Statins for the treatment of dementia

BACKGROUND

The use of statin therapy in established Alzheimer's disease (AD) or vascular dementia (VaD) is a relatively unexplored area. In AD, β-amyloid protein (Aβ) is deposited in the form of extracellular plaques and previous studies have determined Aβ generation is cholesterol dependent. Hypercholesterolaemia has also been implicated in the pathogenesis of VaD. Due to the role of statins in cholesterol reduction, it is biologically plausible they may be efficacious in the treatment of AD and VaD.

OBJECTIVES

To assess the clinical efficacy and safety of statins in the treatment of AD and VaD. To evaluate if the efficacy of statins in the treatment of AD and VaD depends on cholesterol level, ApoE genotype or cognitive level.

SEARCH METHODS

We searched ALOIS, the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and LILACS, as well as many trials registries and grey literature sources (20 January 2014).

SELECTION CRITERIA

Double-blind, randomised controlled trials of statins given for at least six months in people with a diagnosis of dementia.

DATA COLLECTION AND ANALYSIS

Two independent authors extracted and assessed data against the inclusion criteria. We pooled data where appropriate and entered them into a meta-analysis. We used standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We identified four studies (1154 participants, age range 50 to 90 years). All participants had a diagnosis of probable or possible AD according to standard criteria and most participants were established on a cholinesterase inhibitor. The primary outcome in all studies was change in Alzheimer's Disease Assessment Scale - cognitive subscale (ADAS-Cog) from baseline. When we pooled data, there was no significant benefit from statin (mean difference -0.26, 95% confidence interval (CI) -1.05 to 0.52, P value = 0.51). All studies provided change in Mini Mental State Examination (MMSE) from baseline. There was no significant benefit from statins in MMSE when we pooled the data (mean difference -0.32, 95% CI -0.71 to 0.06, P value = 0.10). Three studies reported treatment-related adverse effects. When we pooled data, there was no significant difference between statins and placebo (odds ratio 1.09, 95% CI 0.58 to 2.06, P value = 0.78). There was no significant difference in behaviour, global function or activities of daily living in the statin and placebo groups. We assessed risk of bias as low for all studies. We found no studies assessing role of statins in treatment of VaD.

AUTHORS' CONCLUSIONS

Analyses from the studies available, including two large randomised controlled trials, indicate that statins have no benefit on the primary outcome measures of ADAS-Cog or MMSE.

Statins and cognitive decline in older adults with normal cognition or mild cognitive impairment

OBJECTIVES

To determine the effect of statins on cognitive decline in healthy elderly adults.

DESIGN

Longitudinal.

SETTING

National Institute of Aging network of Alzheimer's Disease Centers.

PARTICIPANTS

Research volunteers with normal cognition at baseline evaluated an average 4.1 times over 3.4 years (1,244 statin users, 2,363 nonusers) and with mild cognitive impairment (MCI) at baseline evaluated an average 3.9 times over 2.8 years (763 users, 917 nonusers).

MEASUREMENTS

Cognitive performance was assessed according to 10 neuropsychological indices and the Clinical Dementia Rating Sum of Boxes (CDR-SOB). Repeated-measures analyses adjusted for age, sex, education, comorbidities, and family history of dementia were conducted.

RESULTS

Of participants with normal cognition at baseline, statin users performed significantly better across all visits in attention (Trails A) and had significantly slower annual worsening in CDR-SOB scores (P = .006) and slower worsening in Mini-Mental State Examination scores than nonusers (which was not significant after adjusting for multiple comparisons, P = .05). For participants with MCI, statin users performed significantly better across all visits on attention measures (Trail-Making Test Part A), verbal skills (Category Fluency), and executive functioning (Trail-Making Test Part B, Digit Symbol, and Digits Backward), but there were no differences in cognitive decline between users and nonusers.

CONCLUSION

Elderly adults with normal cognition at baseline who used statins had a slower rate of annual worsening in CDR-SOB than nonusers.

