Simvastatin Decreases Lipopolysaccharide-induced Pulmonary Inflammation in Healthy Volunteers

RATIONALE:
Simvastatin inhibits inflammatory responses in vitro and in murine models of lung inflammation in vivo. As simvastatin modulates a number of the underlying processes described in acute lung injury (ALI), it may be a potential therapeutic option.
OBJECTIVES:
To investigate in vivo if simvastatin modulates mechanisms important in the development of ALI in a model of acute lung inflammation induced by inhalation of lipopolysaccharide (LPS) in healthy human volunteers.
METHODS:
Thirty healthy subjects were enrolled in a double-blind, placebo-controlled study. Subjects were randomized to receive 40 mg or 80 mg of simvastatin or placebo (n = 10/group) for 4 days before inhalation of 50 microg LPS. Measurements were performed in bronchoalveolar lavage fluid (BALF) obtained at 6 hours and plasma obtained at 24 hours after LPS challenge. Nuclear translocation of nuclear factor-kappaB (NF-kappaB) was measured in monocyte-derived macrophages.
MEASUREMENTS AND MAIN RESULTS:
Pretreatment with simvastatin reduced LPS-induced BALF neutrophilia, myeloperoxidase, tumor necrosis factor-alpha, matrix metalloproteinases 7, 8, and 9, and C-reactive protein (CRP) as well as plasma CRP (all P < 0.05 vs. placebo). There was no significant difference between simvastatin 40 mg and 80 mg. BALF from subjects post-LPS inhalation induced a threefold up-regulation in nuclear NF-kappaB in monocyte-derived macrophages (P < 0.001); pretreatment with simvastatin reduced this by 35% (P < 0.001).
CONCLUSIONS:
Simvastatin has antiinflammatory effects in the pulmonary and systemic compartment in humans exposed to inhaled LPS.

The effect of simvastatin on bone formation and ceramic resorption in a peri-implant defect model

Experimental use of statins as stimulators of bone formation suggests they may have widespread applicability in the field of orthopaedics. With their combined effects on osteoblasts and osteoclasts, statins have the potential to enhance resorption of synthetic materials and improve bone ingrowth. In this study, the effect of oral and local administration of simvastatin to a 0 tricalcium phosphate (beta TCP)-filled defect around an implant was compared with recombinant human bone morphogenetic protein 2 (rhBMP2). On hundred and sixty-two Sprague-Dawley rats were assigned to treatment groups: local application of 0.1, 0.9 or 1.7 mg of simvastatin, oral simvastatin at 5, 10 or 50 mg kg(-1) day(-1) for 20 days, local delivery of I or 10 mu g of rhBMP2, or control. At 6 weeks rhBMP2 increased serum tartrate-resistant acid phosphatase 5b levels and reduced PTCP area fraction, particle size and number compared with control, suggesting increased osteoclast activity. There was reduced stiffness and increased mechanical strength with this treatment. Local simvastatin resulted in a decreased mineral apposition rate at 6 weeks and increased fibrous area fraction, PTCP area fraction, particle size and number at 26 weeks. Oral simvastatin had no effect compared with control. Local application of rhBMP2 increased resorption and improved mechanical strength whereas simvastatin was detrimental to healing. Oral simvastatin was ineffective at promoting either ceramic resorption or bone formation. The effect of statins on the repair of bone defects with graft substitute materials is influenced by its bioavailability. Thus, further studies on the optimal delivery system are needed. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The Pleiotropic Effects of Simvastatin on Retinal Microvascular Endothelium Has Important Implications for Ischaemic Retinopathies

Background: Current guidelines encourage the use of statins to reduce the risk of cardiovascular disease in diabetic patients; however the impact of these drugs on diabetic retinopathy is not well defined. Moreover, pleiotropic effects of statins on the highly specialised retinal microvascular endothelium remain largely unknown. The objective of this study was to investigate the effects of clinically relevant concentrations of simvastatin on retinal endothelium in vitro and in vivo.

