Neuropsychological test performance in healthy volunteers before and after donepezil administration

Stressing out! Effects of acute stress on prepulse inhibition and working memory

Prepulse inhibition (PPI) of the startle reflex serves as a pre-cognitive marker of sensorimotor gating, and its deficit may predict cognitive impairments. Startle reflex is modulated by many factors. Among them, stress has been a topic of interest, but its effects on both pre-cognitive and cognitive variables continue to yield divergent results. This study aims to analyze the effect of acute stress on PPI of the startle reflex and cognitive function (working memory, attention, inhibition, and verbal fluency). Participants were exposed to the MAST stress induction protocol or a stress-neutral task: stress group (n = 54) or control group (n = 54). Following stress induction, participants' startle responses were recorded, and cognition was assessed. The results revealed that participants in the stress group exhibited greater startle magnitude, lower PPI, and lower scores in working memory tests compared with the control group. Additionally, a correlation was found between working memory and PPI across all the participants, independent of stress group. These findings support the notion that after stress, both greater startle magnitude and diminished PPI could play an adaptive role by allowing for increased processing of stimuli potentially dangerous and stress-related. Similarly, our results lend support to the hypothesis that lower PPI may be predictive of cognitive impairment. Considering the impact of stress on both pre-cognitive (PPI) and cognitive (working memory) variables, we discuss the possibility that the effect of stress on PPI occurs through motivational priming and emphasize the relevance of considering stress in both basic and translational science.

Pharmacological targeting of cognitive impairment in depression: recent developments and challenges in human clinical research

Impaired cognition is often overlooked in the clinical management of depression, despite its association with poor psychosocial functioning and reduced clinical engagement. There is an outstanding need for new treatments to address this unmet clinical need, highlighted by our consultations with individuals with lived experience of depression. Here we consider the evidence to support different pharmacological approaches for the treatment of impaired cognition in individuals with depression, including treatments that influence primary neurotransmission directly as well as novel targets such as neurosteroid modulation. We also consider potential methodological challenges in establishing a strong evidence base in this area, including the need to disentangle direct effects of treatment on cognition from more generalised symptomatic improvement and the identification of sensitive, reliable and objective measures of cognition.

Benefits and Harms of 'Smart Drugs' (Nootropics) in Healthy Individuals

'Smart drugs' (also known as 'nootropics' and 'cognitive enhancers' [CEs]) are being used by healthy subjects (i.e. students and workers) typically to improve memory, attention, learning, executive functions and vigilance, hence the reference to a 'pharmaceutical cognitive doping behaviour'. While the efficacy of known CEs in individuals with memory or learning deficits is well known, their effect on non-impaired brains is still to be fully assessed. This paper aims to provide an overview on the prevalence of use; putative neuroenhancement benefits and possible harms relating to the intake of the most popular CEs (e.g. amphetamine-type stimulants, methylphenidate, donepezil, selegiline, modafinil, piracetam, benzodiazepine inverse agonists, and unifiram analogues) in healthy individuals. CEs are generally perceived by the users as effective, with related enthusiastic anecdotal reports; however, their efficacy in healthy individuals is uncertain and any reported improvement temporary. Conversely, since most CEs are stimulants, the related modulation of central noradrenaline, glutamate, and dopamine levels may lead to cardiovascular, neurological and psychopathological complications. Furthermore, use of CEs can be associated with paradoxical short- and long-term cognitive decline; decreased potential for plastic learning; and addictive behaviour. Finally, the non-medical use of any potent psychotropic raises serious ethical and legal issues, with nootropics having the potential to become a major public health concern. Further studies investigating CE-associated social, psychological, and biological outcomes are urgently needed to allow firm conclusions to be drawn on the appropriateness of CE use in healthy individuals.

Functional connectivity and cognitive changes after donepezil treatment in healthy participants

RATIONALE

Donepezil is a potent, noncompetitive, reversible, clinically effective acetylcholinesterase inhibitor. The effects of this drug on healthy brains have seldom been investigated.

OBJECTIVES

The primary objective of the present study was to identify possible functional connectivity markers of the effect of donepezil in healthy young adult volunteers.

METHODS

The study had a double-blind, randomized, crossover design. 30 healthy adult volunteers underwent resting-state MRI scans during 15 days of donepezil or placebo treatment, in accordance with the design.

RESULTS

Results showed significant differences in intrinsic functional connectivity between donepezil and placebo, mainly in the right executive control network (RECN). More specifically, we found a decrease in the connectivity of the right inferior parietal node with other RECN nodes. Analysis using the cingulate cortex and parahippocampal regions as seeds also revealed complex modulation of functional connectivity in the donepezil condition.

CONCLUSIONS

In conclusion, donepezil treatment for 15 days may result in reorganization of resting-state networks, compared with placebo.

