Association between dementia and midlife risk factors: the Radiation Effects Research Foundation Adult Health Study

Epidemiology, associated burden, and current clinical practice for the diagnosis and management of Alzheimer's disease in Japan

The burden of dementia in Japan is large and growing. With the world’s fastest aging population, it is estimated that one in five elderly people will be living with dementia in Japan by 2025. The most common form of dementia is Alzheimer’s disease (AD), accounting for around two-thirds of dementia cases. A systematic review was conducted to examine the epidemiology and associated burden of AD in Japan and to identify how AD is diagnosed and managed in Japan. English and Japanese language databases were searched for articles published between January 2000 and November 2015. Relevant Japanese sources, clinical practice guideline registers, and reference lists were also searched. Systematic reviews and cohort and case–control studies were eligible for inclusion, with a total of 60 studies included. The most recent national survey conducted in six regions of Japan reported the mean prevalence of dementia in people aged ≥65 years to be 15.75% (95% CI: 12.4, 22.2%), which is much higher than the previous estimated rate of 10% in 2010. AD was confirmed as the predominant type of dementia, accounting for 65.8% of all cases. Advancing age and low education were the most consistently reported risk factors for AD dementia. Japanese guidelines for the management of dementia were released in 2010 providing specific guidance for AD about clinical signs, image findings, biochemical markers, and treatment approaches. Pharmacotherapies and non-pharmacotherapies to relieve cognitive symptoms were introduced, as were recommendations to achieve better patient care. No studies reporting treatment patterns were identified. Due to population aging and growing awareness of AD in Japan, health care expenditure and associated burden are expected to soar. This review highlights the importance of early detection, diagnosis, and treatment of AD as strategies to minimize the impact of AD on society in Japan.

Milk Intake at Midlife and Cognitive Decline over 20 Years. The Atherosclerosis Risk in Communities (ARIC) Study

Background: Faster rates of cognitive decline are likely to result in earlier onset of cognitive impairment and dementia. d-galactose, a derivative of lactose, is used in animal studies to induce neurodegeneration. Milk is the primary source of lactose in the human diet, and its effects on cognitive decline have not been fully evaluated. Objective: Assess the association of milk intake with change in cognitive function over 20 years. Methods: A total of 13,751 participants of the Atherosclerosis Risk in Communities (ARIC) cohort completed a food frequency questionnaire and three neurocognitive evaluations from 1990 through 2013. Two single nucleotide polymorphisms (SNPs) were used to determine lactase persistence (LCT-13910 C/T for Whites and LCT-14010 G/C for Blacks). Mixed-effects models were used to study the association of milk intake with cognitive change. Multiple imputations by chained equations were used to account for attrition. Results: Milk intake greater than 1 glass/day was associated with greater decline in the global z-score over a 20-year period. The difference in decline was 0.10 (95% CI: 0.16, 0.03) z-scores, or an additional 10% decline, relative to the group reporting “almost never” consuming milk. Conclusions: Replication of these results is warranted in diverse populations with greater milk intake and higher variability of lactase persistence genotype.

Female sex, early-onset hypertension, and risk of dementia

OBJECTIVE

To evaluate the association of early-adulthood and mid-adulthood hypertension with dementia in men and women.

METHODS

We evaluated 5,646 members of a diverse integrated health care delivery system who had clinical examinations and health survey data from 1964 to 1973 (mean age 32.7 years; early adulthood) and 1978-1985 (mean age 44.3 years; mid-adulthood) and were members as of January 1, 1996 (mean age 59.8 years). Hypertension categories based on measurements of blood pressure (BP) and change in hypertension categories between the 2 examinations (e.g., onset hypertension) were used to predict dementia incidence from January 1, 1996, to September 30, 2015. Cox proportional hazard models were adjusted for demographics, vascular comorbidities, and hypertension treatment; inverse probability weighting accounted for differential attrition between first BP measurement and start of follow-up.

RESULTS

A total of 532 individuals (9.4%) were diagnosed with dementia. Early adulthood hypertension was not associated with dementia, though effect estimates were elevated among women. Mid-adulthood hypertension was associated with 65% (95% confidence interval [CI] 1.25-2.18) increased dementia risk among women but not men. Onset of hypertension in mid-adulthood predicted 73% higher dementia risk in women (95% CI 1.24-2.40) compared to stable normotensive. There was no evidence that hypertension or changes in hypertension increased dementia risk among men.

CONCLUSIONS

Though midlife hypertension was more common in men, it was only associated with dementia risk in women. Sex differences in the timing of dementia risk factors have important implications for brain health and hypertension management.

Physical Activity and Alzheimer's Disease: A Systematic Review

The current literature includes several studies investigating the association between physical activity and risk of Alzheimer's disease (AD). The aim of this review was to systematically evaluate available evidence on this association. Medline via PubMed and CINAHL databases were searched for original English language research articles assessing the relationship between physical activity and incident AD. The review was limited to prospective observational and intervention studies. Criteria for exclusion were studies focusing on individuals with dementia, cross-sectional study design, and case reports. The quality of included studies was assessed in 5 domains of bias. Twenty-four studies met the inclusion criteria. The number of participants ranged from 176 to 5,698. Follow-up time varied from 1 to 34 years. Physical activity was inversely associated with risk of AD in most studies (n = 18). Leisure-time physical activity was particularly protective against AD, but not work-related physical activity. The risk of bias assessment showed that overall quality of evidence was moderate for 16 and low for 8 studies. Beyond all the available general recommendations for health promotion, current evidence does not allow to draw specific practical recommendations concerning the types, frequency, intensity, or duration of physical activity that may be protective against AD.

Physical Activity, Brain Volume, and Dementia Risk: The Framingham Study

Background

Several longitudinal studies found an inverse relationship between levels of physical activity and cognitive decline, dementia, and/or Alzheimer's disease (AD), but results have been inconsistent. We followed an older, community-based cohort for over a decade to examine the association of physical activity with the risk of incident dementia and subclinical brain MRI markers of dementia.

Methods

The physical activity index (PAI) was assessed in the Framingham Study Original and Offspring cohorts, aged 60 years or older. We examined the association between PAI and risk of incident all-cause dementia and AD in participants of both cohorts who were cognitively intact and had available PAI (n = 3,714; 54% women; mean age = 70±7 years). We additionally examined the association between PAI and brain MRI in the Offspring cohort (n = 1,987).

