Statins for the prevention of dementia

The role of statins in amyotrophic lateral sclerosis: protective or not?

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of motor neurons characterized by muscle weakness, muscle twitching, and muscle wasting. ALS is regarded as the third-most frequent neurodegenerative disease, subsequent to Alzheimer's disease (AD) and Parkinson's disease (PD). The World Health Organization (WHO) in 2007 declared that prolonged use of statins may induce development of ALS-like syndrome and may increase ALS risk. Subsequently, different studies have implicated statins in the pathogenesis of ALS. In contrast, results from preclinical and clinical studies highlighted the protective role of statins against ALS neuropathology. Recently, meta-analyses and systematic reviews illustrated no association between long-term use of statins and ALS risk. These findings highlighted controversial points regarding the effects of statins on ALS pathogenesis and risk. The neuroprotective effects of statins against the development and progression of ALS may be mediated by regulating dyslipidemia and inflammatory changes. However, the mechanism for induction of ALS neuropathology by statins may be related to the dysregulation of liver X receptor signaling (LXR) signaling in the motor neurons and reduction of cholesterol, which has a neuroprotective effect against ALS neuropathology. Nevertheless, the exact role of statins on the pathogenesis of ALS was not fully elucidated. Therefore, this narrative review aims to discuss the role of statins in ALS neuropathology.

Hypercholesterolemia and the Increased Risk of Vascular Dementia: a Cholesterol Perspective

PURPOSE OF REVIEW

Vascular dementia (VaD) is the second most prevalent type of dementia after Alzheimer's disease.Hypercholesterolemia may increase the risk of dementia, but the association between cholesterol and cognitive function is very complex. From the perspective of peripheral and brain cholesterol, we review the relationship between hypercholesterolemia and increased risk of VaD and how the use of lipid-lowering therapies affects cognition.

RECENT FINDINGS

Epidemiologic studies show since 1980, non-HDL-C levels of individuals has increased rapidly in Asian countries.The study has suggested that vascular risk factors increase the risk of VaD, such as disordered lipid metabolism. Dyslipidemia has been found to interact with chronic cerebral hypoperfusion to promote inflammation resulting in cognitive dysfunction in the brain.Hypercholesterolemia may be a risk factor for VaD. Inflammation could potentially serve as a link between hypercholesterolemia and VaD. Additionally, the potential impact of lipid-lowering therapy on cognitive function is also worth considering. Finding strategies to prevent and treat VaD is critical given the aging of the population to lessen the load on society. Currently, controlling underlying vascular risk factors is considered one of the most effective methods of preventing VaD. Understanding the relationship between abnormal cholesterol levels and VaD, as well as discovering potential serum biomarkers, is important for the early prevention and treatment of VaD.

Somatic comorbidity and the progression of cognitive impairment

Background

There are usually multiple factors underlying dementia in old age. Somatic comorbidity is one important element that influences the progression of cognitive impairment.

Objective

The goal of this study was to assess the relationship between the progression of cognitive impairment and the presence and severity of comorbidities based on a four-year observation.

Material

Out of 128 patients from the Clinic for Outpatients in Gdansk, who were recruited into the study based on the criteria of the Working Group on Mild Cognitive Impairment, a total of 93 participants completed the four-year observation. Only the data from participants who completed the full period of observations were analysed. The mean age of the group was M = 75.93 (SD = 9.43). The level of progression of cognitive impairment was measured using the Clinical Dementia Rating Scale - Sum of Boxes, the severity of comorbidities was measured using the modified Cumulative Illness Rating Scale, and, additionally, at the time of inclusion in the study, participants were assessed using the MMSE scale and the Activity Scale, and sociodemographic data were collected. The Generalized Estimating Equations method was employed to fit a marginal model for analyzing the data collected in a repeated measures design. The tested model elucidated the role of the overall severity of comorbidities in explaining the progression of cognitive impairment, while controlling for everyday activity and basic demographic variables.

Results

During the four-year observation, a significant decline in cognitive function (B = 1.86, p < 0.01) was observed in the examined sample. The statistical analysis revealed that individuals with higher overall severity of comorbidities exhibited significantly more pronounced progression of cognitive impairment over time. Regarding particular comorbidities, metabolic diseases were found to be associated with a poorer prognosis (rho = 0.41, p < 0.05). Furthermore, a time physical activity interaction was identified as predicting cognitive impairment, indicating that individuals who were more physically active at the beginning of the study exhibited significantly less pronounced progression of cognitive impairment over the course of the 4 years.

Conclusion

This study suggests the important roles of comorbidities and physical activity for the prognosis of mild cognitive impairment.

The relationship between midlife dyslipidemia and lifetime incidence of dementia: A systematic review and meta-analysis of cohort studies

Introduction

We conducted a systematic review and meta-analysis to review the relationship between midlife dyslipidemia and lifetime incident dementia.

Methods

The databases Medline, Embase, Scopus, Web of Science, and Cochrane were searched from inception to February 20, 2022. Longitudinal studies examining the relationship between midlife lipid levels on dementia, dementia subtypes, and/or cognitive impairment were pooled using inverse-variance weighted random-effects meta-analysis.

Results

Seventeen studies (1.2 million participants) were included. Midlife hypercholesterolemia was associated with increased incidence of mild cognitive impairment (effect size [ES] = 2.01; 95% confidence interval [CI] 1.19 to 2.84; I² = 0.0%) and all-cause dementia (ES = 1.14; 95% CI: 1.07 to 1.21; I² = 0.0%). Each 1 mmol/L increase in low-density lipoprotein was associated with an 8% increase (ES = 1.08, 95% CI: 1.03 to 1.14; I² = 0.3%) in incidence of all-cause dementia.

Discussion

Midlife dyslipidemia is associated with an increased risk of cognitive impairment in later life.

Association of Familial Hypercholesterolemia and Statin Use With Risk of Dementia in Norway

IMPORTANCE

Hypercholesterolemia, which is a cardiovascular risk factor, may also be associated with dementia risk. The benefit of statin treatment on dementia risk is controversial.

OBJECTIVE

To determine whether individuals with familial hypercholesterolemia (FH), who have been exposed to lifelong hypercholesterolemia, have an excess risk of dementia and whether statin use is associated with dementia risk.

DESIGN, SETTING, AND PARTICIPANTS

This was a prospective cohort study performed from 2008 to 2018 in Norway. Statistical analysis was performed from January 2021 to February 2022. This study included individuals with genetically verified FH and age-matched and sex-matched controls obtained from the general Norwegian population.

EXPOSURES

Dementia was defined according to International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes F00-03 and G30.

MAIN OUTCOMES AND MEASURES

Incident cases of total dementia, vascular dementia, Alzheimer disease-dementia in Alzheimer disease, and data on lipid-lowering medication were obtained from the Norwegian Patient Registry, Cause of Death Registry, and the Norwegian Prescription Database. Hazard ratios (HRs) for risk of dementia for individuals with FH vs matched controls were calculated using Cox regression. The cumulative sum of defined daily doses (DDDs) of statins prescribed during study follow-up was calculated for individuals with FH and was analyzed as a time-varying covariate with 3 levels: 1 to 4999 DDDs, 5000 to 10 000 DDDs, and more than 10 000 DDDs.