Problems and possible solutions for therapy with statins

Despite issues about the value of statins, benefit for high cardiovascular (CV) risk outweighs problems. However, the practitioner must be aware of concerns, be prepared to respond, and justify statin usage. Symptoms of statin-related myopathy are of more concern than stated by pharmaceutical companies. Occurrence of myopathy symptoms, estimated to be up to 10.4%, can decrease statin adherence of high CV risk patients. Dosage modification, or use of pitavastatin, may help the problematic patient. There are concerns that there may be little benefit of statins for primary prevention in women. However, evidence appears to support statin use in women at high CV risk, both in primary and secondary prevention. Abandoning low-density lipoprotein cholesterol (LDL-C) as a valid target is unwarranted; there is much evidence to support "lower is better." The practitioner must be aware of the complicated processes causing atherosclerosis and when to incorporate new approaches to disease management. Tailoring therapy for CV risk, when indicated, may contribute further to LDL-C reduction. Liver inflammation can occur with statins but is of minimal concern; frequently, statins alleviate the problem. Unless liver transaminases are over three times normal, a statin should be prescribed, if indicated. The net effect of statins on cognition appears to be zero-no harm, no benefit. Despite reports of improved cognition, statins should not be prescribed for this. With diabetes mellitus (DM), statins can increase incidence, but the CV benefit far outweighs any risk. Therefore, statins should be prescribed in DM to reduce CV risk. Statins are a major medical contribution when used appropriately.

The effects of statins on prevention of stroke and dementia: a review

Stroke is the third leading cause of death in the United States and places a heavy toll on health care spending, especially in the elderly population. The prevalence of stroke increases with increasing age. Over the last 2 decades, there have been substantial data supporting the use of statins in the primary, as well as secondary, prevention of stroke. Although most of these studies were designed to evaluate cerebrovascular accidents (CVA) only as secondary endpoints, the data show a significant reduction in strokes associated with statin use. There have been numerous studies that have demonstrated the relationship between serum cholesterol levels, specifically low-density lipoprotein cholesterol, on CVA and the beneficial effects of statins in this setting. Furthermore, in addition to the lipid-lowering properties of statins, these drugs have also been shown to possess cholesterol-independent pleotropic properties that have been associated with neuroprotection. Finally, the role of statins for the prevention of dementia is still highly debatable. We examine the role of this class of drugs in the setting of dementia, particularly from vascular causes and stroke.

KIF6 719Arg allele is associated with statin effects on cholesterol levels in amnestic mild cognitive impairment and Alzheimer's disease patients

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 < 0.001) and LDL (p < 0.001) levels than 719Arg carriers not taking statins. In addition, 719Arg carriers not taking statins had significantly higher TC (p = 0.004) and LDL (p < 0.001) 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 = 0.04), but not LDL (p = 0.06). 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.

Amyloid beta (Aβ) peptide modulators and other current treatment strategies for Alzheimer's disease (AD)

Introduction: Alzheimer's disease (AD) is a common, progressive neurological disorder whose incidence is reaching epidemic proportions. The prevailing "amyloid cascade hypothesis," which maintains that the aberrant proteolysis of beta-amyloid precursor protein (βAPP) into neurotoxic amyloid beta (Aβ) peptides is central to the etiopathology of AD, continues to dominate pharmacological approaches to the clinical management of this insidious disorder. This review is a compilation and update on current pharmacological strategies designed to down-regulate Aβ42 peptide generation in an effort to ameliorate the tragedy of AD. Areas covered: This review utilized online data searches at various open online-access websites including the Alzheimer Association, Alzheimer Research Forum; individual drug company databases; the National Institutes of Health (NIH) Medline; Pharmaprojects database; Scopus; inter-University research communications; and unpublished research data. Expert opinion: Anti-acetylcholinesterase-, chelation-, N-methyl-D-aspartate (NMDA) receptor antagonist-, statin-, Aβ immunization-, β-secretase-, γ-secretase-based, and other strategies to modulate βAPP processing, have dominated pharmacological approaches directed against AD-type neurodegenerative pathology. Cumulative clinical results of these efforts remain extremely disappointing, and have had little overall impact on the clinical management of AD. While a number of novel approaches are in consideration and development, to date there is still no effective treatment or cure for this expanding healthcare concern.