Diabetes and other vascular risk factors for dementia: which factor matters most? A systematic review

Going outdoors and cognitive function among community-dwelling older adults: Moderating role of physical function

AIMS

Identifying the risk factors of cognitive impairment is essential for implementing effective prevention strategies for dementia. Previous studies have shown that the frequency of going outdoors is inversely associated with cognitive decline. Little research has examined whether the relationship between going outdoors and cognitive decline varies with physical functioning in older adults. The aim of the present study was to examine the relationship between going outdoors and cognitive function in older adults with and without physical function limitations.

METHODS

The present study analyzed the data of 4450 individuals (aged 65 years or older) who participated in the Obu Study of Health Promotion for the Elderly. The measures were the Mini-Mental State Examination (MMSE), going outdoors (at least once a week or not), self-reported physical function limitations (with or without), and demographic and health-related factors as potential confounders.

RESULTS

Analysis of covariance and post-hoc comparisons showed that although going outdoors at least once a week was associated with higher MMSE scores among older adults with limited physical function, it was not significantly associated with the MMSE scores among older adults without limited physical function. Similarly, logistic regression analyses, stratified by physical function, showed a significant association between going outdoors and MMSE (<24 points or not) among older adults with limited physical function.

CONCLUSIONS

The results show that going outdoors less than once a week is associated with decreased cognitive function among older adults with limited physical function, but it is not associated with cognitive function among older adults without limited physical function.

Diabetes Mellitus, Cognitive Impairment, and Traditional Chinese Medicine

Diabetes mellitus (DM) is a metabolic disorder affecting a large number of people worldwide. Numerous studies have demonstrated that DM can cause damage to multiple systems, leading to complications such as heart disease, cancer, and cerebrovascular disorders. Numerous epidemiological studies have shown that DM is closely associated with dementia and cognition dysfunction, with recent research focusing on the role of DM-mediated cerebrovascular damage in dementia. Despite the therapeutic benefits of antidiabetic agents for the treatment of DM-mediated cognitive dysfunction, most of these pharmaceutical agents are associated with various undesirable side-effects and their long-term benefits are therefore in doubt. Early evidence exists to support the use of traditional Chinese medicine (TCM) interventions, which tend to have minimal toxicity and side-effects. More importantly, these TCM interventions appear to offer significant effects in reducing DM-related complications beyond blood glucose control. However, more research is needed to further validate these claims and to explore their relevant mechanisms of action. The aims of this paper are (1) to provide an updated overview on the association between DM and cognitive dysfunction and (2) to review the scientific evidence underpinning the use of TCM interventions for the treatment and prevention of DM-induced cognitive dysfunction and dementia.

Glucose regulation, cognition, and brain MRI in type 2 diabetes: a systematic review

Type 2 diabetes is associated with cognitive dysfunction and structural brain changes. Abnormalities in glucose regulation are involved in several complications related to type 2 diabetes, but their role in these cerebral complications is unclear. We systematically reviewed studies of the association between glucose regulation (glycaemia, hypoglycaemic events, insulin concentration, insulin resistance, and glucose-lowering treatment) and cognitive function and brain abnormalities on MRI in people with type 2 diabetes. The 86 papers included showed that glycaemia, particularly high HbA1c concentration and glucose variability, are negatively associated with cognitive function in people with type 2 diabetes without dementia. However, the strength of this association is weak, and HbA1c generally accounted for less than 10% of the variance in cognition. Importantly, few studies have measured long-term cerebral outcomes, such as dementia and structural brain changes on MRI, and the effect of glucose-lowering treatment on these outcomes. More randomised controlled trials are needed to establish the effect of glucose-lowering treatment on long-term cognitive function in people with type 2 diabetes.

Quality of Life in an Adult Population of More than 60 Years of Age without Cognitive Impairment

Objectives

To analyse the quality of life (QoL) of persons over 60 years of age in Bizkaia (Basque Country, Spain), not institutionalised and without cognitive impairment, and the relation and possible influence of the perception of the state of health with the cognitive level and the activities that they carry out.

Subjects and Methods

Evaluation of a sample of 317 persons that belong to a longitudinal study. In 269 cases, there was a reliable informant. The general cognitive state was evaluated by means of the Mini-Mental State Examination (MMSE) and the Global Deterioration Scale (GDS). Two GDS, one of the family member (GDSf) and another of the evaluator (GDSe), were used and memory was evaluated by the Text Memory subtest of the Barcelona Test. The QoL was assessed with the SF-36 Health Survey and the mental, physical and social activities that they carry out were recorded.

Results

In the SF-36, the participants showed values that exceed the reference values of the Spanish population in all dimensions of the SF-36, except in that of bodily pain. There were low correlations between the dimensions of the SF-36 and the mental, physical and social activities. A low correlation was observed between the memory tests and the SF-36. In 59.3% of the cases, there were no differences between the GDSf and the GDSe.

Conclusions

The participants of this study present a better perception of their state of health than the Spanish population, but this perception is not observed to be influenced by the type or by the quantity of activities that they carry out or by their cognitive state. The informants present a vision very close to the cognitive state of their family members.

Cerebral subcortical small vessel disease in subjects with pathologically confirmed Alzheimer disease: a clinicopathologic study in the Oxford Project to Investigate Memory and Ageing (OPTIMA)

The understanding of how cerebrovascular disease (CVD) contributes to dementia is hampered by a lack of agreed and validated pathologic methods to accord weight to the contribution of different aspects of CVD to dementia. A previous study from the Oxford Project to Investigate Memory and Ageing (OPTIMA) validated a scheme for assessing the contribution of subcortical small vessel disease (SVD) toward dementia in the elderly by showing a significant inverse relationship between the severity of SVD and cognition in subjects without any other dementia pathology using this method. In the present paper, the method has been used to assess severity of SVD in 161 cases of neuropathologically confirmed Alzheimer disease. The results showed there was no relationship between the SVD score and cognitive scores acquired in the last 2 years of life. SVD scores were significantly related to age (P<0.0017) and were slightly but significantly higher in females than males (P<0.049). SVD scores were not related to blood pressure at entry to OPTIMA and were significantly lower when compared with the cohort of OPTIMA cases with only CVD (mean 5.06 ± 1.85 vs. 5.9 ± 2.67; P<0.0065). We conclude that when Alzheimer disease pathology is present in elderly subjects, it overwhelms the modest contribution that SVD makes to cognitive impairment.

Diabetes and cognitive outcomes in a nationally representative sample: the National Health and Aging Trends Study

BACKGROUND

The prevalence of both type II diabetes mellitus (DM) and cognitive impairment is high and increasing in older adults. We examined the extent to which DM diagnosis was associated with poorer cognitive performance and dementia diagnosis in a population-based cohort of US older adults.