Results

Over a decade of follow-up, 236 participants developed dementia (188 AD). Participants in the lowest quintile of PAI had an increased risk of incident dementia compared with those in higher quintiles (hazard ratio [HR] = 1.50, 95% confidence interval [CI] = 1.04-1.97, p = .028) in a multivariable-adjusted model. Secondary analysis revealed that this relation was limited to participants who were apolipoprotein (APO)E ε4 allele noncarriers (HR = 1.58, 95% CI = 1.08-2.32; p = .018) and strongest in participants aged 75 years or older. PAI was also linearly related to total brain and hippocampal volumes (β ± SE = 0.24±0.06; p < .01 and 0.004±0.001; p = .003, respectively).

Conclusion

Low physical activity is associated with a higher risk for dementia in older individuals, suggesting that a reduced risk of dementia and higher brain volumes may be additional health benefits of maintaining physical activity into old age.

Defining the Relationship Between Hypertension, Cognitive Decline, and Dementia: a Review

Hypertension is a highly prevalent condition which has been established as a risk factor for cardiovascular and cerebrovascular disease. Although the understanding of the relationship between cardiocirculatory dysfunction and brain health has improved significantly over the last several decades, it is still unclear whether hypertension constitutes a potentially treatable risk factor for cognitive decline and dementia. While it is clear that hypertension can affect brain structure and function, recent findings suggest that the associations between blood pressure and brain health are complex and, in many cases, dependent on factors such as age, hypertension chronicity, and antihypertensive medication use. Whereas large epidemiological studies have demonstrated a consistent association between high midlife BP and late-life cognitive decline and incident dementia, associations between late-life blood pressure and cognition have been less consistent. Recent evidence suggests that hypertension may promote alterations in brain structure and function through a process of cerebral vessel remodeling, which can lead to disruptions in cerebral autoregulation, reductions in cerebral perfusion, and limit the brain's ability to clear potentially harmful proteins such as β-amyloid. The purpose of the current review is to synthesize recent findings from epidemiological, neuroimaging, physiological, genetic, and translational research to provide an overview of what is currently known about the association between blood pressure and cognitive function across the lifespan. In doing so, the current review also discusses the results of recent randomized controlled trials of antihypertensive therapy to reduce cognitive decline, highlights several methodological limitations, and provides recommendations for future clinical trial design.

Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study

Objective To test the hypotheses that physical activity in midlife is not associated with a reduced risk of dementia and that the preclinical phase of dementia is characterised by a decline in physical activity.Design Prospective cohort study with a mean follow-up of 27 years.Setting Civil service departments in London (Whitehall II study).Participants 10 308 participants aged 35-55 years at study inception (1985-88). Exposures included time spent in mild, moderate to vigorous, and total physical activity assessed seven times between 1985 and 2013 and categorised as "recommended" if duration of moderate to vigorous physical activity was 2.5 hours/week or more.Main outcome measures A battery of cognitive tests was administered up to four times from 1997 to 2013, and incident dementia cases (n=329) were identified through linkage to hospital, mental health services, and mortality registers until 2015.Results Mixed effects models showed no association between physical activity and subsequent 15 year cognitive decline. Similarly, Cox regression showed no association between physical activity and risk of dementia over an average 27 year follow-up (hazard ratio in the "recommended" physical activity category 1.00, 95% confidence interval 0.80 to 1.24). For trajectories of hours/week of total, mild, and moderate to vigorous physical activity in people with dementia compared with those without dementia (all others), no differences were observed between 28 and 10 years before diagnosis of dementia. However, physical activity in people with dementia began to decline up to nine years before diagnosis (difference in moderate to vigorous physical activity -0.39 hours/week; P=0.05), and the difference became more pronounced (-1.03 hours/week; P=0.005) at diagnosis.Conclusion This study found no evidence of a neuroprotective effect of physical activity. Previous findings showing a lower risk of dementia in physically active people may be attributable to reverse causation-that is, due to a decline in physical activity levels in the preclinical phase of dementia.

Body mass index in midlife and dementia: Systematic review and meta-regression analysis of 589,649 men and women followed in longitudinal studies

INTRODUCTION

We conducted a meta-analysis of the conflicting epidemiologic evidence on the association between midlife body mass index (BMI) and dementia.

METHODS

We searched standard databases to identify prospective, population-based studies of dementia risk by midlife underweight, overweight, and obesity. We performed random-effects meta-analyses and meta-regressions of adjusted relative risk (RR) estimates and formally explored between-study heterogeneity.

RESULTS

We included 19 studies on 589,649 participants (2040 incident dementia cases) followed up for up to 42 years. Midlife (age 35 to 65 years) obesity (BMI ≥ 30) (RR, 1.33; 95% confidence interval [CI], 1.08-1.63), but not overweight (25 < BMI < 30) (RR, 1.07; 95% CI, 0.96-1.20), was associated with dementia in late life. The association with midlife underweight (RR, 1.39; 95% CI, 1.13-1.70) was potentially driven by residual confounding (P from meta-regression = .004), selection (P = .046), and information bias (P = .007).

DISCUSSION

Obesity in midlife increases the risk of dementia. The association between underweight and dementia remains controversial.

