Over the past twenty years, evidence has accumulated that high cholesterol levels may increase the risk of developing Alzheimer’s disease (AD). With the global use of statins to treat hypercholesterolemia, this finding has led to the hope that statins could prove useful in treating or preventing AD. However, the results of work on this topic are inconsistent: some studies find beneficial effects, others do not. In this first segment of a two-part review, we examine the complex preclinical and clinical literature on cholesterol and AD. First, we review epidemiological research on cholesterol levels and the risk of AD and discuss the relevance of discrepancies among studies as regards participants’ age and clinical status. Next, we assess studies correlating cholesterol with AD-type neuropathology. The potential molecular mechanisms for cholesterol’s apparent adverse effect on the development of AD are then discussed. Finally, we review preclinical studies of statins and AD. Thus, this first portion of our review provides the background and rationale for investigating statins as potential therapeutic agents in AD patients, the subject of the second part.
3-Hydroxy-3-methylglutaryl–coenzyme A (HMG-CoA) reductase inhibitors (statins) are among the most prescribed medications in the United States. Statins act on the rate-limiting step in cholesterol biosynthesis (the conversion of HMG-CoA to mevalonate) and are effective in treating dyslipidemia. However, statins decrease other downstream products of the mevalonate pathway, and it is via these pathways that statins may affect inflammation, nitric oxide synthesis, the coagulation cascade, and other processes. Through these pleiotropic effects, statins may have an effect on neurologic diseases, including ischemic and hemorrhagic stroke, Alzheimer disease, Parkinson disease, and multiple sclerosis. This article reviews the basic biochemistry of statins as it relates to these pleiotropic effects, the potential role of statins in several neurologic disorders, and the results of clinical trials performed for several of these conditions.
The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, more commonly referred to as statins, comprise a family of lipid-lowering drugs that are prescribed on a global scale on account of their demonstrated safety and efficacy in reducing mortality from cardiovascular disease. Beyond their potent pharmacologic inhibition of cholesterol biosynthesis, statins appear to have pleiotropic effects, including modulation of cell growth, apoptosis, and inflammation. Through modulation of these pathways, statins have the potential to influence a wide range of disease processes, including cancer. Much attention has focussed on the association between statins and colorectal cancer, raising the prospect that these well-tolerated compounds could form the basis of future chemopreventive strategies. Herein we review the epidemiologic, clinical, and pre-clinical data relevant to statins and colorectal neoplasia, and discuss the current status and future potential of statins as chemopreventive agents.
Parkinson disease (PD) is second only to Alzheimer disease as the most common neurodegenerative disorder in humans. Despite intense investigations, no effective therapy is available to halt the progression of PD. Although statins are widely used cholesterol-lowering drugs throughout the world, recent studies suggest that these drugs modulate neurodegeneration-related signaling processes and may be beneficial for PD. Simvastatin is the most potent statin in crossing the blood-brain barrier, and this particular statin drug negatively correlates with the incidence of PD and shows efficacy in animal models of PD. However, PD mainly occurs in the aging population, who are more vulnerable to cholesterol or lipid-related disorders, raising questions whether this possible beneficial effect of statins in PD patients is cholesterol dependent or cholesterol independent. This article presents data on the therapeutic efficacy of simvastatin in a chronic MPTP model of PD, reviews recent literature, and discusses the pros and cons of statin therapy in PD.
Parkinson disease; statins; signal transduction; dopamine; neuroprotection
We reported a significant 67% reduction in the hazard risk of incident Alzheimer's disease (AD) with elective statin use in the AD Anti-inflammatory Prevention Trial (ADAPT), without a reduction in risk of incident mild cognitive impairment (MCI).
To assess if cholesterol levels are associated with cognitive performance and determine if statin use alters cognitive performance after onset of MCI.
Fractionated cholesterol levels, neurological and cognitive status were evaluated annually. Comparisons of non-LLA (lipid-lowering agent) users or statin-LLA users were performed blind to the ADAPT medication randomization. Pearson's correlations were validated using a time-dependent linear mixed model.
