Dementia in the oldest old: a multi-factorial and growing public health issue

The impact of nutrition on psycho-affective status in an older Cretan population: a cross-sectional study

BACKGROUND

Cognitive and mood status influence both personal and social daily activities, with great impact on life quality, particularly among the elderly population.

AIM

This cross-sectional study aimed to investigate the psycho-affective status concerning eating habits within an elderly population of the Chania area in Crete, Greece.

METHODS

Cognitive status was assessed in 101 elderly subjects through the Mini-Mental State Examination (MMSE), and mood was evaluated using the Hospital Anxiety and Depression Scale (HADS). Nutritional status was assessed using a validated food frequency questionnaire.

RESULTS

Multivariable statistical analysis, after adjustment for age, marital status, education, and comorbidity, highlighted among males a positive association of the MMSE score with vegetable consumption (RR 1.18; 95%CI 1.03‒1.34) and a negative association with potato consumption (RR 0.83; 95%CI 0.72‒0.95). Conversely, among females, no statistically significant association was observed for any food. Further, among males, a protective effect on affective status was identified for chicken meat (RR 0.45; 95%CI 0.27‒0.77), fish (RR 0.41; 95%CI 0.21‒0.82), fruit (RR 0.70; 95%CI 0.52‒0.94), cereals (RR 0.67; 95%CI 0.53‒0.87), and cheese (RR 0.78; 95%CI 0.63‒0.97) consumption. Among females, the adjusted model showed a significant detrimental effect of vegetable consumption (RR 1.33; 95%CI 1.02‒1.73).

CONCLUSION

A predominantly vegetable-based diet-with the notable exception of fruits and legumes-was associated with better cognitive status in males, albeit not in females. A higher intake of fruit, as well as fish, chicken meat, and cheese among males was associated with a better affective status, indicating that adequate protein supply may play a role in maintaining emotional balance.

Dementia risk in patients with type 2 diabetes: Comparing metformin with no pharmacological treatment

INTRODUCTION

Metformin has been suggested as a therapeutic agent for dementia, but the relevant evidence has been partial and inconsistent.

METHODS

We established a national cohort of 210,237 type 2 diabetes patients in the UK Clinical Practice Research Datalink. Risks of incident dementia were compared between metformin initiators and those who were not prescribed any anti-diabetes medication during follow-up.

RESULTS

Compared with metformin initiators (n = 114,628), patients who received no anti-diabetes medication (n = 95,609) had lower HbA1c and better cardiovascular health at baseline. Both Cox regression and propensity score weighting analysis showed metformin initiators had lower risk of dementia compared to those non-users (adjusted hazard ratio = 0.88 [95% confidence interval: 0.84-0.92] and 0.90 [0.84-0.96]). Patients on long-term metformin treatment had an even lower risk of dementia.

DISCUSSION

Metformin may act beyond its glycemic effect and reduce dementia risk to an even lower level than that of patients with milder diabetes and better health profiles.

HIGHLIGHTS

Metformin initiators had a significantly lower risk of dementia compared with patients not receiving anti-diabetes medication. Compared with metformin initiators, diabetes patients not receiving pharmacological treatment had better glycemic profiles at baseline and during follow-up. Patients on long-term metformin treatment had an even lower risk of subsequent dementia incidence. Metformin may act beyond its effect on hyperglycemia and has the potential of being repurposed for dementia prevention.

Prospective Study of Diet Quality and the Risk of Dementia in the Oldest Old

This study examined the associations between overall diet quality and the risk of dementia in a rural cohort among the oldest old. Included in this prospective cohort study were 2232 participants aged ≥ 80 years and dementia-free at the baseline according to the Geisinger Rural Aging Study (GRAS), a longitudinal cohort in rural Pennsylvania. In 2009, diet quality was assessed by a validated dietary screening tool (DST). Incident cases of dementia during 2009-2021 were identified using diagnosis codes. This approach was validated by a review of electronic health records. Associations between diet quality scores and the incidence of dementia were estimated using the Cox proportional hazards models, adjusted for potential confounders. Across a mean of 6.90 years of follow-up, we identified 408 incident cases of all-cause dementia. Having a higher diet quality was not significantly associated with a lower risk for incidents of all-cause dementia (adjusted HR for the highest compared with the lowest tertile: 1.01, 95% CI: 0.79, 1.29, P-trend = 0.95). Similarly, we did not observe a significant association between diet quality and altered risks of Alzheimer's disease and other forms of dementia. Overall, having a higher diet quality was not significantly associated with a lower risk of dementia among the oldest old during the full follow-up.

Incidence of Parkinson disease in North America

Parkinson disease (PD) is the second most common age-related neurodegenerative condition diagnosed in North America. We recently demonstrated, using multiple epidemiological data sources, that the prevalence of PD diagnoses was greater than previously reported and currently used for clinical, research, and policy decision-making. Prior PD incidence estimates have varied, for unclear reasons. There is a need for improved estimates of PD incidence, not only for care delivery planning and future policy but also for increasing our understanding of disease risk. The objective of this study was thus to investigate the incidence of Parkinson disease across five epidemiological cohorts in North America in a common year, 2012. The cohorts contained data on 6.7 million person-years of adults ages 45 and older, and 9.3 million person-years of adults ages 65 and older. Our estimates of age-sex-adjusted incidence of PD ranged from 108 to 212 per 100,000 among persons ages 65 and older, and from 47 to 77 per 100,00 among persons ages 45 and older. PD incidence increased with age and was higher among males. We also found persistent spatial clustering of incident PD diagnoses in the U.S. PD incidence estimates varied across our data sources, in part due to case ascertainment and diagnosis methods, but also possibly due to the influence of population factors (prevalence of genetic risk factors or protective markers) and geographic location (exposure to environmental toxins). Understanding the source of these variations will be important for health care policy, research, and care planning.

