversibly potentiated by bath application of nefiracetam resulting in a bell-shaped dose-response curve. The minimum effective nefiracetam concentration was 1 nM, and the maximum potentiation to 170% of the control was produced at 10 nM. Nefiracetam potentiation occurred at high NMDA concentrations that evoked the saturated response, and in a manner independent of NMDA concentrations ranging from 3 to 1,000 microM. Glycine at 3 microM potentiated NMDA currents but this effect was attenuated with an increasing concentration of nefiracetam from 1 to 10,000 nM. 7-Chlorokynurenic acid at 1 microM prevented nefiracetam from potentiating NMDA currents. Nefiracetam at 10 nM shifted the dose-response relationship for the 7-chlorokynurenic acid inhibition of NMDA currents in the direction of higher concentrations. Alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid- and kainate-induced currents were not significantly affected by application of 10 nM nefiracetam. It was concluded that nefiracetam potentiated NMDA currents through interactions with the glycine binding site of the NMDA receptor.

The role of the N-methyl-D-aspartate receptor in Alzheimer's disease: therapeutic potential

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with an unknown etiology. Pathologic processes implicated in AD include b-amyloid-induced synaptic failure; tau hyperphosphorylation; inflammation; oxidative stress; abnormal neurotransmission involving acetylcholine, glutamate, norepinephrine, serotonin, and dopamine; and abnormalities in second messengers, protein kinases, and apoptosis. Although each of these pathways offers potential therapeutic targets, pharmacologic manipulation of the glutamatergic N-methyl-D-aspartate receptor pathway, alone or in combination with cholinergic therapies, is emerging as the next promising strategy for the treatment of AD and vascular dementia.

Current Treatment for Alzheimer Disease and Future Prospects

A cascade of pathophysiological events is triggered in Alzheimer disease (AD) that ultimately involves common cellular signaling pathways and leads to cellular and network dysfunction, failure of neurotransmission, cell death, and a common clinical outcome. The process is asynchronous, meaning that viable neurons remain as targets for therapy even in the diseased state, and each stage of the cascade affords the possibility for therapeutic intervention. Cholinesterase inhibitors are the only available treatment in the United States for patients with mild to moderate AD, helping maintain cognitive and functional abilities in most patients and conferring beneficial behavioral effects in some. Memantine is an NMDA receptor antagonist that has recently been approved in Europe for treatment of moderately severe to severe AD and is under investigation in the United States. Its mechanism of action may include enhanced neurotransmission in several systems as well as antiexcitotoxic effects. There are data regarding the effectiveness of the combination of memantine with cholinesterase inhibitors that will be useful for the practicing clinician. Other agents have shown some benefit in clinical trials, including the antioxidants vitamin E, selegiline, and Ginkgo biloba extracts, although the weight of evidence regarding their effects is not sufficient to define clinical practice. Potential future therapies currently are in development that target multiple aspects of the illness cascade, including aberrant inflammation, neurotrophic function, and processing of beta amyloid and tau proteins. These newer approaches hold promise for disease modification but are as yet unproven. Whether or not disease-modifying or preventive therapies become a reality, clinicians will be faced with AD patients who require treatment at all stages of illness for the indefinite future. Cholinergic and emerging noncholinergic medications will likely prevail as the standards of treatment for years to come.

Antagonists and agonists at the glycine site of the NMDA receptor for therapeutic interventions

For decades neuroreceptor research has focused on the development of NMDA glycine-site antagonists, after Johnson and Ascher found out in 1987 about the co-agonistic character of this achiral amino acid at the NMDA receptor. Contrary to the inhibitory glycine receptor (glycine(A)) the glycine binding site on the NMDA receptor (glycine(B)) is strychnine-insensitive. A great diversity of diseases showing a disturbed glutamate neurotransmission have been linked to the NMDA receptor. Glycine site antagonists have been investigated for acute diseases like stroke and head trauma as well as chronic ones like dementia and chronic pain.

Future prospects for the drug treatment of epilepsy

Great progress has been made in the last 150 years in the pharmacological management of epilepsy, and, despite the increasing number of technological advances available, antiepileptic drugs (AEDs) remain the mainstay of treatment for the vast majority of patients with epilepsy. This review looks at possible avenues of development in the drug treatment of epilepsy. The strengths and weaknesses of those AEDs which are currently licensed are examined, and ways in which their use may be improved are discussed (e.g. rational combinations, use of new formulations). Potentially new targets that may allow the development of effective treatments are highlighted (neuroimmunological manipulation, decreasing inherent drug resistance mechanisms, and modification of adenosine neurotransmission), and a summary of the most promising AEDs currently in development is provided [e.g. carabersat, ganaxolone, harkoseride, MDL 27192, safinamide (NW 1015), pregabalin, retigabine, talampanel, valrocemide, losigamone and BIA 2093].