RESULTS

Among the 3520 individuals with FH (1863 women [52.9%]; mean [SD] age at the start of follow-up, 51.8 [11.5] years) and the 69 713 controls (36 958 women [53.0%]; mean [SD] age at the start of follow-up, 51.7 [11.5] years), 62 patients with FH (39 women [62.9%]) and 1294 controls (801 women [61.9%]) had developed dementia over the course of 10 years of follow-up. Most dementia cases occurred among individuals aged 70 years and older (39 patients with FH [62.9%] and 870 patients [67.2%] in the control group). We found no excess risk of dementia in patients with FH vs matched controls (HR for total dementia, 0.9; 95% CI, 0.7-1.2). There was no association between cumulative DDDs of statins and total dementia in patients with FH with HRs of 1.2 (95% CI, 0.4-3.8) for cumulative DDDs of 5000 to 10 000 and 1.9 (95% CI, 0.7-5.0) for cumulative DDDs greater than 10 000.

CONCLUSIONS AND RELEVANCE

These findings suggest that individuals with FH have no excess risk of dementia compared with age-matched and sex-matched controls and that there is no association between use of statins and risk of dementia in patients with FH.

Association between Previous Statin Use and Alzheimer's Disease: A Nested Case-Control Study Using a National Health Screening Cohort

A number of studies report the incidence of Alzheimer’s disease (AD) in patients taking statins, but the results are inconsistent. (1) Background: The present study investigated the cross-sectional association between previous statin use and the risk of AD development in Korean residents. (2) Methods: We used the Korean National Health Insurance Service-National Sample Cohort; 17,172 AD patients were matched by age, gender, income, and region of residence with 68,688 control participants at a ratio of 1:4. We used a multiple conditional logistic regression model to analyse the association between the number of days of statin use and AD occurrence. Further analyses were performed to identify whether this association is maintained for different ages, genders, socioeconomic status groups, and covariates. (3) Results: The odds ratio, which was adjusted for potential confounders, for the days of statin use per year in the AD group compared to the control group was 0.95 (95% confidence interval = 0.92–0.98; p = 0.003). The number of days of statin use in the AD group was significantly smaller in the subgroups of non-smokers and individuals with normal weight, alcohol consumption less than once a week, total cholesterol level below 200 mg/dL, systolic blood pressure below 140, diastolic blood pressure below 90, and fasting blood glucose below 100 mg/dL. (4) Conclusions: Our results suggest that statin use prevents the occurrence of AD. The effects of statin use in preventing AD may be greater in individuals at relatively low risk.

Depression as a Risk Factor for Dementia and Alzheimer's Disease

Preventing the onset of dementia and Alzheimer’s disease (AD), improving the diagnosis, and slowing the progression of these diseases remain a challenge. The aim of this study was to elucidate the association between depression and dementia/AD and to identify possible relationships between these diseases and different sociodemographic and clinical features. In this regard, a case-control study was conducted in Spain in 2018–2019. The definition of a case was: A person ≥ 65 years old with dementia and/or AD and a score of 5–7 on the Global Deterioration Scale (GDS). The sample consisted of 125 controls; among the cases, 96 had dementia and 74 had AD. The predictor variables were depression, dyslipidemia, type 2 diabetes mellitus, and hypertension. The results showed that depression, diabetes mellitus, and older age were associated with an increased likelihood of developing AD, with an Odds Ratio (OR) of 12.9 (95% confidence interval (CI): 4.3–39.9), 2.8 (95% CI: 1.1–7.1) and 1.15 (95% CI: 1.1–1.2), respectively. Those subjects with treated dyslipidemia were less likely to develop AD (OR 0.47, 95% CI: 0.22–1.1). Therefore, depression and diabetes mellitus increase the risk of dementia, whereas treated dyslipidemia has been shown to reduce this risk.

The Consortium for the early identification of Alzheimer's disease-Quebec (CIMA-Q)

Introduction

The Consortium for the early identification of Alzheimer's disease–Quebec (CIMA-Q) created a research infrastructure to recruit, characterize, and track disease progression in individuals at risk of dementia.

Methods

CIMA-Q established standardized clinical, neuropsychological, neuroimaging, blood (plasma, serum, RNA, genomic DNA), cryopreserved peripheral blood mononuclear cells, and cerebrospinal fluid collection protocols. These data and biological materials are available to the research community.

Results

In phase 1, 115 persons with subjective cognitive decline, 88 with mild cognitive impairment, 31 with early probable Alzheimer's disease, and 56 older adults with no worries nor impairments received detailed clinical and cognitive evaluations as well as blood and peripheral blood mononuclear cells collections. Among them, 142 underwent magnetic resonance imaging, 29 a ¹⁸fluorodeoxyglucose positron emission tomography, and 60 a lumbar puncture.

Discussion

CIMA-Q provides procedures and resources to identify early biomarkers and novel therapeutic targets, and holds promise for detecting cognitive decline in Alzheimer's disease.

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Well-ascertained cohort of 290 community-dwelling elderly individuals in Quebec.

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Large number of individuals with subjective cognitive decline studied longitudinally.

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Clinical, neuropsychology, neuroimaging, and biomaterials available for Alzheimer's disease studies.

Advances in developing novel therapeutic strategies for Alzheimer's disease

Alzheimer's Disease (AD), the most prevalent neurodegenerative disease of aging, affects one in eight older Americans. Nearly all drug treatments tested for AD today have failed to show any efficacy. There is a great need for therapies to prevent and/or slow the progression of AD. The major challenge in AD drug development is lack of clarity about the mechanisms underlying AD pathogenesis and pathophysiology. Several studies support the notion that AD is a multifactorial disease. While there is abundant evidence that amyloid plays a role in AD pathogenesis, other mechanisms have been implicated in AD such as tangle formation and spread, dysregulated protein degradation pathways, neuroinflammation, and loss of support by neurotrophic factors. Therefore, current paradigms of AD drug design have been shifted from single target approach (primarily amyloid-centric) to developing drugs targeted at multiple disease aspects, and from treating AD at later stages of disease progression to focusing on preventive strategies at early stages of disease development. Here, we summarize current strategies and new trends of AD drug development, including pre-clinical and clinical trials that target different aspects of disease (mechanism-based versus non-mechanism based, e.g. symptomatic treatments, lifestyle modifications and risk factor management).

Surgery, neuroinflammation and cognitive impairment

Trauma experienced during surgery can contribute to the development of a systemic inflammatory response that can cause multi-organ dysfunction or even failure. Post-surgical neuroinflammation is a documented phenomenon that results in synaptic impairment, neuronal dysfunction and death, and impaired neurogenesis. Various pro-inflammatory cytokines, such as TNFα, maintain a state of chronic neuroinflammation, manifesting as post-operative cognitive dysfunction and post-operative delirium. Furthermore, elderly patients with post-operative cognitive dysfunction or delirium are three times more likely to experience permanent cognitive impairment or dementia. We conducted a narrative review, considering evidence extracted from various databases including Pubmed, MEDLINE and EMBASE, as well as journals and book reference lists. We found that further pre-clinical and well-powered clinical studies are required to delineate the precise pathogenesis of post-operative delirium and cognitive dysfunction. Despite the burden of post-operative neurological sequelae, clinical studies investigating therapeutic agents, such as dexmedetomidine, ibuprofen and statins, have yielded conflicting results. In addition, evidence supporting novel therapeutic avenues, such as nicotinic and HMGB-1 targeting and remote ischaemic pre-conditioning, is limited and necessitates further investigation.