Individual differences among older adults with mild and moderate dementia in social and emotional loneliness and their associations with cognitive and psychological functioning

Background

Loneliness is a major health issue among older adults. The aim of this study was to assess the relationship between loneliness, in its social and emotional facets, and the cognitive (language), and behavioral/psychological functioning as well as quality of life (QoL) in people with mild and moderate dementia, i.e., considering dementia severity as an individual characteristic.

Methods

This cross-sectional study involved 58 people with mild dementia and 55 people with moderate dementia. Participants completed the Social and Emotional Loneliness scale, along with measures assessing their language skills, the frequency and severity of their behavioral and psychological symptoms, and their QoL.

Results

Socio-demographic characteristics and depression, but not loneliness or its social and emotional facets, contributed to explain participants’ behavioral and psychological symptoms, regardless of dementia severity. Loneliness explained, though to a small extent (8% of variance), language skills in people with moderate dementia, with social loneliness only accounting for language skills (18% of variance) in this group. Loneliness also modestly accounted for dysphoria symptoms in both the mildly and moderately impaired (6% and 5% of variance, respectively) individuals with social loneliness predicting dysphoric mood in the former group only (7% of variance). Loneliness also explained, to a larger extent, QoL in both the mildly impaired and moderately impaired individuals (27% and 20% of variance, respectively), its social facet predicting QoL in the mildly impaired (30% of variance), and its emotional facet in the moderately impaired (21% of variance) group.

Conclusion

These findings suggest that loneliness and its facets have a clear impact on perceived QoL, and influence the language skills and dysphoria symptoms of people with dementia, to a degree that depends on dementia severity. The assessment of loneliness and its facets in people with dementia considering dementia severity, and the promotion of social inclusion to reduce it should be considered by professionals.

Activation of NMDA receptors in brain endothelial cells increases transcellular permeability

Neurovascular coupling is a precise mechanism that induces increased blood flow to activated brain regions, thereby providing oxygen and glucose. In this study, we hypothesized that N-methyl-D-aspartate (NMDA) receptor signaling, the most well characterized neurotransmitter signaling system which regulates delivery of essential molecules through the blood–brain barrier (BBB). Upon application of NMDA in both in vitro and in vivo models, increased delivery of bioactive molecules that was mediated through modulation of molecules involved in molecular delivery, including clathrin and caveolin were observed. Also, NMDA activation induced structural changes in the BBB and increased transcellular permeability that showed regional heterogeneity in its responses. Moreover, NMDA receptor activation increased endosomal trafficking and facilitated inactivation of lysosomal pathways and consequently increased molecular delivery mediated by activation of calmodulin-dependent protein kinase II (CaMKII) and RhoA/protein kinase C (PKC). Subsequent in vivo experiments using mice specifically lacking NMDA receptor subunit 1 in endothelial cells showed decreased neuronal density in the brain cortex, suggesting that a deficiency in NMDA receptor signaling in brain endothelial cells induces neuronal losses. Together, these results highlight the importance of NMDA-receptor-mediated signaling in the regulation of BBB permeability that surprisingly also affected CD31 staining.

Estimating the longitudinal trajectory of cognitive function measurement using short-term data with different disease stages: Application in Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by a gradual decline in cognitive function over a few decades. The Mini-Mental State Examination (MMSE) is a widely used measure for evaluating global cognitive functioning. Characterizing the longitudinal trajectory of the MMSE in the population of interest is important to detect AD onset for preventive intervention. In this study, we formulate a new class of longitudinal trajectory modeling for MMSE from short-term individual data based on an ordinary differential equation. The proposed method models the relationship between individual decline speed of MMSE and the average MMSE using the fractional polynomial function model and subsequently estimates the longitudinal trajectory of MMSE by solving the ordinary differential equation for the estimated model. The appropriate model for trajectory estimation is selected based on the proposed criterion for quantifying the goodness of trajectory fit. The accuracy of the trajectory estimation of the proposed method was demonstrated via simulation studies. The proposed method was successfully applied to MMSE data from the Japanese Alzheimer's Disease Neuroimaging Initiative study.

Remembering your A, B, C's: Alzheimer's disease and ABCA1

The function of ATP binding cassette protein A1 (ABCA1) is central to cholesterol mobilization. Reduced ABCA1 expression or activity is implicated in Alzheimer's disease (AD) and other disorders. Therapeutic approaches to boost ABCA1 activity have yet to be translated successfully to the clinic. The risk factors for AD development and progression, including comorbid disorders such as type 2 diabetes and cardiovascular disease, highlight the intersection of cholesterol transport and inflammation. Upregulation of ABCA1 can positively impact APOE lipidation, insulin sensitivity, peripheral vascular and blood–brain barrier integrity, and anti-inflammatory signaling. Various strategies towards ABCA1-boosting compounds have been described, with a bias toward nuclear hormone receptor (NHR) agonists. These agonists display beneficial preclinical effects; however, important side effects have limited development. In particular, ligands that bind liver X receptor (LXR), the primary NHR that controls ABCA1 expression, have shown positive effects in AD mouse models; however, lipogenesis and unwanted increases in triglyceride production are often observed. The longstanding approach, focusing on LXRβ vs. LXRα selectivity, is over-simplistic and has failed. Novel approaches such as phenotypic screening may lead to small molecule NHR modulators that elevate ABCA1 function without inducing lipogenesis and are clinically translatable.

Epidemiology of dementia onset captured in Canadian primary care electronic medical records

BACKGROUND

Dementia is an increasing concern in many countries, especially in those experiencing rapid growth in the proportion of older adults in their population.

OBJECTIVE

This study aims to describe trends and demographic characteristics of incident dementia cases in community-dwelling older adults managed by primary care physicians.

METHODS

We used electronic medical records from the Canadian Primary Care Sentinel Surveillance Network database to conduct a retrospective analysis to determine the number of, and trends for, incident diagnoses of dementia. Age-standardized annual incidence rates were calculated. Participants in our cohort are Canadian community dwelling seniors aged 65+ years who were not diagnosed with dementia before baseline with at least six years of record at their primary care clinics.

