Cognitive, global, and functional benefits of donepezil in Alzheimer's disease and vascular dementia: results from large-scale clinical trials

Comparative efficacy and acceptability of cholinesterase inhibitors and memantine based on dosage in patients with vascular cognitive impairment: a network meta-analysis

BACKGROUND

Considering the lack of direct comparison between cholinesterase inhibitors and memantine in patients with vascular cognitive impairment (VCI), determining how to choose the best treatment plan remains inconclusive. Hence, we conducted the network meta-analysis to compare the efficacy and acceptability of these drugs.

METHODS

PubMed, the Cochrane Central Register of Controlled Trials, Embase and Web of Science were searched for double-blind randomized controlled trials (RCTs) for the treatment of VCI, which involved donepezil, galantamine, rivastigmine, and memantine, from database inception to January 1, 2020. Then, a network meta-analysis based on the frequency method was conducted.

RESULTS

Eleven RCTs were included. Compared with the placebo, in terms of efficacy donepezil 5 mg (standardized mean difference = -1.11, 95% confidence interval = -1.88 to -0.34), donepezil 10 mg (-1.44, -2.31 to -0.56), galantamine 24 mg (-1.99, -3.03 to -0.95), and memantine 20 mg (-1.89, -2.93 to -0.86) were more effective on the cognition of ADAS-cog; and donepezil 5 mg (0.46, 0.12 to 0.81), donepezil 10 mg (0.76, 0.34 to 1.17), and rivastigmine 12mg (0.60, 0.10 to 1.10) exhibited superior benefits on the cognition of MMSE. Donepezil 10 mg (-0.25, -0.44 to -0.06; -1.47, -2.79 to -0.15) exhibited improvements on CDR-SB and EXIT25, respectively. In terms of acceptability, the memantine behaved as the best.

CONCLUSIONS

Donepezil 5 mg, donepezil 10 mg, galantamine 24 mg, memantine 20 mg, and rivastigmine 12 mg have beneficial effects on cognition, and donepezil 10mg provides beneficial effects on executive function and global status. Based on the network meta-analysis, donepezil 10 mg might be the best choice, considering the benefits on cognition function, executive function and global status, but dose-related adverse reactions need to be noted. In the meantime, memantine is a better comprehensive choice, in terms of efficacy and safety acceptability.

Clinical practice with anti-dementia drugs: A revised (third) consensus statement from the British Association for Psychopharmacology

The British Association for Psychopharmacology coordinated a meeting of experts to review and revise its previous 2011 guidelines for clinical practice with anti-dementia drugs. As before, levels of evidence were rated using accepted standards which were then translated into grades of recommendation A-D, with A having the strongest evidence base (from randomised controlled trials) and D the weakest (case studies or expert opinion). Current clinical diagnostic criteria for dementia have sufficient accuracy to be applied in clinical practice (B) and both structural (computed tomography and magnetic resonance imaging) and functional (positron emission tomography and single photon emission computerised tomography) brain imaging can improve diagnostic accuracy in particular situations (B). Cholinesterase inhibitors (donepezil, rivastigmine, and galantamine) are effective for cognition in mild to moderate Alzheimer's disease (A), memantine for moderate to severe Alzheimer's disease (A) and combination therapy (cholinesterase inhibitors and memantine) may be beneficial (B). Drugs should not be stopped just because dementia severity increases (A). Until further evidence is available other drugs, including statins, anti-inflammatory drugs, vitamin E, nutritional supplements and Ginkgo biloba, cannot be recommended either for the treatment or prevention of Alzheimer's disease (A). Neither cholinesterase inhibitors nor memantine are effective in those with mild cognitive impairment (A). Cholinesterase inhibitors are not effective in frontotemporal dementia and may cause agitation (A), though selective serotonin reuptake inhibitors may help behavioural (but not cognitive) features (B). Cholinesterase inhibitors should be used for the treatment of people with Lewy body dementias (both Parkinson's disease dementia and dementia with Lewy bodies), and memantine may be helpful (A). No drugs are clearly effective in vascular dementia, though cholinesterase inhibitors are beneficial in mixed dementia (B). Early evidence suggests multifactorial interventions may have potential to prevent or delay the onset of dementia (B). Though the consensus statement focuses on medication, psychological interventions can be effective in addition to pharmacotherapy, both for cognitive and non-cognitive symptoms. Many novel pharmacological approaches involving strategies to reduce amyloid and/or tau deposition in those with or at high risk of Alzheimer's disease are in progress. Though results of pivotal studies in early (prodromal/mild) Alzheimer's disease are awaited, results to date in more established (mild to moderate) Alzheimer's disease have been equivocal and no disease modifying agents are either licensed or can be currently recommended for clinical use.