Protective effect of carnosine on white matter damage in corpus striatum induced by chronic cerebral hypoperfusion

Subcortical ischemic vascular dementia caused by chronic cerebral hypoperfusion due to small-artery disease is a common subtype of vascular dementia, which is recognized as the second most prevalent type of dementia. The aim of this study was to determine the effect of carnosine on white matter damage in corpus striatum. Adult male mice (C57BL/6 strain) were subjected to right unilateral common carotid arteries occlusion (rUCCAO), and treated with carnosine or saline. Klüver-Barrera staining, immunohistochemical analyses, Western blots and neurochemical analysis were performed after rUCCAO. The white matter in corpus striatum was damaged at day 37 after rUCCAO, which was largely rescued by carnosine (200, 500 mg/kg). Carnosine (200, 500 mg/kg) significantly recovered the expression of myelin basic protein, suppressed the activation of microglia and reversed the decrease of 5-hydroxytryptamine and dopamine levels in corpus striatum. Moreover, carnosine (200, 500 mg/kg) significantly inhibited the apoptosis in corpus striatum. These data suggest that carnosine has the neuroprotective effect in corpus striatum on rUCCAO in mice, may be due to its protection of neurotransmitters and inhibition of apoptosis.

Overview and Current Status of Alzheimer's Disease in Bangladesh

Alzheimer’s disease (AD) is a complex neurological disorder with economic, social, and medical burdens which is acknowledged as leading cause of dementia marked by the accumulation and aggregation of amyloid-β peptide and phosphorylated tau (p-tau) protein and concomitant dementia, neuron loss and brain atrophy. AD is the most prevalent neurodegenerative brain disorder with sporadic etiology, except for a small fraction of cases with familial inheritance where familial forms of AD are correlated to mutations in three functionally related genes: the amyloid-β protein precursor and presenilins 1 and 2, two key γ-secretase components. The common clinical features of AD are memory impairment that interrupts daily life, difficulty in accomplishing usual tasks, confusion with time or place, trouble understanding visual images and spatial relationships. Age is the most significant risk factor for AD, whereas other risk factors correlated with AD are hypercholesterolemia, hypertension, atherosclerosis, coronary heart disease, smoking, obesity, and diabetes. Despite decades of research, there is no satisfying therapy which will terminate the advancement of AD by acting on the origin of the disease process, whereas currently available therapeutics only provide symptomatic relief but fail to attain a definite cure and prevention. This review also represents the current status of AD in Bangladesh.

Hypertension and Risk of Post-Operative Cognitive Dysfunction (POCD): A Systematic Review and Meta-Analysis

Background:

Post-operative cognitive dysfunction (POCD) occurs frequently after major surgery. Hypertension is well-established as a risk factor for age-related cognitive impairment, but it is unclear whether or not it also increases the risk of POCD.

Objective:

To evaluate the role of hypertension in POCD risk in a systematic review and meta-analysis.

Method:

PubMed, Ovid SP and the Cochrane Database of Systematic Reviews were searched for longitudinal studies of adults undergoing surgery with reporting of hypertension, blood pressure and/or anti-hypertensive treatment associations with POCD as relative risks or odds ratios. Fixed-effects meta-analyses were performed using Review Manager (version 5.3).

Results:

Twenty-four studies on 4317 patients (mean age 63 years) were included. None of the studies had set out to assess hypertension as a risk factor for POCD. Hypertension was used as a categorical predictor throughout and only 2 studies adjusted for potential confounders. Across all 24 studies, hypertension was not significantly associated with POCD risk (RR 1.01; 95% CI 0.93, 1.09; p=0.82), though among 8 studies with >75% males, we found hypertension associations with a 27% increased risk of POCD (RR 1.27, 95% CI 1.07, 1.49; p=0.005).

Conclusion:

Our findings do not support the hypothesis that hypertension is a risk factor for POCD. However, since none of the studies included in our analysis were hypothesis-driven and most did not adjust for potential confounders, further systematic investigations are needed to evaluate the role of hypertension in the epidemiology of POCD.

Alzheimer's disease in people with Down's syndrome: the prospects for and the challenges of developing preventative treatments

People with Down's syndrome (DS) are at high risk for developing Alzheimer's disease (AD) at a relatively young age. This increased risk is not observed in people with intellectual disabilities for reasons other than DS and for this reason it is unlikely to be due to non-specific effects of having a neurodevelopmental disorder but, instead, a direct consequence of the genetics of DS (trisomy 21). Given the location of the amyloid precursor protein (APP) gene on chromosome 21, the amyloid cascade hypothesis is the dominant theory accounting for this risk, with other genetic and environmental factors modifying the age of onset and the course of the disease. Several potential therapies targeting the amyloid pathway and aiming to modify the course of AD are currently being investigated, which may also be useful for treating AD in DS. However, given that the neuropathology associated with AD starts many years before dementia manifests, any preventative treatment must start well before the onset of symptoms. To enable trials of such interventions, plasma, CSF, brain, and retinal biomarkers are being studied as proxy early diagnostic and outcome measures for AD. In this systematic review, we consider the prospects for the development of potential preventative treatments of AD in the DS population and their evaluation.

Pathophysiologic relationship between Alzheimer's disease, cerebrovascular disease, and cardiovascular risk: A review and synthesis

As the population ages due to demographic trends and gains in life expectancy, the incidence and prevalence of dementia increases, and the need to understand the etiology and pathogenesis of dementia becomes ever more urgent. Alzheimer's disease (AD), the most common form of dementia, is a complex disease, the mechanisms of which are poorly understood. The more we learn about AD, the more questions are raised about our current conceptual models of disease. In the absence of a cure or the means by which to slow disease progress, it may be prudent to apply our current knowledge of the intersection between AD, cardiovascular disease, and cerebrovascular disease to foster efforts to delay or slow the onset of AD. This review discusses our current understanding of the epidemiology, genetics, and pathophysiology of AD, the intersection between AD and vascular causes of dementia, and proposes future directions for research and prevention.

Safety and Effectiveness of Statins for Prevention of Recurrent Myocardial Infarction in 12 156 Typical Older Patients: A Quasi-Experimental Study

BACKGROUND

There is limited evidence on statin risk and effectiveness for patients aged 80+. We estimated risk of recurrent myocardial infarction, muscle-related and other adverse events, and statin-related incremental costs in "real-world" older patients treated with statins versus no statins.

METHODS

We used primary care electronic medical records from the UK Clinical Practice Research Datalink. Subhazard ratios (competing risk of death) for myocardial infarction recurrence (primary end point), falls, fractures, ischemic stroke, and dementia, and hazard ratios (Cox) for all-cause mortality were used to compare older (60+) statin users and 1:1 propensity-score-matched controls (n = 12,156). Participants were followed-up for 10 years.

RESULTS

Mean age was 76.5±9.2 years; 45.5% were women. Statins were associated with near significant reduction in myocardial infarction recurrence (subhazard ratio = 0.84, 0.69-1.02, p = .073), with protective effect in the 60-79 age group (0.73, 0.57-0.94) but a nonsignificant result in the 80+ group (1.06, 0.78-1.44; age interaction p = .094). No significant associations were found for stroke or dementia. Data suggest an increased risk of falls (1.36, 1.17-1.60) and fractures (1.33, 1.04-1.69) in the first 2 years of treatment, particularly in the 80+ group. Treatment was associated with lower all-cause mortality. Statin use was associated with health care cost savings in the 60-79 group but higher costs in the 80+ group.

CONCLUSIONS

Estimates of statin effectiveness for the prevention of recurrent myocardial infarction in patients aged 60-79 years were similar to trial results, but more evidence is needed in the older group. There may be an excess of falls and fractures in very old patients, which deserves further investigation.