RESULTS

The cohort consisted of 39 067 patients of whom 57% were females; the mean (SD) follow-up was 8.4 (1.5) years. During follow-up, 4935 patients were diagnosed with dementia. The risk for dementia diagnosis increased with increasing age but decreased in the last four years among people aged 80 and older at baseline (P < 0.001). People with dementia were more likely to be females (P = 0.001) and urban residents (P < 0.001), they are less likely to be classified into the least deprived group (P = 0.012).

CONCLUSIONS

The incidence of dementia diagnosis increased with age except in the oldest old in both sexes. This may be attributed to the effect of mortality competing risk. Future research on the association between risk factors and dementia should consider studying dementia among the oldest old separately to minimize bias.

The Role of Individual Characteristics in Predicting Short- and Long-Term Cognitive and Psychological Benefits of Cognitive Stimulation Therapy for Mild-to-Moderate Dementia

Introduction: This study examined the role of individual characteristics in predicting short- and long-term benefits of the Italian version of Cognitive Stimulation Therapy (CST-IT), an evidence-based intervention for people with mild-to-moderate dementia.

Materials and Methods: Data were drawn from a sample (N = 123) of people with dementia (PwD) who took part in a multicenter controlled clinical trial of CST-IT. Assessments at pre-test, immediately after completing the treatment, and 3 months later investigated the following outcomes: general cognitive functioning and language, mood and behavior, everyday functioning, and quality of life. Age, education and baseline (pre-test) cognitive functioning, mood (depression) and behavioral and neuropsychiatric symptoms were considered as predictors of any short- and long-term benefits.

Results: Linear mixed-effects models showed that different individual characteristics -particularly education and age- influenced the benefits of CST-IT, depending on the outcome measures considered. Higher education predicted larger gains in general cognitive functioning and, along with less severe depressive symptoms, in language (magnification effects). Older age was associated with positive changes in mood (compensation effects). Albeit very modestly, older age was also associated with larger gains in everyday functioning (compensation effects). Gains in quality of life were predicted by older age and lower education (compensation effects). Baseline cognitive functioning, mood and/or behavioral symptoms broadly influenced performance too, but their role again depended on the outcomes considered.

Discussion: These findings underscore the importance of considering and further exploring how psychosocial interventions like CST are affected by individual characteristics in order to maximize their efficacy for PwD.

Association between serum urate and CSF markers of Alzheimer's disease pathology in a population-based sample of 70-year-olds

INTRODUCTION

The relationship between urate and biomarkers for Alzheimer's disease (AD) pathophysiology has not been investigated.

METHODS

We examined whether serum concentration of urate was associated with cerebrospinal fluid biomarkers, amyloid beta (Aβ)42, Aβ40, phosphorylated tau (p-tau), total tau (t-tau), neurofilament light (NfL), and Aβ42/Aβ40 ratio, in cognitively unimpaired 70-year-old individuals from Gothenburg, Sweden. We also evaluated whether possible associations were modulated by the apolipoprotein E (APOE) ε4 allele.

RESULTS

Serum urate was positively associated with Aβ42 in males (β = 0.55 pg/mL, P = .04). There was a positive urate-APOE ε4 interaction (1.24 pg/mL, P interaction = .02) in relation to Aβ42 association. The positive urate and Aβ42 association strengthened in male APOE ε4 carriers (β = 1.28 pg/mL, P = .01).

DISCUSSION

The positive association between urate and Aβ42 in cognitively healthy men may suggest a protective effect of urate against deposition of amyloid protein in the brain parenchyma, and in the longer term, maybe against AD dementia.

The role of diet on the risk of dementia in the oldest old: The Monzino 80-plus population-based study

BACKGROUND & AIMS

Longevity also carries its dark side of age-related chronic diseases, dementia being one of the worst and the most prevalent. Since dementia lacks effective treatments, preventing or delaying it is highly desirable. Dietary habits and nutrition have been found to be important modifiable risk factors for many chronic diseases, but evidence on the role of diet on the risk of dementia is still limited, particularly among the very old. Aim of the present work is to study the association of the Mediterranean diet and its components with prevalent and incident dementia in the oldest-old.

METHODS

We analyzed data from the Monzino 80-plus study, a population-based study in subjects 80 years or older in the Varese province, Italy. A validated food frequency questionnaire was used to collect information on 23 different foods consumed in the previous year. A Mediterranean diet score was calculated and its components were classified into tertiles. Multivariable models for dementia prevalence and incidence were adjusted for demographic and clinical characteristics.

RESULTS

Information on nutrition was available for 1390 subjects in the cross-sectional study and 512 subjects in the longitudinal study, mean respective ages 93 and 92. Greater adherence to Mediterranean diet, greater consumption of eggs, fruits and vegetables, carbohydrates, and greater food intake were associated with a lower prevalence of dementia. Increasing number of portions per week and consumption of legumes significantly decreased the incidence of dementia during the 3.6 year mean follow-up: corresponding hazard ratios of highest vs. lowest tertiles (95% confidence intervals) were 0.66 (0.46-0.95) and 0.68 (0.47-0.97), respectively.

CONCLUSION

Oldest-old eating less and having diets with less variety and nutrient density were more frequent among subjects with dementia. The longitudinal analysis confirmed oldest-old subjects who eat more portions, as well as those who have a higher intake of legumes, are at decreased risk of developing dementia even though reverse causality cannot be completely ruled out.

Cerebral Blood Flow Is Associated with Diagnostic Class and Cognitive Decline in Alzheimer's Disease

BACKGROUND

Reliable cerebral blood flow (CBF) biomarkers using a noninvasive imaging technique are sought to facilitate early diagnosis and intervention in early Alzheimer's disease (AD).

OBJECTIVE

We aim to identify brain regions in which CBF values are affected and related to cognitive decline in early AD using a large cohort.