Methods and Findings: Retinal microvascular endothelial cells (RMECs) were treated with 0.01–10 µM simvastatin and a biphasic dose-related response was observed. Low concentrations enhanced microvascular repair with 0.1 µM simvastatin significantly increasing proliferation (p<0.05), and 0.01 µM simvastatin significantly promoting migration (p<0.05), sprouting (p<0.001), and tubulogenesis (p<0.001). High concentration of simvastatin (10 µM) had the opposite effect, significantly inhibiting proliferation (p<0.01), migration (p<0.01), sprouting (p<0.001), and tubulogenesis (p<0.05). Furthermore, simvastatin concentrations higher than 1 µM induced cell death. The mouse model of oxygen-induced retinopathy was used to investigate the possible effects of simvastatin treatment on ischaemic retinopathy. Low dose simvastatin(0.2 mg/Kg) promoted retinal microvascular repair in response to ischaemia by promoting intra-retinal re-vascularisation (p<0.01). By contrast, high dose simvastatin(20 mg/Kg) significantly prevented re-vascularisation (p<0.01) and concomitantly increased pathological neovascularisation (p<0.01). We also demonstrated that the pro-vascular repair mechanism of simvastatin involves VEGF stimulation, Akt phosphorylation, and nitric oxide production; and the anti-vascular repair mechanism is driven by marked intracellular cholesterol depletion and related disorganisation of key intracellular structures.

Conclusions: A beneficial effect of low-dose simvastatin on ischaemic retinopathy is linked to angiogenic repair reducing ischaemia, thereby preventing pathological neovascularisation. High-dose simvastatin may be harmful by inhibiting reparative processes and inducing premature death of retinal microvascular endothelium which increases ischaemia-induced neovascular pathology. Statin dosage should be judiciously monitored in patients who are diabetic or are at risk of developing other forms of proliferative retinopathy.

The effects of lowering LDL cholesterol with simvastatin plus ezetimibe in patients with chronic kidney disease (Study of Heart and Renal Protection):a randomised placebo-controlled trial

Lowering LDL cholesterol with statin regimens reduces the risk of myocardial infarction, ischaemic stroke, and the need for coronary revascularisation in people without kidney disease, but its effects in people with moderate-to-severe kidney disease are uncertain. The SHARP trial aimed to assess the efficacy and safety of the combination of simvastatin plus ezetimibe in such patients.

Effect of simvastatin on physiological and biological outcomes in patients undergoing esophagectomy: a randomised placebo controlled trial

OBJECTIVE: To test whether simvastatin improves physiological and biological outcomes in patients undergoing esophagectomy.

BACKGROUND: One-lung ventilation during esophagectomy is associated with inflammation, alveolar epithelial and systemic endothelial injury, and the development of acute lung injury (ALI). Statins that modify many of the underlying processes are a potential therapy to prevent ALI.

METHODS: We conducted a randomized double-blind placebo-controlled trial in patients undergoing esophagectomy. Patients received simvastatin 80 mg or placebo enterally for 4 days preoperatively and 7 days postoperatively. The primary end point was pulmonary dead space (Vd/Vt) at 6 hours after esophagectomy or before extubation. Inflammation was assessed by plasma cytokines and intraoperative exhaled breath condensate pH; alveolar type 1 epithelial injury was assessed by plasma receptor for advanced glycation end products and systemic endothelial injury by the urine albumin-creatinine ratio.

RESULTS: Thirty-nine patients were randomized; 8 patients did not undergo surgery and were excluded. Fifteen patients received simvastatin and 16 received placebo. There was no difference in Vd/Vt or other physiological outcomes. Simvastatin resulted in a significant decrease in plasma MCP-1 on day 3 and reduced exhaled breath condensate acidification. Plasma receptor for advanced glycation end products was significantly lower in the simvastatin-treated group, as was the urine albumin-creatinine ratio on day 7 postsurgery. ALI developed in 4 patients in the placebo group and no patients in the simvastatin group although this difference was not statistically significant (P = 0.1).

CONCLUSIONS: In this proof of concept study, pretreatment with simvastatin in esophagectomy decreased biomarkers of inflammation as well as pulmonary epithelial and systemic endothelial injury.

Hydroxymethylglutaryl-CoA reductase inhibition with simvastatin in Acute lung injury to Reduce Pulmonary dysfunction (HARP-2) trial: study protocol for a randomized controlled trial

Background: Acute lung injury (ALI) is a common devastating clinical syndrome characterized by life-threatening respiratory failure requiring mechanical ventilation and multiple organ failure. There are in vitro, animal studies and pre-clinical data suggesting that statins may be beneficial in ALI. The Hydroxymethylglutaryl-CoA reductase inhibition with simvastatin in Acute lung injury to Reduce Pulmonary dysfunction (HARP-2) trial is a multicenter, prospective, randomized, allocation concealed, double-blind, placebo-controlled clinical trial which aims to test the hypothesis that treatment with simvastatin will improve clinical outcomes in patients with ALI.