The MMSE performance significantly declined over time in non-LLA users, and, after adjusting for this, a significant positive correlation between MMSE and HDL was identified (p = 0.0002). A negative correlation between total and LDL cholesterol, and immediate and delayed recall of the Rivermead paragraph was significant (total cholesterol, p < 0.003; LDL, p < 0.02). Pilot data suggest a positive signal on delayed recall of both the Hopkins word list and Rivermead paragraph with deterioration in the non-LLA users and improvement in the statin users after conversion to MCI.
Cholesterol levels may be associated with differential performance on the MMSE and measures of learning or memory. The trend for improved delayed recall in statin users with MCI compared to non-LLA users with MCI may have contributed to the reduced hazards risk of incident AD without reducing the risk of MCI.
Alzheimer's disease; Mild cognitive impairment; Cholesterol; Lipid-lowering agents
Statins, long known to be beneficial in conditions where dyslipidemia occurs by lowering serum cholesterol levels, also have been proposed for use in neurodegenerative conditions, including Alzheimer disease. However, it is not clear that the purported effectiveness of statins in neurodegenerative disorders is directly related to cholesterol-lowering effects of these agents; rather, the pleiotropic functions of statins likely play critical roles.
Moreover, it is becoming more apparent with additional studies that statins can have deleterious effects in preclinical studies and lack effectiveness in various recent clinical trials. This perspective paper outlines pros and cons of the use of statins in neurodegenerative disorders, with particular emphasis on Alzheimer disease.
Background: Data from epidemiological studies and animal models imply that disturbances in cholesterol metabolism are linked to Alzheimer's disease susceptibility. Lipid lowering agents (LLAs) may have implications for the prevention of Alzheimer's disease.
Objective: To investigate whether LLAs are associated with a slower cognitive decline in Alzheimer's disease.
Methods: An observational study in 342 Alzheimer patients followed in a memory clinic for 34.8 months (mean age 73.5 years, mini-mental state examination score (MMSE) 21.3 at entry); 129 were dyslipaemic treated with LLAs (47% with statins), 105 were untreated dyslipaemic, and 108 were normolipaemic. The rate of cognitive decline was calculated as the difference between the first and last MMSE score, divided by the time between the measurements, expressed by year. Patients were divided into slow and fast decliners according to their annual rate of decline (lower or higher than the median annual rate of decline in the total population).
Results: Patients treated with LLAs had a slower decline on the MMSE (1.5 point/year, p = 0.0102) than patients with untreated dyslipaemia (2.4 points/year), or normolipaemic patients (2.6 points/year). Patients with a slower decline were more likely to be treated with LLAs. Logistic regression analysis, with low annual cognitive decline as the dependent variable, showed that the independent variable LLA (treated with or not) was positively associated with the probability of lower cognitive decline (odds ratio = 0.45, p = 0.002).
Conclusions: LLAs may slow cognitive decline in Alzheimer's disease and have a neuroprotective effect. This should be confirmed by placebo controlled randomised trials in patients with Alzheimer's disease and no dyslipaemia.
Statins inhibit the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which is required for cholesterol biosynthesis, and are beneficial in the primary and secondary prevention of cardiovascular disease. Most of the benefits of statin therapy are owing to the lowering of serum cholesterol levels. However, by inhibiting HMG-CoA reductase, statins can also inhibit the synthesis of isoprenoids, which are important lipid attachments for intracellular signaling molecules, such as Rho, Rac and Cdc42. Therefore, it is possible that statins might exert cholesterol-independent or ‘pleiotropic’ effects through direct inhibition of these small GTP-binding proteins. Recent studies have shown that statins might have important roles in diseases that are not mediated by cholesterol. Here, we review data from recent clinical trials that support the concept of statin pleiotropy and provide a rationale for their clinical importance.
Lowering cholesterol is associated with reduced CNS amyloid deposition and increased dietary cholesterol increases amyloid accumulation in animal studies. Epidemiologic data suggest that use of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) may decrease the risk of Alzheimer disease (AD) and a single-site trial suggested possible benefit in cognition with statin treatment in AD, supporting the hypothesis that statin therapy is useful in the treatment of AD.