Intensive versus Guideline Blood Pressure and Lipid Lowering in Patients with Previous Stroke: Main Results from the Pilot 'Prevention of Decline in Cognition after Stroke Trial' (PODCAST) Randomised Controlled Trial

Background

Stroke is associated with the development of cognitive impairment and dementia. We assessed the effect of intensive blood pressure (BP) and/or lipid lowering on cognitive outcomes in patients with recent stroke in a pilot trial.

Methods

In a multicentre, partial-factorial trial, patients with recent stroke, absence of dementia, and systolic BP (SBP) 125–170 mmHg were assigned randomly to at least 6 months of intensive (target SBP <125 mmHg) or guideline (target SBP <140 mmHg) BP lowering. The subset of patients with ischaemic stroke and total cholesterol 3.0–8.0 mmol/l were also assigned randomly to intensive (target LDL-cholesterol <1.3 mmol/l) or guideline (target LDL-c <3.0 mmol/l) lipid lowering. The primary outcome was the Addenbrooke’s Cognitive Examination-Revised (ACE-R).

Results

We enrolled 83 patients, mean age 74.0 (6.8) years, and median 4.5 months after stroke. The median follow-up was 24 months (range 1–48). Mean BP was significantly reduced with intensive compared to guideline treatment (difference –10·6/–5·5 mmHg; p<0·01), as was total/LDL-cholesterol with intensive lipid lowering compared to guideline (difference –0·54/–0·44 mmol/l^; p<0·01). The ACE-R score during treatment did not differ for either treatment comparison; mean difference for BP lowering -3.6 (95% CI -9.7 to 2.4), and lipid lowering 4.4 (95% CI -2.1 to 10.9). However, intensive lipid lowering therapy was significantly associated with improved scores for ACE-R at 6 months, trail making A, modified Rankin Scale and Euro-Qol Visual Analogue Scale. There was no difference in rates of dementia or serious adverse events for either comparison.

Conclusion

In patients with recent stroke and normal cognition, intensive BP and lipid lowering were feasible and safe, but did not alter cognition over two years. The association between intensive lipid lowering and improved scores for some secondary outcomes suggests further trials are warranted.

Trial Registration

ISRCTN ISRCTN85562386

Primary and Secondary Prevention Trials in Alzheimer Disease: Looking Back, Moving Forward

The field of Alzheimer disease (AD) prevention has been a culmination of basic science, clinical, and translational research. In the past three years since the new 2011 AD diagnostic guidelines, large-scale collaborative efforts have embarked on new clinical trials with the hope of someday preventing AD. This review will shed light on the historical and scientific contexts in which these trials were based on, as well as discuss potential challenges these trials may face in the coming years. Primary preventive measures, such as lifestyle, multidomain, medication, and supplemental interventions, will be analyzed. Secondary prevention as represented by disease-modifying interventions, such as antiamyloid therapy and pioglitazone, will also be reviewed. Finally, hypotheses on future directions for AD prevention trials will be proposed.

Cognitive decline affects diabetic women

Introduction: DM provokes peripheral complications and changes in central nervous system. Central changes in the course of diabetes mellitus (DM) include changes in brain tissue structure, electrophysiological abnormalities but also disturbances in neurotransmission leading to cognitive decline.

Aim of the study: The aim of our study was to asses cognitive functioning of patients suffering from DM1 for at least 5 years but without any diagnosed complications.

Materials and methods: Cognitive functions were assessed in 59 patients (35 men) with Trail Making Test A (TMT A) and B (TMT B), Maze Test (MT), Stroop Test (SCWT) and Rey Auditory Verbal Learning Test (RAVLT). Mental disorders were excluded with Beck’s Depression Inventory (BT), Mini Mental State Examination (MMSE) and psychiatric examination.

Results: We stated that women, compared with men, presented worsening of executive functions, speed and motor control. Cognitive decline depended on number of episodes of at least moderate hypoglycemia and duration of disease. HbA1c below 8% resulted in better memory, speed and motor control. Cognitive decline was more escalated in the patients with atherogenic lipid profile.

Conclusions: It seems that even apparent lack of complications is not unambiguous with lack of cognitive decline and women seem to be more susceptible. DM1 affects young individuals, whose cognitive functions are in the course of the development, so it is important to find the underlying mechanisms and the areas of disturbed cognitive functioning and further investigations are needed.

Towards onset prevention of cognition decline in adults with Down syndrome (The TOP-COG study): A pilot randomised controlled trial

BACKGROUND

Dementia is very common in Down syndrome (trisomy 21) adults. Statins may slow brain amyloid β (Aβ, coded on chromosome 21) deposition and, therefore, delay Alzheimer disease onset. One prospective cohort study with Down syndrome adults found participants on statins had reduced risk of incident dementia, but there are no randomised controlled trials (RCTs) on this issue. Evidence is sparse on the best instruments to detect longitudinal cognitive decline in older Down syndrome adults.

METHODS

TOP-COG was a feasibility/pilot, double-blind RCT of 12 months simvastatin 40 mg versus placebo for the primary prevention of dementia in Alzheimer disease in Down syndrome adults aged 50 years or older. Group allocation was stratified by age, apolipoprotein E (APOE) ε4 allele status, and cholesterol level. Recruitment was from multiple general community sources over 12 months. Adults with dementia, or simvastatin contraindications, were excluded. Main outcomes were recruitment and retention rates. Cognitive decline was measured with a battery of tests; secondary measures were adaptive behaviour skills, general health, and quality of life. Assessments were conducted pre randomisation and at 12 months post randomisation. Blood Aβ40/Aβ42 levels were investigated as a putative biomarker. Results were analysed on an intention-to-treat basis. A qualitative sub-study was conducted and analysed using the Framework Approach to determine recruitment motivators/barriers, and participation experience.

RESULTS

We identified 181 (78 %) of the likely eligible Down syndrome population, and recruited 21 (11.6 %), from an area with a general population size of 3,135,974. Recruitment was highly labour-intensive. Thirteen (62 %) participants completed the full year. Results favoured the simvastatin group. The most appropriate cognitive instrument (regarding ease of completion and detecting change over time) was the Memory for Objects test from the Neuropsychological Assessment of Dementia in Individuals with Intellectual Disabilities battery. Cognitive testing appeared more sensitive than proxy-rated adaptive behaviour, quality of life, or general health scores. Aβ40 levels changed less for the simvastatin group (not statistically significant). People mostly declined to participate because of not wanting to take medication, and not knowing if they would receive simvastatin or placebo. Participants reported enjoying taking part.

CONCLUSION

A full-scale RCT is feasible. It will need 37 % UK population coverage to recruit the required 160 participants. Information/education about the importance of RCT participation is needed for this population.

TRIAL REGISTRATION

ISRCTN67338640 .

Therapies for Prevention and Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia associated with a progressive neurodegenerative disorder, with a prevalence of 44 million people throughout the world in 2015, and this figure is estimated to double by 2050. This disease is characterized by blood-brain barrier disruption, oxidative stress, mitochondrial impairment, neuroinflammation, and hypometabolism; it is related to amyloid-β peptide accumulation and tau hyperphosphorylation as well as a decrease in acetylcholine levels and a reduction of cerebral blood flow. Obesity is a major risk factor for AD, because it induces adipokine dysregulation, which consists of the release of the proinflammatory adipokines and decreased anti-inflammatory adipokines, among other processes. The pharmacological treatments for AD can be divided into two categories: symptomatic treatments such as acetylcholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists and etiology-based treatments such as secretase inhibitors, amyloid binders, and tau therapies. Strategies for prevention of AD through nonpharmacological treatments are associated with lifestyle interventions such as exercise, mental challenges, and socialization as well as caloric restriction and a healthy diet. AD is an important health issue on which all people should be informed so that prevention strategies that minimize the risk of its development may be implemented.

