Nootropic drugs in Alzheimer's disease: symptomatic treatment with pramiracetam

MGATRx: Discovering Drug Repositioning Candidates Using Multi-View Graph Attention

In-silico drug repositioning or predicting new indications for approved or late-stage clinical trial drugs is a resourceful and time-efficient strategy in drug discovery. However, inferring novel candidate drugs for a disease is challenging, given the heterogeneity and sparseness of the underlying biological entities and their relationships (e.g., disease/drug annotations). By integrating drug-centric and disease-centric annotations as multi-views, we propose a multi-view graph attention network for indication discovery (MGATRx). Unlike most current similarity-based methods, we employ graph attention network on the heterogeneous drug and disease data to learn the representation of nodes and identify associations. MGATRx outperformed four other state-of-art methods used for computational drug repositioning. Further, several of our predicted novel indications are either currently investigated or are supported by literature evidence, demonstrating the overall translational utility of MGATRx.

The Psychonauts' World of Cognitive Enhancers

BACKGROUND

There is growing availability of novel psychoactive substances (NPS), including cognitive enhancers (CEs) which can be used in the treatment of certain mental health disorders. While treating cognitive deficit symptoms in neuropsychiatric or neurodegenerative disorders using CEs might have significant benefits for patients, the increasing recreational use of these substances by healthy individuals raises many clinical, medico-legal, and ethical issues. Moreover, it has become very challenging for clinicians to keep up-to-date with CEs currently available as comprehensive official lists do not exist.

METHODS

Using a web crawler (NPSfinder®), the present study aimed at assessing psychonaut fora/platforms to better understand the online situation regarding CEs. We compared NPSfinder® entries with those from the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and from the United Nations Office on Drugs and Crime (UNODC) NPS databases up to spring 2019. Any substance that was identified by NPSfinder® was considered a CE if it was either described as having nootropic abilities by psychonauts or if it was listed among the known CEs by Froestl and colleagues.

RESULTS

A total of 142 unique CEs were identified by NPSfinder®. They were divided into 10 categories, including plants/herbs/products (29%), prescribed drugs (17%), image and performance enhancing drugs (IPEDs) (15%), psychostimulants (15%), miscellaneous (8%), Phenethylamines (6%), GABAergic drugs (5%), cannabimimetic (4%), tryptamines derivatives (0.5%), and piperazine derivatives (0.5%). A total of 105 chemically different substances were uniquely identified by NPSfinder®. Only one CE was uniquely identified by the EMCDDA; no CE was uniquely identified by the UNODC.

CONCLUSIONS

These results show that NPSfinder® is helpful as part of an Early Warning System, which could update clinicians with the growing numbers and types of nootropics in the increasingly difficult-to-follow internet world. Improving clinicians' knowledge of NPS could promote more effective prevention and harm reduction measures in clinical settings.

Diisopropyl{2-[2-(2-oxopyrrolidin-1-yl)acetamido]ethyl}ammonium hydrogen sulfate

The structure of the title compound, C₁₄H₂₈N₃O₂⁺·HSO₄⁻, a nootropic drug (pramiracetam) investigated for cognition-enhancing properties, is closely similar to that of the previously determined acetonitrile solvate, both structures being characterized by the presence of ribbons of hydrogen-bonded ions. The pyrrolidine ring adopts an envelope conformation.

Clinically tested drugs for Alzheimer's disease

Alzheimer's disease poses a major health problem in developed countries and vigorous research is underway aimed at finding effective treatments. Acetylcholinesterase inhibitors are approved but give only temporary cognitive benefit to a percentage of patients. Their relative ineffectiveness is not surprising since the neuronal loss comprises much more than the forebrain cholinergic system. What is needed is a drug that will halt the neuronal death and thus progression of the disease. Avenues being explored are aimed at pathological features of the disease, i.e., drugs aimed at removing the amyloid burden which forms the plaques or reducing the neurotoxic neuroinflammation and oxidative stress which characterise the diseased brain regions. There are some promising leads, but more definitive clinical trials are required. Any agent designed to slow progression should clearly be used at an early stage of the disorder; therefore methods of early diagnosis are also essential.

Aniracetam restores object recognition impaired by age, scopolamine, and nucleus basalis lesions

Object recognition was investigated in adult and aging male rats in a two-trials, unrewarded, test that assessed a form of working-episodic memory. Exploration time in the first trial, in which two copies of the same object were presented, was recorded. In the second trial, in which one of the familiar objects and a new object were presented, the time spent exploring the two objects was separately recorded and a discrimination index was calculated. Adult rats explored the new object longer than the familiar object when the intertrial time ranged from 1 to 60 min. Rats older than 20 months of age did not discriminate between familiar and new objects. Object discrimination was lost in adult rats after scopolamine (0.2 mg/kg SC) administration and with lesions of the nucleus basalis, resulting in a 40% decrease in cortical ChAT activity. Both aniracetam (25, 50, 100 mg/kg os) and oxiracetam (50 mg/kg os) restored object recognition in aging rats, in rats treated with scopolamine, and with lesions of the nucleus basalis. In the rat, object discrimination appears to depend on the integrity of the cholinergic system, and nootropic drugs can correct its disruption.