To determine if the lipid-lowering agent simvastatin slows the progression of symptoms in AD.
This randomized, double-blind, placebo-controlled trial of simvastatin was conducted in individuals with mild to moderate AD and normal lipid levels. Participants were randomly assigned to receive simvastatin, 20 mg/day, for 6 weeks then 40 mg per day for the remainder of 18 months or identical placebo. The primary outcome was the rate of change in the Alzheimer's Disease Assessment Scale–cognitive portion (ADAS-Cog). Secondary outcomes measured clinical global change, cognition, function, and behavior.
A total of 406 individuals were randomized: 204 to simvastatin and 202 to placebo. Simvastatin lowered lipid levels but had no effect on change in ADAS-Cog score or the secondary outcome measures. There was no evidence of increased adverse events with simvastatin treatment.
Simvastatin had no benefit on the progression of symptoms in individuals with mild to moderate AD despite significant lowering of cholesterol.
Classification of evidence:
This study provides Class I evidence that simvastatin 40 mg/day does not slow decline on the ADAS-Cog.
Preclinical and epidemiologic studies suggest a protective effect of statins on Alzheimer disease (AD). Experimental evidence indicates that some statins can cross the blood-brain barrier, alter brain cholesterol metabolism, and may ultimately decrease the production of amyloid-β (Aβ) peptide. Despite these promising leads, clinical trials have yielded inconsistent results regarding the benefits of statin treatment in AD. Seeking to detect a biological signal of statins effect on AD, we conducted a 12-week open-label trial with simvastatin 40 mg/d and then 80 mg/d in 12 patients with AD or amnestic mild cognitive impairment and hypercholesterolemia. We quantified cholesterol precursors and metabolites and AD biomarkers of Aβ and tau in both plasma and cerebrospinal fluid at baseline and after the 12-week treatment period. We found a modest but significant inhibition of brain cholesterol biosynthesis after simvastatin treatment, as indexed by a decrease of cerebrospinal fluid lathosterol and plasma 24S-hydroxycholesterol. Despite this effect, there were no changes in AD biomarkers. Our findings indicate that simvastatin treatment can affect brain cholesterol metabolism within 12 weeks, but did not alter molecular indices of AD pathology during this short-term treatment.
Alzheimer disease; simvastatin; cholesterol; biomarker
Lipid lowering agents, such as HMG CoA reductase inhibitors or statins, have been shown to reduce cardiovascular events. However, growing evidence from recent clinical trials suggest that some of the beneficial effects of statins may be unrelated to changes in LDL-C. In animal studies, many of the cholesterol-independent or “pleiotropic” effects of statins are mediated by inhibition of Rho kinase (ROCK). Indeed, ROCK has been implicated in the regulation of vascular tone, proliferation, inflammation, and oxidative stress. To what extent ROCK activity is inhibited in patients on lipid lowering therapy, in particular, statins, is not known, but may have important clinical and therapeutic implications. This review will attempt to make the case that, in addition to lipid lowering, inhibition of ROCK contributes to some of the benefits of statin therapy in patients with cardiovascular disease.
Statins (3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) can significantly decrease cardiovascular mortality and morbidity, irrespective of the patients’ cholesterol status. This paper reviews the effects of perioperative statin therapy in patients undergoing noncardiac surgery.
A systematic literature review was undertaken of all published literature on this subject using Medline and cross-referenced. All published relevant papers on the perioperative use of statins were used.
Perioperative statin therapy is associated with a lower perioperative morbidity and mortality in patients undergoing elective or emergency surgery. The effects are due to a combination of lipid-lowering and pleiotropic properties of statins.
Ideally a large scale multi-centre randomized controlled trial of perioperative statin therapy should be performed but this may be difficult to conduct since there is already overwhelming evidence in the literature to suggest perioperative cardiovascular protective properties. Statins may still be under-prescribed in surgical patients.
perioperative, cardiac complications; morbidity, mortality; outcome; statins; vascular; noncardiac surgery
Statins alter lipid concentrations. This systematic review determined the efficacy of particular statins, in terms of their ability to alter cholesterol.