METHODS

Perfusion MRIs using continuous arterial spin labeling were acquired at 1.5 T in 58 normal controls (NC), 50 mild cognitive impairments (MCI), and 40 AD subjects from the Cardiovascular Health Study Cognition Study. Regional absolute CBF and normalized CBF (nCBF) values, without and with correction of partial volume effects, were compared across three groups. Association between regional CBF values and Modified Mini-Mental State Examination (3MSE) were investigated by multiple linear regression analyses adjusted for cardiovascular risk factors.

RESULTS

After correcting for partial volume effects and cardiovascular risk factors, ADs exhibited decreased nCBF with the strongest reduction in the bilateral posterior cingulate & precuneus region (p < 0.001) compared to NCs, and the strongest reduction in the bilateral superior medial frontal region (p < 0.001) compared to MCIs. MCIs exhibited the strongest nCBF decrease in the left hippocampus and nCBF increase in the right inferior frontal and insular region. The 3MSE scores within the symptomatic subjects were significantly associated with nCBF in the bilateral posterior and middle cingulate and parietal (p < 0.001), bilateral superior medial frontal (p < 0.001), bilateral temporoparietal (p < 0.02), and right hippocampus (p = 0.02) regions.

CONCLUSION

Noninvasive perfusion MRI can detect functional changes across diagnostic class and serve as a staging biomarker of cognitive status.

Bile acid synthesis, modulation, and dementia: A metabolomic, transcriptomic, and pharmacoepidemiologic study

BACKGROUND

While Alzheimer disease (AD) and vascular dementia (VaD) may be accelerated by hypercholesterolemia, the mechanisms underlying this association are unclear. We tested whether dysregulation of cholesterol catabolism, through its conversion to primary bile acids (BAs), was associated with dementia pathogenesis.

METHODS AND FINDINGS

We used a 3-step study design to examine the role of the primary BAs, cholic acid (CA), and chenodeoxycholic acid (CDCA) as well as their principal biosynthetic precursor, 7α-hydroxycholesterol (7α-OHC), in dementia. In Step 1, we tested whether serum markers of cholesterol catabolism were associated with brain amyloid accumulation, white matter lesions (WMLs), and brain atrophy. In Step 2, we tested whether exposure to bile acid sequestrants (BAS) was associated with risk of dementia. In Step 3, we examined plausible mechanisms underlying these findings by testing whether brain levels of primary BAs and gene expression of their principal receptors are altered in AD. Step 1: We assayed serum concentrations CA, CDCA, and 7α-OHC and used linear regression and mixed effects models to test their associations with brain amyloid accumulation (N = 141), WMLs, and brain atrophy (N = 134) in the Baltimore Longitudinal Study of Aging (BLSA). The BLSA is an ongoing, community-based cohort study that began in 1958. Participants in the BLSA neuroimaging sample were approximately 46% male with a mean age of 76 years; longitudinal analyses included an average of 2.5 follow-up magnetic resonance imaging (MRI) visits. We used the Alzheimer's Disease Neuroimaging Initiative (ADNI) (N = 1,666) to validate longitudinal neuroimaging results in BLSA. ADNI is an ongoing, community-based cohort study that began in 2003. Participants were approximately 55% male with a mean age of 74 years; longitudinal analyses included an average of 5.2 follow-up MRI visits. Lower serum concentrations of 7α-OHC, CA, and CDCA were associated with higher brain amyloid deposition (p = 0.041), faster WML accumulation (p = 0.050), and faster brain atrophy mainly (false discovery rate [FDR] p = <0.001-0.013) in males in BLSA. In ADNI, we found a modest sex-specific effect indicating that lower serum concentrations of CA and CDCA were associated with faster brain atrophy (FDR p = 0.049) in males.Step 2: In the Clinical Practice Research Datalink (CPRD) dataset, covering >4 million registrants from general practice clinics in the United Kingdom, we tested whether patients using BAS (BAS users; 3,208 with ≥2 prescriptions), which reduce circulating BAs and increase cholesterol catabolism, had altered dementia risk compared to those on non-statin lipid-modifying therapies (LMT users; 23,483 with ≥2 prescriptions). Patients in the study (BAS/LMT) were approximately 34%/38% male and with a mean age of 65/68 years; follow-up time was 4.7/5.7 years. We found that BAS use was not significantly associated with risk of all-cause dementia (hazard ratio (HR) = 1.03, 95% confidence interval (CI) = 0.72-1.46, p = 0.88) or its subtypes. We found a significant difference between the risk of VaD in males compared to females (p = 0.040) and a significant dose-response relationship between BAS use and risk of VaD (p-trend = 0.045) in males.Step 3: We assayed brain tissue concentrations of CA and CDCA comparing AD and control (CON) samples in the BLSA autopsy cohort (N = 29). Participants in the BLSA autopsy cohort (AD/CON) were approximately 50%/77% male with a mean age of 87/82 years. We analyzed single-cell RNA sequencing (scRNA-Seq) data to compare brain BA receptor gene expression between AD and CON samples from the Religious Orders Study and Memory and Aging Project (ROSMAP) cohort (N = 46). ROSMAP is an ongoing, community-based cohort study that began in 1994. Participants (AD/CON) were approximately 56%/36% male with a mean age of 85/85 years. In BLSA, we found that CA and CDCA were detectable in postmortem brain tissue samples and were marginally higher in AD samples compared to CON. In ROSMAP, we found sex-specific differences in altered neuronal gene expression of BA receptors in AD. Study limitations include the small sample sizes in the BLSA cohort and likely inaccuracies in the clinical diagnosis of dementia subtypes in primary care settings.

CONCLUSIONS

We combined targeted metabolomics in serum and amyloid positron emission tomography (PET) and MRI of the brain with pharmacoepidemiologic analysis to implicate dysregulation of cholesterol catabolism in dementia pathogenesis. We observed that lower serum BA concentration mainly in males is associated with neuroimaging markers of dementia, and pharmacological lowering of BA levels may be associated with higher risk of VaD in males. We hypothesize that dysregulation of BA signaling pathways in the brain may represent a plausible biologic mechanism underlying these results. Together, our observations suggest a novel mechanism relating abnormalities in cholesterol catabolism to risk of dementia.