Longitudinal and postural changes of blood pressure predict dementia: the Malmö Preventive Project

The role of blood pressure (BP) changes in dementia is debatable. We aimed to analyse how resting and postural BP changes relate to incident dementia over a long-term follow-up. In the prospective population-based Malmö Preventive Project, 18,240 study participants (mean age: 45 ± 7 years, 63% male) were examined between 1974 and 1992 with resting and standing BP measurement, and re-examined between 2002 and 2006 at mean age of 68 ± 6 years with resting BP. A total of 428 participants (2.3%) were diagnosed with dementia through Dec 31, 2009. The association of resting and postural BP changes with risk of dementia was studied using multivariable-adjusted Cox regression models controlling for traditional risk factors. Diastolic BP (DBP) decrease on standing indicated higher risk of dementia [Hazard ratio (HR) per 10 mmHg: 1.22; 95% confidence interval (CI) 1.01-1.44, p = 0.036], which was mainly driven by increased risk in normotensive individuals. Higher systolic (SBP) and diastolic BP at re-examination was associated with lower risk of dementia (HR per 10 mmHg: 0.94; 95% CI 0.89-0.99, p = 0.011; and 0.87; 0.78-0.96, p = 0.006, respectively). Extreme decrease in SBP/DBP between baseline and re-examination (4th quartile; -7 ± 12/-15 ± 7 mmHg, respectively) indicated higher risk of dementia (HR 1.46; 95% CI 1.11-1.93, p = 0.008, and 1.54; 95% CI 1.14-2.08, p = 0.005; respectively) compared with reference group characterised by pronounced BP increase over the same period (1st quartile; +44 ± 13/+15 ± 7 mmHg). Diastolic BP decrease on standing in the middle age, decline in BP between middle-and advanced age, and lower BP in advanced age are independent risk factors of developing dementia.

Nutrition and Cognition in Older Adults With Heart Failure: A Systematic Review

Cognitive impairment is commonly observed in older adults with heart failure; nutrition is a possible contributing factor. The purpose of the current systematic review is to examine the relationship between nutrition and cognition in older adults with heart failure. A literature review was performed through August 2015 that examined published, peer-reviewed studies from PubMed, PsycINFO, CINAHL, and Web of Science. Four articles were selected for inclusion. Findings revealed that poorer nutritional habits were associated with poorer attention, executive functioning, and memory in older adults with heart failure. Nutritional biomarkers, including anemia, hyponatremia, hypokalemia, hyperglycemia, and hypoalbuminemia, were also associated with cognitive impairment. More research is needed to explore the relationship between nutrition and cognition in this population. Descriptive studies will inform scientists as they design and test nutritional interventions to optimize cognitive function in older adults with heart failure.

Age of onset of hypertension and risk of dementia in the oldest-old: The 90+ Study

INTRODUCTION

We investigated the association between age of onset of hypertension and dementia risk in an oldest-old cohort.

METHODS

Participants are from The 90+ Study, a population-based longitudinal study of people aged 90+ who are survivors from the Leisure World Cohort Study. We estimated hypertension onset age using self-reported information from The 90+ Study and Leisure World Cohort Study, collected about 20 years earlier. A total of 559 participants without dementia were followed every 6 months for up to 10 years.

RESULTS

A total of 224 participants developed dementia during follow-up (mean = 2.8 years). Compared with those without hypertension, participants whose hypertension onset age was 80 to 89 years had a lower dementia risk (hazard ratio = 0.58, P = .04) and participants with an onset age of 90+ years had the lowest risk (hazard ratio = 0.37, P = .004).

DISCUSSION

Developing hypertension at older ages may protect against dementia. Understanding the mechanisms for this lower risk is important for determining ways to prevent dementia in the very elderly.

Meta-Analysis of Milk Consumption and the Risk of Cognitive Disorders

The association between milk intake and cognitive disorders has been investigated in several epidemiological studies, but the findings are still conflicting. No quantitative assessment has been performed to evaluate the potential relationship of milk intake and cognitive disorders. From the inception to October 2016, the PubMed and the Embase databases were searched for observational studies reporting the association of milk consumption and cognitive disorders (Alzheimer’s disease, dementia, and cognitive decline/impairment). A generic inverse-variance random-effects method was used to pool the Odds Ratios (ORs) and corresponding 95% confidence intervals (CIs) for the highest compared with the lowest level of milk intake. Subgroup and meta-regression analyses were used to assess the heterogeneity between subgroups. We identified seven articles involving a total of 10,941 participants. The highest level of milk consumption was significantly associated with a decreased risk of cognitive disorders, and the pooled OR (95% CI) was 0.72 (0.56, 0.93), with evidence of significant heterogeneity (I² = 64%, p = 0.001). Subgroup analysis indicated that the association was more pronounced in ischemic stroke patients based on a single study. Furthermore, the inverse association between milk intake and cognitive disorders was limited to Asian subjects, and the African populations showed an intermediate non-significant trend. Although we have obtained a significant association, an established relationship cannot be drawn due to the study limitation. Large prospective studies are needed to quantify the potential dose-response patterns of milk intake and to explore the association in populations with different characteristics.

Glucose level decline precedes dementia in elderly African Americans with diabetes

INTRODUCTION

High blood glucose levels may be responsible for the increased risk for dementia in diabetic patients.

METHODS

A secondary data analysis merging electronic medical records (EMRs) with data collected from the Indianapolis-Ibadan Dementia project (IIDP). Of the enrolled 4105 African Americans, 3778 were identified in the EMR. Study endpoints were dementia, mild cognitive impairment (MCI), or normal cognition. Repeated serum glucose measurements were used as the outcome variables.

RESULTS

Diabetic participants who developed incident dementia had a significant decrease in serum glucose levels in the years preceding the diagnosis compared to the participants with normal cognition (P = .0002). They also had significantly higher glucose levels up to 9 years before the dementia diagnosis (P = .0367).

DISCUSSION

High glucose levels followed by a decline occurring years before diagnosis in African American participants with diabetes may represent a powerful presymptomatic metabolic indicator of dementia.

Alzheimer's disease due to loss of function: A new synthesis of the available data

Alzheimer's Disease (AD) is a highly complex disease involving a broad range of clinical, cellular, and biochemical manifestations that are currently not understood in combination. This has led to many views of AD, e.g. the amyloid, tau, presenilin, oxidative stress, and metal hypotheses. The amyloid hypothesis has dominated the field with its assumption that buildup of pathogenic β-amyloid (Aβ) peptide causes disease. This paradigm has been criticized, yet most data suggest that Aβ plays a key role in the disease. Here, a new loss-of-function hypothesis is synthesized that accounts for the anomalies of the amyloid hypothesis, e.g. the curious pathogenicity of the Aβ42/Aβ40 ratio, the loss of Aβ caused by presenilin mutation, the mixed phenotypes of APP mutations, the poor clinical-biochemical correlations for genetic variant carriers, and the failure of Aβ reducing drugs. The amyloid-loss view accounts for recent findings on the structure and chemical features of Aβ variants and their coupling to human patient data. The lost normal function of APP/Aβ is argued to be metal transport across neuronal membranes, a view with no apparent anomalies and substantially more explanatory power than the gain-of-function amyloid hypothesis. In the loss-of-function scenario, the central event of Aβ aggregation is interpreted as a loss of soluble, functional monomer Aβ rather than toxic overload of oligomers. Accordingly, new research models and treatment strategies should focus on remediation of the functional amyloid balance, rather than strict containment of Aβ, which, for reasons rationalized in this review, has failed clinically.

