OBJECTIVES: To assess the clinical effects, including adverse effects, of galantamine in people with probable or possible Alzheimer's disease or mild cognitive impairment, and to investigate potential moderators of effect.
SEARCH METHODS: We systematically searched the Cochrane Dementia and Cognitive Improvement Group's Specialised Register on 14 December 2022 using the term 'galantamine'. The Register contains records of clinical trials identified from major electronic databases (including CENTRAL, MEDLINE, and Embase), trial registries, grey literature sources, and conference proceedings. We manually searched reference lists and collected information from US Food and Drug Administration documents and unpublished trial reports. We imposed no language restrictions.
SELECTION CRITERIA: We included double-blind, parallel-group, randomised controlled trials comparing oral galantamine with placebo for a treatment duration exceeding four weeks in people with dementia due to Alzheimer's disease or with mild cognitive impairment.
DATA COLLECTION AND ANALYSIS: Working independently, two review authors selected studies for inclusion, assessed their quality, and extracted data. Outcomes of interest included cognitive function, change in global function, activities of daily living, functional disability, behavioural function, and adverse events. We used a fixed-effect model for meta-analytic synthesis, and presented results as Peto odds ratios (OR) or weighted mean differences (MD) with 95% confidence intervals. We used Cochrane's original risk of bias tool (RoB 1) to assess the risk of bias in the included studies.
MAIN RESULTS: We included 21 studies with a total of 10,990 participants. The average age of participants was 74 years, and 37% were male. The studies' durations ranged from eight weeks to two years, with 24 weeks being the most common duration. One newly included study assessed the effects of galantamine at two years, and another newly included study involved participants with severe Alzheimer's disease. Nineteen studies with 10,497 participants contributed data to the meta-analysis. All studies had low to unclear risk of bias for randomisation, allocation concealment, and blinding. We judged four studies to be at high risk of bias due to attrition and two due to selective outcome reporting. Galantamine for dementia due to Alzheimer's disease We summarise only the results for galantamine given at 8 to 12 mg twice daily (total galantamine 16 mg to 24 mg/day), assessed at six months. See the full review for results of other dosing regimens and assessment time points. There is high-certainty evidence that, compared to placebo, galantamine improves: cognitive function, as assessed with the Alzheimer's Disease Assessment Scale - Cognitive Subscale (ADAS-cog) (MD-2.86, 95% CI -3.29 to -2.43; 6 studies, 3049 participants; minimum clinically important effect (MCID) = 2.6- to 4-point change); functional disability, as assessed with the Disability Assessment for Dementia (DAD) scale (MD 2.12, 95% CI 0.75 to 3.49; 3 studies, 1275 participants); and behavioural function, as assessed with the Neuropsychiatric Inventory (NPI) (MD -1.63, 95% CI -3.07 to -0.20; 2 studies, 1043 participants) at six months. Galantamine may improve global function at six months, as assessed with the Clinician's Interview-Based Impression of Change plus Caregiver Input (CIBIC-plus) (OR 1.58, 95% CI 1.36 to 1.84; 6 studies, 3002 participants; low-certainty evidence). Participants who received galantamine were more likely than placebo-treated participants to discontinue prematurely (22.7% versus 17.2%) (OR 1.41, 95% CI 1.19 to 1.68; 6 studies, 3336 participants; high-certainty evidence), and experience nausea (20.9% versus 8.4%) (OR 2.89, 95% CI 2.40 to 3.49; 7 studies, 3616 participants; high-certainty evidence) during the studies. Galantamine reduced death rates at six months: 1.3% of participants in the galantamine groups had died compared to 2.3% in the placebo groups (OR 0.56, 95% CI 0.33 to 0.96; 6 studies, 3493 participants; high-certainty evidence). Galantamine for mild cognitive impairment We summarise results, assessed at two years, from two studies that gave participants galantamine at 8 to 12 mg twice daily (total galantamine 16 mg to 24 mg/day). Compared to placebo, galantamine may not improve cognitive function, as assessed with the expanded ADAS-cog for mild cognitive impairment (MD -0.21, 95% CI -0.78 to 0.37; 2 studies, 1901 participants; low-certainty evidence) or activities of daily living, assessed with the Alzheimer's Disease Cooperative Study - Activities of Daily Living scale for mild cognitive impairment (MD 0.30, 95% CI -0.26 to 0.86; 2 studies, 1901 participants; low-certainty evidence). Participants who received galantamine were probably more likely to discontinue prematurely than placebo-treated participants (40.7% versus 28.6%) (OR 1.71, 95% CI 1.42 to 2.05; 2 studies, 2057 participants) and to experience nausea (29.4% versus 10.7%) (OR 3.49, 95% CI 2.75 to 4.44; 2 studies, 2057 participants), both with moderate-certainty evidence. Galantamine may not reduce death rates at 24 months compared to placebo (0.5% versus 0.1%) (OR 5.03, 95% CI 0.87 to 29.10; 2 studies, 2057 participants; low-certainty evidence). Results from subgroup analysis and meta-regression suggest that an imbalance in discontinuation rates between galantamine and placebo groups, together with the use of the 'last observation carried forward' approach to outcome assessment, may potentially bias cognitive outcomes in favour of galantamine.
AUTHORS' CONCLUSIONS: Compared to placebo, galantamine (when given at a total dose of 16 mg to 24 mg/day) slows the decline in cognitive function, functional ability, and behaviour at six months in people with dementia due to Alzheimer's disease. Galantamine probably also slows declines in global function at six months. The changes observed in cognition, assessed with the ADAS-cog scale, were clinically meaningful. Gastrointestinal-related adverse events are the primary concerns associated with galantamine use in people with dementia, which may limit its tolerability. Although death rates were generally low, participants in the galantamine groups had a reduced risk of death compared to those in the placebo groups. There is no evidence to support the use of galantamine in people with mild cognitive impairment.