Theoretical impact of the AT(N) framework on dementia using a community autopsy sample

The AT(N) research framework categorizes eight biomarker profiles using amyloid (A), tauopathy (T), and neurodegeneration (N), regardless of dementia status. We evaluated associations with dementia risk in a community-based cohort by approximating AT(N) profiles using autopsy-based neuropathology correlates, and considered cost implications for clinical trials for secondary prevention of dementia based on AT(N) profiles. We used Consortium to Establish a Registry for Alzheimer's Disease (moderate/frequent) to approximate A+, Braak stage (IV-VI) for T+, and temporal pole lateral ventricular dilation for (N)+. Outcomes included dementia prevalence at death and incidence in the last 5 years of life. A+T+(N)+ was the most common profile (31%). Dementia prevalence ranged from 14% (A-T-[N]-) to 79% (A+T+[N]+). Between 8% (A+T-[N]-) and 68% (A+T+[N]-) of decedents developed incident dementia in the last 5 years of life. Clinical trials would incur substantial expense to characterize AT(N). Many people with biomarker-defined preclinical Alzheimer's disease will never develop clinical dementia during life, highlighting resilience to clinical expression of AD neuropathologic changes and the need for improved tools for prediction beyond current AT(N) biomarkers.

Modifiable Risk Factors and Change in Cognition of Māori and Non-Māori in Advanced Age: LiLACS NZ

OBJECTIVE

This study investigated whether previously identified modifiable risk factors for dementia were associated with cognitive change in Māori (indigenous people of New Zealand) and non-Māori octogenarians of LiLACS NZ (Life and Living in Advanced Age; a Cohort Study in New Zealand), a longitudinal study.

METHOD

Multivariable repeated-measure mixed effect regression models were used to assess the association between modifiable risk factors and sociodemographic variables at baseline, and cognitive change over 6 years, with p values of <.05 regarded as statistically significant.

RESULTS

Modifiable factors associated with cognitive change differed between ethnic groups. Depression was a negative factor in Māori only, secondary education in non-Māori was protective, and obesity predicted better cognition over time for Māori. Diabetes was associated with decreased cognition for both Māori and non-Māori.

CONCLUSION

Our results begin to address gaps in the literature and increase understanding of disparities in dementia risk by ethnicity. These findings have implications for evaluating the type and application of culturally appropriate methods to improve cognition.

Interdisciplinary Research in Alzheimer's Disease and the Roles International Societies Can Play

An ever-increasing ageing population has elevated Alzheimer's disease to be one of the biggest challenges in modern medicine. Alzheimer's disease is highly complex, and we are still no closer to understanding the causes, let alone an effective treatment. The lack of good experimental models and lack of critical understanding has led to high failure rates of clinical trials with high associated costs, as well as difficulties in implementing treatments. The multifaceted nature of this disease highlights the need for an interdisciplinary approach to address these concerns. In this essay, we suggest how collaborative work can be useful in addressing some of the above issues. We then propose that international organisations and publishers need to support interdisciplinary research by creating platforms, lobbying funders, and pushing for interdisciplinary publications. We further highlight some of the issues involved in implementing these suggestions and argue that willpower of the research community, together with a re-evaluation of evaluation metrics and incentive systems, are needed in order to foster interdisciplinary research. Overall, we emphasise the need for interdisciplinary research in Alzheimer's disease and suggest that international societies should play a huge role in this endeavour.

Health and social correlates of dementia in oldest-old Mexican-origin populations

INTRODUCTION

Substantial gaps in research remain across oldest-old ethnic populations while the burden of dementia increases exponentially with age among Mexican and Mexican American older adults.

METHODS

Prevalence and correlates of dementia among individuals ≥82 years of age were examined using two population-based cohort studies: The Mexican Health and Aging Study (MHAS, n = 1078, 2012) and the Hispanic Established Populations for the Epidemiologic Study of the Elderly (HEPESE, n = 735, 2012-2013). The analytic MHAS and HEPESE samples had an average age of 86.4 and 88.0 years, 1.2 and 1.8 women to men, and 2.7 and 5.1 average years of education, respectively.

RESULTS

We identified 316 (29.2%) and 267 (36.3%) cases of likely dementia in the MHAS and HEPESE cohorts, respectively. For Mexicans but not Mexican Americans, age-adjusted prevalence rates of likely dementia were higher in women than men. For both populations prevalence rates increased with age and decreased with education for Mexican Americans but not for Mexicans. In both populations, odds of likely dementia increased with age. Health insurance for the low-income was significantly associated with higher odds of likely dementia for Mexican American men and women and Mexican women but not men. Living in extended households increased the odds of likely dementia in women, but not in men for both studies. Multiple cardiovascular conditions increased the odds of likely dementia for Mexicans but not for Mexican Americans.

DISCUSSION

Our study provides evidence of the high burden of dementia among oldest-old Mexicans and Mexican Americans and its association with health and social vulnerabilities.

Effects of kidney function, serum albumin and hemoglobin on dementia severity in the oldest old people with newly diagnosed Alzheimer's disease in a residential aged care facility: a cross-sectional study

Background

Chronic kidney disease (CKD), low serum albumin, and anemia are known risk factors for cognitive decline in older people. We investigated the association between kidney function and cognitive impairment severity in oldest-old people with a diagnosis of Alzheimer’s disease (AD).

Methods

A cross-sectional study of patients aged 80 years and older was conducted at a veterans’ home in Taiwan between 2012 and 2016. Their estimated glomerular filtration rate (eGFR) was determined using the Modification of Diet in Renal Diseases (MDRD) equation. Cognitive function was evaluated with the Mini-Mental State Examination (MMSE) and Clinical Dementia Rating (CDR).