Statins for the prevention of dementia

BACKGROUND

This is an update of a Cochrane review first published in 2001 and then updated in 2009. Vascular risk factors including high cholesterol levels increase the risk of dementia due to Alzheimer's disease and of vascular dementia. Some observational studies have suggested an association between statin use and lowered incidence of dementia.

OBJECTIVES

To evaluate the efficacy and safety of statins for the prevention of dementia in people at risk of dementia due to their age and to determine whether the efficacy and safety of statins for this purpose depends on cholesterol level, apolipoprotein E (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, LILACS, ClinicalTrials.gov and the World Health Organization (WHO) Portal on 11 November 2015.

SELECTION CRITERIA

We included double-blind, randomised, placebo-controlled trials in which statins were administered for at least 12 months to people at risk of dementia.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included two trials with 26,340 participants aged 40 to 82 years of whom 11,610 were aged 70 or older. All participants had a history of, or risk factors for, vascular disease. The studies used different statins (simvastatin and pravastatin). Mean follow-up was 3.2 years in one study and five years in one study. The risk of bias was low. Only one study reported on the incidence of dementia (20,536 participants, 31 cases in each group; odds ratio (OR) 1.00, 95% confidence interval (CI) 0.61 to 1.65, moderate quality evidence, downgraded due to imprecision). Both studies assessed cognitive function, but at different times using different scales, so we judged the results unsuitable for a meta-analysis. There were no differences between statin and placebo groups on five different cognitive tests (high quality evidence). Rates of treatment discontinuation due to non-fatal adverse events were less than 5% in both studies and there was no difference between statin and placebo groups in the risk of withdrawal due to adverse events (26,340 participants, 2 studies, OR 0.94, 95% CI 0.83 to 1.05).

AUTHORS' CONCLUSIONS

There is good evidence that statins given in late life to people at risk of vascular disease do not prevent cognitive decline 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. However, indication bias may have been a factor in these studies and the evidence from subsequent RCTs has been negative. There were limitations in the included studies involving the cognitive assessments used and the inclusion of participants at moderate to high vascular risk only.

Protective effects of carnosine on white matter damage induced by chronic cerebral hypoperfusion

Carnosine is a dipeptide that scavenges free radicals, inhibits inflammation in the central nervous system, and protects against ischemic and hypoxic brain damage through its anti-oxidative and anti-apoptotic actions. Therefore, we hypothesized that carnosine would also protect against white matter damage caused by subcortical ischemic injury. White matter damage was induced by right unilateral common carotid artery occlusion in mice. The animals were treated with 200, 500 or 750 mg/kg carnosine by intraperitoneal injection 30 minutes before injury and every other day after injury. Then, 37 days later, Klüver-Barrera staining, toluidine blue staining and immunofluorescence staining were performed. Carnosine (200, 500 mg/kg) substantially reduced damage to the white matter in the corpus callosum, internal capsule and optic tract, and it rescued expression of myelin basic protein, and alleviated the loss of oligodendrocytes. However, carnosine at the higher dose of 750 mg/kg did not have the same effects as the 200 and 500 mg/kg doses. These findings show that carnosine, at a particular dose range, protects against white matter damage caused by chronic cerebral ischemia in mice, likely by reducing oligodendroglial cell loss.

Statins Reduces the Risk of Dementia in Patients with Late-Onset Depression: A Retrospective Cohort Study

Objective

Patients with late-onset depression (LOD) have been reported to run a higher risk of subsequent dementia. The present study was conducted to assess whether statins can reduce the risk of dementia in these patients.

Methods

We used the data from National Health Insurance of Taiwan during 1996–2009. Standardized Incidence Ratios (SIRs) were calculated for LOD and subsequent dementia. The criteria for LOD diagnoses included age ≥65 years, diagnosis of depression after 65 years of age, at least three service claims, and treatment with antidepressants. The time-dependent Cox proportional hazards model was applied for multivariate analyses. Propensity scores with the one-to-one nearest-neighbor matching model were used to select matching patients for validation studies. Kaplan-Meier curve estimate was used to measure the group of patients with dementia living after diagnosis of LOD.

Results

Totally 45,973 patients aged ≥65 years were enrolled. The prevalence of LOD was 12.9% (5,952/45,973). Patients with LOD showed to have a higher incidence of subsequent dementia compared with those without LOD (Odds Ratio: 2.785; 95% CI 2.619–2.958). Among patients with LOD, lipid lowering agent (LLA) users (for at least 3 months) had lower incidence of subsequent dementia than non-users (Hazard Ratio = 0.781, 95% CI 0.685–0.891). Nevertheless, only statins users showed to have reduced risk of dementia (Hazard Ratio = 0.674, 95% CI 0.547–0.832) while other LLAs did not, which was further validated by Kaplan-Meier estimates after we used the propensity scores with the one-to-one nearest-neighbor matching model to control the confounding factors.

Conclusions

Statins may reduce the risk of subsequent dementia in patients with LOD.

Cardiovascular risk factors and cognitive decline in older people with type 2 diabetes

AIMS/HYPOTHESIS

The aim of this work was to assess the role of well-established cardiovascular risk factors in the late-life cognitive decline of patients with type 2 diabetes.

METHODS

Data from 831 participants (aged 60-75 years) attending the 4 year follow-up of the Edinburgh Type 2 Diabetes Study (ET2DS) were used. Smoking history (pack-years), BP, HbA1c, plasma glucose and cholesterol were determined at baseline clinics (single time measurements) and/or from serial data recorded on a clinical management database from diagnosis until recruitment ('historical' data). Principal component analysis derived a factor, g, of general ability from seven cognitive tests. Linear regression models of follow-up g were adjusted for baseline g to represent 4 year cognitive change. 'Accelerated late-life cognitive decline' was defined as scoring in the lowest tertile of '4 year cognitive change' regression scores. Analyses controlled for age and sex.

RESULTS

A baseline history of moderate/heavy smoking (≥ 10 pack-years) and a 1% increased historical HbA1c (equivalent to an increase by 11 mmol/mol) predicted a 64% (OR 1.64; 95% CI 1.14, 2.34; p = 0.007) and 21% (OR 1.21; 95% CI 1.00, 1.45; p = 0.046) increased risk of accelerated cognitive decline, respectively. When treated as continuous measures, higher pack-years, historical HbA1c and historical BP emerged as significant independent predictors of 4 year decline in g (standardised β range -0.07 to -0.14; all p ≤ 0.05).

CONCLUSIONS/INTERPRETATION

Increased smoking and poorer glycaemic control (with relatively weaker findings for BP) during the life-course were independently associated with accelerated late-life cognitive decline. Where possible, evaluation is warranted of these risk factors as targets for intervention to reduce the burden of cognitive impairment in diabetes.