METHODS

We studied 7,606 participants in the National Health and Aging Trends Study, a nationally representative cohort of Medicare beneficiaries aged 65 years and older. DM and dementia diagnosis were based on self-report from participants or proxy respondents, and participants completed a word-list memory test, the Clock Drawing Test, and gave a subjective assessment of their own memory.

RESULTS

In unadjusted analyses, self-reported DM diagnosis was associated with poorer immediate and delayed word recall, worse performance on the Clock Drawing Test, and poorer self-rated memory. After adjusting for demographic characteristics, body mass index, depression and anxiety symptoms, and medical conditions, DM was associated with poorer immediate and delayed word recall and poorer self-rated memory, but not with the Clock Drawing Test performance or self-reported dementia diagnosis. After excluding participants with a history of stroke, DM diagnosis was associated with poorer immediate and delayed word recall and the Clock Drawing Test performance, and poorer self-rated memory, but not with self-reported dementia diagnosis.

CONCLUSIONS

In this recent representative sample of older Medicare enrollees, self-reported DM was associated with poorer cognitive test performance. Findings provide further support for DM as a potential risk factor for poor cognitive outcomes. Studies are needed that investigate whether DM treatment prevents cognitive decline.

Magnesium protects cognitive functions and synaptic plasticity in streptozotocin-induced sporadic Alzheimer's model

Alzheimer's disease (AD) is characterized by profound synapse loss and impairments of learning and memory. Magnesium affects many biochemical mechanisms that are vital for neuronal properties and synaptic plasticity. Recent studies have demonstrated that the serum and brain magnesium levels are decreased in AD patients; however, the exact role of magnesium in AD pathogenesis remains unclear. Here, we found that the intraperitoneal administration of magnesium sulfate increased the brain magnesium levels and protected learning and memory capacities in streptozotocin-induced sporadic AD model rats. We also found that magnesium sulfate reversed impairments in long-term potentiation (LTP), dendritic abnormalities, and the impaired recruitment of synaptic proteins. Magnesium sulfate treatment also decreased tau hyperphosphorylation by increasing the inhibitory phosphorylation of GSK-3β at serine 9, thereby increasing the activity of Akt at Ser473 and PI3K at Tyr458/199, and improving insulin sensitivity. We conclude that magnesium treatment protects cognitive function and synaptic plasticity by inhibiting GSK-3β in sporadic AD model rats, which suggests a potential role for magnesium in AD therapy.

Insulin resistance in Alzheimer's disease

Insulin is a key hormone regulating metabolism. Insulin binding to cell surface insulin receptors engages many signaling intermediates operating in parallel and in series to control glucose, energy, and lipids while also regulating mitogenesis and development. Perturbations in the function of any of these intermediates, which occur in a variety of diseases, cause reduced sensitivity to insulin and insulin resistance with consequent metabolic dysfunction. Chronic inflammation ensues which exacerbates compromised metabolic homeostasis. Since insulin has a key role in learning and memory as well as directly regulating ERK, a kinase required for the type of learning and memory compromised in early Alzheimer's disease (AD), insulin resistance has been identified as a major risk factor for the onset of AD. Animal models of AD or insulin resistance or both demonstrate that AD pathology and impaired insulin signaling form a reciprocal relationship. Of note are human and animal model studies geared toward improving insulin resistance that have led to the identification of the nuclear receptor and transcription factor, peroxisome proliferator-activated receptor gamma (PPARγ) as an intervention tool for early AD. Strategic targeting of alternate nodes within the insulin signaling network has revealed disease-stage therapeutic windows in animal models that coalesce with previous and ongoing clinical trial approaches. Thus, exploiting the connection between insulin resistance and AD provides powerful opportunities to delineate therapeutic interventions that slow or block the pathogenesis of AD.

Potential for primary prevention of Alzheimer's disease: an analysis of population-based data

BACKGROUND

Recent estimates suggesting that over half of Alzheimer's disease burden worldwide might be attributed to potentially modifiable risk factors do not take into account risk-factor non-independence. We aimed to provide specific estimates of preventive potential by accounting for the association between risk factors.

METHODS

Using relative risks from existing meta-analyses, we estimated the population-attributable risk (PAR) of Alzheimer's disease worldwide and in the USA, Europe, and the UK for seven potentially modifiable risk factors that have consistent evidence of an association with the disease (diabetes, midlife hypertension, midlife obesity, physical inactivity, depression, smoking, and low educational attainment). The combined PAR associated with the risk factors was calculated using data from the Health Survey for England 2006 to estimate and adjust for the association between risk factors. The potential of risk factor reduction was assessed by examining the combined effect of relative reductions of 10% and 20% per decade for each of the seven risk factors on projections for Alzheimer's disease cases to 2050.

FINDINGS

Worldwide, the highest estimated PAR was for low educational attainment (19·1%, 95% CI 12·3-25·6). The highest estimated PAR was for physical inactivity in the USA (21·0%, 95% CI 5·8-36·6), Europe (20·3%, 5·6-35·6), and the UK (21·8%, 6·1-37·7). Assuming independence, the combined worldwide PAR for the seven risk factors was 49·4% (95% CI 25·7-68·4), which equates to 16·8 million attributable cases (95% CI 8·7-23·2 million) of 33·9 million cases. However, after adjustment for the association between the risk factors, the estimate reduced to 28·2% (95% CI 14·2-41·5), which equates to 9·6 million attributable cases (95% CI 4·8-14·1 million) of 33·9 million cases. Combined PAR estimates were about 30% for the USA, Europe, and the UK. Assuming a causal relation and intervention at the correct age for prevention, relative reductions of 10% per decade in the prevalence of each of the seven risk factors could reduce the prevalence of Alzheimer's disease in 2050 by 8·3% worldwide.

INTERPRETATION

After accounting for non-independence between risk factors, around a third of Alzheimer's diseases cases worldwide might be attributable to potentially modifiable risk factors. Alzheimer's disease incidence might be reduced through improved access to education and use of effective methods targeted at reducing the prevalence of vascular risk factors (eg, physical inactivity, smoking, midlife hypertension, midlife obesity, and diabetes) and depression.

FUNDING

National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care for Cambridgeshire and Peterborough.

Diabetes and dementia in older people: a Best Clinical Practice Statement by a multidisciplinary National Expert Working Group

Both dementia and diabetes mellitus are long-term disabling conditions and each may be a co-morbidity of the other. Type 2 diabetes is associated with a 1.5- to 2-fold higher risk of dementia. Diabetes also may occur for the first time in many individuals with mental ill health, including cognitive impairment and dementia, and this may complicate management and lead to difficulties in self-care. Case finding is often poor for cognitive impairment in medical settings and for diabetes in mental health settings and this needs to be addressed in the development of care pathways for both conditions. Many other deficiencies in quality care (both for dementia and diabetes) currently exist, but we hope that this Best Clinical Practice Statement will provide a platform for further work in this area. We have outlined the key steps in an integrated care pathway for both elements of this clinical relationship, produced guidance on identifying each condition, dealt with the potentially hazardous issue of hypoglycaemia, and have outlined important competencies required of healthcare workers in both medical/diabetes and mental health settings to enhance clinical care.

