Effects of statins on cognitive function in patients with Alzheimer's disease in galantamine clinical trials

Effect of Statin Therapy on Cognitive Decline and Incident Dementia in Older Adults

BACKGROUND

The neurocognitive effect of statins in older adults remain uncertain.

OBJECTIVES

The aim of this study was to investigate the associations of statin use with cognitive decline and incident dementia among older adults.

METHODS

This analysis included 18,846 participants ≥65 years of age in a randomized trial of aspirin, who had no prior cardiovascular events, major physical disability, or dementia initially and were followed for 4.7 years. Outcome measures included incident dementia and its subclassifications (probable Alzheimer's disease, mixed presentations); mild cognitive impairment (MCI) and its subclassifications (MCI consistent with Alzheimer's disease, other MCI); and changes in domain-specific cognition, including global cognition, memory, language and executive function, psychomotor speed, and the composite of these domains. Associations of baseline statin use versus nonuse with dementia and MCI outcomes were examined using Cox proportional hazards models and with cognitive change using linear mixed-effects models, adjusting for potential confounders. The impact of statin lipophilicity on these associations was further examined, and effect modifiers were identified.

RESULTS

Statin use versus nonuse was not associated with dementia, MCI, or their subclassifications or with changes in cognitive function scores over time (p > 0.05 for all). No differences were found in any outcomes between hydrophilic and lipophilic statin users. Baseline neurocognitive ability was an effect modifier for the associations of statins with dementia (p for interaction < 0.001) and memory change (p for interaction = 0.02).

CONCLUSIONS

In adults ≥65 years of age, statin therapy was not associated with incident dementia, MCI, or declines in individual cognition domains. These findings await confirmation from ongoing randomized trials.

Overview the effect of statin therapy on dementia risk, cognitive changes and its pathologic change: a systematic review and meta-analysis

Background

Many studies have reported on the role of statin therapy in dementia, but its efficacy remains controversial. We aimed to search for reliable and meaningful articles to assess the efficacy of statin therapy for dementia risk, cognitive items, and pathologic markers.

Methods

Related literature for this study was published in the period from January 1, 1987 to January 1, 2018. Odds ratio (OR) and 95% confidence interval (95% CI) estimates were pooled in either fixed or random effects models.

Results

A total of 23 relevant studies were included after the application of the search strategy. The pooled results showed that statin therapy would downregulate dementia risk according to an analysis of 1,314,431 dementia patients and 1,836,539 healthy controls (OR: 0.64, 95% CI: 0.50, 0.81). In addition, specific changes in mini-mental state examination (MMSE) score were observed in individuals with dementia with statin therapy (OR: 0.46, 95% CI: 0.17, 0.74). However, the results of this meta-analysis showed that statin therapy did not significantly modify the Alzheimer's Disease Assessment Scale (ADAS-cog) score (OR: -0.26, 95% CI: -1.13, 0.62). No significant association was found between statin therapy and activities of daily living performance (OR: -0.69, 95% CI: -4.12, 2.74). When investigating pathological markers, our results indicated a significant influence of statin therapy on plasma amyloid β₄₀ (Aβ₄₀) (OR: 9.27, 95% CI: 0.71, 17.84), plasma Aβ₄₂ (OR: 2.60, 95% CI: 1.07, 4.13), plasma low-density lipoprotein (LDL) cholesterol (OR: -16.95, 95% CI: -25.54, -8.37), plasma lathosterol (OR: -0.11, 95% CI: -0.14, -0.07), plasma 24s-hydroxycholesterol (OR: -10.41, 95% CI: -15.57, -5.25), and cerebrospinal fluid (CSF) lathosterol (OR: -0.07, 95% CI: -0.12, -0.01).

Conclusions

The available data indicate that statin therapy may reduce dementia risk, altering cognitive items and pathologic markers.