Blood Pressure and Risk of Vascular Dementia: Evidence From a Primary Care Registry and a Cohort Study of Transient Ischemic Attack and Stroke

BACKGROUND AND PURPOSE

Vascular dementia is the second most common form of dementia but reliable evidence on age-specific associations between blood pressure (BP) and risk of vascular dementia is limited and some studies have reported negative associations at older ages.

METHODS

In a cohort of 4.28 million individuals, free of known vascular disease and dementia and identified from linked electronic primary care health records in the United Kingdom (Clinical Practice Research Datalink), we related BP to time to physician-diagnosed vascular dementia. We further determined associations between BP and dementia in a prospective population-based cohort of incident transient ischemic attack and stroke (Oxford Vascular Study).

RESULTS

For a median follow-up of 7.0 years, 11 114 initial presentations of vascular dementia were observed in the primary care cohort after exclusion of the first 4 years of follow-up. The association between usual systolic BP and risk of vascular dementia decreased with age (hazard ratio per 20 mm Hg higher systolic BP, 1.62; 95% confidence interval, 1.13-2.35 at 30-50 years; 1.26, 1.18-1.35 at 51-70 years; 0.97, 0.92-1.03 at 71-90 years; P trend=0.006). Usual systolic BP remained predictive of vascular dementia after accounting for effect mediation by stroke and transient ischemic attack. In the population-based cohort, prior systolic BP was predictive of 5-year risk of dementia with no evidence of negative association at older ages.

CONCLUSIONS

BP is positively associated with risk of vascular dementia, irrespective of preceding transient ischemic attack or stroke. Previous reports of inverse associations in old age could not be confirmed.

Antihypertensive Therapies and Cognitive Function: a Review

Increasing life expectancy has made old age-related health problems like dementia and cognitive decline more prevalent, and these are rapidly becoming important causes of disability and poor quality of life, causing significant add-ons to health-care costs worldwide. Hypertension is the most important modifiable vascular risk factor for the development and progression of both cognitive decline and dementia. In many observational and randomized studies, antihypertensive therapies have been shown to be beneficial in slowing cognitive decline. However, due to observed discrepancies by these studies, there is a lack of consensus on the best antihypertensive strategy for the prevention or slowing of cognitive decline. It is also not clear whether the beneficial effect of antihypertensive therapy is due to the use of a specific class of agents or combination therapy. Thus, we present a comprehensive review of overall antihypertensive therapies and cognition and of the individual antihypertensive therapy classes with their specific protective mechanisms and available clinical evidence behind their effect on cognitive function.

Physical Activity as Protective Factor against Dementia: A Prospective Population-Based Study (NEDICES)

The aim of this study was to analyze whether physical activity (PA) is a protective factor for the incidence of dementia after 3 years of follow-up. The Neurological Disorders in Central Spain (NEDICES) is a prospective population-based survey of older adults (age 65 years and older) that comprised 5278 census-based participants at baseline (1994-1995). A broad questionnaire was used to assess participants' sociodemographic characteristics, health status, and lifestyle. Subsequently, a modified version of Rosow-Breslau questionnaire was applied to classify individuals' baseline PA into groups (i.e., sedentary, light, moderate, and high). Cox regression models adjusted for several covariates (age, sex, education, previous stroke, alcohol consumption, hypertension, health related variables) were carried out to estimate the association between the PA groups and risk of dementia at the 3-year follow-up (1997-1998). A total of 134 incident dementia cases were identified among 3105 individuals (56.6% female; mean age=73.15 ± 6.26) after 3 years. Hazard ratios (HRs) of the light, moderate, and high PA groups (vs. sedentary group) were 0.40 (95% confidence interval {CI} [0.26, 0.62]; p<.001), 0.32 (95% CI [0.20, 0.54]; p<.001) and 0.23 (95% CI [0.13, 0.40]; p<.001), respectively. Even after controlling for covariates and the exclusion of doubtful dementia cases, HRs remained significant. However, a supplementary analysis showed that the dose-effect hypothesis did not reach statistical significance. PA is a protective factor of incident dementia in this population-based cohort.

Estimating the cognitive effects of prevalent diabetes, recent onset diabetes, and the duration of diabetes among older adults

BACKGROUND

Little evidence is available on the effects of incident diabetes or diabetes duration on cognitive aging.

METHODS

We evaluated the effects of prevalent and incident diabetes on deteriorations in cognitive function, based on participants (n = 8,671) aged 65+ in the Health and Retirement Study in 2000. Inverse probability weighting was used to account for selective attrition and time-varying confounding of incident diabetes.

RESULTS

Prevalent diabetes predicted higher odds of dementia [odds ratio 1.27; 95% confidence interval (CI) 1.03-1.58] and worse memory (-0.06 in z-score units; 95% CI -0.10 to -0.02), but incident diabetes or diabetes duration up to 8 years of follow-up was not predictive.

CONCLUSION

Prevalent diabetes predicted lower cognition but not recent onset diabetes.

Models and mechanisms of vascular dementia

Vascular dementia (VaD) is the second leading form of dementia after Alzheimer's disease (AD) plaguing the elderly population. VaD is a progressive disease caused by reduced blood flow to the brain, and it affects cognitive abilities especially executive functioning. VaD is poorly understood and lacks suitable animal models, which constrain the progress on understanding the basis of the disease and developing treatments. This review article discusses VaD, its risk factors, induced cognitive disability, various animal (rodent) models of VaD, pathology, and mechanisms of VaD and treatment options.