A systematic review of type 2 diabetes mellitus and hypertension in imaging studies of cognitive aging: time to establish new norms

The rising prevalence of type 2 diabetes (T2DM) and hypertension in older adults, and the deleterious effect of these conditions on cerebrovascular and brain health, is creating a growing discrepancy between the "typical" cognitive aging trajectory and a "healthy" cognitive aging trajectory. These changing health demographics make T2DM and hypertension important topics of study in their own right, and warrant attention from the perspective of cognitive aging neuroimaging research. Specifically, interpretation of individual or group differences in blood oxygenation level dependent magnetic resonance imaging (BOLD MRI) or positron emission tomography (PET H2O(15)) signals as reflective of differences in neural activation underlying a cognitive operation of interest requires assumptions of intact vascular health amongst the study participants. Without adequate screening, inclusion of individuals with T2DM or hypertension in "healthy" samples may introduce unwanted variability and bias to brain and/or cognitive measures, and increase potential for error. We conducted a systematic review of the cognitive aging neuroimaging literature to document the extent to which researchers account for these conditions. Of the 232 studies selected for review, few explicitly excluded individuals with T2DM (9%) or hypertension (13%). A large portion had exclusion criteria that made it difficult to determine whether T2DM or hypertension were excluded (44 and 37%), and many did not mention any selection criteria related to T2DM or hypertension (34 and 22%). Of all the surveyed studies, only 29% acknowledged or addressed the potential influence of intersubject vascular variability on the measured BOLD or PET signals. To reinforce the notion that individuals with T2DM and hypertension should not be overlooked as a potential source of bias, we also provide an overview of metabolic and vascular changes associated with T2DM and hypertension, as they relate to cerebrovascular and brain health.

Repurposing diabetes drugs for brain insulin resistance in Alzheimer disease

A growing body of clinical and epidemiological research suggests that two of the most common diseases of aging, type 2 diabetes (T2DM) and Alzheimer disease (AD), are linked. The nature of the association is not known, but this observation has led to the notion that drugs developed for the treatment of T2DM may be beneficial in modifying the pathophysiology of AD and maintaining cognitive function. Recent advances in the understanding of the biology of T2DM have resulted in a growing number of therapies that are approved or in clinical development for this disease. This review summarizes the evidence that T2DM and AD are linked, with a focus on the cellular and molecular mechanisms in common, and then assesses the various clinical-stage diabetes drugs for their potential activity in AD. At a time when existing therapies for AD offer only limited symptomatic benefit for some patients, additional clinical trials of diabetes drugs are needed to at least advance the care of T2DM patients at risk for or with comorbid AD and also to determine their value for AD in general.

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?

Linking Alzheimer's disease and type 2 diabetes mellitus via aberrant insulin signaling and inflammation

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are two progressive and devastating health disorders afflicting millions of people worldwide. The probability and incidence of both have increased considerably in recent years consequent to increased longevity and population growth. Progressively more links are being continuously found between inflammation and central nervous system disorders like AD, Parkinson's disease, Huntington's disease, motor neuron disease, multiple sclerosis, stroke, traumatic brain injury and even cancers of the nervous tissue. The depth of the relationship depends on the timing and extent of anti- or pro-inflammatory gene expression. Inflammation has also been implicated in T2DM. Misfolding and fibrillization (of tissue specific and/or non-specific proteins) are features common to both AD and T2DM and are induced by as well as contribute to inflammation and stress (oxidative/ glycation). This review appraises the roles of inflammation and abnormalities in the insulin signaling system as important shared features of T2DM and AD. The capacity of anti-cholinesterases in reducing the level of certain common inflammatory markers in particular if they may provide therapeutic potential to mitigate awry mechanisms leading to AD.

Midlife type 2 diabetes and poor glycaemic control as risk factors for cognitive decline in early old age: a post-hoc analysis of the Whitehall II cohort study

BACKGROUND

Type 2 diabetes increases the risk for dementia, but whether it affects cognition before old age is unclear. We investigated whether duration of diabetes in late midlife and poor glycaemic control were associated with accelerated cognitive decline.

METHODS

5653 participants from the Whitehall II cohort study (median age 54.4 years [IQR 50.3-60.3] at first cognitive assessment), were classified into four groups: normoglycaemia, prediabetes, newly diagnosed diabetes, and known diabetes. Tests of memory, reasoning, phonemic and semantic fluency, and a global score that combined all cognitive tests, were assessed three times over 10 years (1997-99, 2002-04, and 2007-09). Mean HbA1c was used to assess glycaemic control during follow-up. Analyses were adjusted for sociodemographic characteristics, health-related behaviours, and chronic diseases.

FINDINGS

Compared with normoglycaemic participants, those with known diabetes had a 45% faster decline in memory (10 year difference in decline -0.13 SD, 95% CI -0.26 to -0.00; p=0.046), a 29% faster decline in reasoning (-0.10 SD, -0.19 to -0.01; p=0.026), and a 24% faster decline in the global cognitive score (-0.11 SD, -0.21 to -0.02; p=0.014). Participants with prediabetes or newly diagnosed diabetes had similar rates of decline to those with normoglycaemia. Poorer glycaemic control in participants with known diabetes was associated with a significantly faster decline in memory (-0.12 [-0.22 to -0.01]; p=0.034) and a decline in reasoning that approached significance (-0.07 [-0.15 to 0.00]; p=0.052).

INTERPRETATION

The risk of accelerated cognitive decline in middle-aged patients with type 2 diabetes is dependent on both disease duration and glycaemic control.

FUNDING

US National Institutes of Health, UK Medical Research Council.

Dementia and cognitive decline in type 2 diabetes and prediabetic stages: towards targeted interventions

Type 2 diabetes is associated with dementia, and also with more slight cognitive decrements. In this Review we discuss trajectories from normal cognition to dementia in people with type 2 diabetes, and explore opportunities for treatment. Slight diabetes-associated cognitive decrements and dementia affect different age groups and show a different evolution. These cognitive entities should therefore not be regarded as a continuum, although their effects might be additive. Vascular damage is a key underlying process in both entities. Glucose-mediated processes and other metabolic disturbances might also have a role. No treatment has been established, but management of vascular risk factors and optimisation of glycaemic control could have therapeutic benefit. We identify possible opportunities for intervention to improve cognitive outcomes in people with type 2 diabetes, and suggest how treatment can be tailored to individual risk profiles and comorbidities.