Neuronal AChE splice variants and their non-hydrolytic functions: redefining a target of AChE inhibitors?

AChE enzymatic inhibition is a core focus of pharmacological intervention in Alzheimer's disease (AD). Yet, AChE has also been ascribed non-hydrolytic functions, which seem related to its appearance in various isoforms. Neuronal AChE presents as a tailed form (AChE-T) predominantly found on the neuronal synapse, and a facultatively expressed readthough form (AChE-R), which exerts short to medium-term protective effects. Notably, this latter form is also found in the periphery. While these non-hydrolytic functions of AChE are most controversially discussed, there is evidence for them being additional targets of AChE inhibitors. This review aims to provide clarification as to the role of these AChE splice variants and their interplay with other cholinergic parameters and their being targets of AChE inhibition: AChE-R is particularly involved in the mediation of (anti-)apoptotic events in cholinergic cells, involving adaptation of various cholinergic parameters and a time-dependent link to the expression of neuroprotective factors. The AChE-T C-terminus is central to AChE activity regulation, while isolated AChE-T C-terminal fragments mediate toxic effects via the α7 nicotinic acetylcholine receptor. There is direct evidence for roles of AChE-T and AChE-R in neurodegeneration and neuroprotection, with these roles involving AChE as a key modulator of the cholinergic system: in vivo data further encourages the use of AChE inhibitors in the treatment of neurodegenerative conditions such as AD since effects on both enzymatic activity and the enzyme's non-hydrolytic functions can be postulated. It also suggests that novel AChE inhibitors should enhance protective AChE-R, while avoiding the concomitant up-regulation of AChE-T.

Developing interventions for cancer-related cognitive dysfunction in childhood cancer survivors

Survivors of childhood cancer frequently experience cancer-related cognitive dysfunction, commonly months to years after treatment for pediatric brain tumors, acute lymphoblastic leukemia (ALL), or tumors involving the head and neck. Risk factors for cancer-related cognitive dysfunction include young age at diagnosis, treatment with cranial irradiation, use of parenteral or intrathecal methotrexate, female sex, and pre-existing comorbidities. Limiting use and reducing doses and volume of cranial irradiation while intensifying chemotherapy have improved survival and reduced the severity of cognitive dysfunction, especially in leukemia. Nonetheless, problems in core functional domains of attention, processing speed, working memory and visual-motor integration continue to compromise quality of life and performance. We review the epidemiology, pathophysiology and assessment of cancer-related cognitive dysfunction, the impact of treatment changes for prevention, and the broad strategies for educational and pharmacological interventions to remediate established cognitive dysfunction following childhood cancer. The increased years of life saved after childhood cancer warrants continued study toward the prevention and remediation of cancer-related cognitive dysfunction, using uniform assessments anchored in functional outcomes.

Clinical practice with anti-dementia drugs: a revised (second) consensus statement from the British Association for Psychopharmacology

The British Association for Psychopharmacology (BAP) coordinated a meeting of experts to review and revise its first (2006) Guidelines for clinical practice with anti-dementia drugs. As before, levels of evidence were rated using accepted standards which were then translated into grades of recommendation A to D, with A having the strongest evidence base (from randomized controlled trials) and D the weakest (case studies or expert opinion). Current clinical diagnostic criteria for dementia have sufficient accuracy to be applied in clinical practice (B) and brain imaging can improve diagnostic accuracy (B). Cholinesterase inhibitors (donepezil, rivastigmine, and galantamine) are effective for mild to moderate Alzheimer's disease (A) and memantine for moderate to severe Alzheimer's disease (A). Until further evidence is available other drugs, including statins, anti-inflammatory drugs, vitamin E and Ginkgo biloba, cannot be recommended either for the treatment or prevention of Alzheimer's disease (A). Neither cholinesterase inhibitors nor memantine are effective in those with mild cognitive impairment (A). Cholinesterase inhibitors are not effective in frontotemporal dementia and may cause agitation (A), though selective serotonin reuptake inhibitors may help behavioural (but not cognitive) features (B). Cholinesterase inhibitors should be used for the treatment of people with Lewy body dementias (Parkinson's disease dementia and dementia with Lewy bodies (DLB)), especially for neuropsychiatric symptoms (A). Cholinesterase inhibitors and memantine can produce cognitive improvements in DLB (A). There is no clear evidence that any intervention can prevent or delay the onset of dementia. Although the consensus statement focuses on medication, psychological interventions can be effective in addition to pharmacotherapy, both for cognitive and non-cognitive symptoms. Many novel pharmacological approaches involving strategies to reduce amyloid and/or tau deposition are in progress. Although results of pivotal studies are awaited, results to date have been equivocal and no disease-modifying agents are either licensed or can be currently recommended for clinical use.