Association between intake of dairy products and short-term memory with and without adjustment for genetic and family environmental factors: A twin study

BACKGROUND & AIMS

Previous studies have indicated associations between intake of dairy products and better cognitive function and reduced risk of dementia. However, these studies did not adjust for genetic and family environmental factors that may influence food intake, cognitive function, and metabolism of dairy product nutrients. In the present study, we investigated the association between intake of dairy products and short-term memory with and without adjustment for almost all genetic and family environmental factors using a genetically informative sample of twin pairs.

METHODS

A cross-sectional study was conducted among twin pairs aged between 20 and 74. Short-term memory was assessed as primary outcome variable, intake of dairy products was analyzed as the predictive variable, and sex, age, education level, marital status, current smoking status, body mass index, dietary alcohol intake, and medical history of hypertension or diabetes were included as possible covariates. Generalized estimating equations (GEE) were performed by treating twins as individuals and regression analyses were used to identify within-pair differences of a twin pair to adjust for genetic and family environmental factors. Data are reported as standardized coefficients and 95% confidence intervals (CI).

RESULTS

Analyses were performed on data from 78 men and 278 women. Among men, high intake of dairy products was significantly associated with better short-term memory after adjustment for the possible covariates (standardized coefficients = 0.22; 95% CI, 0.06-0.38) and almost all genetic and family environmental factors (standardized coefficients = 0.38; 95% CI, 0.07-0.69). Among women, no significant associations were found between intake of dairy products and short-term memory. Subsequent sensitivity analyses were adjusted for small samples and showed similar results.

CONCLUSIONS

Intake of dairy product may prevent cognitive declines regardless of genetic and family environmental factors in men.

Midlife Hypertension Risk and Cognition in the Non-Demented Oldest Old: Framingham Heart Study

Midlife cardiovascular risk, hypertension (HTN) in particular, has been related cross-sectionally to poorer neuropsychological (NP) performance in middle age and older adults. This study investigated whether a similar relationship persists between midlife HTN or systolic blood pressure (SBP) and NP performance approximately 30 years later. 378 Framingham stroke and dementia-free Original cohort participants, with HTN and SBP ascertained between 50-60 years of age (mean age 55 ± 1, 65% women), were administered a NP assessment at age ≥80 years. Tests included Logical Memory, Visual Reproduction, Paired Associate, Hooper Visual Organization Test, Trail Making A & B, Digit Span Forward and Backward, Controlled Word Association Test (COWAT), and Similarities. Multivariable linear regression, adjusted for age, time interval between risk factor and NP testing, gender, and premorbid intelligence, assessed association between midlife HTN/SBP and NP outcomes. Midlife HTN was not significantly associated with NP outcome measures. Midlife SBP was associated with poorer Digit Span Forward and COWAT performance (p <  0.05). No significant interaction of age on HTN/SBP to NP associations was found. There was a significant interaction between ApoE4 status and SBP in their effects on COWAT (pinteraction = 0.074); SBP was negatively associated with COWAT only in those with the ApoE4 allele (p = 0.025). While midlife HTN is not associated with late life cognitive impairment, midlife SBP is related to late life attention and verbal fluency impairments, particularly among ApoE4+ individuals. These results offer insight into processes that are operative in the absence of overt cognitive impairment and dementia.

Cognitive impairment and cardiovascular diseases in the elderly. A heart-brain continuum hypothesis

The aging population is increasing and, therefore, a higher prevalence of cardiac disease is emerging; including hypertension, coronary artery disease, atrial fibrillation and chronic heart failure. Large cohort studies have revealed a relationship among increased risk for cognitive impairment and dementia in cardiovascular diseases probably due to embolic stroke or chronic cerebral hypoperfusion. Thus, the aim of the present review is to overview the studies that investigate the presence and/or the development of cognitive impairments and dementia in patients with varied types of cardiovascular disease. Finally, a continuum among hypertension, coronary artery disease, atrial fibrillation and chronic heart failure with to the development of cognitive impairment and progression to dementia has been hypothesized.

Hypertension, brain damage and cognitive decline

Loss of cognitive function is one the most devastating manifestations of ageing and vascular disease. Cognitive decline is rapidly becoming an important cause of disability worldwide and contributes significantly to increased mortality. There is growing evidence that hypertension is the most important modifiable vascular risk factor for development and progression of both cognitive decline and dementia. High blood pressure contributes to cerebral small and large vessel disease resulting in brain damage and dementia. A decline in cerebrovascular reserve capacity and emerging degenerative vascular wall changes underlie complete and incomplete brain infarcts, haemorrhages and white matter hyperintensities. This review discusses the complexity of factors linking hypertension to brain functional and structural changes, and to cognitive decline and dementia. The evidence for possible clinical markers useful for prevention of decreased cognitive ability, as well as recent data on vascular mechanism in the pathogenesis of cognitive decline, and the role of antihypertensive therapies in long-term prevention of late-life cognitive decline will be reviewed.

Diabetes, dysglycemia and cognitive dysfunction

Evidence from the last decade supports the hypothesis that diabetes may be viewed as a disease of accelerated cognitive ageing. It is a risk factor for the development of dementia, for an accelerated rate of cognitive decline and for cognitive dysfunction. Thus, 'diabetes-related cognitive dysfunction' may be viewed as another long-term complication of diabetes. This article will review the evidence supporting this hypothesis and will elaborate on the implications for patient care, as well as discuss potential treatment options and their limitation. The final section reviews possible mechanistic explanations.

Antihypertensive and neuroprotective effects of catestatin in spontaneously hypertensive rats: interaction with GABAergic transmission in amygdala and brainstem

The chromogranin A-derived peptide catestatin (CST) exerts sympathoexcitatory and hypertensive effects when microinjected into the rostral ventrolateral medulla (RVLM: excitatory output); it exhibits sympathoinhibitory and antihypertensive effects when microinjected into the caudal ventrolateral medulla (CVLM: inhibitory output) of vagotomized normotensive rats. Here, continuous infusion of CST into the central amygdalar nucleus (CeA) of spontaneously hypertensive rats (SHRs) for 15 days resulted in a marked decrease of blood pressure (BP) in 6-month- (by 37 mm Hg) and 9-month- (by 65 mm Hg)old rats. Whole-cell patch-clamp recordings on pyramidal CeA neurons revealed that CST increased both spontaneous inhibitory postsynaptic current (sIPSC) amplitude plus frequency, along with reductions of sIPSC rise time and decay time. Inhibition of GABAA receptors (GABAARs) by bicuculline completely abolished CST-induced sIPSC, corroborating that CST signals occur through this major neuroreceptor complex. Hypertension is a major risk factor for cerebrovascular diseases, leading to vascular dementia and neurodegeneration. We found a marked neurodegeneration in the amygdala and brainstem of 9-month-old SHRs, while CST and the GABAAR agonist Muscimol provided significant neuroprotection. Enhanced phosphorylation of Akt and ERK accounted for these neuroprotective effects through anti-inflammatory and anti-apoptotic activities. Overall our results point to CST exerting potent antihypertensive and neuroprotective effects plausibly via a GABAergic output, which constitute a novel therapeutic measure to correct defects in blood flow control in disorders such as stroke and Alzheimer's disease.