Prevention studies in Alzheimer's disease: progress towards the development of new therapeutics

Alzheimer's disease (AD) is the most common form of dementia and is a major cause of disability and dependency amongst older people. AD drugs approved so far are symptomatic treatments and are not thought to affect the underlying disease process. Trials conducted with agents aiming to slow or stop disease progression in patients with AD have all failed, perhaps because they were tested too late in the disease process. Therefore, there has been a move towards prevention of AD. This paper presents an overview of trials testing pharmacological interventions for sporadic AD prevention. Those tested to date were initially developed for the treatment of AD or for the treatment of other conditions, rather than being specifically developed for AD prevention. Associated issues, such as evidence of 'proof-of-concept,' doses and safety, are discussed. A major shift has taken place in the methodology of AD prevention trials since the results of the first trials were published in the 1990s. New directions that are currently being considered in ongoing or future prevention trials are discussed, in terms of endpoints, target populations, and study design. The use of AD-specific drugs to prevent AD in high-risk individuals is currently limited by a lack of validated predictive and surrogate markers. Population approaches, such as lifestyle changes, are an alternative strategy that could be of public health interest, but may provide only limited benefits for individuals. The best chance of preventing AD may come from a combination of individual and population prevention approaches.

Statins, cognition, and dementia—systematic review and methodological commentary

Firm conclusions about whether mid-life or long-term statin use has an impact on cognitive decline and dementia remain elusive. Here, our objective was to systematically review, synthesize and critique the epidemiological literature that examines the relationship between statin use and cognition, so as to assess the current state of knowledge, identify gaps in our understanding, and make recommendations for future research. We summarize the findings of randomized controlled trials (RCTs) and observational studies, grouped according to study design. We discuss the methods for each, and consider likely sources of bias, such as reverse causation and confounding. Although observational studies that considered statin use at or near the time of dementia diagnosis suggest a protective effect of statins, these findings could be attributable to reverse causation. RCTs and well-conducted observational studies of baseline statin use and subsequent cognition over several years of follow-up do not support a causal preventative effect of late-life statin use on cognitive decline or dementia. Given that much of the human research on statins and cognition in the future will be observational, careful study design and analysis will be essential.

Do statins impair cognition? A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

In 2012, the United States Food and Drug Administration (FDA) issued a warning regarding potential adverse effects of HMG-CoA reductase inhibitors (statins) on cognition, based on the Adverse Events Reporting System and a review of the medical literature. We aimed to synthesize randomized clinical trial (RCTs) evidence on the association between statin therapy and cognitive outcomes.

METHODS

We searched MEDLINE, EMBASE, and Cochrane CENTRAL through December 2012, and reviewed published systematic reviews of statin treatment. We sought RCTs that compared statin treatment versus placebo or standard care, and reported at least one cognitive outcome (frequency of adverse cognitive events or measurements using standard neuropsychological cognitive test scores). Studies reporting sufficient information to calculate effect sizes were included in meta-analyses. Standardized and unstandardized mean differences were calculated for continuous outcomes for global cognition and for pre-specified cognitive domains. The main outcome was change in cognition measured by neuropsychological tests; an outcome of secondary interest was the frequency of adverse cognitive events observed during follow-up.

RESULTS

We identified 25 RCTs (all placebo-controlled) reporting cognitive outcomes in 46,836 subjects, of which 23 RCTs reported cognitive test results in 29,012 participants. Adverse cognitive outcomes attributable to statins were rarely reported in trials involving cognitively normal or impaired subjects. Furthermore, meta-analysis of cognitive test data (14 studies; 27,643 participants) failed to show significant adverse effects of statins on all tests of cognition in either cognitively normal subjects (standardized mean difference 0.01, 95% confidence interval, CI, -0.01 to 0.03, p = 0.42) or Alzheimer's disease subjects (standardized mean difference -0.05, 95% CI -0.19 to 0.10, p = 0.38).

CONCLUSIONS

Statin therapy was not associated with cognitive impairment in RCTs. These results raise questions regarding the continued merit of the FDA warning about potential adverse effects of statins on cognition.

Systematic review of atorvastatin for the treatment of Alzheimer's disease

Objective:

To assess the clinical efficacy and safety of atorvastatin in the treatment of Alzheimer's disease.

Data Sources:

Medline (1948/2011-04), Embase (1966/2011-04), Cochrane Library (Issue 3, 2011), Chinese National Knowledge Infrastructure (1989/2011-04), and the Chinese Biomedical Literature Database (1979/2011-04) were searched for randomized clinical trials regardless of language. Abstracts of conference papers were manually searched. Furthermore, Current Controlled Trials (http://controlled-trials.com), Clinical Trials.gov (http://clinicaltrials.gov), and Chinese Clinical Trial Registry (http://www.chictr.org) were also searched. Key words included Alzheimer disease, dementia, cognition, affection, memory dysfunction, hydroxymethylglutaryl-CoA reductase inhibitors, atorvastatin and statins.

Data Selection:

Randomized controlled trials of grade A or B according to quality evaluation criteria of the Cochrane Collaboration were selected, in which atorvastatin and placebo were used to evaluate the effects of atorvastatin in the treatment of Alzheimer's disease. Study methodological quality was evaluated based on criteria described in Cochrane Reviewer's Handbook 5.0.1. Revman 5.1 software was used for data analysis.

Main Outcome Measures:

Clinical efficacy, safety, withdrawal from the studies, and withdrawal due to adverse effects.

Results:

Two randomized controlled trials were included, one was scale A, and the other was scale B. All patients (n = 710, age range 50–90 years) were diagnosed as probable or possible mild to moderate Alzheimer's disease according to standard criteria and treated with atorvastatin 80 mg/d or placebo. There was no difference between the two groups in the final follow-up for Clinical Global Impression of Change scale (WMD = 0.13, 95%CI: –0.15 to 0.40), the Alzheimer's Disease Assessment Scale-cognitive subscale (WMD = 1.05, 95%CI: –3.06 to 6.05), Mini-Mental State Examination Scale (WMD = 0.77, 95%CI: –0.57 to 2.10), and the Neuropsychiatric Instrument (WMD = 2.07, 95%CI: –1.59 to 5.73). The rates of abnormal liver function, withdrawal from treatment, and withdrawal due to adverse effects were higher in the treatment group (OR = 7.86, 95%CI: 2.50-24.69; OR = 4.70, 95%CI: 2.61-8.44; and OR = 5.47, 95%CI: 3.01-9.94; respectively) compared with the placebo group.

Conclusion:

There is insufficient evidence to recommend atorvastatin for the treatment of mild to moderate Alzheimer's disease, because there was no benefit on general function, cognitive function or mental/behavior abnormality outcome measures. Efficacy and safety need to be confirmed by larger and higher quality randomized controlled trials, especially for moderate to severe Alzheimer's disease, because results of this systematic review may be limited by selection bias, implementation bias, as well as measurement bias.

Statin use and cognitive function: population-based observational study with long-term follow-up

We aimed to evaluate the association between statin use and cognitive function. Cognitive function was measured with the Ruff Figural Fluency Test (RFFT; worst score, 0; best score, 175 points) and the Visual Association Test (VAT; low performance, 0-10; high performance, 11-12 points) in an observational study that included 4,095 community-dwelling participants aged 35-82 years. Data on statin use were obtained from a computerized pharmacy database. Analysis were done for the total cohort and subsamples matched on cardiovascular risk (N = 1232) or propensity score for statin use (N = 3609). We found that a total of 904 participants (10%) used a statin. Statin users were older than non-users: mean age (SD) 61 (10) vs. 52 (11) years (p<0.001). The median duration of statin use was 3.8 (interquartile range, 1.6-4.5) years. Unadjusted, statin users had worse cognitive performance than non-users. The mean RFFT score (SD) in statin users and non-users was 58 (23) and 72 (26) points, respectively (p<0.001). VAT performance was high in 261 (29%) statin users and 1351 (43%) non-users (p<0.001). However, multiple regression analysis did not show a significant association of RFFT score with statin use (B, -0.82; 95%CI, -2.77 to 1.14; p = 0.41) nor with statin solubility, statin dose or duration of statin use. Statin users with high doses or long-term use had similar cognitive performance as non-users. This was found in persons with low as well as high cardiovascular risk, and in younger as well as older subjects. Also, the mean RFFT score per quintile of propensity score for statin use was comparable for statin users and non-users. Similar results were found for the VAT score as outcome measure. In conclusion, statin use was not associated with cognitive function. This was independent of statin dose or duration of statin use.