The use of medications for cognitive enhancement

OBJECTIVE

To provide Canadian physicians and allied health care professionals with the evidence they need to help them make treatment decisions in the management of patients with Alzheimer's disease or other dementias.

OPTIONS

The full range and quality of diagnostic and therapeutic modalities available to Canadian physicians for the management of dementia.

OUTCOMES

Improvement in the treatment of dementias, leading to reduced suffering, increased functional capacity and decreased economic burden. EVIDENCE AND VALUES: The creation of these evidence-based consensus statements involved literature reviews of the subject by the authors; comparison of alternative clinical pathways and description of the methods whereby published data were analyzed; definition of the level of evidence for data in each case; evaluation and revision in a conference setting (involving primary care physicians, neurologists, psychiatrists, geriatricians, psychologists, consumers and other interested parties); insertion of tables showing key variables and data from various studies and tables of data with recommendations; and reassessment by all authors.

BENEFITS, HARMS, AND COSTS

A rational plan for the therapy of dementias is likely to lead to substantial benefits in both human and economic terms.

RECOMMENDATIONS

Treatment decisions should be made taking into account the severity or stage of the disease, the availability of caregivers, the presence of disease affecting other bodily systems and the ability of the subject to pay the cost of the medications. Donepezil is considered to have positive effects upon certain tests of neuropsychological function and may produce some improvement in Alzheimer's disease of mild to moderate severity as measured by rating scales. Its ability to improve quality of life remains uncertain. No other drug treatments (apart from symptomatic therapies) are at present approved for the treatment of Alzheimer's disease*.

VALIDATION

These recommendations were created by a writing committee, evaluated and revised at a consensus conference and further reviewed and revised by the writing committee prior to publication.

The role of glutamate in dementia

Glutamate is an excitatory neurotransmitter, but may also act as an endogenous neurotoxin. There is good evidence for an involvement of the glutamatergic system in the pathophysiology of dementia. The glutamatergic transmission machinery is quite complex and provides a gallery of possible drug targets. There are good arguments both for an agonist and an antagonist strategy. When following the antagonist strategy, the goal is to provide neuroprotective effects via glutamate receptor antagonisms without inhibiting the physiological transmission that is required for learning and memory formation. When following the agonist strategy, the goal is to activate glutamatergic transmission without neurotoxic side effects. Several available antidementia drugs may modulate the glutamatergic transmission.

Biphasic and region-specific MAO-B response to aging in normal human brain

Variations of monoamine oxidases (MAO) A and B were studied during aging in 27 human subjects (age range 17-93 years) in 18 brain structures of temporal cortex, frontal gyrus, hippocampal formation, striatum, cerebellum, and brainstem. [3H]Ro41-1049 and [3H]lazabemide were used as selective radioligands to image and quantify MAO-A and MAO-B respectively by enzyme autoradiography. Postmortem delay or time of tissue storage did not affect MAO-A or MAO-B levels. There was, moreover, no evidence of sexual dimorphism. A marked age-related increase in MAO-B was observed in most structures. This increase started at the age of 50-60 years. Before this age, MAO-B levels were constant in all structures studied. MAO-B-rich senile plaques were observed in some cortical areas but they did not significantly influence the age-related MAO-B increase. Surprisingly, no age-related MAO-B changes were observed in the substantia nigra. In contrast to MAO-B, no clear age-related changes in MAO-A were observed, indicating an independent regulation of the two isoenzymes, also suggested by the cross-correlation analysis of these data.

Research on the cognitively impaired: lessons and warnings from the emergency research debate

OBJECTIVES

To demonstrate that the recent events in emergency research have broad implications for the conduct of human subjects research with the cognitively impaired. This essay illustrates the similarities between the two kinds of research and suggests how understanding these similarities might help to resolve issues in human subjects research on the cognitively impaired.

METHODS

A review of pertinent journal articles, books, regulations, and court cases.

RESULTS

The emergency research controversy resulted in large part because of conflicting interpretations of arguably inadequate research regulations. The proposed Food and Drug Administration (FDA) regulations include advance informed consent, a broad role for family in approving a subject's participation, replacement of a threshold of permissible risk, called minimal risk, with a more sensible balancing of risks and benefits, and a role for the community in research approval. The current state of research on the cognitively impaired suggests that many of the same problems exist now that existed in emergency research before the FDA issued its proposed regulations. The ongoing case of T.D. et al. vs N.Y. State Office of Mental Health suggest that unless steps are taken similar to those taken in emergency research, much of clinical research on the cognitively impaired could cease.