Acting Before; A Combined Strategy to Counteract the Onset and Progression of Dementia

Brain aging and aging-related neurodegenerative disorders are posing a significant challenge for health systems worldwide. To date, most of the therapeutic efforts aimed at counteracting dementiarelated behavioral and cognitive impairment have been focused on addressing putative determinants of the disease, such as β-amyloid or tau. In contrast, relatively little attention has been paid to pharmacological interventions aimed at restoring or promoting the synaptic plasticity of the aging brain. The review will explore and discuss the most recent molecular, structural/functional, and behavioral evidence that supports the use of non-pharmacological approaches as well as cognitive-enhancing drugs to counteract brain aging and early-stage dementia.

Stress and cognition: A user's guide to designing and interpreting studies

Fueling the rapid growth in our understanding of how stress influences cognition, the number of studies examining the effects of stress on various cognitive processes has grown substantially over the last two decades. Despite this growth, few published guidelines exist for designing these studies, and divergent paradigm designs can diminish typical effects of stress or even reverse them. The goal of this review, therefore, is to survey necessary considerations (e.g., validating a stress induction), important considerations (e.g., specifying the timing of the stressor and cognitive task), and best practices (e.g., using Bayesian analyses) when designing a study that aims at least in part to examine the effects of acute stress on some cognitive process or function. These guidelines will also serve to help readers of these studies interpret what may otherwise be very confusing, anomalous results. Designing and interpreting studies with these considerations and practices in mind will help to move the field of stress and cognition forward by clarifying how, exactly, stress influences performance on a given cognitive task in a population of interest.

Nootropic drugs: Methylphenidate, modafinil and piracetam - Population use trends, occurrence in the environment, ecotoxicity and removal methods - A review

Pharmaceuticals which originally were designed to treat people with neurological and psychiatric conditions, e.g. Alzheimer's disease or attention deficit hyperactivity disorder (ADHD), are nowadays often misused by students as a 'brain doping' substances. These substances are known as nootropic drugs, smart drugs or cognitive enhancers, as they increase memory, attention and concentration of healthy individuals. Since they are easily available illicitly, their consumption is observed to be growing. Currently, these pharmaceuticals started gaining researchers' attention, especially since they have been recently detected in wastewater, surface water and even drinking water. This review summarises the current state of knowledge on nootropic drugs in terms of their population use trends and ethics, occurrence in the environment and detection techniques, toxicity and removal methods, in example of methylphenidate, modafinil and piracetam - three most popular nootropics. It points out that the main sources of knowledge on cognitive enhancers illicit use are often inconsistent questionnaires, which are not supported by wastewater analysis to become more veracious. Simultaneously, the studies concerning toxicity and removal methods of nootropic drugs are still limited and in many cases environmentally irrelevant. Although the prescription rules has been subjected to more strict control in developed countries, regulatory frameworks with regard to their ecosystem occurrence are still lacking and should be introduced. Moreover, the use of environmentally relevant concentrations in toxicity studies should be a standard, leading to proper ecotoxicity risk assessment. Based on this review, it is recommended to routinely monitor nootropics and their metabolites in waste- and surface waters.

TAK-071, a novel M1 positive allosteric modulator with low cooperativity, improves cognitive function in rodents with few cholinergic side effects

The muscarinic M₁ receptor (M₁R) is a promising target for treating cognitive impairment associated with cholinergic deficits in disorders such as Alzheimer's disease and schizophrenia. We previously reported that cooperativity (α-value) was key to lowering the risk of diarrhea by M₁R positive allosteric modulators (M₁ PAMs). Based on this, we discovered a low α-value M₁ PAM, TAK-071 (α-value: 199), and characterized TAK-071 using T-662 as a reference M₁ PAM with high α-value of 1786. Both TAK-071 and T-662 were potent and highly selective M₁ PAMs, with inflection points of 2.7 and 0.62 nM, respectively. However, T-662 but not TAK-071 augmented isolated ileum motility. TAK-071 and T-662 increased hippocampal inositol monophosphate production through M₁R activation and improved scopolamine-induced cognitive deficits in rats at 0.3 and 0.1 mg/kg, respectively. TAK-071 and T-662 also induced diarrhea at 10 and 0.1 mg/kg, respectively, in rats. Thus, taking into consideration the fourfold lower brain penetration ratio of T-662, TAK-071 had a wider margin between cognitive improvement and diarrhea induction than T-662. Activation of M₁R increases neural excitability via membrane depolarization, reduced afterhyperpolarization, and generation of afterdepolarization in prefrontal cortical pyramidal neurons. T-662 induced all three processes, whereas TAK-071 selectively induced afterdepolarization. Combining sub-effective doses of TAK-071, but not T-662, with an acetylcholinesterase inhibitor, significantly ameliorated scopolamine-induced cognitive deficits in rats. TAK-071 may therefore provide therapeutic opportunities for cognitive dysfunction related to cholinergic deficits or reduced M₁R expression, while minimizing peripheral cholinergic side effects.