PubMed, the Cochrane Library, references lists of reports, and reviews were searched (September 2001) for randomised, double blind trials of statins for cholesterol in trials of 12 weeks or longer. Mean change in total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides was calculated using pooled data for particular statins, and for particular doses of a statin. Pre-planned sensitivity analyses were used to determine the effects of initial concentration of total cholesterol, study duration, the effects of major trials, and effects in placebo versus active controlled trials. Information was not collected on adverse events.
Different statins at a range of doses reduced total cholesterol by 17–35% and LDL-cholesterol by 24–49% from baseline. Lower doses of statins generally produced less cholesterol lowering, though for most statins in trials of 12 weeks or longer there was at best only a weak relationship between dose and cholesterol reduction. Duration of treatment and baseline total cholesterol concentration did not alter the amount of the benefit attained.
Statins are effective medicines and confer benefit to patients in terms of primary and secondary prevention of coronary heart disease. Reductions in total cholesterol of 25% or more and LDL cholesterol of more than 30% were recorded for fixed doses of simvastatin 40 mg, atorvastatin 10 mg, and rosuvastatin 5 mg and 10 mg.
Statins have been prescribed extensively for their cholesterol-lowering properties and efficacy in cardiovascular disease. Compelling evidence now exists, however, that statins also possess extensive immunomodulatory properties that operate independently of lipid lowering. Consequently, much attention has been directed towards their potential as therapeutic agents in the treatment of autoimmune disease. Modulation of post-translational protein prenylation seems to be a key mechanism by which statins alter immune function. In this article, the effect of statin therapy on immune function, and how this impacts on the pathogenesis of autoimmune disease, will be reviewed alongside current opinion of the key biological targets.
Ezetimibe is a new lipid-lowering agent that inhibits intestinal absorption of dietary cholesterol. It substantially lowers low-density lipoprotein cholesterol levels when used alone or in combination with statins. However, its effect on cardiovascular mortality remains unknown. We reviewed peer-reviewed published literature on the effect of ezetimibe on different phases of atherosclerosis. MEDLINE, EMBASE, BIOSIS, and other Web of Knowledge databases were searched for relevant abstracts and articles published in the English language that compared ezetimibe and statins as modulators of atherosclerosis. On the basis of the available evidence, ezetimibe appears to reduce inflammation when used in combination with statins, but its effect on endothelial function is mixed and less clear. The effect of ezetimibe on coronary disease progression or prevention of cardiovascular events is currently unknown. Use of ezetimibe as a second- or third-line agent to achieve low-density lipoprotein cholesterol treatment goals seems appropriate on the basis of the available evidence.
Importance of the Field
HMG-CoA inhibitors (statins), a class of drugs that reduce cholesterol, are used to manage and prevent coronary heart disease. They are among the most commonly prescribed drugs worldwide. Contrary to early concerns over the carcinogenicity of statins, a growing body of evidence suggests statins may in fact have a chemopreventive potential against cancer.
Areas Covered in This Review
In this paper, we review evidence on the association between statin use and cancer risk. Specifically, we report on clinical trials and observational studies that measured all cancer or site-specific cancers of the breast, colorectal, lung, prostate, and reproductive organs associated with statin use.
What the reader will gain
An understanding of the evidence, including strengths and limitations, to support an association between statins and cancer. Information on the current state of the field and future directions are also discussed.