Methods/Design: Patients fulfilling the American-European Consensus Conference Definition of ALI will be randomized in a 1: 1 ratio to receive enteral simvastatin 80 mg or placebo once daily for a maximum of 28 days. Allocation to randomized groups will be stratified with respect to hospital of recruitment and vasopressor requirement. Data will be recorded by participating ICUs until hospital discharge, and surviving patients will be followed up by post at 3, 6 and 12 months post randomization. The primary outcome is number of ventilator-free days to day 28. Secondary outcomes are: change in oxygenation index and sequential organ failure assessment score up to day 28, number of non pulmonary organ failure free days to day 28, critical care unit mortality; hospital mortality; 28 day post randomization mortality and 12 month post randomization mortality; health related quality of life at discharge, 3, 6 and 12 months post randomization; length of critical care unit and hospital stay; health service use up to 12 months post-randomization; and safety. A total of 540 patients will be recruited from approximately 35 ICUs in the UK and Ireland. An economic evaluation will be conducted alongside the trial. Plasma and urine samples will be taken up to day 28 to investigate potential mechanisms by which simvastatin might act to improve clinical outcomes.

Simvastatin decreases the level of heparin-binding protein in patients with acute lung injury

Heparin-binding protein is released by neutrophils during inflammation and disrupts the integrity of the alveolar and capillary endothelial barrier implicated in the development of acute lung injury and systemic organ failure. We sought to investigate whether oral administration of simvastatin to patients with acute lung injury reduces plasma heparin-binding protein levels and improves intensive care unit outcome.

Simvastatin in the Acute Respiratory Distress Syndrome

Background

Studies in animals and in vitro and phase 2 studies in humans suggest that statins may be beneficial in the treatment of the acute respiratory distress syndrome (ARDS). This study tested the hypothesis that treatment with simvastatin would improve clinical outcomes in patients with ARDS.

Methods

In this multicenter, double-blind clinical trial, we randomly assigned (in a 1:1 ratio) patients with an onset of ARDS within the previous 48 hours to receive enteral simvastatin at a dose of 80 mg or placebo once daily for a maximum of 28 days. The primary outcome was the number of ventilator-free days to day 28. Secondary outcomes included the number of days free of nonpulmonary organ failure to day 28, mortality at 28 days, and safety.

Results

The study recruited 540 patients, with 259 patients assigned to simvastatin and 281 to placebo. The groups were well matched with respect to demographic and baseline physiological variables. There was no significant difference between the study groups in the mean (±SD) number of ventilator-free days (12.6±9.9 with simvastatin and 11.5±10.4 with placebo, P=0.21) or days free of nonpulmonary organ failure (19.4±11.1 and 17.8±11.7, respectively; P=0.11) or in mortality at 28 days (22.0% and 26.8%, respectively; P=0.23). There was no significant difference between the two groups in the incidence of serious adverse events related to the study drug.

Conclusions

Simvastatin therapy, although safe and associated with minimal adverse effects, did not improve clinical outcomes in patients with ARDS. (Funded by the U.K. National Institute for Health Research Efficacy and Mechanism Evaluation Programme and others; HARP-2 Current Controlled Trials number, ISRCTN88244364.)

Randomized controlled trial assessing the effect of simvastatin in primary biliary cirrhosis

Background This study evaluated the effect of statins in Primary biliary cirrhosis (PBC) on endothelial function, anti-oxidant status and vascular compliance. Methods Primary biliary cirrhosis patients with hypercholesterolaemia were randomized to receive 20mg simvastatin or placebo in a single blind, randomized controlled trial. Body mass index, blood pressure, glucose, liver function, lipid profile, immunoglobulin levels, serological markers of endothelial function and anti-oxidant status were measured as well as vascular compliance, calculated from pulse wave analysis and velocity, at recruitment and again at 3, 6, 9 and 12months. Results Twenty-one PBC patients (F=20, mean age = 55) were randomized to simvastatin 20mg (n=11) or matched placebo (n=10). At completion of the trial, serum cholesterol levels in the simvastatin group were significantly lower compared with the placebo group (4.91mmol/L vs. 6.15mmol/L, P=0.01). Low-density lipoprotein (LDL) levels after 12months were also significantly lower in the simvastatin group (2.33mmol/L vs. 3.53mmol/L, P=0.01). After 12months of treatment, lipid hydroperoxides were lower (0.49mol/L vs. 0.59mol/L, P=0.10) while vitamin C levels were higher (80.54mol/L vs. 77.40mol/L, P=0.95) in the simvastatin group. Pulse wave velocity remained similar between treatment groups at 12months (8.45m/s vs. 8.80m/s, P=0.66). Only one patient discontinued medication owing to side effects. No deterioration in liver transaminases was noted in the simvastatin group. Conclusions Statin therapy in patients with PBC appears safe and effective towards overall reductions in total cholesterol and LDL levels. Our initial study suggests that simvastatin may also confer advantageous effects on endothelial function and antioxidant status.