Three midlife strategies to prevent cognitive impairment due to Alzheimer's disease

The slow, progressive accumulation of pathology characteristic of Alzheimer's disease is the principal determinant of cognitive decline leading to dementia. Risk-reduction strategies during midlife focus on raising the clinical threshold for the appearance of cognitive symptoms and on reducing the extent of Alzheimer pathology. Best available evidence suggests an approach based on three, conceptually distinct strategies. (1) Raise the threshold for cognitive symptoms by improving brain health. To achieve this goal, the tactic is to reduce cerebrovascular risks mediated by hypertension, diabetes, cigarette smoking, and hyperlipidemia. (2) Raise the threshold for cognitive symptoms by enhancing cognitive reserve. Here, tactics focus on mental stimulation associated with occupation, leisure activities and social engagement. (3) Reduce the burden of Alzheimer pathology. The most promising tactic toward this end is regular aerobic exercise. Tactics in support of strategies to reduce cognitive impairment due to Alzheimer pathology are not yet substantiated by robust, consistent clinical trial evidence. There is pressing need for well-designed pragmatic trials to provide stronger evidence on preventive strategies for late-life cognitive decline and dementia.

Cognitive Impairment and Age-Related Vision Disorders: Their Possible Relationship and the Evaluation of the Use of Aspirin and Statins in a 65 Years-and-Over Sardinian Population

Neurological disorders (Alzheimer’s disease, vascular and mixed dementia) and visual loss (cataract, age-related macular degeneration, glaucoma, and diabetic retinopathy) are among the most common conditions that afflict people of at least 65 years of age. An increasing body of evidence is emerging, which demonstrates that memory and vision impairment are closely, significantly, and positively linked and that statins and aspirin may lessen the risk of developing age-related visual and neurological problems. However, clinical studies have produced contradictory results. Thus, the intent of the present study was to reliably establish whether a relationship exist between various types of dementia and age-related vision disorders, and to establish whether statins and aspirin may or may not have beneficial effects on these two types of disorders. We found that participants with dementia and/or vision problems were more likely to be depressed and displayed worse functional ability in basic and instrumental activities of daily living than controls. Mini mental state examination scores were significantly lower in patients with vision disorders compared to subjects without vision disorders. A closer association with macular degeneration was found in subjects with Alzheimer’s disease than in subjects without dementia or with vascular dementia, mixed dementia, or other types of age-related vision disorders. When we considered the associations between different types of dementia and vision disorders and the use of statins and aspirin, we found a significant positive association between Alzheimer’s disease and statins on their own or in combination with aspirin, indicating that these two drugs do not appear to reduce the risk of Alzheimer’s disease or improve its clinical evolution and may, on the contrary, favor its development. No significant association in statin use alone, aspirin use alone, or the combination of these was found in subjects without vision disorders but with dementia, and, similarly, none in subjects with vision disorders but without dementia. Overall, these results confirm the general impression so far; namely, that macular degeneration may contribute to cognitive disorders (Alzheimer’s disease in particular). In addition, they also suggest that, while statin and aspirin use may undoubtedly have some protective effects, they do not appear to be magic pills against the development of cognitive impairment or vision disorders in the elderly.

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.

Vascular cognitive impairment in dementia

Vascular risk factors and cerebrovascular disease are common causes of dementia. Shared risk factors for vascular dementia and Alzheimer's disease, as well as frequent coexistence of these pathologies in cognitively impaired older people, suggests convergence of the aetiology, prevention and management of the commonest dementias affecting older people. In light of this understanding, the cognitive impairment associated with cerebrovascular disease is an increasingly important and recognised area of the medicine of older people. Although the incidence of cerebrovascular events is declining in many populations, the overall burden associated with brain vascular disease will continue to increase associated with population ageing. A spectrum of cognitive disorders related to cerebrovascular disease is now recognised. Cerebrovascular disease in older people is associated with specific clinical and imaging findings. Although prevention remains the cornerstone of management, the diagnosis of brain vascular disease is important because of the potential to improve clinical outcomes through clear diagnosis, enhanced control of risk factors, lifestyle interventions and secondary prevention. Specific pharmacological intervention may also be indicated for some patients with cognitive impairment and cerebrovascular disease. However the evidence base to guide intervention remains relatively sparse.

Toward onset prevention of cognitive decline in adults with Down syndrome (the TOP-COG study): study protocol for a randomized controlled trial

BACKGROUND

Early-onset dementia is common in Down syndrome adults, who have trisomy 21. The amyloid precursor protein gene is on chromosome 21, and so is over-expressed in Down syndrome, leading to amyloid β (Aβ) over-production, a major upstream pathway leading to Alzheimer disease (AD). Statins (microsomal 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors), have pleiotropic effects including potentially increasing brain amyloid clearance, making them plausible agents to reduce AD risk. Animal models, human observational studies, and small scale trials support this rationale, however, there are no AD primary prevention trials in Down syndrome adults. In this study we study aim to inform the design of a full-scale primary prevention trial.

METHODS/DESIGN

TOP-COG is a feasibility and pilot double-blind randomized controlled trial (RCT), with a nested qualitative study, conducted in the general community. About 60 Down syndrome adults, aged ≥50 will be included. The intervention is oral simvastatin 40 mg at night for 12 months, versus placebo. The primary endpoint is recruitment and retention rates. Secondary endpoints are (1) tolerability and safety; (2) detection of the most sensitive neurocognitive instruments; (3) perceptions of Down syndrome adults and caregivers on whether to participate, and assessment experiences; (4) distributions of cognitive decline, adaptive behavior, general health/quality of life, service use, caregiver strain, and sample size implications; (5) whether Aβ42/Aβ40 is a cognitive decline biomarker. We will describe percentages recruited from each source, the number of contacts to achieve this, plus recruitment rate by general population size. We will calculate summary statistics with 90% confidence limits where appropriate, for each study outcome as a whole, by treatment group and in relation to baseline age, cognitive function, cholesterol and other characteristics. Changes over time will be summarized graphically. The sample size for a definitive RCT will be estimated under alternative assumptions.

DISCUSSION

This study is important, as AD is a major problem for Down syndrome adults, for whom there are currently no effective preventions or treatments. It will also delineate the most suitable assessment instruments for this population. Recruitment of intellectually disabled adults is notoriously difficult, and we shall provide valuable information on this, informing future studies.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN Register ID: ISRCTN67338640 (17 November 2011).