Take Home Message
Few strong or consistent associations between statins and cancer incidence overall or for any of the sites reviewed were detected. Data is lacking for any effects of statins on cancer prognosis and secondary prevention; with the exception of consistent evidence that statins are associated with reduced risk of advanced/aggressive prostate cancer. Statins appear safe in relation to cancer risk but any chemopreventive effect in humans remains to be established and should not be recommended outside the context of clinical trials. It is encouraging that numerous trials are on-going. The prospect of reducing the incidence and burden of some of the most prevalent cancers with a safe, affordable, and tolerable medication that already reduces the risk of the leading cause of death, cardiovascular disease, warrants further exploration in clinical trials and observational studies of prognosis and survival.
statins; HMG-CoA inhibitors; cancer; prevention; treatment; drug safety
Convincing evidence from basic research and animal studies shows that HMG CoA reductase inhibitors or statins, exert cardiovascular protective effects beyond cholesterol-lowering. Because of the central role of LDL-C in mediating vascular pathology and the efficacy of statins for lowering LDL-C, the clinical importance of these additional non-lipid effects remains to be determined. Nevertheless, there is growing evidence from recent clinical trials, which suggests that some of the beneficial effects of statins may be unrelated to changes in LDL-C. Indeed, in animal studies, many of the cholesterol-independent or “pleiotropic” effects of statins are due predominantly to inhibition of isoprenoid, but not cholesterol synthesis. Thus, with the recent findings of the HPS and ASCOT-LLA, the potential cholesterol-independent effects of statins have shifted the treatment strategy from numerical lipid parameters to the global assessment of cardiovascular risks.
Statin-induced myopathy is well-known, but the effect of cholesterol-lowering agents on myasthenia gravis (MG) has not been studied in detail. We investigated statin use and its effects on MG among patients with this disease. Statin information was systemically obtained from 170 patients being treated at the Neuromuscular Disease Clinic at the University of Alabama at Birmingham. When a new myalgic syndrome or worsening of MG developed within 4 months after statin treatment, no other likely cause was found, and clinical improvement occurred either with or without discontinuation of the statin, we considered these symptoms to be statin-induced. Fifty-four patients (31%) were on statins. The statin group had proportionally more males, and older patients compared with the non-statin group. A myalgic syndrome was noted in 7 (13%) patients, but it resolved without any sequelae after withdrawal of the statin. MG worsening occurred in 6 (11%) patients without regard to type of MG or brand of statin. MG worsening occurred independently of myalgic syndrome and involved predominantly oculobulbar symptoms within 1-16 weeks of statin treatment. In 4 patients, additional treatment was needed to reverse MG worsening. Statins are safe in the majority of MG patients, but their use must be accompanied by close observation for possible MG worsening.
drug side effect; HMG coenzyme A reductase inhibitor; myasthenia gravis; myotoxicity; statin
Although preclinical and epidemiological data suggest that statins may have antineoplastic properties, the impact of statin use on patient survival after a curative resection of stage III colon cancer is unknown.
We conducted a prospective observational study of 842 patients with stage III colon cancer enrolled in a randomized adjuvant chemotherapy trial from April 1999 to May 2001 to investigate the relationship between statin use and survival. Disease-free survival (DFS), recurrence-free survival (RFS), and overall survival (OS) were investigated by Kaplan–Meier curves and log-rank tests in the overall study population and in a subset of patients stratified by KRAS mutation status (n = 394), and Cox proportional hazards regression was used to assess the simultaneous impact of confounding variables. All statistical tests were two-sided.
Among 842 patients, 134 (15.9%) reported statin use after completing adjuvant chemotherapy. DFS among statin users and nonusers was similar (hazard ratio [HR] of cancer recurrence or death = 1.04, 95% confidence interval [CI] = 0.73 to 1.49). RFS and OS were also similar between statin users and nonusers (adjusted HR of cancer recurrence = 1.14, 95% CI = 0.77 to 1.69; adjusted HR of death = 1.15, 95% CI = 0.77 to 1.71). Survival outcomes were similar regardless of increasing duration of statin use before cancer diagnosis (Ptrend = .63, .63, and .59 for DFS, RFS, and OS, respectively). The impact of statin use did not differ by tumor KRAS mutation status, with similar DFS, RFS, and OS for statin use among mutant and wild-type subgroups (Pinteraction = .84, .67, and .98 for DFS, RFS, and OS, respectively).
Statin use during and after adjuvant chemotherapy was not associated with improved DFS, RFS, or OS in patients with stage III colon cancer, regardless of KRAS mutation status.