Evaluating early administration of the hydroxymethylglutaryl-CoA reductase inhibitor simvastatin in the prevention and treatment of delirium in critically ill ventilated patients (MoDUS trial): Study protocol for a randomized controlled trial

Background: The incidence of delirium in ventilated patients is estimated at up to 82%, and it is associated with longer intensive care and hospital stays, and long-term cognitive impairment and mortality. The pathophysiology of delirium has been linked with inflammation and neuronal apoptosis. Simvastatin has pleiotropic properties; it penetrates the brain and, as well as reducing cholesterol, reduces inflammation when used at clinically relevant doses over the short term. This is a single centre randomised, controlled trial which aims to test the hypothesis that treatment with simvastatin will modify delirium incidence and outcomes. 

Methods/Design: The ongoing study will include 142 adults admitted to the Watford General Hospital Intensive Care Unit who require mechanical ventilation in the first 72 hours of admission. The primary outcome is the number of delirium- and coma-free days in the first 14 days. Secondary outcomes include incidence of delirium, delirium- and coma-free days in the first 28 days, days in delirium and in coma at 14 and 28 days, number of ventilator-free days at 28 days, length of critical care and hospital stay, mortality, cognitive decline and healthcare resource use. Informed consent will be taken from patient's consultee before randomisation to receive either simvastatin (80 mg) or placebo once daily. Daily data will be recorded until day 28 after randomisation or until discharge from the ICU if sooner. Surviving patients will be followed up on at six months from discharge. Plasma and urine samples will be taken to investigate the biological effect of simvastatin on systemic markers of inflammation, as related to the number of delirium- and coma-free days, and the potential of cholinesterase activity and beta-amyloid as predictors of the risk of delirium and long-term cognitive impairment. 

Discussion: This trial will test the efficacy of simvastatin on reducing delirium in the critically ill. If patients receiving the statin show a reduced number of days in delirium compared with the placebo group, the inflammatory theory implicated in the pathogenesis of delirium will be strengthened. 

Can statins prevent or help treat Alzheimer's disease?

Evidence accumulating from biological and epidemiological studies suggests that high levels of serum cholesterol may promote the pathological processes that lead to Alzheimer's disease (AD). Lowering cholesterol in experimental animal models slows the expression of Alzheimer's pathology. These findings raise the possibility that treating humans with cholesterol lowering medications might reduce the risk of developing AD or help treat it. The statins (lovastatin, pravastatin, simvastatin, and others) are powerful cholesterol lowering agents of proven benefit in vascular disease. Several clinical studies comparing the occurrence of AD between users and non-users of statins suggested that risk of AD was substantially reduced among the users. However, because these studies were not randomized trials, they provided insufficient evidence to recommend statin therapy. Cochrane reviews are based on the best available information about healthcare interventions and they focus primarily on randomized controlled trials (RCTs). On the issue of prevention, two randomized trials have been carried out and neither showed any reduction in occurrence of AD in patients treated with statins compared to those given placebo. Statins cannot therefore be recommended for the prevention of AD. Regarding treatment of AD, the large RCTs which have assessed this outcome have not published their results. Initial analysis from the studies available indicate statins have no benefit on the outcome measure ADAS-Cog but have a significant beneficial effect on MMSE as an outcome. We need to await full results from the RCTs before we can be certain. In addition statins were not detrimental to cognition in either systematic review.

A randomized clinical trial of hydroxymethylglutaryl-Coenzyme A reductase inhibition for Acute Lung Injury (The HARP study)

Rationale: There is no effective pharmacological treatment for acute lung injury (ALI). Statins are a potential new therapy because they modify many of the underlying processes important in ALI.

Objectives: To test whether simvastatin improves physiological and biological outcomes in ALI.