Results

A total of 84 patients (age mean ± SD, 86.6 ± 3.9 years) had MMSE scores of 10.1 ± 6.7, and CDR scores of 1.6 ± 0.7. The average eGFR was 61.7 ± 21.5 mL/min/1.73m². The mean hemoglobin concentration was 12.7 ± 1.7 g/dl, and the mean albumin concentration was 4.5 ± 4.8 g/dl. Multivariate regression analyses showed that scores of CDR were significantly correlated with eGFR after adjustment for potential confounders. The scores of MMSE were significantly correlated with serum albumin and hemoglobin after adjustment for potential confounders.

Conclusions

We found dementia severity was significantly associated with kidney function, serum albumin, and hemoglobin in the oldest-old with AD. We recommend that oldest-old people with a diagnosis of AD be evaluated to determine kidney function, as well as nutritional and hematological status. Further study is needed to establish whether prevention of CKD deterioration, and correction of malnutrition and anemia may help to slow cognitive decline in oldest-old people with dementia.

Statistical Disease Progression Modeling in Alzheimer Disease

Background: The characterizing symptom of Alzheimer disease (AD) is cognitive deterioration. While much recent work has focused on defining AD as a biological construct, most patients are still diagnosed, staged, and treated based on their cognitive symptoms. But the cognitive capability of a patient at any time throughout this deterioration reflects not only the disease state, but also the effect of the cognitive decline on the patient's pre-disease cognitive capability. Patients with high pre-disease cognitive capabilities tend to score better on cognitive tests that are sensitive early in disease relative to patients with low pre-disease cognitive capabilities at a similar disease stage. Thus, a single assessment with a cognitive test is often not adequate for determining the stage of an AD patient. Repeated evaluation of patients' cognition over time may improve the ability to stage AD patients, and such longitudinal assessments in combinations with biomarker assessments can help elucidate the time dynamics of biomarkers. In turn, this can potentially lead to identification of markers that are predictive of disease stage and future cognitive decline, possibly before any cognitive deficit is measurable.

Methods and Findings: This article presents a class of statistical disease progression models and applies them to longitudinal cognitive scores. These non-linear mixed-effects disease progression models explicitly model disease stage, baseline cognition, and the patients' individual changes in cognitive ability as latent variables. Maximum-likelihood estimation in these models induces a data-driven criterion for separating disease progression and baseline cognition. Applied to data from the Alzheimer's Disease Neuroimaging Initiative, the model estimated a timeline of cognitive decline that spans ~15 years from the earliest subjective cognitive deficits to severe AD dementia. Subsequent analyses demonstrated how direct modeling of latent factors that modify the observed data patterns provides a scaffold for understanding disease progression, biomarkers, and treatment effects along the continuous time progression of disease.

Conclusions: The presented framework enables direct interpretations of factors that modify cognitive decline. The results give new insights to the value of biomarkers for staging patients and suggest alternative explanations for previous findings related to accelerated cognitive decline among highly educated patients and patients on symptomatic treatments.

Alzheimer's Disease and Cardiovascular Disease: A Particular Association

Methods

This review is based on the material obtained via MEDLINE (PubMed), EMBASE, and Clinical Trials databases, from January 1980 until May 2019. The search term used was "Alzheimer's disease," combined with "cardiovascular disease," "hypertension," "dyslipidaemia," "diabetes mellitus," "atrial fibrillation," "coronary artery disease," "heart valve disease," and "heart failure." Out of the 1,328 papers initially retrieved, 431 duplicates and 216 records in languages other than English were removed. Among the 681 remaining studies, 98 were included in our research material on the basis of the following inclusion criteria: (a) the community-based studies; (b) using standardized diagnostic criteria; (c) reporting raw prevalence data; (d) with separate reported data for sex and age classes.

Results

While AD and CVD alone may be considered deleterious to health, the study of their combination constitutes a clinical challenge. Further research will help to clarify the real impact of vascular factors on these diseases. It may be hypothesized that there are various mechanisms underlying the association between AD and CVD, the main ones being hypoperfusion and emboli, atherosclerosis, and the fact that, in both the heart and brain of AD patients, amyloid deposits may be present, thus causing damage to these organs.

Conclusions

AD and CVD are frequently associated. Further studies are needed in order to understand the effect of CVD and its risk factors on AD in order to better comprehend the effects of subclinical and clinical CVD on the brain. Finally, we need to clarify the impact of the underlying hypothesized mechanisms of this association and to investigate gender issues.

Prevalence, Incidence, and Risk Factors for Overall, Physical, and Cognitive Independence Among Those From Exceptionally Long-Lived Families: The Long Life Family Study

BACKGROUND

The Long Life Family Study (LLFS) enrolled families exhibiting exceptional longevity. The goal of this article was to determine the prevalence and predictors of remaining independent after 7 years in the oldest generation.

METHODS

We examined 7-year change in physical (free of activities of daily living difficulty), cognitive (Mini-Mental State Examination score ≥ 24), and overall independence (physically/cognitively independent) in adults aged 90.3 ± 6.3 from LLFS's oldest generation. Potential predictors (n = 28) of remaining independent included demographics, diseases, biomarkers, anthropometrics, and physical and cognitive performance tasks and were determined using generalized estimating equations (α: p < .05). This was a discovery/exploratory analysis, so no multiple testing correction was employed and the results require independent replication.

RESULTS

At baseline (n = 1442), 67.3%, 83.8%, and 79.7% were overall, physically, and cognitively independent, respectively. After 7 years, 66% died, 7.5% were lost to follow-up, and the prevalence of overall independence decreased to 59.1% in survivors (-8.2%, 95% confidence interval: -14.1%, 2.2%). Of those with baseline independence, 156/226 (69.0%) remained independent. Predictors of remaining physically independent included younger age, better Short Physical Performance Battery score and lung function, smaller waist circumference, and lower soluble receptor for advanced glycation end-product levels (p < .05). Predictors of remaining cognitively independent included no cancer history, better Digit Symbol Substitution Test performance, and higher body weight (p < .05).

CONCLUSIONS

The prevalence of independence decreased by only 8.2% after 7 years, demonstrating the close correspondence between disability and mortality. Further, despite a mean baseline age of 90 years, a large proportion of survivors remained independent, suggesting this exceptional subgroup may harbor protective mechanisms.