Hypercholesterolaemia and vascular dementia

Vascular dementia (VaD) is the second commonest cause of dementia. Stroke is the leading cause of disability in adults in developed countries, the second major cause of dementia and the third commonest cause of death. Traditional vascular risk factors-diabetes, hypercholesterolaemia, hypertension and smoking-are implicated as risk factors for VaD. The associations between cholesterol and small vessel disease (SVD), stroke, cognitive impairment and subsequent dementia are complex and as yet not fully understood. Similarly, the effects of lipids and lipid-lowering therapy on preventing or treating dementia remain unclear; the few trials that have assessed lipid-lowering therapy for preventing (two trials) or treating (four trials) dementia found no evidence to support the use of lipid-lowering therapy for these indications. It is appropriate to treat those patients with vascular risk factors that meet criteria for lipid-lowering therapy for the primary and secondary prevention of cardiovascular and cerebrovascular events, and in line with current guidelines. Managing the individual patient in a holistic manner according to his or her own vascular risk profile is recommended. Although the paucity of randomized controlled evidence makes for challenging clinical decision making, it provides multiple opportunities for on-going and future research, as discussed here.

Impact on cognitive function-are all statins the same?

Dementia is a major public health concern, affecting an estimated 7% of the population over 65 and 30% over 80 years of age. There is mounting evidence in the literature from meta-analyses of high-quality prospective cohort studies that statins may have a positive impact in reducing the incidence of dementia. Little is known, however, on whether certain types of statins are more impactful than others. This narrative review specifically explores the various properties of different statin types and whether these differences lead to a clinically significant differential impact on cognitive function. We critically evaluate the literature, emphasizing interesting and important new findings, and overall aim to bring the reader up-to-date on evidence-based recommendations.

Treatment of vascular risk factors in patients with a diagnosis of Alzheimer's disease: a systematic review

BACKGROUND

Increasing evidence suggests vascular risk factors (VRF) play a role in the pathogenesis of Alzheimer's disease (AD). Epidemiological studies have found associations between VRF and risk of AD. Treating VRF in patients with AD offers a potential treatment option but ineffective treatments should be avoided in this group who are frequently on multiple medications and in whom compliance may be challenging.

METHODS

Studies containing information on the treatment of VRF in patients with a diagnosis of AD were identified using a defined search strategy. Randomised controlled trials and observational studies were included.

RESULTS

The pre-specified search strategy retrieved 11,992 abstract articles, and 25 papers including those identified on review of reference lists and reviews met the inclusion criteria. Of these, 11 were randomised controlled trials (RCTs) and 14 observational studies. Observational studies suggested that a VRF package and treatment of hypertension and statin therapy may be associated with improved outcome but these studies suffered from potential bias. The few RCTs performed were mostly small with short duration follow-up, and do not provide clear evidence either way.

CONCLUSIONS

Observational data raises the possibility that treating VRF could alter the rate of decline in AD. However RCT data are not yet available to support this hypothesis and to alter clinical practice. RCTs in larger numbers of individuals with longer follow-up, ideally in the early stages of AD, are required to address this potentially important treatment question.

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.

Traditional Korean East Asian medicines and herbal formulations for cognitive impairment

Hanbang, the Traditional Korean Medicine (TKM), is an inseparable component of Korean culture both within the country, and further afield. Korean traditional herbs have been used medicinally to treat sickness and injury for thousands of years. Oriental medicine reflects our ancestor’s wisdom and experience, and as the elderly population in Korea is rapidly increasing, so is the importance of their health problems. The proportion of the population who are over 65 years of age is expected to increase to 24.3% by 2031. Cognitive impairment is common with increasing age, and efforts are made to retain and restore the cognition ability of the elderly. Herbal materials have been considered for this purpose because of their low adverse effects and their cognitive-enhancing or anti-dementia activities. Herbal materials are reported to contain several active compounds that have effects on cognitive function. Here, we enumerate evidence linking TKMs which have shown benefits in memory improvements. Moreover, we have also listed Korean herbal formulations which have been the subject of scientific reports relating to memory improvement.

Cochrane review on 'Statins for the treatment of dementia'

OBJECTIVES

This review aimed to assess the clinical efficacy and tolerability of statins in the treatment of dementia.