The older patient with diabetes: a practical approach

Type 2 diabetes mellitus is very prevalent among persons aged 60-80 years old. This population is expected to increase in number and is characterized by the presence of comorbidities, long standing diabetes, frailty, high rate of cognitive impairment and limited life expectancy. These characteristics have a significant impact on diabetes and treatment among the elderly, much as diabetes predisposes to these conditions. In this article we will describe mechanisms that may lead to insulin resistance and diabetes among the elderly and also how these conditions contribute to the development of frailty and cognitive impairment. Hypoglycemia and it's consequences are important considerations when planning the treatment of diabetes. Treatment options in light of new goals and the danger of hypoglycemia will be detailed.

Gender and incidence of dementia in the Framingham Heart Study from mid-adult life

BACKGROUND

Gender-specific risks for dementia and Alzheimer's disease (AD) starting in midlife remain largely unknown.

METHODS

Prospectively ascertained dementia/AD and cause-specific mortality in Framingham Heart Study (FHS) participants was used to generate 10- to 50-year risk estimates of dementia/AD on the basis of the Kaplan-Meier method (cumulative incidence) or accounting for competing risk of death (lifetime risk [LTR]).

RESULTS

Overall, 777 cases of incident dementia (601 AD) occurred in 7901 participants (4333 women) over 136,266 person-years. Whereas cumulative incidences were similar in women and men, LTRs were higher in women older than 85 years of age. LTR of dementia/AD at age 45 was 1 in 5 in women and 1 in 10 in men. Cardiovascular mortality was higher in men with rate ratios decreasing from approximately 6 at 45 to 54 years of age to less than 2 after age 65.

CONCLUSION

Selective survival of men with a healthier cardiovascular risk profile and hence lower propensity to dementia might partly explain the higher LTR of dementia/AD in women.

Dysglycemia, brain volume and vascular lesions on MRI in a memory clinic population

OBJECTIVE

It is unclear, if the association between abnormalities in glucose metabolism (dysglycemia) and impaired cognitive functioning is primarily driven by degenerative or vascular brain damage. We therefore examined the relation between dysglycemia and brain volume and vascular lesions on MRI in a memory clinic population.

METHODS

The relations between markers of glycemia (HbA1c and fasting glucose levels) and normalized brain volume, medial temporal lobe atrophy and vascular lesions (white matter hyperintensities, lacunes) were assessed in 274 consecutive patients attending a memory clinic, using linear regression analyses.

RESULTS

Clinical diagnoses were subjective complaints (n=117), mild cognitive impairment (n=62), Alzheimer's disease (n=61) and other type of dementia (n=34). Twenty patients had a history of diabetes. Across the whole study population there was no relation between HbA1c or fasting glucose and the brain MRI measurements, after adjustments for age, sex and diagnostic group. Secondary analyses after stratification by diabetes status, diagnosis and median age (67 years) did not change the results.

CONCLUSION

In this memory clinic population, dysglycemia was not associated with either brain volume or vascular lesions. Apparently, dysglycemia is not associated with a specific class of brain pathology in patients with cognitive complaints.

Cardiovascular risks and brain function: a functional magnetic resonance imaging study of executive function in older adults

Cardiovascular (CV) risk factors, such as hypertension, diabetes, and hyperlipidemia are associated with cognitive impairment and risk of dementia in older adults. However, the mechanisms linking them are not clear. This study aims to investigate the association between aggregate CV risk, assessed by the Framingham general cardiovascular risk profile, and functional brain activation in a group of community-dwelling older adults. Sixty participants (mean age: 64.6 years) from the Brain Health Study, a nested study of the Baltimore Experience Corps Trial, underwent functional magnetic resonance imaging using the Flanker task. We found that participants with higher CV risk had greater task-related activation in the left inferior parietal region, and this increased activation was associated with poorer task performance. Our results provide insights into the neural systems underlying the relationship between CV risk and executive function. Increased activation of the inferior parietal region may offer a pathway through which CV risk increases risk for cognitive impairment.

Diabetes cognitive impairments and the effect of traditional chinese herbs

The problem of cognitive impairment resulting from diabetes is gaining more acceptance and attention. Both type 1 and type 2 diabetes mellitus have been proved to be associated with reduced performance on numerous domains of cognitive function. Although the exact mechanisms of cognitive impairments in diabetes have not been completely understood, hyperglycemia and insulin resistance seem to play significant roles. And other possible risk factors such as hypoglycemia, insulin deficiency, vascular risk factors, hyperactive HPA axis, depression, and altered neurotransmitters will also be examined. In the meanwhile, this review analyzed the role of the active ingredient of Chinese herbal medicine in the treatment of diabetes cognitive impairments.

B-type natriuretic peptide and severity of cognitive disorder

BACKGROUND

Natriuretic peptides have been linked to cognitive disorder in previous studies. The aim of this study was to examine the association between the severity of cognitive disorder and the levels of B-type natriuretic peptide (BNP) in an older general population.

MATERIAL AND METHODS

This study is a part of the larger population-based, multidisciplinary Kuopio 75+ health study. A total of 601 subjects aged 75 or older participated in the study. A subgroup of 126 individuals was diagnosed with cognitive disorder, and the severity of the disease was assessed. The participants were tested for BNP. Analysis of covariance was carried out to study the relationship between BNP and the stage of cognitive disorder.

RESULTS

The association between the level of cognitive disorder and BNP resembled an inverse U-shaped curve, with higher levels of BNP observed among participants with mild cognitive disorder when compared to cognitively intact participants or counterparts with more severe cognitive disorder. This effect remained after adjustment for age (P = 0.02). However, association between BNP and level of cognitive disorder was lost in further adjustment with covariates connected to the levels of BNP.

CONCLUSION

The previously reported elevation of natriuretic peptides among individuals with diagnosed cognitive disorder was found only in people with milder stages of the disorder.

Vascular risk factors and cognitive disorders

Delaying the onset of dementia by just a few years could have a major impact on the prevalence of the disease at the population level. Vascular risk factors are modifiable and may offer an important opportunity for preventive approaches. Several studies have shown that diabetes, hypertension, obesity, and smoking are associated with an increased risk of cognitive decline and dementia, but other groups have not observed such a relation. Positive associations were observed mainly in studies where risk factors were assessed in midlife, suggesting that age is an important modulator in the relation between vascular risk factors and cognition. The population attributable risk of dementia is particularly high for hypertension. Associations of vascular risk factors with cognitive decline and dementia are probably mediated largely by cerebrovascular disease, including both stroke and covert vascular brain injury, which can have additive or synergistic effects with coexisting neurodegenerative lesions. To date, randomized trials have not convincingly demonstrated that treating vascular risk factors is associated with a reduction in cognitive decline or dementia risk. Of eight randomized trials testing the effect of antihypertensive agents on dementia risk, only one was positive, and another in a subgroup of individuals with recurrent stroke. In most trials, cognition and dementia were secondary outcomes, follow-up was short and treatment was initiated at an older age. No effect on cognitive decline or dementia could be demonstrated for statins and intensive glycemic control. Future areas of investigation could include differential class effects of antihypertensive drugs on cognitive outcomes and identification of high risk individuals as target population for clinical trials initiated in midlife.