Serotonergic and cholinergic modulation of functional brain connectivity: A comparison between young and older adults

Aging is accompanied by changes in neurotransmission. To advance our understanding of how aging modifies specific neural circuitries, we examined serotonergic and cholinergic stimulation with resting state functional magnetic resonance imaging (RS-fMRI) in young and older adults. The instant response to the selective serotonin reuptake inhibitor citalopram (30 mg) and the acetylcholinesterase inhibitor galantamine (8 mg) was measured in 12 young and 17 older volunteers during a randomized, double blind, placebo-controlled, crossover study. A powerful dataset consisting of 522 RS-fMRI scans was obtained by acquiring multiple scans per subject before and after drug administration. Group × treatment interaction effects on voxelwise connectivity with ten functional networks were investigated (p < .05, FWE-corrected) using a non-parametric multivariate analysis technique with cerebrospinal fluid, white matter, heart rate and baseline measurements as covariates. Both groups showed a decrease in sensorimotor network connectivity after citalopram administration. The comparable findings after citalopram intake are possibly due to relatively similar serotonergic systems in the young and older subjects. Galantamine altered connectivity between the occipital visual network and regions that are implicated in learning and memory in the young subjects. The lack of a cholinergic response in the elderly might relate to the well-known association between cognitive and cholinergic deterioration at older age.

MAM-E17 rat model impairments on a novel continuous performance task: effects of potential cognitive enhancing drugs

RATIONALE

Impairments in attention and inhibitory control are endophenotypic markers of neuropsychiatric disorders such as schizophrenia and represent key targets for therapeutic management. Robust preclinical models and assays sensitive to clinically relevant treatments are crucial for improving cognitive enhancement strategies.

OBJECTIVES

We assessed a rodent model with neural and behavioral features relevant to schizophrenia (gestational day 17 methylazoxymethanol acetate treatment (MAM-E17)) on a novel test of attention and executive function, and examined the impact of putative nootropic drugs.

METHODS

MAM-E17 and sham control rats were trained on a novel touchscreen-based rodent continuous performance test (rCPT) designed to closely mimic the human CPT paradigm. Performance following acute, systemic treatment with an array of pharmacological compounds was investigated.

RESULTS

Two cohorts of MAM-E17 rats were impaired on rCPT performance including deficits in sensitivity (d') and increased false alarm rates (FARs). Sulpiride (0-30 mg/kg) dose-dependently reduced elevated FAR in MAM-E17 rats whereas low-dose modafinil (8 mg/kg) only improved d' in sham controls. ABT-594 (5.9-19.4 μg/kg) and modafinil (64 mg/kg) showed expected stimulant-like effects, while LSN2463359 (5 mg/kg), RO493858 (10 mg/kg), atomoxetine (0.3-1 mg/kg), and sulpiride (30 mg/kg) showed expected suppressant effects on performance across all animals. Donepezil (0.1-1 mg/kg) showed near-significant enhancements in d', and EVP-6124 (0.3-3 mg/kg) exerted no effects in the rCPT paradigm.

CONCLUSION

The MAM-E17 model exhibits robust and replicable impairments in rCPT performance that resemble attention and inhibitory control deficits seen in schizophrenia. Pharmacological profiles were highly consistent with known drug effects on cognition in preclinical and clinical studies. The rCPT is a sensitive and reliable tool with high translational potential for understanding the etiology and treatment of disorders affecting attention and executive dysfunction.

EEG machine learning for accurate detection of cholinergic intervention and Alzheimer's disease

Monitoring effects of disease or therapeutic intervention on brain function is increasingly important for clinical trials, albeit hampered by inter-individual variability and subtle effects. Here, we apply complementary biomarker algorithms to electroencephalography (EEG) recordings to capture the brain’s multi-faceted signature of disease or pharmacological intervention and use machine learning to improve classification performance. Using data from healthy subjects receiving scopolamine we developed an index of the muscarinic acetylcholine receptor antagonist (mAChR) consisting of 14 EEG biomarkers. This mAChR index yielded higher classification performance than any single EEG biomarker with cross-validated accuracy, sensitivity, specificity and precision ranging from 88–92%. The mAChR index also discriminated healthy elderly from patients with Alzheimer’s disease (AD); however, an index optimized for AD pathophysiology provided a better classification. We conclude that integrating multiple EEG biomarkers can enhance the accuracy of identifying disease or drug interventions, which is essential for clinical trials.

A randomized, double-blind, placebo controlled, parallel group, efficacy study of alpha BRAIN® administered orally

OBJECTIVE

Alpha BRAIN® is a nootropic supplement that purports to enhance cognitive functioning in healthy adults. The goal of this study was to investigate the efficacy of this self-described cognitive enhancing nootropic on cognitive functioning in a group of healthy adults by utilizing a randomized, double blind, placebo-controlled design.

METHODS

A total of 63-treatment naïve individuals between 18 and 35 years of age completed the randomized, double-blind, placebo controlled trial. All participants completed a 2-week placebo run in before receiving active product, Alpha BRAIN® or new placebo, for 6 weeks. Participants undertook a battery of neuropsychological tests at randomization and at study completion. Primary outcome measures included a battery of neuropsychological tests and measures of sleep.