[Hypertension and dementia]

Prevention and treatment of dementia has turned into a major public health challenge. Several epidemiological studies have indicated a significant association between the presence of hypertension and the onset of dementia (vascular or Alzheimer's type) several years later. Cognitive disorder may be related to focal cerebral lesions of vascular origin (infarctus, lacunae) and/or chronic ischemia of the white matter (white matter lesions) related to arteriosclerosis and/or lipohyalinosis of small perforating arteries high blood pressure in mid-life to later cognitive decline and dementia. Moreover, disorders of cerebral microcirculation and endothelial dysfunction may be associated to blood brain barrier dysfunction and amyloid plaques formation leading to Alzheimer's process. Few randomized clinical trials have included a cognitive assessment and dementia as outcome in their design. They all raise some major criticisms: cognitive assessment was never the main outcome, too short follow-up to study dementia; incomplete assessment of cognition, lost of follow-up and a small proportion of subjects at risk for dementia at inclusion. However, the results of therapeutic trials (SYST-EUR, PROGRESS) open the way to the prevention of dementia (vascular or Alzheimer's type) or cognitive decline by antihypertensive treatments. A meta-analysis including randomized controlled studies, suggests a significant decrease in the risk of dementia with antihypertensive treatment compared to placebo.

Milk, dairy products, and their functional effects in humans: a narrative review of recent evidence

Milk is a widely consumed beverage that is essential to the diet of several millions of people worldwide because it provides important macro- and micronutrients. Milk is recognized as being useful during childhood and adolescence because of its composition; however, its relatively high saturated fat proportion raises issues of potential detrimental effects, namely on the cardiovascular system. This review evaluates the most recent literature on dairy and human health, framed within epidemiologic, experimental, and biochemical evidence. As an example, the effects of milk (notably skimmed milk) on body weight appear to be well documented, and the conclusions of the vast majority of published studies indicate that dairy consumption does not increase cardiovascular risk or the incidence of some cancers. Even though the available evidence is not conclusive, some studies suggest that milk and its derivatives might actually be beneficial to some population segments. Although future studies will help elucidate the role of milk and dairy products in human health, their use within a balanced diet should be considered in the absence of clear contraindications.

Environment and Brain Plasticity: Towards an Endogenous Pharmacotherapy

Brain plasticity refers to the remarkable property of cerebral neurons to change their structure and function in response to experience, a fundamental theoretical theme in the field of basic research and a major focus for neural rehabilitation following brain disease. While much of the early work on this topic was based on deprivation approaches relying on sensory experience reduction procedures, major advances have been recently obtained using the conceptually opposite paradigm of environmental enrichment, whereby an enhanced stimulation is provided at multiple cognitive, sensory, social, and motor levels. In this survey, we aim to review past and recent work concerning the influence exerted by the environment on brain plasticity processes, with special emphasis on the underlying cellular and molecular mechanisms and starting from experimental work on animal models to move to highly relevant work performed in humans. We will initiate introducing the concept of brain plasticity and describing classic paradigmatic examples to illustrate how changes at the level of neuronal properties can ultimately affect and direct key perceptual and behavioral outputs. Then, we describe the remarkable effects elicited by early stressful conditions, maternal care, and preweaning enrichment on central nervous system development, with a separate section focusing on neurodevelopmental disorders. A specific section is dedicated to the striking ability of environmental enrichment and physical exercise to empower adult brain plasticity. Finally, we analyze in the last section the ever-increasing available knowledge on the effects elicited by enriched living conditions on physiological and pathological aging brain processes.

Cardiovascular disease and risk of Alzheimer's disease

Several recent studies demonstrate associations between cardiovascular disease and its risk factors and the incidence of Alzheimer's disease. This review will examine the evidence for these associations and possible pathogenetic pathways. Clinical relevance and implications of these associations will also be discussed.

Impact of aerobic exercise on neurobehavioral outcomes

Numerous studies have examined the relationship between physical activity and cognitive function, demonstrating that greater physical activity is associated with lower incidence of cognitive impairment in later life. Due to an increasingly large number of older adults at risk for cognitive impairment, the relationship between physical activity and cognition has garnered increasing public health relevance and multiple randomized trials have demonstrated that exercise interventions among sedentary adults improve cognitive performance in multiple domains of function. This article will examine the relationship between physical activity and cognitive function by reviewing several different areas of literature, including the prevalence of cognitive impairment, assessment methods, observational studies examining physical activity and cognition, and intervention studies. The present review is intended to provide a historical tutorial of existing literature linking physical activity, exercise, and cognitive function among both healthy and clinical populations.

Diabetes as a risk factor for dementia and mild cognitive impairment: a meta-analysis of longitudinal studies

This study examined the association of diabetes with the onset of dementia (including Alzheimer's disease (AD), vascular dementia (VD) and any dementia) and mild cognitive impairment (MCI) by using a quantitative meta-analysis of longitudinal studies. EMBASE and MEDLINE were searched for articles published up to December 2010. All studies that examined the relationship between diabetes and the onset of dementia or MCI were included. Pooled relative risks were calculated using fixed and random effects models. Nineteen studies met our inclusion criteria for this meta-analysis, and 6184 subjects with diabetes and 38 530 subjects without diabetes were included respectively. All subjects were without dementia or MCI at baseline. The quantitative meta-analysis showed that subjects with diabetes had higher risk for AD (relative risk (RR):1.46, 95% confidence interval (CI): 1.20-1.77), VD (RR: 2.48, 95% CI: 2.08-2.96), any dementia (RR: 1.51, 95% CI: 1.31-1.74) and MCI (RR: 1.21, 95% CI: 1.02-1.45) than those without. The quantitative meta-analysis showed that diabetes was a risk factor for incident dementia (including AD, VD and any dementia) and MCI.