OBJECTIVES: To evaluate the effects of withdrawal or continuation of cholinesterase inhibitors or memantine, or both, in people with dementia on: cognitive, neuropsychiatric and functional outcomes, rates of institutionalisation, adverse events, dropout from trials, mortality, quality of life and carer-related outcomes.
SEARCH METHODS: We searched the Cochrane Dementia and Cognitive Improvement Group's Specialised Register up to 17 October 2020 using terms appropriate for the retrieval of studies of cholinesterase inhibitors or memantine. The Specialised Register contains records of clinical trials identified from monthly searches of a number of major healthcare databases, numerous trial registries and grey literature sources.
SELECTION CRITERIA: We included all randomised, controlled clinical trials (RCTs) which compared withdrawal of cholinesterase inhibitors or memantine, or both, with continuation of the same drug or drugs.
DATA COLLECTION AND ANALYSIS: Two review authors independently assessed citations and full-text articles for inclusion, extracted data from included trials and assessed risk of bias using the Cochrane risk of bias tool. Where trials were sufficiently similar, we pooled data for outcomes in the short term (up to 2 months after randomisation), medium term (3-11 months) and long term (12 months or more). We assessed the overall certainty of the evidence for each outcome using GRADE methods.
MAIN RESULTS: We included six trials investigating cholinesterase inhibitor withdrawal, and one trial investigating withdrawal of either donepezil or memantine. No trials assessed withdrawal of memantine only. Drugs were withdrawn abruptly in five trials and stepwise in two trials. All participants had dementia due to Alzheimer's disease, with severities ranging from mild to very severe, and were taking cholinesterase inhibitors without known adverse effects at baseline. The included trials randomised 759 participants to treatment groups relevant to this review. Study duration ranged from 6 weeks to 12 months. There were too few included studies to allow planned subgroup analyses. We considered some studies to be at unclear or high risk of selection, performance, detection, attrition or reporting bias. Compared to continuing cholinesterase inhibitors, discontinuing treatment may be associated with worse cognitive function in the short term (standardised mean difference (SMD) -0.42, 95% confidence interval (CI) -0.64 to -0.21; 4 studies; low certainty), but the effect in the medium term is very uncertain (SMD -0.40, 95% CI -0.87 to 0.07; 3 studies; very low certainty). In a sensitivity analysis omitting data from a study which only included participants who had shown a relatively poor prior response to donepezil, inconsistency was reduced and we found that cognitive function may be worse in the discontinuation group in the medium term (SMD -0.62; 95% CI -0.94 to -0.31). Data from one longer-term study suggest that discontinuing a cholinesterase inhibitor is probably associated with worse cognitive function at 12 months (mean difference (MD) -2.09 Standardised Mini-Mental State Examination (SMMSE) points, 95% CI -3.43 to -0.75; moderate certainty). Discontinuation may make little or no difference to functional status in the short term (SMD -0.25, 95% CI -0.54 to 0.04; 2 studies; low certainty), and its effect in the medium term is uncertain (SMD -0.38, 95% CI -0.74 to -0.01; 2 studies; very low certainty). After 12 months, discontinuing a cholinesterase inhibitor probably results in greater functional impairment than continuing treatment (MD -3.38 Bristol Activities of Daily Living Scale (BADLS) points, 95% CI -6.67 to -0.10; one study; moderate certainty). Discontinuation may be associated with a worsening of neuropsychiatric symptoms over the short term and medium term, although we cannot exclude a minimal effect (SMD - 0.48, 95% CI -0.82 to -0.13; 2 studies; low certainty; and SMD -0.27, 95% CI -0.47 to -0.08; 3 studies; low certainty, respectively). Data from one study suggest that discontinuing a cholinesterase inhibitor may result in little to no change in neuropsychiatric status at 12 months (MD -0.87 Neuropsychiatric Inventory (NPI) points; 95% CI -8.42 to 6.68; moderate certainty). We found no clear evidence of an effect of discontinuation on dropout due to lack of medication efficacy or deterioration in overall medical condition (odds ratio (OR) 1.53, 95% CI 0.84 to 2.76; 4 studies; low certainty), on number of adverse events (OR 0.85, 95% CI 0.57 to 1.27; 4 studies; low certainty) or serious adverse events (OR 0.80, 95% CI 0.46 to 1.39; 4 studies; low certainty), and on mortality (OR 0.75, 95% CI 0.36 to 1.55; 5 studies; low certainty). Institutionalisation was reported in one trial, but it was not possible to extract data for the groups relevant to this review.
AUTHORS' CONCLUSIONS: This review suggests that discontinuing cholinesterase inhibitors may result in worse cognitive, neuropsychiatric and functional status than continuing treatment, although this is supported by limited evidence, almost all of low or very low certainty. As all participants had dementia due to Alzheimer's disease, our findings are not transferable to other dementia types. We were unable to determine whether the effects of discontinuing cholinesterase inhibitors differed with baseline dementia severity. There is currently no evidence to guide decisions about discontinuing memantine. There is a need for further well-designed RCTs, across a range of dementia severities and settings. We are aware of two ongoing registered trials. In making decisions about discontinuing these drugs, clinicians should exercise caution, considering the evidence from existing trials along with other factors important to patients and their carers.