RESULTS

Compared with placebo, Alpha BRAIN® significantly improved on tasks of delayed verbal recall and executive functioning. Results also indicated significant time-by-group interaction in delayed verbal recall for the Alpha BRAIN® group.

CONCLUSIONS

The use of Alpha BRAIN® for 6 weeks significantly improved recent verbal memory when compared with controls, in a group of healthy adults. While the outcome of the study is encouraging, this is the first randomized controlled trial of Alpha BRAIN®, and the results merit further study.

Effects of Ncl. Basalis Meynert volume on the Trail-Making-Test are restricted to the left hemisphere

BACKGROUND

Cortical acetylcholine released from cells in the basal forebrain facilitates cue detection and improves attentional performance. Cholinergic fibres to the cortex originate from the CH4 cell group, sometimes referred to as the Nucleus basalis of Meynert and the Nucleus subputaminalis of Ayala. The aim of this work was to investigate the effects of volumes of cholinergic nuclei on attention and executive function.

METHODS

The volumes of CH4 and CH4p subregions were measured in a subgroup of 38 subjects (33.5 ± 11 years, 20 females) from a population-based cohort study of smokers and never-smokers who have undergone additional MR imaging. To define regions of interest, we applied a DARTEL-based procedure implemented in SPM8 and a validated probabilistic map of the basal forebrain. Attention and executive function were measured with Trail-Making Test (TMT A+B) and Stroop-Task.

RESULTS

We found a quadratic effect of the left CH4 subregion on performance of the TMT. Extremely small as well as extremely large volumes are associated with poor test performance.

CONCLUSIONS

Our results indicate that a small CH4 volume predisposes for a hypocholinergic state, whereas an extremely large volume predisposes for a hypercholinergic state. Both extremes have detrimental effects on attention. Comparable nonlinear effects have already been reported in pharmacological studies on the effects cholinergic agonists on attention.

Six psychotropics for pre-symptomatic & early Alzheimer's (MCI), Parkinson's, and Huntington's disease modification

The quest for neuroprotective drugs to slow the progression of neurodegenerative diseases (NDDs), including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD), has been largely unrewarding. Preclinical evidence suggests that repurposing quetiapine, lithium, valproate, fluoxetine, donepezil, and memantine for early and pre-symptomatic disease-modification in NDDs may be promising and can spare regulatory barriers. The literature of these psychotropics in early stage and pre-symptomatic AD, PD, and HD is reviewed and propitious findings follow. Mild cognitive impairment (MCI) phase of AD: salutary human randomized controlled trial findings for low-dose lithium and, in selected patients, donepezil await replication. Pre-symptomatic AD: human epidemiological data indicate that lithium reduces AD risk. Animal model studies (AMS) reveal encouraging results for quetiapine, lithium, donepezil, and memantine. Early PD: valproate AMS findings show promise. Pre-symptomatic PD: lithium and valproate AMS findings are encouraging. Early HD: uncontrolled clinical data indicate non-progression with lithium, fluoxetine, donepezil, and memantine. Pre-symptomatic HD: lithium and valproate are auspicious in AMS. Many other promising findings awaiting replication (valproate in MCI; lithium, valproate, fluoxetine in pre-symptomatic AD; lithium in early PD; lithium, valproate, fluoxetine in pre-symptomatic PD; donepezil in early HD; lithium, fluoxetine, memantine in pre-symptomatic HD) are reviewed. Dose- and stage-dependent effects are considered. Suggestions for signal-enhancement in human trials are provided for each NDD stage.

Learning effect of computerized cognitive tests in older adults

OBJECTIVE

To evaluate the learning effect of computerized cognitive testing in the elderly.

METHODS

Cross-sectional study with 20 elderly, 10 women and 10 men, with average age of 77.5 (± 4.28) years. The volunteers performed two series of computerized cognitive tests in sequence and their results were compared. The applied tests were: Trail Making A and B, Spatial Recognition, Go/No Go, Memory Span, Pattern Recognition Memory and Reverse Span.

RESULTS

Based on the comparison of the results, learning effects were observed only in the Trail Making A test (p=0.019). Other tests performed presented no significant performance improvements. There was no correlation between learning effect and age (p=0.337) and education (p=0.362), as well as differences between genders (p=0.465).

CONCLUSION

The computerized cognitive tests repeated immediately afterwards, for elderly, revealed no change in their performance, with the exception of the Trail Making test, demonstrating high clinical applicability, even in short intervals.