Statins inhibit 3-hydroxy-3-methylglutaryl CoA reductase (HMG-CoA), the rate-limiting enzyme in the cholesterol biosynthetic pathway, and they are widely used to control plasma cholesterol levels and prevent cardiovascular disease. However, emerging evidence indicates that the beneficial effects of statins extend to the central nervous system. Statins have been shown to improve the outcome of stroke and traumatic brain injury, and statin use has been associated with a reduced prevalence of Alzheimer’s disease (AD) and dementia. However, prospective studies with statins in AD have produced mixed results. Recently, we reported that simvastatin, a widely used statin in humans, enhances learning and memory in non-transgenic mice as well as in transgenic mice with AD-like pathology on a mixed genetic background. However, the cellular and molecular mechanisms underlying the beneficial effects of simvastatin on learning and memory remain elusive. The present study was undertaken to investigate the effect of acute simvastatin treatment on hippocampal long-term potentiation (LTP), a cellular model of learning and memory, in brain slices from C57BL/6 mice. Our results demonstrate that a prolonged in vitro simvastatin treatment for 2-4 hrs, but not a short-term 20-min exposure, significantly increases the magnitude of LTP at CA3-CA1 synapses without altering basal synaptic transmission or the paired-pulse facilitation ratio in hippocampal slices. Furthermore, we show that phosphorylation of Akt (protein kinase B) is increased significantly in the CA1 region following 2-hour treatment with simvastatin, and that inhibition of Akt phosphorylation suppresses the simvastatin-induced enhancement of LTP. These findings suggest activation of Akt as a molecular pathway for augmented hippocampal LTP by simvastatin treatment, and implicate enhancement of hippocampal LTP as a potential cellular mechanism underlying the beneficial effects of simvastatin on cognitive function.
statins; synaptic plasticity; learning and memory; cognitive function; protein phosphorylation; Alzheimer’s disease
The literature on the cost-effectiveness of statin drugs in primary prevention of coronary heart disease is complex. The objective of this study is to compare the disparate results of recent cost-effectiveness analyses of statins.
We conducted a systematic review of the literature on statin cost-effectiveness. The four studies that met inclusion criteria reported varying conclusions about the cost-effectiveness of statin treatment, without a clear consensus as to whether statins are cost-effective for primary prevention. However, after accounting for each study’s assumptions about statin costs, we found substantial agreement among the studies. Studies that assumed statins to be more expensive found them to be less cost-effective, and vice-versa. Furthermore, treatment of low-risk groups became cost-effective as statins became less expensive.
Drug price is the primary determinant of statin cost-effectiveness within a given risk group. As more statin drugs become generic, patients at low risk for coronary disease may be treated cost-effectively. Though many factors must be weighed in any medical decision, from a cost-effectiveness perspective, statins may now be considered an appropriate therapy for many patients at low risk for heart disease.
Statin; Cost-effectiveness; Primary prevention; Drug cost; Systematic review
Cholesterol is vital to normal brain function including learning and memory but that involvement is as complex as the synthesis, metabolism and excretion of cholesterol itself. Dietary cholesterol influences learning tasks from water maze to fear conditioning even though cholesterol does not cross the blood brain barrier. Excess cholesterol has many consequences including peripheral pathology that can signal brain via cholesterol metabolites, proinflammatory mediators and antioxidant processes. Manipulations of cholesterol within the central nervous system through genetic, pharmacological, or metabolic means circumvent the blood brain barrier and affect learning and memory but often in animals already otherwise compromised. The human literature is no less complex. Cholesterol reduction using statins improves memory in some cases but not others. There is also controversy over statin use to alleviate memory problems in Alzheimer’s disease. Correlations of cholesterol and cognitive function are mixed and association studies find some genetic polymorphisms are related to cognitive function but others are not. In sum, the field is in flux with a number of seemingly contradictory results and many complexities. Nevertheless, understanding cholesterol effects on learning and memory is too important to ignore.