Glucose levels and risk of dementia

BACKGROUND

Diabetes is a risk factor for dementia. It is unknown whether higher glucose levels increase the risk of dementia in people without diabetes.

METHODS

We used 35,264 clinical measurements of glucose levels and 10,208 measurements of glycated hemoglobin levels from 2067 participants without dementia to examine the relationship between glucose levels and the risk of dementia. Participants were from the Adult Changes in Thought study and included 839 men and 1228 women whose mean age at baseline was 76 years; 232 participants had diabetes, and 1835 did not. We fit Cox regression models, stratified according to diabetes status and adjusted for age, sex, study cohort, educational level, level of exercise, blood pressure, and status with respect to coronary and cerebrovascular diseases, atrial fibrillation, smoking, and treatment for hypertension.

RESULTS

During a median follow-up of 6.8 years, dementia developed in 524 participants (74 with diabetes and 450 without). Among participants without diabetes, higher average glucose levels within the preceding 5 years were related to an increased risk of dementia (P=0.01); with a glucose level of 115 mg per deciliter (6.4 mmol per liter) as compared with 100 mg per deciliter (5.5 mmol per liter), the adjusted hazard ratio for dementia was 1.18 (95% confidence interval [CI], 1.04 to 1.33). Among participants with diabetes, higher average glucose levels were also related to an increased risk of dementia (P=0.002); with a glucose level of 190 mg per deciliter (10.5 mmol per liter) as compared with 160 mg per deciliter (8.9 mmol per liter), the adjusted hazard ratio was 1.40 (95% CI, 1.12 to 1.76).

CONCLUSIONS

Our results suggest that higher glucose levels may be a risk factor for dementia, even among persons without diabetes. (Funded by the National Institutes of Health.)

History of medically treated diabetes and risk of Alzheimer disease in a nationwide case-control study

OBJECTIVE

Type 2 diabetes in midlife or late life increases the risk of Alzheimer disease (AD), and type 1 diabetes has been associated with a higher risk of detrimental cognitive outcomes, although studies from older adults are lacking. We investigated whether individuals with AD were more likely to have a history of diabetes than matched controls from the general aged population.

RESEARCH DESIGN AND METHODS

Information on reimbursed diabetes medication (including both type 1 and 2 diabetes) of all Finnish individuals with reimbursed AD medication in 2005 (n = 28,093) and their AD-free control subjects during 1972-2005 was obtained from a special reimbursement register maintained by the Social Insurance Institute of Finland.

RESULTS

The prevalence of diabetes was 11.4% in the whole study population, 10.7% (n = 3,012) among control subjects, and 12.0% (n = 3,372) among AD case subjects. People with AD were more likely to have diabetes than matched control subjects (unadjusted OR 1.14 [95% CI 1.08-1.20]), even after adjusting for cardiovascular diseases (OR 1.31 [1.22-1.41]). The associations were stronger with diabetes diagnosed at midlife (adjusted OR 1.60 [1.34-1.84] and 1.25 [1.16-1.36] for midlife and late-life diabetes, respectively).

CONCLUSIONS

Individuals with clinically verified AD are more likely to have a history of clinically verified and medically treated diabetes than the general aged population, although the difference is small.

Associations between retinal microvascular changes and dementia, cognitive functioning, and brain imaging abnormalities: a systematic review

Retinal microvascular changes can be visualized noninvasively and have been associated with cognitive decline and brain changes in relation to aging and vascular disease. We systematically reviewed studies, published between 1990 and November 2012, on the association between retinal microvascular changes and dementia, cognitive functioning, and brain imaging abnormalities, in the context of aging and vascular risk factors. In cross-sectional studies (k=26), retinal microvascular changes were associated with the presence of dementia (range of odds ratios (ORs) 1.17;5.57), with modest decrements in cognitive functioning in nondemented people (effect sizes -0.25;0.03), and with brain imaging abnormalities, including atrophy and vascular lesions (ORs 0.94;2.95). Longitudinal studies were more sparse (k=9) and showed no consistent associations between retinal microvascular changes and dementia or cognitive dysfunctioning 3 to 15 years later (ORs and hazard ratios 0.77;1.55). However, there were indications of prospective associations with brain imaging abnormalities ((ORs) 0.81;3.19). In conclusion, particularly in cross-sectional studies there is a correlation between retinal microvascular changes and dementia, cognitive impairment, and brain imaging abnormalities. Associations are strongest for more severe retinal microvascular abnormalities. Retinal microvascular abnormalities may offer an important window on the brain for etiological studies.

Smoking, death, and Alzheimer disease: a case of competing risks

If smoking is a risk factor for Alzheimer disease (AD) but a smoker dies of another cause before developing or manifesting AD, smoking-related mortality may mask the relationship between smoking and AD. This phenomenon, referred to as competing risk, complicates efforts to model the effect of smoking on AD. Typical survival regression models assume that censorship from analysis is unrelated to an individual's probability for developing AD (ie, censoring is noninformative). However, if individuals who die before developing AD are younger than those who survive long enough to develop AD, and if they include a higher percentage of smokers than nonsmokers, the incidence of AD will appear to be higher in older individuals and in nonsmokers. Further, age-specific mortality rates are higher in smokers because they die earlier than nonsmokers. Therefore, if we fail to take into account the competing risk of death when we estimate the effect of smoking on AD, we bias the results and are in fact only comparing the incidence of AD in nonsmokers with that in the healthiest smokers. In this study, we demonstrate that the effect of smoking on AD differs in models that are and are not adjusted for competing risks.