Prediction of dementia risk in low-income and middle-income countries (the 10/66 Study): an independent external validation of existing models

BACKGROUND

To date, dementia prediction models have been exclusively developed and tested in high-income countries (HICs). However, most people with dementia live in low-income and middle-income countries (LMICs), where dementia risk prediction research is almost non-existent and the ability of current models to predict dementia is unknown. This study investigated whether dementia prediction models developed in HICs are applicable to LMICs.

METHODS

Data were from the 10/66 Study. Individuals aged 65 years or older and without dementia at baseline were selected from China, Cuba, the Dominican Republic, Mexico, Peru, Puerto Rico, and Venezuela. Dementia incidence was assessed over 3-5 years, with diagnosis according to the 10/66 Study diagnostic algorithm. Discrimination and calibration were tested for five models: the Cardiovascular Risk Factors, Aging and Dementia risk score (CAIDE); the Study on Aging, Cognition and Dementia (AgeCoDe) model; the Australian National University Alzheimer's Disease Risk Index (ANU-ADRI); the Brief Dementia Screening Indicator (BDSI); and the Rotterdam Study Basic Dementia Risk Model (BDRM). Models were tested with use of Cox regression. The discriminative accuracy of each model was assessed using Harrell's concordance (c)-statistic, with a value of 0·70 or higher considered to indicate acceptable discriminative ability. Calibration (model fit) was assessed statistically using the Grønnesby and Borgan test.

FINDINGS

11 143 individuals without baseline dementia and with available follow-up data were included in the analysis. During follow-up (mean 3·8 years [SD 1·3]), 1069 people progressed to dementia across all sites (incidence rate 24·9 cases per 1000 person-years). Performance of the models varied. Across countries, the discriminative ability of the CAIDE (0·52≤c≤0·63) and AgeCoDe (0·57≤c≤0·74) models was poor. By contrast, the ANU-ADRI (0·66≤c≤0·78), BDSI (0·62≤c≤0·78), and BDRM (0·66≤c≤0·78) models showed similar levels of discriminative ability to those of the development cohorts. All models showed good calibration, especially at low and intermediate levels of predicted risk. The models validated best in Peru and poorest in the Dominican Republic and China.

INTERPRETATION

Not all dementia prediction models developed in HICs can be simply extrapolated to LMICs. Further work defining what number and which combination of risk variables works best for predicting risk of dementia in LMICs is needed. However, models that transport well could be used immediately for dementia prevention research and targeted risk reduction in LMICs.

FUNDING

National Institute for Health Research, Wellcome Trust, WHO, US Alzheimer's Association, and European Research Council.

Olesoxime improves cerebral mitochondrial dysfunction and enhances Aβ levels in preclinical models of Alzheimer's disease

BACKGROUND

Approved drugs for Alzheimer's disease (AD) only have a symptomatic effects and do not intervene causally in the course of the disease. Olesoxime (TRO19622) has been tested in AD disease models characterized by improved amyloid precursor protein processing (AβPP) and mitochondrial dysfunction.

METHODS

Three months old Thy-1-AβPP_SL (tg) and wild type mice (wt) received TRO19622 (100 mg/kg b.w.) in supplemented food pellets for 15 weeks (tg TRO19622). Mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) levels were determined in dissociated brain cells (DBC). Respiration was analyzed in mitochondria isolated from brain tissue. Citrate synthase (CS) activity and beta-amyloid peptide (Aβ_1-40) levels were determined in brain tissue. Malondialdehyde (MDA) levels were determined as an indicator for lipid peroxidation. DBC and brain homogenates were additionally stressed with Rotenone and FeCl₂, respectively. Mitochondrial respiration and Aβ_1-40 levels were also determined in HEK-AβPP_sw-cells.

RESULTS

Treatment of mice did not affect the body weight. TRO19622 was absorbed after oral treatment (plasma levels: 6,2 μg/ml). Mitochondrial respiration was significantly reduced in brains of tg-mice. Subsequently, DBC isolated from brains of tg-mice showed significantly lower MMP but not ATP levels. TRO19622 increased the activity of respiratory chain complexes and reversed complex IV (CIV) activity and MMP. Moreover, DBC isolated from brains of tg TRO19622 mice were protected from Rotenone induced inhibition of complex I activity. TRO19622 also increased the respiratory activity in HEKsw-cells. MDA basal levels were significantly higher in brain homogenates isolated from tg-mice. TRO19622 treatment had no effects on lipid peroxidation. TRO19622 increased cholesterol levels but did not change membrane fluidity of synaptosomal plasma and mitochondrial membranes isolated from brain of mice. TRO19622 significantly increased levels of Aβ_1-40 in both, in brains of tg TRO19622 mice and in HEK_sw cells.

CONCLUSIONS

TRO19622 improves mitochondrial dysfunction but enhances Aβ levels in disease models of AD. Further studies must evaluate whether TRO19622 offers benefits at the mitochondrial level despite the increased formation of Aβ, which could be harmful.

Cognitive deficit, and neuropathological correlates, in the oldest-old

Several disorders are usually involved in the cognitive deficit of the oldest old. Alzheimer disease is the commonest. It is usually characterized by progressive memory impairment - neocortical symptoms occurring much later in the course of the disease. Alzheimer disease should not be considered any more as the single cause of a cognitive deficit in a very old patient. Vascular alterations, possibly causing microinfarcts, are commonly associated, especially in cerebral amyloid angiopathy. A slowly progressive memory deficit with negative CSF biomarkers of Alzheimer's disease may be due to hippocampal sclerosis that may be the consequence of multiple causes: in most of the cases, it is associated with neuronal TDP-43 inclusions. Recently, a distribution of these inclusions to a territory more extensive than the hippocampus has been reported and attributed to a new entity, called Limbic-predominant Age-related TDP-43 Encephalopathy (LATE) with or without hippocampal sclerosis. The presence of cortical Lewy bodies may cause an intellectual deficit or contribute to it. The prevalence of dementia with cortical Lewy bodies in the oldest old is discussed. Tau inclusions in cortical glia have also been shown to participate to the intellectual deficit. Association of neurodegenerative and vascular changes is the most frequent situation in the very old patients. Systemic diseases such as diabetes or heart failure, prescription drugs (when misused), or toxic such as alcohol may also contribute to the cognitive impairment and be amenable to treatment.

