Donepezil in vascular dementia: combined analysis of two large-scale clinical trials

Diagnosis and management of vascular cognitive impairment

Accurate diagnosis of vascular cognitive impairment (VCI) is important but may be difficult. VCI diagnoses depend on determinations of the presence of both cognitive impairment and cerebrovascular disease (CVD), temporal causal links between cognitive impairment and CVD, and the presence or absence of other potential contributors to cognitive impairment, such as Alzheimer's disease (AD). Diagnostic criteria differ across currently utilized systems, resulting in widely differing VCI prevalence rates. Also, current systems may not be able to differentiate "pure" VCI from "mixed" AD and CVD. National Institute of Neurological Disorders and Stroke harmonization criteria for VCI have been developed for study and validation to help bridge gaps in our understanding of VCI diagnosis. VCI management begins with atherogenic risk factor control. Current VCI treatment options demonstrate statistical improvement but not consistent global clinical efficacy. Future clinical trials should concentrate on both primary risk factor control and development of new therapeutic agents to treat patients already diagnosed with VCI.

Cholinesterase inhibition modulates visual and attentional brain responses in Alzheimer's disease and health

Visuo-attentional deficits occur early in Alzheimer's disease (AD) and are considered more responsive to pro-cholinergic therapy than characteristic memory disturbances. We hypothesised that neural responses in AD during visuo-attentional processing would be impaired relative to controls, yet partially susceptible to improvement with the cholinesterase inhibitor physostigmine. We studied 16 mild AD patients and 17 age-matched healthy controls, using fMRI-scanning to enable within-subject placebo-controlled comparisons of effects of physostigmine on stimulus- and attention- related brain activations, plus between-group comparisons for these. Subjects viewed face or building stimuli while performing a shallow judgement (colour of image) or a deep judgement (young/old age of depicted face or building). Behaviourally, AD subjects performed slower than controls in both tasks, while physostigmine benefited the patients for the more demanding age-judgement task. Stimulus-selective (face minus building, and vice versa) BOLD signals in precuneus and posterior parahippocampal cortex were attenuated in patients relative to controls, but increased following physostigmine. By contrast, face-selective responses in fusiform cortex were not impaired in AD and showed decreases following physostigmine for both groups. Task-dependent responses in right parietal and prefrontal cortices were diminished in AD but improved following physostigmine. A similar pattern of group and treatment effects was observed in two extrastriate cortical regions that showed physostigmine-induced enhancement of stimulus-selectivity for the deep versus shallow task. Finally, for the healthy group, physostigmine decreased stimulus and task-dependent effects, partly due to an exaggeration of selectivity during the shallow relative to deep task. The differences in brain activations between groups and treatments were not attributable merely to performance (reaction time) differences. Our results demonstrate that physostigmine can improve both stimulus- and attention-dependent responses in functionally affected extrastriate and frontoparietal regions in AD, while perturbing the normal pattern of responses in many of the same regions in healthy controls.

A randomized controlled trial of the group reminiscence approach in patients with vascular dementia

AIM

To evaluate the beneficial effect of the group reminiscence approach (GRA) in patients with vascular dementia on the aspect of cognitive and observed behavioral parameters.

METHODS

Sixty patients who were diagnosed to have vascular dementia were randomly assigned to three arms: group reminiscence arm, social contact arm, and control arm. A 1-hour session of GRA and social contact was given once a week for 3 months to the group reminiscence and the social contact arm, respectively. Only supportive care was given in the control arm. Improvement in cognitive function and behavioral activities were defined as the primary outcome.

RESULTS

No significant improvements in the main outcome measures were demonstrated.

CONCLUSION

These results do not support the hypothesis that GRA is beneficial to patients with vascular dementia.

Efficacy and adverse effects of cholinesterase inhibitors and memantine in vascular dementia: a meta-analysis of randomised controlled trials

BACKGROUND

Cholinesterase inhibitors and memantine do not have regulatory approval in most of the world for treatment of vascular dementia. A systematic review and meta-analysis was undertaken to assess the evidence for efficacy and safety of cholinesterase inhibitors and memantine in vascular dementia.