Earlier age of dementia onset and shorter survival times in dementia patients with diabetes

Diabetes is a risk factor for dementia, but relatively little is known about the epidemiology of the association. A retrospective population study using Western Australian hospital inpatient, mental health outpatient, and death records was used to compare the age at index dementia record (proxy for onset age) and survival outcomes in dementia patients with and without preexisting diabetes (n = 25,006; diabetes, 17.3%). Inpatient records from 1970 determined diabetes history in this study population with incident dementia in years 1990-2005. Dementia onset and death occurred an average 2.2 years and 2.6 years earlier, respectively, in diabetic compared with nondiabetic patients. Age-specific mortality rates were increased in patients with diabetes. In an adjusted proportional hazard model, the death rate was increased with long-duration diabetes, particularly with early age onset dementia. In dementia diagnosed before age 65 years, those with a ≥15-year history of diabetes died almost twice as fast as those without diabetes (hazard ratio = 1.9, 95% confidence interval: 1.3, 2.9). These results suggest that, in patients with diabetes, dementia onset occurs on average 2 years early and survival outcomes are generally poorer. The effect of diabetes on onset, survival, and mortality is greatest when diabetes develops before middle age and after 15 years' diabetes duration. The impact of diabetes on dementia becomes progressively attenuated in older age groups.

Diabetes mellitus and risk of dementia: A meta-analysis of prospective observational studies

AIMS/INTRODUCTION

The aim of the present study was to investigate the association between diabetes and the risk of all type dementia (ATD), Alzheimer's disease (AD) and vascular dementia (VaD).

MATERIALS AND METHODS

Prospective observational studies describing the incidence of ATD, AD and VaD in patients with diabetes mellitus were extracted from PubMed, EMBASE and other databases up to January 2012. Pooled relative risk (RR) estimates and 95% confidence intervals (CIs) were calculated using the random-effects model. Subgroup analyses and sensitivity analysis were also carried out.

RESULTS

A total of 28 studies contributed to the analysis. Pooled RR of developing ATD (n = 20) was 1.73 (1.65-1.82, I (2) = 71.2%), AD (n = 20) was 1.56 (1.41-1.73, I (2) = 9.8%) and VaD (n = 13) was 2.27 (1.94-2.66, I (2) = 0%) in patients with diabetes mellitus. Higher and medium quality studies did not show any significant difference for pooled RR for ATD, AD or VaD. Sensitivity analyses showed robustness of pooled RR among ATD, AD and VaD, showing no single study had a major impact on pooled RR.

CONCLUSIONS

The results showed a 73% increased risk of ATD, 56% increase of AD and 127% increase of VaD in diabetes patients.

Autonomic dysfunction in type 2 diabetes mellitus with and without vascular dementia

INTRODUCTION

Autonomic dysfunction has been implicated in sudden cardiac death and cognitive impairment in diabetes.

OBJECTIVES

Objectives of the study were to examine the associations between vascular, metabolic risk factors, autonomic and cognitive function in patients with diabetes mellitus.

METHOD

We investigate autonomic function in 45 participants with type 2 diabetes and in 23 age related normal subjects, using Ewing's tests and power spectral analysis of heart rate variability. Mini Mental State Examination and Hachinski's ischemic scale were used to identify vascular dementia. Only 11 patients were diagnosed with vascular dementia.

RESULTS

The glycosylated haemoglobin, triglycerides, and systolic blood pressure had much larger values in vascular dementia patients compared to the controls. The averages of results obtained in heart rate deep-breathing, Valsalva ratio and lying-to-standing tests for vascular dementia patients are statistically lower than the averages for controls. Vascular dementia patients had a greater fall in blood pressure on standing (p<0.001) and reduced blood pressure responses to isometric exercise (p<0.001) in comparison with controls. Also they had an increase in the mean heart rate at rest (p<0.05), a decrease in time domain parameters of heart rate variability (p<0.001), and an increase in the low/high frequency component ratio (p<0.001) indicating a vagal-sympathetic dysfunction.

CONCLUSIONS

Using standard cardiovascular reflex tests and analysis of heart rate variability we demonstrated an impairment of the autonomic nervous system in vascular dementia patients with marked parasympathetic dysfunction and sympathetic predominance.

The prognostic capacity of B-type natriuretic peptide on cognitive disorder varies by age

INTRODUCTION

It is known that blood levels of natriuretic peptides associate with cognitive disorder among the middle-aged. We aimed to test whether this association is valid in an older population aged 75 years or older.

METHODS

A total of 601 older subjects aged 75 or older participated in the study. A subgroup of 137 with a diagnosed cognitive disorder were tested for natriuretic peptides (ANP, NT-proANP, and BNP), and compared with age-matched controls (n = 464). The control group was followed-up for 5 years, and the association of the baseline BNP with the occurrence of cognitive impairment was studied.

RESULTS

In the youngest age tertile (75-78 y), BNP was significantly associated with a diagnosed cognitive disorder when other factors with a known effect on natriuretic peptides were taken into account. In the oldest tertile (83-96 y), higher BNP values suggested the absence of cognitive dysfunction. ANP and NT-proANP did not associate with the presence of cognitive impairment. Among the control group, BNP predicted a cognitive disorder at follow-up, but only in the youngest tertile.

CONCLUSIONS

The previously found link between a high BNP concentration and cognitive disorder in older people is only valid among those aged less than 79 years.

The association of anxiety and depression with future dementia diagnosis: a case-control study in primary care

BACKGROUND

Depression is identified as a risk factor for dementia. Little research has been carried out on the importance of anxiety, despite strong evidence of co-morbidity with depression.

OBJECTIVE

To examine the association of anxiety and depression with future dementia diagnosis.

METHODS

This case-control study was set in the Consultations in Primary Care Archive. Cases (n = 400), were patients aged >65 years old. About 1353 controls were matched to cases by gender, practice, age group and year of case diagnosis. Read codes of risk factors for dementia were searched in patient records. The associations of prior consultations for anxiety and depression, with future diagnosis of dementia were determined using multivariable logistic regression.

RESULTS

A past anxiety diagnosis was associated with a future dementia diagnosis [odds ratio 2.76 (95% confidence interval 2.11-3.62)]. The association of depression with dementia was attenuated by the high prevalence of anxiety within those who have depression. Including an interaction of depression and anxiety showed that having only depression was associated with future dementia diagnosis but a diagnosis of depression alongside anxiety did not increase the likelihood of a dementia diagnosis compared to having just an anxiety diagnosis.

CONCLUSION

Prior diagnosis of anxiety was strongly associated with dementia diagnosis after adjustment for other risk factors. The independent effect of depression was weaker compared to anxiety. Given the higher prevalence of anxiety primary care physicians should consider anxiety as well as depression as premorbid risk factors of dementia to improve early recognition and facilitate greater access to services.

Midlife obesity and dementia: meta-analysis and adjusted forecast of dementia prevalence in the United States and China

OBJECTIVE

Obesity is a risk factor of dementia. Current forecasts of dementia prevalence fail to take the rising obesity prevalence into account.

DESIGN AND METHODS

Embase and Medline were searched for observational studies on the association between overweight (BMI 25-30 kg/m(2)) or obesity (BMI > 30 kg/m(2)) and dementia and pooled the effect sizes by meta-analysis. The population attributable risk (PAR) was calculated for different time points and adjusted them for confounders. Based on current prevalence rates of dementia and demographic forecasts, patient numbers were calculated and adjusted by the growth rates of PAR.