METHODS

We searched 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 (27 October 2008). Double-blind, randomized controlled trials of statins given for at least 6 months in people with a diagnosis of dementia were included. Two independent authors extracted and assessed data independently against the inclusion criteria. Data were pooled where appropriate and entered into a meta-analysis.

RESULTS

Three studies were identified (748 participants, age range 50-90 years). All patients had a diagnosis of probable or possible Alzheimer's disease according to standard criteria, and most patients were established on a cholinesterase inhibitor. Change in Alzheimer's Disease Assessment Scale cognitive subscale from baseline was a primary outcome in three studies; when data were pooled, statins did not provide any beneficial effect in this cognitive measure (mean difference -1.12; 95% confidence interval -3.99, 1.75; p = 0.44). All studies provided a change in Mini-Mental State Examination from baseline; there was no significant benefit from statins in this cognitive measure when the data were pooled (mean difference -1.53; 95% confidence interval -3.28; 0.21, p = 0.08). There were no studies identified assessing the role of statins in treatment of vascular dementia. There was no evidence that statins were detrimental to cognition.

CONCLUSIONS

There is insufficient evidence to recommend statins for the treatment of dementia.

A randomized, double-blind, placebo-controlled trial of simvastatin to treat Alzheimer disease

BACKGROUND

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.

OBJECTIVE

To determine if the lipid-lowering agent simvastatin slows the progression of symptoms in AD.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

The Role of Statins in the Prevention and Treatment of Alzheimer's Disease

Objective:

To review the role of statins (3-hydroxy-3-methylglutaryl coenzyme A [HMG-CoA] reductase inhibitors) in the prevention and treatment of Alzheimer's disease (AD).

Data Sources:

Literature was retrieved from EMBASE (1980–2010, week 22) and MEDLINE (1950-May 2010, week 4), using the key words statins, HMG-CoA reductase inhibitors, and Alzheimer's disease, as well as a bibliographic review of published articles.

Study Selection and Data Extraction:

All clinical trials that involved humans, were published in the English language, and evaluated statins in the prevention and/or treatment of AD were included in this review.

Data Synthesis:

Recent studies have evaluated the use of statins in the prevention and treatment of AD; results from these studies are conflicting. One randomized, placebo-controlled trial found that statins may improve the ADAS-Cog (Alzheimer's Disease Assessment Scale on Cognition) by 0.1–1.8 points in patients with AD during the first 6 months of treatment. Alternatively, another randomized controlled trial found that atorvastatin did not provide benefit on the ADAS-Cog. Although many of the prevention trials did find potential benefit with statin use, these trials were observational.

Conclusions:

Due to insufficient evidence of benefit in both the prevention and treatment of AD, statins cannot be recommended at this time.

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 ss-amyloid protein (Ass) is deposited in the form of extracellular plaques and previous studies have determined Ass 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 dementia.

OBJECTIVES

To assess the clinical efficacy and tolerability of statins in the treatment of dementia.

SEARCH STRATEGY

We searched 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 (27 October 2008).

SELECTION CRITERIA

Double-blind, randomized 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 independently against the inclusion criteria. Data were pooled where appropriate and entered into a meta-analysis.