Pharmacological cognitive enhancement-how neuroscientific research could advance ethical debate

There are numerous ways people can improve their cognitive capacities: good nutrition and regular exercise can produce long-term improvements across many cognitive domains, whilst commonplace stimulants such as coffee temporarily boost levels of alertness and concentration. Effects like these have been well-documented in the medical literature and they raise few (if any) ethical issues. More recently, however, clinical research has shown that the off-label use of some pharmaceuticals can, under certain conditions, have modest cognition-improving effects. Substances such as methylphenidate and modafinil can improve capacities such as working memory and concentration in some healthy individuals. Unlike their more mundane predecessors, these methods of “cognitive enhancement” are thought to raise a multitude of ethical issues. This paper presents the six principal ethical issues raised in relation to pharmacological cognitive enhancers (PCEs)—issues such as whether: (1) the medical safety-profile of PCEs justifies restricting or permitting their elective or required use; (2) the enhanced mind can be an “authentic” mind; (3) individuals might be coerced into using PCEs; (4), there is a meaningful distinction to be made between the treatment vs. enhancement effect of the same PCE; (5) unequal access to PCEs would have implications for distributive justice; and (6) PCE use constitutes cheating in competitive contexts. In reviewing the six principal issues, the paper discusses how neuroscientific research might help advance the ethical debate. In particular, the paper presents new arguments about the contribution neuroscience could make to debates about justice, fairness, and cheating, ultimately concluding that neuroscientific research into “personalized enhancement” will be essential if policy is to be truly informed and ethical. We propose an “ethical agenda” for neuroscientific research into PCEs.

Evaluation of symptomatic drug effects in Alzheimer's disease: strategies for prediction of efficacy in humans

In chronic diseases such as Alzheimer's disease (AD), the arsenal of biomarkers available to determine the effectiveness of symptomatic treatment is very limited. Interpretation of the results provided in literature is cumbersome and it becomes difficult to predict their standardization to a larger patient population. Indeed, cognitive assessment alone does not appear to have sufficient predictive value of drug efficacy in early clinical development of AD treatment. In recent years, research has contributed to the emergence of new tools to assess brain activity relying on innovative technologies of imaging and electrophysiology. However, the relevance of the use of these newer markers in treatment response assessment is waiting for validation. This review shows how the early clinical assessment of symptomatic drugs could benefit from the inclusion of suitable pharmacodynamic markers. This review also emphasizes the importance of re-evaluating a step-by-step strategy in drug development.

Effects of donepezil on cognitive performance after sleep deprivation

OBJECTIVES

To identify tasks that were sensitive to a temporary decline in cognitive performance after sleep deprivation and to investigate the ability of the acetylcholinesterase inhibitor donepezil to reverse any sleep deprivation-induced impairment.

METHODS

Thirty healthy volunteers were administered either a 5-mg daily dose of donepezil or placebo for 14-17 days, in a double-blind parallel group design, then underwent either 24 h sleep deprivation or a normal night of sleep in non-blinded crossover, and were subsequently tested on a battery of cognitive tasks designed to measure different components of memory and executive function.

RESULTS

Sleep deprivation selectively impaired performance on several memory tasks whilst also impairing non-memory function on these tasks. Performance on other tasks was spared. Despite partially reversing the decline in subjective alertness associated with sleep deprivation, treatment with donepezil failed to significantly reverse the decline in cognitive performance on any of the tasks.

CONCLUSIONS

The results demonstrate the sensitivity of certain tests, particularly those that measure memory function, to cognitive impairment after sleep deprivation. The inability of donepezil to reverse this performance decline suggests that the sleep deprivation model of cognitive impairment may not be suitable for detecting pro-cognitive effects of cholinergic augmentation.

Cognitive impairment in acquired brain injury: a predictor of rehabilitation outcomes and an opportunity for novel interventions

Cognitive impairment is a common sequela in acquired brain injury and one that predicts rehabilitation outcomes. There is emerging evidence that impairments in cognitive functions can be manipulated by both pharmacologic and nonpharmacologic interventions to improve rehabilitation outcomes. By using stroke as a model for acquired brain injury, we review the evidence that links cognitive impairment to poor rehabilitation outcomes and discuss possible mechanisms to explain this association. Furthermore, we examine nascent promising research that suggests that interventions that target cognitive impairments can lead to better rehabilitation outcomes.

Acetylcholinesterase inhibitors and memantine for neuroenhancement in healthy individuals: a systematic review

The term neuroenhancement refers to improvement in the cognitive, emotional and motivational functions of healthy individuals through, inter alia, the use of drugs. Of known interventions, psychopharmacology provides readily available options, such as the anti-dementia drugs, e.g. acetylcholinesterase inhibitors (donepezil, galantamine, rivastigmine) and memantine. Based on a systematic review we found that expectations about the potential of these drugs exceed their actual effects, as has been demonstrated in randomised controlled trials. Both single and repeated dose trials were included in the systematic review, however repeated dose trials have only been conducted for donepezil. In six small trials lasting 14-42 days, the following results emerged: donepezil improved the retention of training on complex aviation tasks and verbal memory for semantically processed words. In one study episodic memory was improved, whereas in others it remained unaffected by donepezil. In a sleep deprivation trial, donepezil reduced the memory and attention deficits resulting from 24h of sleep deprivation. Two studies reported even transient negative effects. Regarding the safety profile of donepezil, these studies found that it was rather well tolerated. In any case, since large longitudinal studies are not available no conclusions can be drawn. Seven small studies about the effects of a single dose of memantine, and one study with a single dose of rivastigmine have been reported. Again, these studies are not adequate to answer our research question. If, as here and elsewhere suggested, the concept of pharmaceutical neuroenhancement is not to be rejected in principle, the decision of healthy individuals to take drugs for the purpose of neuroenhancement should be based on exhaustive information. At the moment, the research that would support or oppose the use of acetylcholinesterase inhibitors and memantine for neuroenhancement by healthy individuals has not yet been performed.