RESULTS

Compared to normal weight, midlife obesity increases the risk of dementia later in life (BMI 25-30: RR = 1.34 [95% CI 1.08, 1.66], BMI > 30: RR = 1.91 [1.4, 2.62]). If obesity is included into forecast models, the prevalence of dementia is estimated to be 7.1 million (6.9, 7.3) and 11.3 million (10.9, 11.7) for the United States in 2030 and 2050, respectively. In China, the estimate is 13.1 million (12.8, 13.3) in 2030 and 26.2 million (25.1, 27.4) in 2050. These figures are 9% and 19% higher for the United States and China, respectively, than forecasts that rely solely on the demographic change.

CONCLUSION

The past and ongoing increase in midlife obesity prevalence will contribute significantly to the future prevalence of dementia and public health measures to reduce midlife obesity are simultaneously primary prevention measures to reduce the risk of dementia.

Diabetes and the elderly brain: sweet memories?

Type 2 diabetes is common in older people and is associated with higher risk of both vascular dementia and Alzheimer's disease. This review examines the evidence for increased risk of dementia and mild cognitive impairment in patients with diabetes and the role of potential confounders. The relationship of diabetes and impaired fasting glucose with brain structure is also reviewed, focusing on longitudinal studies in older people. The pathophysiology underlying cognitive change in type 2 diabetes is examined with reference to vascular disease, hypoglycaemia, inflammation and insulin levels. Implications for clinical care in older people with diabetes are discussed, with a recommendation for cognitive evaluation as a routine part of end-organ, diabetes complication review.

An update on type 2 diabetes, vascular dementia and Alzheimer's disease

The risk of dementia is increased in people with type 2 diabetes mellitus (T2DM). This review gives an update on the relation between T2DM and specific dementia subtypes - i.e. Alzheimer's disease and vascular dementia - and underlying pathologies. We will show that while epidemiological studies link T2DM to Alzheimer's disease as well as vascular dementia, neuropathological studies attribute the increased dementia risk in T2DM patients primarily to vascular lesions in the brain. Risk factors for dementia among patients with T2DM are also addressed. Currently, there is evidence that microvascular complications, atherosclerosis and severe hypoglycemic events increase dementia risk. However, for a more complete understanding of risk factors for dementia in T2DM a life time perspective is needed. This should identify which individuals are at increased risk, what are vulnerable periods in life, and what are windows of opportunity for treatment. Currently, there are no DM specific treatments for dementia, but we will review observations from clinical trials that tried to prevent cognitive decline through intensified glycemic control and address other clinical implications of the association between T2DM and dementia.

Development of vascular risk factors over 15 years in relation to cognition: the Hoorn Study

OBJECTIVES

To investigate the development of vascular risk factor levels at four points over 15 years in relation to late-life cognitive functioning.

DESIGN

Longitudinal population-based study.

SETTING

The Hoorn Study, a community-based cohort study of glucose metabolism and cardiovascular risk.

PARTICIPANTS

Three hundred eighty individuals without dementia (mean baseline age 57.7 ± 5.5).

MEASUREMENTS

Four extensive medical examinations were conducted over 15 years. Cognition was assessed in detail at the fourth examination. The time course of vascular risk factors across the examinations was compared between individuals in the highest tertile (good performance) and those in the lowest tertile (poor performance) of cognitive functioning on three cognitive domains (memory, information processing speed, and attention and executive functioning (A&EF)).

RESULTS

Individuals with poor information processing speed had higher levels of systolic blood pressure at baseline (mean difference (standard error) 11.6 (2.6) mmHg, P < .001) than those with good information processing speed. Individuals with poor A&EF had a higher waist:hip ratio (3.03 (1.15), P = .009), glycosylated hemoglobin (0.29% (0.10%), P = .005) and total cholesterol:high-density lipoprotein cholesterol ratio (0.38 (0.19), P = .04) at baseline than individuals with good A&EF, although the differences in vascular risk factor levels between the poor and good cognition group diminished with increasing age.

CONCLUSION

High blood pressure, adiposity, hypercholesterolemia, and hyperglycemia at midlife are associated with late-life cognitive dysfunction, but for most risk factors, this relationship gradually attenuates with increasing age. These results suggest that timing of vascular treatment strategies to prevent cognitive impairment is critical.

Reduction of Long-Term Care Dependence After an 8-Year Primary Care Prevention Program for Stroke and Dementia: The INVADE Trial

BACKGROUND

Stroke and dementia are the major causes for long-term care (LTC) dependence in old age. This intervention trial compared a multidomain prevention program for stroke and dementia with usual medical care in reducing the need for LTC.

METHODS AND RESULTS

The Intervention Project on Cerebrovascular Disease and Dementia in the District of Ebersberg (INVADE) was a general practice-based 8-year trial in 2 defined catchment areas in Upper Bavaria, Germany. All 11 317 insurants of a statutory health insurance plan who were ≥55 years of age and lived in the intervention district were offered the opportunity to participate in a prevention program; 3908 enrolled. The 13 301 insurants in the reference district received usual medical care. The intervention consisted of the systematic identification and evidence-based treatment of vascular risk factors. The primary clinical end point was incidence of LTC dependence according to external assessment by a special medical service in the framework of the statutory German LTC insurance. Age- and sex-specific incidence rates from the reference district were used to calculate the expected number of cases of LTC dependence under usual medical care. The expected number was compared with the observed number of cases in the intervention district. Analysis was by intention to treat. During the 5 years after completion of the recruitment period, significantly fewer incident cases of LTC dependence arose in the intervention district than expected (χ(2)=13.25; P<0.001). In women, the incidence was reduced by 10% (P<0.01). In men, the incidence was reduced by 9.6% (P<0.05).

CONCLUSIONS

Our results support the feasibility and effectiveness of a primary care prevention program for stroke and dementia to reduce the risk of developing LTC dependence.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01107548. (J Am Heart Assoc. 2012;1:e000786 doi: 10.1161/JAHA.112.000786.).

Diabetes and cognitive dysfunction

Cognitive dysfunction in type 1 and type 2 diabetes share many similarities, but important differences do exist. A primary distinguishing feature of type 2 diabetes is that people with this disorder often (but not invariably) do poorly on measures of learning and memory, whereas deficits in these domains are rarely seen in people with type 1 diabetes. Chronic hyperglycaemia and microvascular disease contribute to cognitive dysfunction in both type 1 and type 2 diabetes, and both disorders are associated with mental and motor slowing and decrements of similar magnitude on measures of attention and executive functioning. Additionally, both types are characterised by neural slowing, increased cortical atrophy, microstructural abnormalities in white matter tracts, and similar, but not identical, changes in concentrations of brain neurometabolites. Disconcertingly, the rapid rise in obesity and type 2 diabetes in all age groups might result in a substantial increase in prevalence of diabetes-related cognitive dysfunction.