Canadian guidelines for the development of antidementia therapies: a conceptual summary

The magnitude of the problems faced by Canadian society as a result of an aging population has been identified. Perhaps the most important concern related to this greying of Canada is the increasing incidence of dementia and Alzheimer's disease. Therapeutic options for these disorders have been limited to date. Advances in biotechnology and molecular biology will offer novel approaches to treatment. These and the expansion of more traditional therapeutic avenues require guidelines with the aim of optimizing their development.

Piracetam and other structurally related nootropics

Nearly three decades have now passed since the discovery of the piracetam-like nootropics, compounds which exhibit cognition-enhancing properties, but for which no commonly accepted mechanism of action has been established. This review covers clinical, pharmacokinetic, biochemical and behavioural results presented in the literature from 1965 through 1992 (407 references) of piracetam, oxiracetam, pramiracetam, etiracetam, nefiracetam, aniracetam and rolziracetam and their structural analogues. The piracetam-like nootropics are capable of achieving reversal of amnesia induced by, e.g., scopolamine, electroconvulsive shock and hypoxia. Protection against barbiturate intoxication is observed and some benefit in clinical studies with patients suffering from mild to moderate degrees of dementia has been demonstrated. No affinity for the alpha 1-, alpha 2-, beta-, muscarinic, 5-hydroxytryptamine-, dopamine, adenosine-A1-, mu-opiate, gamma-aminobutyric acid (GABA) (except for nefiracetam (GABAA)), benzodiazepine and glutamate receptors has been found. The racetams possess a very low toxicity and lack serious side effects. Increased turnover of different neurotransmitters has been observed as well as other biochemical findings, e.g., inhibition of enzymes such as prolylendopeptidase. So far, no generally accepted mechanism of action has, however, emerged. We believe that the effect of the racetams is due to a potentiation of already present neurotransmission and that much evidence points in the direction of a modulated ion flux by, e.g., potentiated calcium influx through non-L-type voltage-dependent calcium channels, potentiated sodium influx through alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor gated channels or voltage-dependent channels or decreases in potassium efflux. Effects on carrier mediated ion transport are also possible.

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.

Elevated corticosteroid levels block the memory-improving effects of nootropics and cholinomimetics

Oral pretreatment of mice with aldosterone or corticosterone blocked the memory-enhancing effects of piracetam, pramiracetam, aniracetam and oxiracetam in a dose-related manner, without, however, impairing the animals' learning performance. The improvement of memory induced by physostigmine, arecoline, and tacrine (THA) was similarly inhibited. The fact that elevated steroid levels suppress the memory-enhancing effects of entirely different substances could indicate that these substances have a common site of action. In the light of new observations showing increased cortisol concentrations in Alzheimer patients, this steroid dependency of the effects of memory enhancers might explain why only a limited number of these patients respond to therapy with nootropics or cholinomimetics.

Behavioral screening for cognition enhancers: from indiscriminate to valid testing: Part I

Preclinical efforts to detect and characterize potential cognition enhancers appear to have been dominated by a strategy of demonstrating a wide variety of apparently beneficial behavioral effects with little attention given to the specific psychological mechanisms underlying behavioral enhancement. In particular, the question of whether or not behavioral facilitation is based on relevant mnemonic mechanisms and is independent of the stimulus properties and/or the motivational and attentional components of a task is not often considered. As a result, an overwhelming number of compounds have failed to produce the clinical effects predicted for them on the basis of preclinical research. The available data suggest that a more successful approach requires deductive research strategies rather than the indiscriminate accumulation of apparently beneficial effects in a variety of behavioral tasks and animal models. The first step towards such an approach is a systematic and rigorous evaluation of the different aspects of validity for the models most frequently used in preclinical research. It is concluded that a combination of good construct validity and good face validity represents a necessary condition for screening tests with predictive validity, and that the most popular paradigms fail to fulfil these criteria. Future screening programs for cognition enhancers will probably be characterized by a depreciation of "fast and dirty tests" in favor of approaches focussing on the validity of the effects of potential cognition enhancers.

Taking stock of cognition enhancers

An increasing number of structurally heterogeneous compounds, which may act via very different categories of neuronal mechanisms, have been proposed to facilitate attentional abilities and acquisition, storage and retrieval of information, and/or to attenuate the impairments of such cognitive functions associated with age or dementia. In this article, Martin Sarter briefly reviews the data on putative cognition enhancers and examines the possible bases for the discrepancy between preclinical predictions of efficacy and the fact that unequivocal demonstration of drug-induced cognition enhancement in humans has only rarely been reported. Previous preclinical research strategies appear to have focused on the demonstration of drug effects in a wide variety of tests of uncertain validity, rather than on determination of the specific psychological and neurobiological processes affected by putative cognition enhancers. Some criteria are proposed for evaluating the validity of preclinical tests for cognition enhancers.