Acute cognitive effects of donepezil in young, healthy volunteers

OBJECTIVE

The acute nootropic potential of donepezil in young healthy volunteers has not been adequately investigated mainly because in previous studies: (1) effects were assessed before peak-plasma concentration (Tmax) was reached; (2) only a few cognitive processes were assessed. Here we investigated a myriad of cognitive effects of augmentation of acetylcholine using an acute dose of donepezil in healthy adults at theoretical Tmax.

METHODS

This was a double-blind, placebo controlled, parallel group design study of cognitive effects of acute oral donepezil (5 mg). Subjects were tested twice after donepezil ingestion: 90 min (time that coincides with previous testing in the literature) and 210 min. (theoretical Tmax). The test battery included tasks that tap cognitive domains that are sensitive to acetylcholine manipulations.

RESULTS

At both testing times donepezil improved long-term recall of prose, objects recall, recall of spatial locations, and integration of objects with their locations, some effects having been related to self-reported mood enhancement. However, improvement of performance in the central executive measure (backward digit span) occurred only at Tmax.

CONCLUSION

Positive cognitive effects of acute donepezil can be observed in various cognitive domains including mood, but its full nootropic potential is more clearly found close to theoretical peak-plasma concentration.

Methodological improvements in quantifying cognitive change in clinical trials: an example with single-dose administration of donepezil

OBJECTIVES

Change in cognitive function in response to a pharmacologic challenge can be observed with greater sensitivity by employing cognitive tests with optimal psychometric properties and a statistical approach that more accurately accounts for individual variability in performance. To demonstrate this approach we examined the cognitive effects of a single acute dose administration of an acetylcholinesterase inhibitor, donepezil, in healthy older adults and in older adults with mild Alzheimer's disease (AD).

DESIGN

Placebo-controlled crossover study with three separate testing days: baseline, placebo, and donepezil, with assessments at baseline, and 1-, 2-, 3-, 6-, and 8-hrs post-dosing on each day.

SETTING

Early phase I clinical trial.

PARTICIPANTS

15 healthy older adults; 14 older adults with mild Alzheimer's disease.

INTERVENTION

Single acute dose of 5mg donepezil.

MEASUREMENTS

Performance on the Groton Maze Learning Test (GMLT), a computerized neuropsychological measure of spatial working memory and error monitoring.

RESULTS

A single acute dose of donepezil improved GMLT performance in healthy older adults (effect size: 0.83 at 6 hrs post-dosing) and older adults with mild AD (effect size: 0.58 at 3 hrs post-dosing).

CONCLUSION

The GMLT detected cognitive improvement following a single, acute dose administration of donepezil in healthy older adults and older adults with mild AD. The choice of cognitive tests designed for repeated administration, as well as an analytic approach that emphasizes individual-level change in cognitive function, provides a sensitive approach to detecting central nervous system drug penetration and activity of cognitive-enhancing agents.

Methylthioninium chloride reverses cognitive deficits induced by scopolamine: comparison with rivastigmine

RATIONALE

The cholinergic system is involved in cognition as well as in age-related cognitive decline and Alzheimer disease (AD). Cholinergic enhancers ameliorate AD symptoms and represent the main current therapy for AD. MTC (Methylthioninium chloride), an antioxidant with metabolism-enhancing properties may be a novel candidate with pro-cognitive capacities.

OBJECTIVES

This study was performed: (1) to assess the pro-cognitive efficacy of MTC and establish its dose-response; (2) to compare the efficacy of MTC with rivastigmine and (3) to determine the potential for combination therapy by co-administration of MTC and rivastigmine.

METHODS

Spatial cognition of female NMRI mice was tested in a reference memory water maze task. Subjects received intra-peritoneal injections of scopolamine (0.5 mg/kg) followed by vehicle, and/or MTC and/or rivastigmine (0.15-4 mg/kg MTC; 0.1-0.5 mg/kg rivastigmine) in mono or combination treatment.

RESULTS

Scopolamine treatment prevented spatial learning in NMRI female mice and the deficit was reversed by both rivastigmine and MTC in a dose-dependent manner. Mono-therapy with high doses of rivastigmine (>0.5 mg/kg) caused severe side effects but MTC was safe up to 4 mg/kg. Co-administration of sub-effective doses of both drugs acted synergistically in reversing learning deficits and scopolamine-induced memory impairments.