Alzheimer’s disease; apolipoprotein E; ATP binding cassette transporters; cholesterol-fed rabbit; classical conditioning; eyeblink conditioning; fear conditioning; low-density lipoprotein receptors; statins; water maze; 24S-hydroxcholesterol
KIF6 719Arg allele carriers are thought to have a greater lipid lowering response from statin therapy than non-carriers. Given the continued interest in the relationship between cholesterol, statin use, amnestic mild cognitive impairment (aMCI), and Alzheimer’s disease (AD) investigating the role of KIF6 719Arg carrier status in these relationships may be of importance. Data from 86 patients (36 aMCI, 50 AD) with an average age of 76.87±8.22 years were used for this study. Total cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL), and triglycerides were the outcome variables. 719Arg carriers taking statins had significantly lower TC (p < .001) and LDL (p < .001) levels than 719Arg carriers not taking statins. In addition, 719Arg carriers not taking statins had significantly higher TC (p = .004) and LDL (p < .001) than 719Arg non-carriers taking statins. Additional analyses indicated that ApoE ε4 carrier status and statin use interaction is also associated with lower TC (p = .04), but not LDL (p = .06). The interaction between 719Arg and ApoE ε4 carrier status on TC and LDL was not significant. This study is the first to demonstrate an association between lower cholesterol levels and statin use among KIF6 719Arg allele carriers with aMCI and AD. Accounting for 719Arg carrier status may be important in future studies investigating the link between cholesterol and AD and also for AD and aMCI clinical trials using statins as a treatment.
mild cognitive impairment; Alzheimer’s disease; cholesterol; KIF6; ApoE4
The lipid-lowering drugs, 3-hydroxy-3-methylgulutaryl-coenzyme A (HMG-CoA) reductase inhibitors or statins, are used in the prevention and treatment of cardiovascular diseases. Recent experimental and clinical studies suggest that statins may exert vascular protective effects beyond cholesterol reduction. For example, statins improve endothelial function by cholesterol-dependent and -independent mechanisms. The cholesterol-independent or “pleiotropic” effects of statins include the upregulation and activation of endothelial NO synthase (eNOS). Because statins inhibit an early step in the cholesterol biosynthetic pathway, they also inhibit the synthesis of isoprenoids such as farnesylpyrophosphate and geranylgeranylpyrophosphate, which are important posttranslational lipid attachments for intracellular signaling molecules such as the Rho GTPases. Indeed, decrease in Rho GTPase responses as a consequence of statin treatment increases the production and bioavailability of endothelium-derived NO. The mechanism involves, in part, Rho/Rho-kinase (ROCK)-mediated changes in the actin cytoskeleton, which leads to decreases in eNOS mRNA stability. The regulation of eNOS by Rho GTPases, therefore, may be an important mechanism underlying the cardiovascular protective effect of statins.
statin; Rho; Rho-kinase; endothelium; nitric oxide
Statins can reduce biliary cholesterol secretion independently of their ability to inhibit cholesterol synthesis. They also prevent formation of gallstones in animal studies, although the effect of statins on human gallstone disease has been controversial.
We examined the relationship between use of statins and the risk of cholecystectomy in a cohort of U.S. women. As part of the prospective Nurses’ Health Study, participants biennially reported history of gallstone disease and whether they had undergone cholecystectomy. Women also reported lifetime use of statins retrospectively in 2000. We conducted a retrospective analysis of statin using data collected in 2000, to define use from 1994 forward, and a prospective analysis for general lipid-lowering drugs from 1994 to 2004.
In the statin analysis we ascertained 2,479 cases of cholecystectomy during 305,197 person-years of follow-up. The multivariate relative risk for current statin users, compared with nonusers, was 0.82 (95% confidence interval, 0.70 to 0.96). In the analysis of general cholesterol-lowering drugs, we ascertained 3,420 cases of cholecystectomy during 511,411 person-years of follow-up. Compared with nonusers, the multivariate relative risk for current users of general cholesterol-lowering drugs, mostly statins in this cohort, was 0.88 (95% confidence interval, 0.79 to 0.98).
Statin use appears to reduce the risk of cholecystectomy in women.
statins; lipid-lowering drugs; HMG-CoA reductase inhibitors; gallstones; cholecystectomy; women