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.

Changes in brain volume and cognition in a randomized trial of exercise and social interaction in a community-based sample of non-demented Chinese elders

Physical exercise has been shown to increase brain volume and improve cognition in randomized trials of non-demented elderly. Although greater social engagement was found to reduce dementia risk in observational studies, randomized trials of social interventions have not been reported. A representative sample of 120 elderly from Shanghai, China was randomized to four groups (Tai Chi, Walking, Social Interaction, No Intervention) for 40 weeks. Two MRIs were obtained, one before the intervention period, the other after. A neuropsychological battery was administered at baseline, 20 weeks, and 40 weeks. Comparison of changes in brain volumes in intervention groups with the No Intervention group were assessed by t-tests. Time-intervention group interactions for neuropsychological measures were evaluated with repeated-measures mixed models. Compared to the No Intervention group, significant increases in brain volume were seen in the Tai Chi and Social Intervention groups (p < 0.05). Improvements also were observed in several neuropsychological measures in the Tai Chi group, including the Mattis Dementia Rating Scale score (p = 0.004), the Trailmaking Test A (p = 0.002) and B (p = 0.0002), the Auditory Verbal Learning Test (p = 0.009), and verbal fluency for animals (p = 0.01). The Social Interaction group showed improvement on some, but fewer neuropsychological indices. No differences were observed between the Walking and No Intervention groups. The findings differ from previous clinical trials in showing increases in brain volume and improvements in cognition with a largely non-aerobic exercise (Tai Chi). In addition, intellectual stimulation through social interaction was associated with increases in brain volume as well as with some cognitive improvements.

Heart disease as a risk factor for dementia

As life expectancy lengthens, dementia is becoming a significant human condition in terms of its prevalence and cost to society worldwide. It is important in that context to understand the preventable and treatable causes of dementia. This article exposes the link between dementia and heart disease in all its forms, including coronary artery disease, myocardial infarction, atrial fibrillation, valvular disease, and heart failure. This article also explores the cardiovascular risk factors and emphasizes that several of them are preventable and treatable. In addition to medical therapies, the lifestyle changes that may be useful in retarding the onset of dementia are also summarized.

Midlife cardiovascular risk factors and late cognitive impairment

Cardiovascular risk factors increase the risk of dementia in later life. The aims of the current study were to assess the effect of multiple midlife cardiovascular risk factors on the risk of cognitive impairment in later life, and to assess the validity of the previously suggested CAIDE Study risk score predicting dementia risk 20 years later. A total of 2,165 Finnish twins were followed and at the end of the follow-up their cognitive status was assessed with a validated telephone interview. The assessment of the risk factors at baseline was based on a self-report questionnaire. Relative risk ratios (RR) were calculated and receiver operating characteristic analyses performed. Midlife obesity (RR 2.42, 95 % CI 1.47-3.98), hypertension (RR 1.38, 95 % CI 1.01-1.88) and low leisure time physical activity (RR 2.52, 95 % CI 1.10-5.76) increased the risk of cognitive impairment after a mean follow-up of 22.6 ± 2.3 years. Hypercholesterolemia did not significantly increase the risk (RR 1.52, 95 % CI 0.92-2.51). Overweight individuals who gained more than 10 % weight between 1981 and 1990 had an increased risk of cognitive impairment (RR 4.27, 95 % CI 1.62-11.2). The CAIDE Study risk score combining various individual risk factors had an area-under-curve of 0.74 (95 % CI 0.69-0.79, n = 591), and there was a strong association between an increasing risk score and the risk of cognitive impairment. The results indicate that multiple midlife cardiovascular risk factors increase the risk of cognitive impairment in later life. Also, a risk score including easily measurable midlife factors predicts an individual's cognitive impairment risk well.

The association between midlife cardiorespiratory fitness levels and later-life dementia: a cohort study

BACKGROUND

Primary prevention of Alzheimer disease and other types of dementia (all-cause dementia) is an important public health goal. Evidence to date is insufficient to recommend any lifestyle change to prevent or delay the onset of dementia.

OBJECTIVE

To assess the association between objectively measured midlife cardiorespiratory fitness ("fitness") levels and development of all-cause dementia in advanced age.

DESIGN

Prospective, observational cohort study.

SETTING

Preventive medicine clinic.

PATIENTS

19 458 community-dwelling, nonelderly adults who had a baseline fitness examination.

MEASUREMENTS

Fitness levels, assessed using the modified Balke treadmill protocol between 1971 and 2009, and incident all-cause dementia using Medicare Parts A and B claims data from 1999 to 2009.

RESULTS

1659 cases of incident all-cause dementia occurred during 125 700 person-years of Medicare follow-up (median follow-up, 25 years [interquartile range, 19 to 30 years]). After multivariable adjustment, participants in the highest quintile of fitness level had lower hazard of all-cause dementia than those in the lowest quintile (hazard ratio, 0.64 [95% CI, 0.54 to 0.77]). Higher fitness levels were associated with lower hazard of all-cause dementia with previous stroke (hazard ratio, 0.74 [CI, 0.53 to 1.04]) or without previous stroke (hazard ratio, 0.74 [CI, 0.61 to 0.90]).

LIMITATIONS

Dementia diagnoses were based on Medicare claims, and participants generally were non-Hispanic white, healthy, and well-educated and had access to preventive health care. This study evaluated fitness levels, so a specific exercise prescription cannot be generated from results and the findings may not be causal.

CONCLUSION

Higher midlife fitness levels seem to be associated with lower hazards of developing all-cause dementia later in life. The magnitude and direction of the association were similar with or without previous stroke, suggesting that higher fitness levels earlier in life may lower risk for dementia later in life, independent of cerebrovascular disease.

PRIMARY FUNDING SOURCE

The Cooper Institute; University of Texas Southwestern Medical Center; National Heart, Lung, and Blood Institute; and American Heart Association.