CONCLUSIONS

In our model, MTC reversed the spatial learning impairment. When combined with the ChEI rivastigmine, the effect of MTC appeared to be amplified indicating that combination therapy could potentially improve not only symptoms but also contribute beneficially to neuronal metabolism by minimising side effects at lower doses.

Cognitive testing in early-phase clinical trials: Development of a rapid computerized test battery and application in a simulated Phase I study

BACKGROUND

Inclusion of cognitive assessment in Phase I trials of novel pharmaceutical agents may help identify subtle yet meaningful CNS effects early in clinical development, and lead to a greater understanding of the pharmacokinetic/pharmacodynamic relationship prior to entering pivotal late-phase trials.

AIMS

To examine issues surrounding the inclusion of a computerised cognitive test battery in Phase I clinical trials.

METHODS

A 12-minute battery of five computerized cognitive tasks was administered to 28 healthy males in a double-blind, single ascending dose study using three doses of midazolam (0.6 mg, 1.75 mg and 5.25 mg) with placebo insertion. Subjects were enrolled and assessed at two Phase I units. Statistical analyses sought to determine the sensitivity of the test battery to sedation-related cognitive dysfunction, any between-site differences in outcome, and also the effects of repeated test administration (i.e., practice or learning effects).

RESULTS

There were no significant differences in data collected between sites. All standard safety measurements were completed. No substantial technical issues were noted. No learning effects were observed on four of the five cognitive tasks. ANOVA comparing baseline to post-baseline results revealed significant cognitive deterioration on all five cognitive tasks 1 h following administration of 5.25 mg midazolam. The magnitude of these changes were very large according to conventional statistical criteria. Smaller but significant changes were observed on a subset of memory and learning tasks at 1 h post-dosing in 1.75 mg condition, and at 2 h post-dosing in the 5.25 mg condition.

CONCLUSIONS

The cognitive test battery was well tolerated by subjects and research unit staff. The tests demonstrated minimal learning effects, were unaffected by language and cultural differences between sites, and were sensitive to the sedative effects of midazolam. Inclusion of this cognitive test battery in future studies may allow identification of cognitive impairment or enhancement early in the clinical development cycle.

Memory enhancing drugs and Alzheimer's disease: enhancing the self or preventing the loss of it?

In this paper we analyse some ethical and philosophical questions related to the development of memory enhancing drugs (MEDs) and anti-dementia drugs. The world of memory enhancement is coloured by utopian thinking and by the desire for quicker, sharper, and more reliable memories. Dementia is characterized by decline, fragility, vulnerability, a loss of the most important cognitive functions and even a loss of self. While MEDs are being developed for self-improvement, in Alzheimer's Disease (AD) the self is being lost. Despite this it is precisely those patients with AD and other forms of dementia that provide the subjects for scientific research on memory improvement. Biomedical research in the field of MEDs and anti-dementia drugs appears to provide a strong impetus for rethinking what we mean by 'memory', 'enhancement', 'therapy', and 'self'. We conclude (1) that the enhancement of memory is still in its infancy, (2) that current MEDs and anti-dementia drugs are at best partially and minimally effective under specific conditions, (3) that 'memory' and 'enhancement' are ambiguous terms, (4) that there is no clear-cut distinction between enhancement and therapy, and (5) that the research into MEDs and anti-dementia drugs encourages a reductionistic view of the human mind and of the self.

A randomized, double-blind, placebo-controlled trial of donepezil to improve memory in epilepsy

PURPOSE

To determine whether an acetylcholinesterase inhibitor, such as donepezil, would improve memory or other cognitive/psychological functions in epilepsy patients with subjective memory complaints.

METHODS

Twenty-three epilepsy patients with subjective memory difficulty were randomized to either 3 months of donepezil (10 mg/day) or 3 months of placebo treatment, and then crossed over to the other treatment arm. Patients and physicians were blinded to treatment phase throughout data acquisition. Assessment of memory and other cognitive functions, subjective memory, mood, and self-rated quality of life (QOL) and social functioning was performed at baseline and following completion of both treatment phases. Seizure frequency and severity as well as treatment emergent adverse effects were also monitored.

RESULTS

Donepezil treatment was not associated with improvement in memory or other cognitive functions, mood, social functioning or QOL. Comparable increases in self-rated memory functioning relative to baseline were evident during donepezil and placebo phases. Donepezil treatment was not associated with increased seizure frequency or severity. Similar to group results, analysis of change within individual patients as a function of treatment phase also showed neither significant benefit nor detriment associated with donepezil.

CONCLUSION

This study found no benefit on memory or other cognitive/psychological functions in a heterogeneous group of epilepsy patients with subjective memory difficulty. Further investigation would be required to determine whether individual patients, or those with particular epilepsy syndromes, might benefit from donepezil or other acetylcholinesterase inhibitors, or if a higher dosage might be effective.

Cognitive testing in early phase clinical trials: outcome according to adverse event profile in a Phase I study

BACKGROUND

It has been proposed that objective cognitive testing provides additional information to that collected via adverse event (AE) recordings. However, in clinical trials of compounds with potentially negative effects on cognition, the results of cognitive testing may overlap with AE recordings.