Methods: We conducted a randomized, double-blinded, placebo-controlled trial in patients with ALI. Patients received 80 mg simvastatin or placebo until cessation of mechanical ventilation or up to 14 days. Extravascular lung water was measured using thermodilution. Measures of pulmonary and nonpulmonary organ function were assessed daily. Pulmonary and systemic inflammation was assessed by bronchoalveolar lavage fluid and plasma cytokines. Systemic inflammation was also measured by plasma C-reactive protein.

Measurements and Main Results: Sixty patients were recruited. Baseline characteristics, including demographics and severity of illness scores, were similar in both groups. At Day 7, there was no difference in extravascular lung water. By Day 14, the simvastatin-treated group had improvements in nonpulmonary organ dysfunction. Oxygenation and respiratory mechanics improved, although these parameters failed to reach statistical significance. Intensive care unit mortality was 30% in both groups. Simvastatin was well tolerated, with no increase in adverse events. Simvastatin decreased bronchoalveolar lavage IL-8 by 2.5-fold (P = 0.04). Plasma C-reactive protein decreased in both groups but failed to achieve significance in the placebo-treated group.

Conclusions: Treatment with simvastatin appears to be safe and may be associated with an improvement in organ dysfunction in ALI. These clinical effects may be mediated by a reduction in pulmonary and systemic inflammation.

Statins for the prevention of dementia

Background: This is an update of a Cochrane review first published in 2001. At that stage there was insufficient evidence to recommend statins for the prevention of Alzheimer's disease (AD). The scope of this review has been expanded to include all forms of dementia.
Objectives: To assess the effects of statins in the prevention of dementia.
Search strategy: The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and LILACS were searched on 10 October 2007 using the terms statin*, lovastatin*, pravastatin*, simvastatin*, fluvastatin*, atorvastatin* and rosuvastatin*. The CDCIG Register contains records from many healthcare databases, SIGLE, LILACS as well as many trials databases and is updated regularly.
Selection criteria: Double-blind randomized placebo-controlled trials of statins in people at risk of AD and dementia.
Data collection and analysis: Two independent reviewers extracted and assessed data independently and agreement was reached after discussion. Adverse effects were noted.
Main results: Two trials were identified with 26,340 participants; HPS 2002 and PROSPER 2002. Age range was 40-82 years across the two studies, PROSPER 2002 included 5804 patients aged 70-82 years and HPS included 20,536 patients with 5806 at least 70 years old at study entry. Mean total cholesterol 5.9 mmol/l, LDL cholesterol 3.4 mmol/l at study entry with mean reduction in LDL cholesterol of 1.0mmol/l in simvastatin treated patients compared to placebo in HPS 2002. Mean total cholesterol 5.7 mmol/l, LDL cholesterol 3.8 mmol/l at study entry with mean reduction in LDL cholesterol of 1.02 mmol/l in pravastatin treated patients compared to placebo in PROSPER 2002. Mean follow-up 3.2 years in PROSPER, 5 years in HPS 2002. Cognition was measured at different times and with different scales so could not be combined in a meta-analysis. There was no difference in incidence of dementia in HPS 2002 (31 cases in simvastatin group, 31 cases in placebo group) nor in performance on the modified Telephone Interview for Cognitive Status at final follow-up (23.7% simvastatin group cognitively impaired vs 24.2% in placebo group). There was no difference in cognition between groups either in relation to age at study entry or previous history of cerebrovascular disease. Cognitive function declined at the same rate in both treatment groups in PROSPER 2002, there was no significant difference between pravastatin treated and placebo groups in performance on letter digit codes, picture word learning test, Stroop and Mini Mental State Examination. There was no evidence that statins were detrimental to cognition.
Authors' conclusions : There is good evidence from RCTs that statins given in late life to individuals at risk of vascular disease have no effect in preventing AD or dementia. Biologically it seems feasible that statins could prevent dementia due to their role in cholesterol reduction and initial evidence from observational studies was very promising. Indication bias may have been a factor in these studies however and the evidence from subsequent RCTs has been negative.