Homocysteine, methylenetetrahydrofolate reductase C677T polymorphism and cognitive impairment: the health in men study

High total plasma homocysteine (tHcy) has been associated with cognitive impairment in later life, but it is unclear if this association is causal or is due to confounding. The C677T polymorphism of the 5,10 methylenetetrahydrofolate reductase gene (MTHFR) increases basal tHcy, but its contribution to cognitive impairment has not been established. We designed this study to determine if tHcy is causally related to cognitive impairment in later life by investigating its association with high tHcy and the MTHFR-C677T polymorphism. We recruited 1778 older men from the Health in Men Study cohort and established caseness on the basis of the participants' scores on a Telephone Interview for Cognitive Status score 27 in 2008. Exposure to tHcy, gene status and other variables of interest were obtained from assessments 4-7 years earlier. Multivariate logistic regression showed that the odds of cognitive impairment increased with a doubling of tHcy (adjusted odds ratio, OR 1.36; 95% confidence interval, 95% CI 1.02-1.82). Compared with the wild CC genotype, participants with the MTHFR-TT genotype had 46% greater odds of cognitive impairment (OR 1.46, 95% CI 1.01-2.11, P=0.043). The results of this study are consistent with, but do not prove the hypothesis that high tHcy causes cognitive impairment in later life.

Prevalence and incidence rates of dementia and cognitive impairment no dementia in the Mexican population: data from the Mexican Health and Aging Study

OBJECTIVE

To estimate the prevalence and incidence of dementia and cognitive impairment without dementia (CIND) in the Mexican population.

METHOD

The MHAS study is a prospective panel study of health and aging in Mexico with 7,000 elders that represent eight million participants nationally. Using measurements of cognition and activities of daily living of dementia cases and CIND were identified at baseline and follow-up. Overall incidence rates and specific rates for sex, age, and education were calculated.

RESULTS

Prevalence was 6.1% and 28.7% for dementia and CIND, respectively. Incidence rates were 27.3 per 1,000 person-years for dementia and 223 per 1,000 persons-year for CIND. Rates of dementia and CIND increased with advancing age and decreased with higher educational level; sex had a differential effect depending on the age strata. Hypertension, diabetes, and depression were risk factors for dementia but not for CIND.

DISCUSSION

These data provide estimates of prevalence and incidence of dementia and cognitive impairment in the Mexican population for projection of future burden.

Vascular risk factors and dementia: 40-year follow-up of a population-based cohort

AIMS

Our aim was to evaluate the longitudinal associations of individual and multiple vascular risk factors with the subsequent development of dementia and Alzheimer's disease (AD).

METHODS

The Uppsala Longitudinal Study of Adult Men started in 1970 when the 2,268 participants were 50 years old. Baseline investigations included determinations of blood pressure, fasting glucose, cholesterol, BMI and smoking status. Over a maximum follow-up of 40 years, 349 participants were diagnosed with dementia, out of which 127 had AD. Analyses were repeated using a re-examination of the cohort at 70 years of age as a baseline.

RESULTS

No associations between vascular risk factors and AD were found. For all-type dementia, the association between high systolic blood pressure and dementia was the most consistent. High fasting glucose was associated with increased risk of all-type dementia only when measured at 70 years. Individuals with both an APOE ε4 allele and vascular risk factors had the greatest dementia risk.

CONCLUSION

Vascular risk factors influence the future risk of dementia, in particular vascular and mixed-type rather than AD. The impact of vascular risk factors on dementia in a longitudinal study depends on the age at baseline and the length of follow-up.

Insulin resistance and pathological brain ageing

Sir Harold Himsworth's prescient observations 75 years ago have recently been expanded to include a clear relationship between insulin resistance and central nervous system function. Insulin is a master regulator of corporeal ageing in all known species, determining the rate and expression of ageing in multiple body systems. Thus, it is not surprising that insulin also plays an important role in brain ageing and cognitive decline that is associated with pathological brain ageing. Brain ageing is accompanied by reduced insulin effectiveness, either by an inadequate cellular response to insulin or by insulin deficiency attributable to reduced insulin transport across the blood-brain barrier. Age-associated brain insulin abnormalities may contribute to cognitive decline in ageing, as have been documented in older adults with Type 2 diabetes mellitus and hypertension. With more extreme pathology, brain insulin resistance may be associated with neurogenerative diseases such as Alzheimer's disease, and the condition which precedes Alzheimer's disease, known as amnestic mild cognitive impairment. In the following review, we discuss the mechanisms through which insulin resistance may induce or potentiate pathological brain ageing and thereby create a neurobiological environment that promotes neurodegeneration and associated cognitive decline. This topic is timely, given that insulin resistance-associated conditions such as diabetes and obesity have reached epidemic proportions. The prevalence of such chronic conditions, in combination with a rapidly ageing population, may result in a corresponding increase in the prevalence of Alzheimer's disease and other cognitive disorders. Fortunately, insulin resistance-associated conditions are amenable to both pharmacologic and lifestyle interventions that may reduce the deleterious impact of insulin resistance on the ageing brain.

Mini-Mental State Examination score and B-type natriuretic peptide as predictors of cardiovascular and total mortality in an elderly general population

INTRODUCTION. The aim of the present study was to examine the power of B-type natriuretic peptide (BNP) and mild cognitive impairment as independent predictors of total and cardiovascular mortality in combination with established cardiovascular risk markers in an elderly general population without severe cognitive impairment. METHODS. A total of 499 individuals, aged more than 75 years, were examined and followed up for a median of 7.9 years in a prospective population-based stratified cohort study carried out in eastern Finland. The Cox proportional hazards regression model was used to determine the impact of multiple factors on total and cardiovascular mortality. RESULTS. In a multivariable model including established cardiovascular risk factors and conditions, both continuous BNP (adjusted hazard ratio (HR) 1.44 for a 1-SD change; 95% confidence interval (CI) 1.22-1.77; P < 0.001) and continuous MMSE score (HR 0.81 for a 1-SD change; 95% CI 0.70-0.94; P = 0.007) were independently associated with all-cause mortality. In a multivariable model, BNP remained a significant predictor of cardiovascular mortality, while MMSE score lost its significance. CONCLUSIONS. BNP, a measure of cardiovascular burden, and MMSE score 18-23, an indicator of mild cognitive impairment, are both independent predictors of total mortality. BNP and MMSE score may potentially be useful in screening elderly patients for elevated risk of mortality.