AIMS

To examine cognitive function in subjects who do and do not report sedation-related AEs in a Phase I clinical trial.

METHODS

Five computerized cognitive tasks were administered to 28 healthy male volunteers enrolled in a simulated Phase I study using midazolam to induce sedation-related AEs and cognitive dysfunction. For each subject, the magnitude of cognitive change between pre-dose and 1 hr post-dose assessments was calculated. Group and individual level cognitive outcome was compared between subjects who did and did not report sedation-related AEs following administration of 1.75 and 5.25 mg midazolam.

RESULTS

At both doses of midazolam, cognitive dysfunction was observed in both subject groups (i.e., those who did and did not report AEs). Analysis of individual outcomes identified consistent cognitive dysfunction among subjects who reported sedation-related AEs. Further, in the 5.25 mg condition a subset of individuals (66.7%) who did not report sedation-related AEs nevertheless displayed substantial cognitive dysfunction.

CONCLUSIONS

Following administration of oral midazolam, there is a dissociation between sedation-related AE recordings and performance on computerized cognitive tests of motor function, attention, strategy use and problem solving, learning and delayed recall. Inclusion of computerized cognitive tests in early phase trials may allow identification of subtle cognitive change, beyond that which is possible by self-report and clinical observation.

Cholinergic enhancement of episodic memory in healthy young adults

RATIONALE

Acetylcholine esterase (AchE) inhibitors are known to remediate symptoms of Alzheimer's disease. However, only few systematic data exist on the effects of cholinergic treatment on cognitive functions in normal subjects.

OBJECTIVE

This study evaluated the effects of donepezil, an inhibitor of AchE, on cognitive performance in young and healthy subjects.

METHODS

We used a randomised double-blind parallel group placebo-controlled repeated measures design to investigate changes of cognitive functions in a group of 30 young healthy male subjects (mean age 23.9 years+/-2.24 SD) upon application of donepezil or placebo for 30 days. Attentional and executive functions, visual and verbal short-term and working memory, semantic memory, as well as verbal and visual episodic memory were investigated using an extensive neuropsychological test battery.

RESULTS

Time-by-group interactions demonstrated significant drug effects that were specific to episodic memory in both the verbal and visual domain. Additionally, donezepil significantly improved long-term visual episodic recall. In none of the other functions under investigation any significant treatment effects were observed.

CONCLUSION

Given this specific drug effect and the well-known relevance of the hippocampal region for episodic memory, we conclude that this region appears to be the major target of cholinergic enhancement in healthy subjects due to long-term inhibition of AchE.

Cognition-Enhancing Effects of Donepezil in Traumatic Brain Injury

The purpose of this study was to investigate the effects of donepezil, a cholinergic agent, on chronic cognitive impairment due to traumatic brain injury (TBI). Chronic patients underwent two standardized neuropsychological evaluations--one before and the other 3 months following treatment with donepezil. Together with global inventories that appraised behaviour, fatigue, anxiety and depression, these evaluations also assessed executive functioning, memory and attention. Of the 10 patients who followed the therapy, 8 reported subjective improvement in at least one cognitive domain following therapy and most of them reported better functioning in everyday activities. This effect was supported by a slight global improvement when considering the global score of the different affectivo-behavioural scales. At the neuropsychological level, although we could observe a slight improvement in the majority of the considered tests, significant positive changes were mainly found in tests assessing speed of processing, learning and divided attention. These findings suggest that donepezil may lead to better general functioning and improve attentional skills in patients with chronic TBI.

Neuropsychological test performance in healthy elderly volunteers before and after donepezil administration: a randomized, controlled study

Neuropsychological performance was examined in healthy elderly participants administered the cholinesterase inhibitor donepezil. Of principal interest was examination of the sensitivity of a series of neuropsychological measures to detect cognitive changes after drug administration using typical phase I research parameters (eg, a small sample over a short treatment period). In this double-blind parallel study over a period of 6 weeks, 26 healthy elderly participants (aged 55 to 75 years) were randomized into 1 of 2 arms (14 donepezil and 12 placebo) and completed 14 days of donepezil (5 mg, twice a day) or placebo (twice a day). A battery of neuropsychological tests was administered on days 0, 14 (prerandomization), 28 (end of treatment), and 42 (washout). After 2 weeks of donepezil treatment (day 28), subjects in the donepezil group performed slightly but significantly worse on 2 tests of speed, attention, and short-term memory (P < 0.05) compared with the placebo group. No significant improvement in performance was present on any test during treatment with donepezil. These results are consistent with a previous study in healthy young participants in which transient mild worsening on some cognitive tests during donepezil administration was observed, possibly caused by perturbation of an already optimized cholinergic system in healthy participants. These results are important to consider when designing clinical development plans for putative cognitive-enhancing drugs; in addition, these results raise questions about when the optimal point to begin treatment is for patients who have not yet met criteria for dementia.