CONCLUSION

Representatives of the government, medicine, and the public must recognize the unresolved issues and inadequate regulations relating to research on the cognitively impaired. The proposed FDA regulations for emergency research may provide guidance for a settlement of these issues.

Treatment of Alzheimer's disease: future directions

Following the introduction of tacrine hydrochloride (Cognex) in the United States and several other countries, researchers are pursuing two broad therapeutic strategies for Alzheimer's disease (AD). The first involves identifying agents or combinations of agents whose actions can compensate for the considerable cerebral damage that has typically occurred by the time the diagnosis of AD is made. Such therapeutic approaches include the development of additional cholinesterase inhibitors, agents that work on the receptors of other systems damaged by the disease process, and anti-inflammatory and immunomodulatory agents. The second and ultimately more promising strategy involves the development of approaches to retard, halt, or even prevent disease progression. Such protective approaches, which depend on the development of more effective methods for predicting and diagnosing AD, include the administration of nerve growth factor and other neurotrophins and the use of pharmacologic or genetic interventions to limit amyloid deposition and the formation of neurofibrillary tangles.

[New therapeutic prospects in Alzheimer disease]

The approval for marketing of tacrine (Cognex), an acetylcholinesterase inhibitor, allowed physicians and the general people to attract attention to a degenerative disease, which prevalence dramatically increases every year. This drug is hopeful. Meanwhile, we must keep in mind that it has only a symptomatic effect. Its hepatotoxicity requires regular biological tests. Many medications are actually in earlier stages of development along with various etiological approaches.

Clobazam, oxcarbazepine, tiagabine, topiramate, and other new antiepileptic drugs

Clinical investigators recently have studied at least 21 new antiepileptic drugs (AEDs) in people with epilepsy. This review briefly examines 15 of these new AEDs: clobazam (CLB), dezinamide, flunarizine (FNR), loreclezole, milacemide (MLM), MK-801, nafimidone, ORG-6370, oxcarbazepine (OCBZ), progabide (PGB), ralitoline, stiripentol, tiagabine (TGB), topiramate (TPM), and zonisamide (ZNS). CLB, PGB, and TGB represent agents that act on the GABA system, and MLM acts on the glycine system. MK-801 and ZNS (in part) are excitatory amino acid antagonists, and FNR is a calcium-channel antagonist. OCBZ is a keto analogue of carbamazepine, which is not metabolized to the epoxide and may have fewer side effects. The remaining agents are novel compounds with a variety of suspected mechanisms. TPM appears especially effective for intractable partial seizures but has a high incidence of cognitive side effects. None of these new AEDs is useful for all patients with inadequate seizure control or ongoing toxicity. The role of each will require further clinical study and experience.

Emerging drugs for Alzheimer's disease. Mechanisms of action and prospects for cognitive enhancing medications

This article has discussed various possible pharmacologic approaches to Alzheimer's disease. Despite generally encouraging results, no agent to date has proved to be dramatically effective. At present, treatment options are limited for the clinicians. Tacrine is available on the market. In the doses recommended, efficacy is modest, and side effects require vigilance in monitoring. Other cholinesterase inhibitors may be approved for clinical use in the near future but are likely to have similar modest clinical effects. L-deprenyl is marketed for Parkinson's disease but has not been adequately tested for efficacy in Alzheimer's disease. Newer drugs in earlier stages of development are generally intended to affect cholinergic systems in various other ways. The effects of these drugs on behavioral symptoms, in severe dementia, and in non-Alzheimer's dementia have not been adequately assessed. In the absence of known cause, and in the face of uncertainty regarding pathophysiology, efforts in the near future will focus on encouraging theoretical leads, sensible empiric trials, and symptomatic treatment research. Although public anticipation will be raised over each announced "breakthrough," only results from carefully conducted trials should be accepted.