Cognitive effects of statin medications

The demonstrated benefits of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) for cardiovascular and cerebrovascular disease are well established in the medical literature, and this class of medications is among those most commonly prescribed in the USA. In 2012, the US Food and Drug Administration issued updated recommendations regarding statin medications, and the panel's comments regarding memory impairment fostered clinical confusion (in part because of the lay media's amplification). Cognitive data from several large epidemiological studies have not reliably demonstrated a robust association between incident cognitive impairment and statin use, with some studies reporting a protective effect, some reporting an increased risk and others finding no association. Although several interventional studies have evaluated statins as a possible adjunctive treatment for Alzheimer's disease, none have clearly demonstrated a benefit. A small number of case series have reported infrequent memory difficulties associated with statin use. In these series, the patients' cognitive symptoms resolved after statin discontinuation. The existing medical literature does not suggest that cognitive considerations should play a major role in medical decision making to prescribe statins for the large majority of patients. As with any medication prescribed for older adults, careful clinical monitoring for side effects should be exercised. If a patient is suspected of having idiosyncratic memory impairment associated with use of a statin medication, the drug can be discontinued. The patient should then be followed with careful clinical observation for 1-3 months for resolution of the cognitive symptoms.

Diabetes. Cognitive decline and T2DM--a disconnect in the evidence?

Type 2 diabetes mellitus is associated with an increased risk of cognitive decline and dementia. Observational data suggest that hyperglycaemia, hypertension and dyslipidaemia might be involved in the causal pathway underlying this link, but data from the ACCORD MIND investigators challenge these findings. Why are the findings of observational and intervention studies so disconnected?

Advances in the prevention of Alzheimer's disease and dementia

BACKGROUND

Definitions and diagnostic criteria for all medical conditions are regularly subjected to reviews and revisions as knowledge advances. In the field of Alzheimer's disease (AD) research, it has taken almost three decades for diagnostic nomenclature to undergo major re-examination. The shift towards presymptomatic and pre-dementia stages of AD has brought prevention and treatment trials much closer to each other than before.

METHODS

Here we discuss: (i) the impact of diagnostic reliability on the possibilities for developing preventive strategies for AD; (ii) the scientific evidence to support moving from observation to action; (iii) ongoing intervention studies; and (iv) the methodological issues and prospects for balancing strategies for high-risk individuals with those for broad population-based prevention.

RESULTS

The associations between neuropathology and cognition are still not entirely clear. In addition, the risk factors for AD dementia and the neuropathological hallmarks of AD may not necessarily be the same. Cognitive impairment has a clearer clinical significance and should therefore remain the main focus of prevention. Risk/protective factors for dementia/AD need to be studied from a life-course perspective. New approaches in prevention trials include enrichment strategies based on genetic risk factors or beta-amyloid biomarkers (at least four ongoing pharmacological trials), and multidomain interventions simultaneously targeting various vascular and lifestyle-related risk factors (at least three ongoing trials). Experience from prevention programmes in other chronic diseases can provide additional methodological improvements.

CONCLUSIONS

Building infrastructures for international collaborations is necessary for managing the worldwide public health problem of AD and dementia. The International Database on Aging and Dementia (IDAD) and the European Dementia Prevention Initiative (EDPI) are examples of ongoing international efforts aiming to improve the methodology of preventive studies and provide the basis for larger intervention trials.

Diabetes mellitus and dementia

Growing epidemiologic evidence has suggested that people with diabetes mellitus are at an increased risk for the development of dementia. However, the results for the subtypes of dementia are inconsistent. This review examines the risk of dementia in people with diabetes mellitus, and discusses the possible mechanism underpinning this association. Diabetes mellitus is associated with a 1.5- to 2.5-fold greater risk of dementia among community-dwelling elderly people. Notably, diabetes mellitus is a significant risk factor for not only vascular dementia, but also Alzheimer's disease. The mechanisms underpinning the association are unclear, but it may be multifactorial in nature, involving factors such as cardiovascular risk factors, glucose toxicity, changes in insulin metabolism and inflammation. The optimal management of these risk factors in early life may be important to prevent late-life dementia. Furthermore, novel therapeutic strategies will be needed to prevent or reduce the development of dementia in people with diabetes mellitus.

Brain cholesterol metabolism, oxysterols, and dementia

Cholesterol metabolism is implicated in the etiology of Alzheimer's disease (AD) and amyloid production in the brain. While brain cholesterol cannot be measured directly in vivo, the oxysterol, 24S-hydroxycholesterol (24-OHC), is the predominant metabolite of brain cholesterol and can be measured in the blood. The aim of this review is to evaluate plasma 24-OHC as a potential biomarker of AD risk and discuss factors related to its levels in the brain and blood. This systematic review examines studies published between 1950 and June 2012 that examined the relationship between plasma 24-OHC, cognition, brain structure, and dementia using the following key words ("24S-hydroxycholesterol" or "24-hydroxycholesterol") and ("Brain" or "Cognitive"). We found a total of 28 studies of plasma 24-OHC and neurodegenerative disease, including a subset of 12 that used dementia as a clinical endpoint. These studies vary in the direction of the observed associations. Results suggest plasma 24-OHC may be higher in the early stages of cognitive impairment and lower in more advanced stages of AD when compared to cognitively normal controls. Measures of 24-OHC in the blood may be an important potential marker for cholesterol metabolism in the brain and risk of AD. Further studies of plasma 24-OHC and dementia must account for the stage of disease, establish the temporal trends in oxysterol concentrations, and employ neuroimaging modalities to assess the structural and metabolic changes occurring in the brain prior to the onset of cognitive impairment.

Markers of cholesterol transport are associated with amyloid deposition in the brain

Cholesterol is implicated in the development of late-onset Alzheimer's disease (AD). We sought to determine the associations between beta amyloid (Aβ) plaque deposition in vivo using Pittsburgh compound B (PiB) and several indices of cholesterol homeostasis (i.e., total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, apolipoprotein E (ApoE), clusterin, oxysterol metabolites of cholesterol, and previously reported genes associated with late-onset AD) in 175 nondemented elderly subjects. High Aβ deposition was associated significantly with a lower Mini-Mental State Examination score (<27 points, p = 0.04), high systolic blood pressure (p = 0.04), carrying the apolipoprotein E epsilon 4 allele (p < 0.01), and lower plasma ApoE levels (p = 0.02), and variation in the ABCA7 (p = 0.02) and EPHA1 genes (p = 0.02). Cholesterol measures were not related to Aβ deposition in this cohort of nondemented elderly adults. However, plasma and genetic factors relating to cholesterol transport were associated with Aβ deposition in the brain. A better understanding of cholesterol transport mechanisms may lead to the design of potential targets for the prevention of Aβ deposition in the brain.

Impact of a multi-nutrient diet on cognition, brain metabolism, hemodynamics, and plasticity in apoE4 carrier and apoE knockout mice

Lipid metabolism and genetic background together strongly influence the development of both cardiovascular and neurodegenerative diseases like Alzheimer's disease (AD). A non-pharmacological way to prevent the genotype-induced occurrence of these pathologies is given by dietary behavior. In the present study, we tested the effects of long-term consumption of a specific multi-nutrient diet in two models for atherosclerosis and vascular risk factors in AD: the apolipoprotein ε4 (apoE4) and the apoE knockout (apoE ko) mice. This specific multi-nutrient diet was developed to support neuronal membrane synthesis and was expected to contribute to the maintenance of vascular health. At 12 months of age, both genotypes showed behavioral changes compared to control mice and we found increased neurogenesis in apoE ko mice. The specific multi-nutrient diet decreased anxiety-related behavior in the open field, influenced sterol composition in serum and brain tissue, and increased the concentration of omega-3 fatty acids in the brain. Furthermore, we found that wild-type and apoE ko mice fed with this multi-nutrient diet showed locally increased cerebral blood volume and decreased hippocampal glutamate levels. Taken together, these data suggest that a specific dietary intervention has beneficial effects on early pathological consequences of hypercholesterolemia and vascular risk factors for AD.