The effect of donepezil treatment on cardiovascular mortality

The acetylcholinesterase inhibitor donepezil hydrochloride improves cognitive function in patients with Alzheimer's disease and vascular dementia. Given acetylcholine's important actions on the heart, we undertook a retrospective cohort investigation to assess whether donepezil usage affects cardiovascular mortality. In patients treated with donepezil, hazard ratios for total and cardiovascular mortality were 0.68 (P = 0.045, 95% confidence interval 0.46-0.99) and 0.54 (P = 0.042, 95% confidence interval 0.30-0.98), respectively. The apparent survival benefit in donepezil-treated patients should not be overinterpreted. Prospective clinical trials are warranted.

Beyond mild cognitive impairment: vascular cognitive impairment, no dementia (VCIND)

Identifying the causes of dementia is important in the search for effective preventative and treatment strategies. The concept of mild cognitive impairment (MCI), as prodromal dementia, has been useful but remains controversial since in population-based studies it appears to be a limited predictor of progression to dementia. Recognising the relative contribution of neurodegenerative and vascular causes, as well as their interrelationship, may enhance predictive accuracy. The concept of vascular cognitive impairment (VCI) has been introduced to describe the spectrum of cognitive change related to vascular causes from early cognitive decline to dementia. A recent review of this concept highlighted the need for diagnostic criteria that encompass the full range of the VCI construct. However, very little is known regarding the mildest stage of VCI, generally termed 'vascular cognitive impairment, no dementia' (VCIND). Whether mild cognitive change in the context of neurodegenerative pathologies is distinct from that in the context of cerebrovascular diseases is not known. This is key to the definition of VCIND and whether it is possible to identify this state. Distinguishing between vascular (that is, VCIND) and non-vascular (that is, MCI) cognitive disorders and determining how well each might predict dementia may not be possible due to the overlap in pathologies observed in the older population. Here, we review the concept of VCIND in an effort to identify recent developments and areas of controversy in nosology and the application of VCIND for screening individuals at increased risk of dementia secondary to vascular disease and its risk factors.

Alzheimer's and non-alzheimer's dementia: a critical review of pharmacological and nonpharmacological strategies

OBJECTIVE

Dementia is an age-related progressive neurodegenerative disorder afflicting about 5% of the world's population, and it is expected to grow dramatically in the future keeping in view our ageing society. Currently available medications appear to be able to produce moderate symptomatic benefits but do not to stop disease progression. In this article, the management of the disorder, including the currently available drugs as well as psychosocial strategies, is discussed.

METHODS

A computerized search on Pubmed from 1980 to 2006 was carried out and all articles evaluated and graded on NICE guidelines.

RESULTS AND CONCLUSIONS

Currently evaluated and accepted medications only bring about a reduction in the deteriorating course. A combination of pharmacotherapy and psychosocial management is the need of the hour.

Efficacy and safety of donepezil over 3 years: an open-label, multicentre study in patients with Alzheimer's disease

OBJECTIVE

This 132-week, open-label extension study assessed the long-term efficacy and safety of donepezil in 579 patients with mild to moderate Alzheimer's disease (AD) who had previously participated in a 24-week double-blind study of 5 or 10 mg/day donepezil vs placebo.

METHOD

Patients enrolled in the present study had a 6-week single-blind placebo washout period followed by treatment with donepezil 5 mg/day for 6 weeks with an optional increase in dosage to 10 mg/day between weeks 6 and 32.

RESULTS

After 6 weeks of open-label treatment with donepezil 5 mg/day, mean Alzheimer's Disease Assessment Scale -- cognitive subscale scores (ADAS-cog) improved by approximately two points, while after 12 weeks of open-label treatment (with a majority of patients receiving 10 mg/day), the mean ADAS-cog score was 1 point better than the score at the end of the placebo washout period. Scores then declined gradually over the remainder of the study. Mean changes in Clinical Dementia Rating-Sum of Boxes scores showed slight improvement over the first 12 weeks of open-label treatment and then slowly declined for the remainder of the study period. Donepezil was well tolerated over the entire 162-week study period. Overall, 85% of patients experienced at least one adverse event (AE). The most common included diarrhoea (12%), nausea (11%), infection (11%) and accidental injury (10%). Some patients discontinued the study due to AEs (15%).