METHODS

PubMed, BIOSIS, International Pharmaceutical Abstracts, and Cochrane registries were searched for randomised, placebo-controlled trials on cholinesterase inhibitors and memantine in patients with vascular dementia. Trial methods, clinical characteristics, outcomes, and adverse events were extracted and checked. Meta-analytic methods using fixed-effects models were used to give summaries of each drug's effects.

FINDINGS

Three donepezil, two galantamine, one rivastigmine, and two memantine trials, comprising 3093 patients on the study drugs and 2090 patients on placebo, met the selection criteria. Trials were of 6-month duration with similar vascular dementia criteria and outcome measures. Cognitive effects on the Alzheimer's Disease Assessment scale were significant for all drugs, ranging from a -1.10 point mean difference (95% CI -2.15 to -0.05) for rivastigmine to -2.17 for 10 mg daily donepezil (95% CI -2.98 to -1.35). Only 5 mg daily donepezil had an effect on the Clinicians' Global Impression of Change scale (odds ratio 1.51 [95% CI 1.11-2.07]). No behavioural or functional benefits were observed, except for a -0.95 point difference (95% CI -1.74 to -0.16) with 10 mg daily donepezil on the Alzheimer's Disease Functional Assessment and Change Scale. Compared with placebo, more dropouts and adverse events (anorexia, nausea, vomiting, diarrhoea, and insomnia) occurred with the cholinesterase inhibitors, but not with memantine.

INTERPRETATION

Cholinesterase inhibitors and memantine produce small benefits in cognition of uncertain clinical significance in patients with mild to moderate vascular dementia. Data are insufficient to support widespread use of these drugs in vascular dementia. Individual patient analyses are needed to identify subgroups of patients with vascular dementia who might benefit.

[A contribution to the current discussion on anti-dementia drugs in Germany]

In Germany, the role of acetylcholinesterase inhibitors in the treatment of Alzheimer's disease (AD) has become a topic of recent discussion. The present article addresses issues which, in the opinion of the authors, have not received sufficient attention. These include the distinction between statistical and clinical significance, outcome parameters, the duration of clinical trials, variability in treatment response and the definition of treatment responders. The authors argue that these issues need to be considered in an in-depth evaluation of acetylcholinesterase inhibitors in the treatment of 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.

Cholinergic precursors in the treatment of cognitive impairment of vascular origin: ineffective approaches or need for re-evaluation?

Inhibition of endogenous acetylcholine degradation through cholinesterase inhibitors represents a milestone in symptomatic treatment of cognitive symptoms in mild to moderate stages of Alzheimer's disease. Cholinesterase inhibitors are also under investigation for treating cognitive dysfunction of cerebrovascular origin, but to date they do not have specific indication for vascular dementia or vascular cognitive impairment. This paper reviews the main clinical studies assessing the activity of cholinergic precursors in the treatment of adult-onset dementia disorders of vascular origin. The first cholinergic precursor used phosphatidylcholine (lecithin) did not show any clear clinical benefit on symptoms of dementia disorders. The same is not true for other phospholipids involved in choline biosynthetic pathways such as cytidine 5'-diphosphocholine (CDP-choline) and choline alphoscerate for which a modest improvement of cognitive dysfunction in dementia of neurodegenerative and vascular origin is documented. Positive results obtained with selected cholinergic precursors cannot be generalized due to the small numbers of patients studied in appropriate clinical trials. However, they probably would justify reconsideration of the most promising molecules in larger carefully controlled studies.

Disease progression in vascular cognitive impairment: Cognitive, functional and behavioural outcomes in the Consortium to Investigate Vascular Impairment of Cognition (CIVIC) cohort study

BACKGROUND AND PURPOSE

Empirical studies to clarify the outcomes in Vascular Cognitive Impairment (VCI) are needed. We compared cognitive, functional, and behavioural outcomes in patients with VCI to patients with no cognitive impairment (NCI), and Alzheimer's disease (AD).

METHODS

Secondary analysis of the Consortium to Investigate Vascular Impairment of Cognition (CIVIC), a multi-centre Canadian memory clinic 30-month cohort study.