The Italian version of the Alzheimer's Disease Assessment Scale (ADAS): psychometric and normative characteristics from a normal aged population

The Alzheimer's Disease Assesment Scale (ADAS) was specifically proposed for the clinical assessment of patients suffering from dementia and is used in different countries. The Italian version of ADAS is presented in this paper together with the description of criteria used in transforming the American edition in the Italian edition. Psychometric and normative data are illustrated and discussed. A sample of 95 healthy volunteers of both sexes ranging in age from 50 to 79 years were recruited from the general population in different parts of Italy and from different social and educational levels. Their performance on the ADAS was analysed by sex, age, and educational level. Results indicated a specific influence of subjects' educational level on the Cognitive Subscale Total Score of ADAS and the need for an adequate correction was evidenced. The two objective measures of memory which constitute, together with the Cognitive Subscale Total Score, the cognitive subscale of ADAS were sensitive to both age and educational level, requiring corrections. The factor structure of the cognitive subscale of ADAS confirms the validity of distinguishing between the clinical-functional scores, which are summarized by the Cognitive Subscale Total Score (CSTS), from those of the objective memory tasks, which are kept separate and used to quantify specific memory characteristics. The main components of the CSTS were 3 factors. The first factor was

Cognitive effects of milacemide and methylphenidate in healthy young adults

Cognitive effects of the novel glycine prodrug milacemide (400 mg), the catecholaminergic agonist methylphenidate (20 mg), and placebo were evaluated in 48 healthy young adults. Throughout a 6-h drug treatment day, subjects repeatedly performed tests of target-detection vigilance, immediate and delayed verbal free recall, and Buschke Selective Reminding; total free recall and forced-choice recognition tests were administered at the end of the day. Significant improvement in both vigilance reaction time and Selective Reminding Sum Recall was observed in the methylphenidate group. Contrary to expectations, the milacemide group evidenced significant declines in both vigilance perceptual sensitivity and free-recall difference scores (delayed-immediate). Vigilance reaction times significantly decreased over repeat testing in all groups, but only the methylphenidate group differed from placebo. The reaction-time functions for milacemide and placebo were similar, suggesting arousal was not diminished under milacemide and could not account for the cognitive decrements. No significant drug effects obtained for total free recall or recognition performance. Although the glycine prodrug milacemide was ineffective as a cognitive enhancer, the involvement of the NMDA receptor in memory function reported in the literature supports continued exploration of other approaches for manipulating NMDA receptor activity.

Fasting for 24 h reveals liver microsteatosis after continuous i.v. infusion of milacemide in the rat

Milacemide (2-n-pentylaminoacetamide) hydrochloride was administered by continuous i.v. infusion for up to 7 days, at 300 and 600 mg/kg per day to male Sprague-Dawley rats. This was intended to provide high and sustained exposure to evaluate the effect of a preterminal 24-h fast on liver lipid content. Liver lipid content, as assessed by triglyceride concentration and histopathology, was not different in saline controls or rats infused with up to 600 mg/kg per day for up to 7 days, when they had access to food up to sacrifice. When the rats were fasted for 24 h before sacrifice, milacemide produced microsteatosis in the periportal and midzonal areas. The effect was significant after 2 days of infusion at 600 mg/kg per day and increased in intensity with duration of administration. After 7 days of infusion, at 600 mg/kg per day, liver triglycerides increased by more than 4-fold in rats fasted for the last 24 h. No other differences from the controls were observed at light microscopy or in liver protein content and AST activity. Liver ALT activity was decreased by 28% and plasma ALT activity by 23%. Plasma triglyceride levels were lowered by milacemide, in both fasted and fed rats. This study demonstrates that fasting for 24 h triggers the development of liver microsteatosis in rats exposed to milacemide. Fasting has been previously described to increase liver microsteatosis after administration of sodium valproate, 4-en valproate and pentenoic acid in the rat. These findings might help to identify the mechanism of the hepatic effects of milacemide.(ABSTRACT TRUNCATED AT 250 WORDS)

Advances in the pharmacotherapy of Alzheimer's disease

The authors reviewed the literature on the agents proposed for the treatment of Alzheimer's disease (AD). Different classes of drugs have been tested for this indication including psychostimulants, anticoagulants, vasodilators, hyperbaric oxygen, hormones, nootropics, cholinomimetics, monoaminergics and neuropeptides without conclusive evidence of being beneficial for the treatment of this condition. Among the cholinomimetics recent research data seems to indicate that they might produce modest benefits in mild-to-moderate AD patients. Recently, other drugs have also been proposed including neurotrophic factors, phosphatidylserine, angiotension [corrected] converting enzyme (ACE) inhibitors, calcium channel blockers, acetyl-L-carnitine, xanthine derivatives, anti-inflammatory agents, aluminum chelate agents, and D-cycloserine. Of these new strategies few hold promise of more substantial benefits for AD, with the possibility of altering the course of the disease, but these drugs await confirmatory trials.