CONCLUSIONS

These results support the conclusion that donepezil is safe and effective for the long-term treatment of patients with mild to moderate AD.

Donepezil: an update

Donepezil hydrochloride is the most widely prescribed drug for Alzheimer's disease (AD). The main mechanism of action through which it influences cognition and function is presumed to be the inhibition of acetylcholinesterase enzyme in the brain; however, donepezil may also impact the pathophysiology of AD at several other points. Officially approved for mild-to-moderate and severe AD, donepezil has also been shown to be effective in early-stage AD, vascular dementia, Parkinson's disease dementia/Lewy body disease and cognitive symptoms associated with multiple sclerosis. In addition, one study suggested that donepezil may delay the onset of AD in subjects with mild cognitive impairment, a prodrome to AD. The pharmacokinetics, pharmacodynamics, safety/tolerability profile and drug interaction properties of donepezil make it an easy and safe agent to use. However, in general, the efficacy of donepezil is limited, and ongoing studies are investigating other agents that may ultimately overtake its present position as the mainstay of anti-AD therapy.

New treatment options for vascular dementia

Clinical trials performed in patients defined as affected by vascular dementia have so far achieved unsatisfactory results. Recently, preliminary results have been published demonstrating a generally stable performance in cognitive tasks, with a slightly better performance in executive functions and a better behavioral response, in a group of subcortical vascular dementia patients treated with rivastigmine. A recent proposal is that vascular dementia is not an univocal and unique pathology: the etiopathogenesis of multi-infarct dementia is quite different to that of subcortical vascular dementia. Future studies need to consider those entities separately to obtain good results for a group of patients for whom, until now, there have been few therapeutic options. The aim of this review is to summarize the consolidated notions, perspectives and new therapeutic options to better define the possible future treatment of vascular dementia.

In vitro characterization of a gamma-secretase radiotracer in mammalian brain

Inhibition of gamma-secretase is a potential therapeutic target for Alzheimer's disease (AD). The present studies have characterized the in vitro properties of a radiolabeled small molecule gamma-secretase inhibitor, [3H]compound D (Yan et al., 2004, J. Neurosci.24, 2942-2952) in mammalian brain. [3H]Compound D was shown to bind with nanomolar affinity (Kd = 0.32-1.5 nM) to a single population of saturable sites in rat, rhesus and human brain cortex homogenates, the density of binding sites ranging from 4 to 7 nM across the species. Competition studies with a structurally diverse group of gamma-secretase inhibitors with a wide range of binding affinities showed that the binding affinities of these compounds correlated well with their ability to inhibit gamma-secretase in vitro. Autoradiographic studies showed that the specific binding of [3H]compound D was widely distributed throughout adult rat, rhesus and normal human brain. There did not appear to be any difference in distribution of [3H]compound D specific binding sites in AD cortex compared with control human cortex as measured using tissue section autoradiography, nor any correlation between gamma-secretase binding and plaque burden as measured immunohistochemically. [3H]compound D is a useful tool to probe the expression and pharmacology of gamma-secretase in mammalian brain.

The underdiagnosis of the vascular contribution to dementia

The existence of vascular dementia (VaD) was first identified by Marie, who described the etat lacunaire, and by Binswanger, who identified white matter lesions in the brain subcortical areas. Alois Alzheimer, when defining the disease now bearing his name, did so in a patient with a presenile onset. The majority of demented elderly people were then believed to have cerebral arteriosclerosis underlying their cognitive decline. The role of cortical vascular lesions, while clear to clinicians, was highlighted only later, by the pathological studies of Tomlinson et al. and the clinical demonstrations of Hachinski et al. who have defined multi-infarct dementia. Lately, the emphasis shifted to pathogenic mechanisms for vascular brain disease with the identification of a multitude of processes, such as lipohyalinosis, cardiac dysfunction and genetic causes, to name only a few. Epidemiologic studies have demonstrated the high frequency of vascular lesions in brains of demented individuals, as well as the fact that vascular factors can contribute to Alzheimer's disease (AD). Moreover, many factors, which were identified as contributing to cerebrovascular disease in general and VaD in particular, are frequently suspected as predisposing to AD as well. All these considerations converge to the realization that vascular components are extremely important in the pathogenesis of old-age dementia and that prevention and perhaps treatment of dementia are within reach. These surprising findings highlight the importance of mixed vascular-degenerative dementia as a disorder that has to be properly defined.