Statin Use and Survival from Lung Cancer: A Population-Based Cohort Study

Background: Preclinical evidence from lung cancer cell lines and animal models suggest that statins could have anticancer properties. We investigated whether statin users had reduced risk of cancer-specific mortality in a population based cohort of lung cancer patients.
Methods: Newly diagnosed lung cancer patients, from 1998 to 2009, were identified from English cancer registry data and linked to the UK Clinical Practice Research Datalink, providing prescription records, and to Office of National Statistics mortality data up to 2012. Cox regression models were used to calculate hazard ratios (HR) for cancer-specific mortality and 95% confidence intervals (CIs) by statin use before and after diagnosis and to adjust these HRs for potential confounders.
Results: In 3,638 lung cancer patients, there was some evidence that statin use after diagnosis was associated with reduced lung cancer-specific mortality (adjusted HR=0.89, 95% CI 0.78, 1.02; P=0.09). Associations were more marked after 12 prescriptions (adjusted HR=0.81, 95% CI 0.67, 0.98; P=0.03) and when lipophilic statins were investigated (adjusted HR=0.81, 95% CI 0.70, 0.94; P=0.01) but were attenuated in some sensitivity analyses. Furthermore, in 11,051 lung cancer patients, statin use before diagnosis was associated with reduced lung cancer-specific mortality (adjusted HR=0.88, 95% CI, 0.83, 0.93; P<0.001).
Conclusions: There was some evidence that lung cancer patients who used statins, and particularly simvastatin, had reduced rates of cancer-specific mortality.
 Impact: These findings should first be confirmed in observational studies, but provide some support for conducting randomized controlled trials of simvastatin as adjuvant cancer therapy in lung cancer patients.

Pharmacological interventions for dementia in people with Down Syndrome (Protocol).

Background: People with Down syndrome are vulnerable to developing dementia at an earlier age than the general population. Alzheimer’s disease and cognitive decline in people with Down syndrome can place a significant burden on both the person with Down syndrome and their family and carers. Various pharmacological interventions, including donepezil, galantamine, memantine and rivastigmine, appear to have some effect in treating cognitive decline in people without Down syndrome, but their effectiveness for those with Down syndrome remains unclear. Objectives: To assess the effectiveness of anti-dementia pharmacological interventions and nutritional supplements for treating cognitive decline in people with Down syndrome. Search methods In January 2015, we searched CENTRAL, ALOIS (the Specialised Register of the Cochrane Dementia and Cognitive Improvement Group), Ovid MEDLINE, Embase, PsycINFO, seven other databases, and two trials registers. In addition, we checked the references of relevant reviews and studies and contacted study authors, other researchers and relevant drug manufacturers to identify additional studies. Selection criteria: Randomised controlled trials (RCTs) of anti-dementia pharmacological interventions or nutritional supplements for adults (aged 18 years and older) with Down syndrome, in which treatment was administered and compared with either placebo or no treatment. Data collection and analysis Two review authors independently assessed the risk of bias of included trials and extracted the relevant data. Review authors contacted study authors to obtain missing information where necessaryMain results Only nine studies (427 participants) met the inclusion criteria for this review. Four of these (192 participants) assessed the effectiveness of donepezil, two (139 participants) assessed memantine, one (21 participants) assessed simvastatin, one study (35 participants) assessed antioxidants, and one study (40 participants) assessed acetyl-L-carnitine. Five studies focused on adults aged 45 to 55 years, while the remaining four studies focused on adults aged 20 to 29 years. Seven studies were conducted in either the USA or UK, one between Norway and the UK, and one in Japan. Follow-up periods in studies ranged from four weeks to two years. The reviewers judged all included studies to be at low or unclear risk of bias. Analyses indicate that for participants who received donepezil, scores in measures of cognitive functioning (standardised mean difference (SMD) 0.52, 95% confidence interval (CI) -0.27 to 1.13) and measures of behaviour (SMD 0.42, 95% CI -0.06 to 0.89) were similar to those who received placebo. However, participants who received donepezil were significantly more likely to experience an adverse event (odds ratio (OR) 0.32, 95% CI 0.16 to 0.62). The quality of this body of evidence was low. None of the included donepezil studies reported data for carer stress, institutional/home care, or death. For participants who received memantine, scores in measures of cognitive functioning (SMD 0.05, 95% CI -0.43 to 0.52), behaviour (SMD -0.17, 95% CI -0.46 to 0.11), and occurrence of adverse events (OR 0.45, 95% CI 0.18 to 1.17) were similar to those who received placebo. The quality of this body of evidence was low. None of the included memantine studies reported data for carer stress, institutional/home care, or death. Due to insufficient data, it was possible to provide a narrative account only of the outcomes for simvastatin, antioxidants, and acetylL-carnitine. Results from one pilot study suggest that participants who received simvastatin may have shown a slight improvement in cognitive measures. Authors’ conclusions Due to the low quality of the body of evidence in this review, it is difficult to draw conclusions about the effectiveness of any pharmacological intervention for cognitive decline in people with Down syndrome.