RESULTS

Of 1347 patients, 938 were eligible for follow-up, of whom 239 (24.5%) were lost and 29 (3%) had died. Of the remaining 697 patients, 125 had NCI, 229 had VCI, and 343 had AD at baseline. Compared to people with NCI, of whom 20-40% showed progression based on cognitive and functional measures, those with VCI were more likely to progress (50-65%), as were people with AD (50-80%) (p<0.01). More people with VCI showed progression of affective symptoms (30%) than those with NCI (12%) or AD (15% p<0.01). Progression of impaired judgment (rated clinically) in VCI (15%) was similar to AD (11%) but more common than in NCI (4%, p<0.01).

CONCLUSIONS

Most people with VCI show readily detectable progression by 30 months. Depressive symptoms were more common and more progressive in VCI than in Alzheimer's disease, whereas clinical evidence of progressive executive dysfunction was common in both AD and VCI.

Cognitive function following stroke and vascular cognitive impairment

PURPOSE OF REVIEW

This review of the cognitive status following stroke and vascular cognitive impairment starts by questioning the concept of vascular dementia and related concepts. Our position is that in many cases these labels promote a superficial conceptualization of an inherently complex and heterogeneous phenomenon hampering a more detailed understanding.

RECENT FINDINGS

After stroke or disease of the cerebral vasculature, the cognitive and emotional outcome is dependent on a combination of three factors with the relative importance differing between causes. First, focal damage may lead to selective impairments that are dependent on the localization of the (grey matter) lesion. Second, diffuse neuronal dysfunction produces a more uniform profile of a decrease in mental speed, memory problems, and reduced executive functioning. Third, cognitive outcome is further modulated - notably in terms of severity - by patient variables such as age, sex, premorbid level of functioning, and comorbidity (e.g. hypertension).

SUMMARY

The complex character of the cognitive repercussions of stroke can be better harnessed by employing modern neuropsychological assessment procedures. This allows both a detailed categorization of the patients for the selection and effectiveness of therapeutic intervention, as well as the construction of reliable prognostic models.

'I think therefore I am': improving cognition

PURPOSE OF REVIEW

In the absence of a specific treatment for dementia, the effective management of cognitive symptoms is a clinical priority.

RECENT FINDINGS

Although some differences have been observed in the profile of cognitive complaints observed in subtypes of dementia, there is increasing recognition of common, interacting neurobiological causes suggesting the need to seek a common treatment applicable to all causes of cognitive deterioration. There also exists increasing interest in intervening at the level of minor cognitive dysfunction by reducing risk factors for subclinical states.

SUMMARY

Pharmacological treatment of cognitive disorder is beneficial but has only temporary benefit for a subgroup of patients. Pharmacogenetics may have an important future role to play in deciding which patients may best benefit from the treatment. Low side effect therapies such as cognitive therapy and acupuncture show some benefits but their utility in combination with pharmacotherapies remains to be demonstrated. Prevention of milder forms of cognitive disorder by controlling risk factors such as hypertension and diabetes may reduce rates of more severe cognitive degeneration. Persons with cognitive dysfunction are commonly excluded from making decisions about the implementation of cognition-enhancing treatments although they wish to do so.

Use of antidementia agents in vascular dementia: beyond Alzheimer disease

Vascular dementia (VaD) is the second leading cause of dementia and is often underdiagnosed. Stroke is the leading cause of VaD, although it may also develop secondary to a variety of other cerebrovascular or cardiovascular conditions. Currently, no drugs are approved for the treatment of VaD. However, because cholinergic deficits have been found in patients with VaD, similar to those found in patients with Alzheimer disease (AD), it is believed that cholinesterase inhibitors, which are indicated for the treatment of mild to moderate AD, may also provide benefit for patients with VaD. Clinical trials of donepezil, galantamine, and rivastigmine have supported this idea, although as yet, large-scale, prospective studies in VaD have only been reported for donepezil. Donepezil was shown to provide benefits in cognition, global function, and activities of daily living compared with placebo. The N-methyl-D-aspartate receptor antagonist memantine may also provide some cognitive benefit in VaD, particularly in patients with more advanced disease. These data suggest that antidementia drugs currently used for treatment of AD should be considered for treatment of VaD as well.