MAIN RESULTS

Three studies were identified (748 participants, age range 50-90 years). All patients had a diagnosis of probable or possible AD according to standard criteria and most patients were established on a cholinesterase inhibitor. Treatment in ADCLT 2005 consisted of 80mg atorvastatin compared to placebo for 52 weeks, serum low density lipoprotein (LDL) cholesterol was reduced by 54% in the atorvastatin group. Treatment in Simons 2002 consisted of 40mg simvastatin compared to placebo for 26 weeks, serum LDL cholesterol was reduced by 52% in the simvastatin group. Treatment in LEADe 2010 consisted of 80mg atorvastatin compared to placebo for 72 weeks, LDL cholesterol was reduced by 50.2% by month 3 and remained constant through month 18. Change in Alzheimer's Disease Assessment Scale- cognitive subscale (ADAS-Cog) from baseline was a primary outcome in 3 studies; when data were pooled there was considerable heterogeneity so the random effects model was used, statins did not provide any beneficial effect in this cognitive measure [mean difference -1.12, 95% CI -3.99, 1.75, p = 0.44]. All studies provided change in Mini Mental State Examination (MMSE) from baseline; again random effects model was used due to considerable heterogeneity: there was no significant benefit from statins in this cognitive measure when the data were pooled [mean difference -1.53, 95% CI -3.28, 0.21, p = 0.08]. There was some evidence that patients on statins in ADCLT 2005 maintained better cognitive function if serum cholesterol was high at baseline, MMSE was higher at baseline or if they had an apolipoprotein E4 allele present. This would need to be confirmed in larger studies however. Treatment related adverse effects were available from two studies, LEADe 2010 and Simons 2002; when data were pooled there was no significant difference between statins and placebo [odds ratio 2.45, 95% CI 0.69, 8.62, p = 0.16]. There was no significant difference in global function, behaviour or activities of daily living in the statin and placebo groups. One large randomised controlled trial (RCT) ( CLASP 2008) has not yet published its results. There were no studies identified assessing role of statins in treatment of VaD. There was no evidence that statins were detrimental to cognition.

AUTHORS' CONCLUSIONS

There is insufficient evidence to recommend statins for the treatment of dementia. Analysis from the studies available, including one large RCT, indicate statins have no benefit on the outcome measures ADAS-Cog or MMSE. We need to await full results from CLASP 2008 before we can be certain. This Cochrane review will be updated as these results become available.

Secondary stroke prevention strategies for the oldest patients: possibilities and challenges

Older adults are not only at higher risk of experiencing stroke, but also have multiple co-morbidities that make treatment for secondary stroke prevention challenging. Very few clinical trials specifically related to secondary stroke prevention treatment efficacy have focused on the oldest-old (>or=85 years) and, therefore, evidence-based recommendations for treatment specific to this population are not available. Some of the special considerations for stroke prevention treatments in older patients include careful titration of blood-pressure-lowering drugs to avoid hypotension, the risk of haemorrhagic stroke with HMG-CoA reductase inhibitors (statins) and weighing the risk of recurrent ischaemia versus bleeding in patients taking antiplatelet or anticoagulant therapy. The risk of peri-procedural complications appears to be high with both carotid angioplasty and stenting and carotid endarterectomy in older patients with carotid stenosis. Other common issues in older patients include adverse drug events, recognizing the risk of dementia, depression and osteoporosis and deciding when to discontinue secondary stroke prevention. In this review, we provide the practitioner with the evidence related to specific approaches to secondary stroke prevention in older patients, and identify the knowledge gaps that currently limit our ability to appropriately treat this vulnerable population.

β-Amyloid (Aβ40, Aβ42) binding to modified LDL accelerates macrophage foam cell formation

Apart from its role as a risk factor in arteriosclerosis, plasma cholesterol is increasingly recognized to play a major role in the pathogenesis of Alzheimer's disease (AD). Moreover, alterations of intracellular cholesterol metabolism in neuronal and vascular cells are of considerable importance for the understanding of AD. Cellular cholesterol accumulation enhances the deposition of insoluble beta-amyloid peptides, which is considered a hallmark in the pathogenesis of AD. In order to test the hypothesis, whether exogenous beta-amyloid peptides (Abeta42, Abeta40) might contribute to cellular cholesterol accumulation by opsonization of lipoproteins, we compared the binding and uptake of native LDL, enzymatically modified LDL (E-LDL), copper oxidized LDL (Ox-LDL) and HDL as control, preincubated either in the absence or presence of Abeta42 or Abeta40, by human monocytes or monocyte-derived macrophages. Incubation of monocytes and macrophages with Abeta-lipoprotein-complexes lead to increased cellular free and esterified cholesterol when compared to non-opsonized lipoproteins, except for HDL. Furthermore, the cellular uptake of these complexes regulated Abeta-receptors such as FPRL-1 or LRP/CD91. In summary, our results suggest that Abeta42 and Abeta40 act as potent opsonins for LDL, E-LDL and Ox-LDL and enhance cellular cholesterol accumulation as well as Abeta-deposition in vessel wall macrophages.