A warning index used in prescreening for Alzheimer's disease, based on self-reported cognitive deficits and vascular risk factors for dementia in elderly patients with type 2 diabetes

Background/Aims. Diabetes might increase the risk of Alzheimer's disease (AD). For detecting dementia, it is typical to obtain informants' perceptions of cognitive deficits, but such interviews are usually difficult in routine care. We aimed to develop a model for predicting mild to moderate AD using a self-reported questionnaire and by evaluating vascular risk factors for dementia in elderly subjects with diabetes. Methods. We recruited 286 diabetic and 155 nondiabetic elderly subjects. There were 25 patients with AD and 261 cognitively normal individuals versus 30 with AD and 125 normal subjects, respectively. Each participant answered subjective questions on memory deficits and daily functioning. Information on vascular risk factors was obtained from clinical charts, and multivariate logistic regression was used to develop a model for predicting AD. Results. The predicted probabilities used in screening for AD in diabetic subjects constituted age, education, lower diastolic blood pressure, subjective complaints of memory dysfunction noticeable by others, and impaired medication, shopping, and travel outside a familiar locality. Receiver operating characteristic analysis revealed a satisfactory discrimination for AD specific for diabetic elderly subjects, with 95.2% sensitivity and 90.6% specificity. Conclusion. This is the first useful index that can prescreen for AD in elderly subjects with diabetes.

Dairy constituents and neurocognitive health in ageing

Age-related cognitive decline (ARCD) and dementia are of increasing concern to an ageing population. In recent years, there has been considerable research focused on effective dietary interventions that may prevent or ameliorate ARCD and dementia. While a number of studies have considered the impact that dairy products may have on physiological health, particularly with regard to the metabolic syndrome and cardiovascular health, further research is currently needed in order to establish the impact that dairy products have in the promotion of healthy brain function during ageing. The present review considers the available evidence for the positive effects of dairy products on the metabolic syndrome and glucose regulation, with consideration of the implications for neurocognitive health. A literature search of current (September 2010) meta-analyses/reviews and original research regarding dairy products and cognition was conducted through SCOPUS using the following search terms for dairy consituents: dairy, milk, cheese, yoghurt, probiotics, whey protein, alpha lactalbumin, calcium, B-12, bioactive peptides and colostrinin (CLN). These search terms for dairy products were combined with the following search terms related to cognition and health: cognition, cognitive decline, dementia, Alzheimer's disease, metabolic syndrome, diabetes, insulin resistance and glucose regulation. Concerns regarding SFA and other fatty acids found in dairy products are also reviewed in relation to different forms of dairy products. The review also considers recent evidence for positive neurocognitive effects associated with bioactive peptides, CLN and proline-rich polypeptides, α-lactalbumin, vitamin B12, calcium and probiotics. Future directions for the extraction and purification of beneficial constituents are also discussed. It is concluded that low-fat dairy products, when consumed regularly as part of a balanced diet, may have a number of beneficial outcomes for neurocognitive health during ageing.

Epidemiology of Alzheimer disease

The global prevalence of dementia has been estimated to be as high as 24 million, and is predicted to double every 20 years until at least 2040. As the population worldwide continues to age, the number of individuals at risk will also increase, particularly among the very old. Alzheimer disease is the leading cause of dementia beginning with impaired memory. The neuropathological hallmarks of Alzheimer disease include diffuse and neuritic extracellular amyloid plaques in brain that are frequently surrounded by dystrophic neurites and intraneuronal neurofibrillary tangles. The etiology of Alzheimer disease remains unclear, but it is likely to be the result of both genetic and environmental factors. In this review we discuss the prevalence and incidence rates, the established environmental risk factors, and the protective factors, and briefly review genetic variants predisposing to disease.

The association between dairy product consumption and cognitive function in the National Health and Nutrition Examination Survey

The present cross-sectional study sought to determine the potential relationships between the intake of dairy foods (total dairy products, milk and cheese) and cognitive function through information garnered in the National Health and Nutrition Examination Surveys (1988-94 and 1999-2002). Cognitive measures of vasomotor speed, coding speed and immediate memory recall were assessed from a simple reaction time task (SRTT), symbol-digit substitution test (SDST) and serial digit learning task, respectively, in adults 20-59 years of age. A summation of the percentile rank scores on each of the three tests provided a measure of overall cognitive function. In adults 60 years of age and above, a story recall test and a digit-symbol substitution test (DSST) were utilised to determine cognitive function in an elderly population. The results indicated that cognitive scores for the SRTT were not different between consumers and non-consumers of dairy foods. However, there were associations observed between 20- and 59-year-old consumers of total dairy foods and a higher SDST percentile score (53.2 (SE 1.3) to 49.4 (SE 2.0)) and a calculated global cognitive percentile score (53.3 (SE 1.1) to 50.2 (SE 1.4)) compared with non-consumers. A similar significant association was observed with cheese consumers. In adults over 60 years of age, an association between total dairy product consumption and higher DSST percentile scores (51.5 (SE 1.9) to 46.2 (se 3.0)) was also observed. These findings highlight the need for additional research on how dairy products may affect cognition and by what mechanisms, through its nutrients or other components.

Antihypertensives for combating dementia? A perspective on candidate molecular mechanisms and population-based prevention

Age-related increases in prevalent dementia over the next 30-40 years risk collapsing medical resources or radically altering the way we treat patients. Better prevention of dementia therefore needs to be one of our highest medical priorities. We propose a perspective on the pathological basis of dementia based on a cerebrovascular-Alzheimer disease spectrum that provides a more powerful explanatory framework when considering the impact of possible public health interventions. With this in mind, a synthesis of evidence from basic, clinical and epidemiological studies indeed suggests that the enhanced treatment of hypertension could be effective for the primary prevention of dementia of either Alzheimer or vascular etiology. In particular, we focus on candidate preventative mechanisms, including reduced cerebrovascular disease, disruption of hypoxia-dependent amyloidogenesis and the potential neuroprotective properties of calcium channel blockers. Following the successful translation of large, long-term and resource-intense trials in cardiology into improved vascular health outcomes in many countries, new multinational prevention trials with dementia-related primary outcomes are now urgently required.