High blood pressure in dementia: How low can we go?

Hypertension is an important public health concern. The prevalence keeps increasing, and it is a risk factor for several adverse health outcomes including a decline in cognitive function. Recent data also show that the prevalence of hypertension and age-related dementia is rising in Asian countries, including in the oldest old group. This study aims to discuss possible treatments for high blood pressure in the elderly and propose an optimal target for BP relative to cognitive outcomes. This review discusses several studies on related blood pressure treatments that remain controversial and the consequences if the treatment target is too low or aggressive. Longitudinal, cross-sectional, and RCT studies were included in this review. An optimum systolic blood pressure of 120-130 mm Hg is recommended, especially in nondiabetic hypertensive patients with significant risk factors. In the oldest old group of patients, hypertension might have a protective effect. The use of calcium channel blockers (CCB) and angiotensin receptor blocker (ARB) is independently associated with a decreased risk of dementia in older people. However, personalized care for patients with hypertension, especially for patients who are frail or very old, is encouraged.

The role of Apolipoprotein E epsilon4 in the association between psychosocial working conditions and dementia

In this population-based prospective study, we examined the association of job demand-control combinations with dementia, and explored the roles of Apolipoprotein E epsilon4 (APOE ɛ4) and work duration in this association. A total of 2,579 dementia-free individuals aged 60+ years from Sweden were followed over 12 years. Dementia diagnosis was made by physicians. Lifelong occupational experience was collected, and job demands and control were assessed using a psychosocial job-exposure matrix. Data were analyzed using multivariate Cox proportional hazard models. During the follow-up, 282 people developed dementia. Passive jobs (low control/low demands) were related to a higher risk of dementia compared with active jobs (high control/high demands) among the younger-old (aged ≤72 years), but not among the older-old (aged ≥78 years). Among the younger-old, compared to those with no passive job experience, those with 11+ years in passive jobs had a higher dementia risk. The joint-effect analyses showed that APOE ɛ4 carriers with passive jobs had an even higher risk of dementia compared to APOE ɛ4 non-carriers with active jobs. These findings suggest that passive jobs are related to a higher dementia risk among the younger-old. APOE ɛ4 and long work duration may amplify the impact of passive jobs on dementia.

Aging, Diabetes, Obesity, and Cognitive Decline: A Population-Based Study

BACKGROUND/OBJECTIVES

To investigate potential mechanisms underlying the well-established relationship of diabetes and obesity with cognitive decline, among older adults participating in a population-based study.

DESIGN/SETTING

Ten-year population-based cohort study.

PARTICIPANTS

A total of 478 individuals aged 65 years and older.

MEASUREMENTS

We assayed fasting blood for markers of glycemia (glucose and hemoglobin A1c [HbA1c]), insulin resistance (IR) (insulin and homeostatic model assessment of IR), obesity (resistin, adiponectin, and glucagon-like peptide-1), and inflammation (C-reactive protein). We modeled these indices as predictors of the slope of decline in global cognition, adjusting for age, sex, education, APOE*4 genotype, depressive symptoms, waist-hip ratio (WHR), and systolic blood pressure, in multivariable regression analyses of the entire sample and stratified by sex-specific median WHR. We then conducted WHR-stratified machine-learning (Classification and Regression Tree [CART]) analyses of the same variables.

RESULTS

In multivariable regression analyses, in the entire sample, HbA1c was significantly associated with cognitive decline. After stratifying by median WHR, HbA1c remained associated with cognitive decline in those with higher WHR. No metabolic indices were associated with cognitive decline in those with lower WHR. Cross-validated WHR-stratified CART analyses selected no predictors in participants older than 87 to 88 years. Faster cognitive decline was associated, in lower WHR participants younger than 87 years, with adiponectin of 11 or greater; and in higher WHR participants younger than 88 years, with HbA1c of 6.2% or greater.

CONCLUSIONS

Our population-based data suggest that, in individuals younger than 88 years with central obesity, even modest degrees of hyperglycemia might independently predispose to faster cognitive decline. In contrast, among those younger than 87 years without central obesity, adiponectin may be a novel independent risk factor for cognitive decline. J Am Geriatr Soc 68:991-998, 2020.

The puzzle of preserved cognition in the oldest old

Although epidemiological studies predict an exponential increase in the prevalence of dementia with age, recent studies have demonstrated that the oldest old are actually less frequently affected by dementia than the younger elderly. To explain this, I suggest a parallel between brain ageing and Alzheimer's disease (AD) and assume that theories concerning the brain's vulnerability to AD and its individual variability may also explain why some of the oldest old remain cognitively efficient. Some theories argue that AD is due to the continuing presence of the immature neurones vulnerable to amyloid beta protein (Aß) that are normally involved in brain development and then removed as a result of cell selection by the proteins associated with both brain development and AD. If a dysfunction in cell selection allows these immature neurones to survive, they degenerate early as a result of the neurotoxic action of Aß accumulation, which their mature counterparts can withstand. Consequently, age at the time of onset of AD and its clinical presentations depend on the number and location of such immature cells. I speculate that the same mechanism is responsible for the variability of normal brain ageing: the oldest old with well-preserved cognitive function are people genetically programmed for extreme ageing who have benefited from better cell selection during prenatal and neonatal life and therefore have fewer surviving neurones vulnerable to amyloid-promoted degeneration, whereas the process of early life cell selection was less successful in the oldest old who develop dementia.

Limbic-predominant age-related TDP-43 encephalopathy (LATE): consensus working group report

We describe a recently recognized disease entity, limbic-predominant age-related TDP-43 encephalopathy (LATE). LATE neuropathological change (LATE-NC) is defined by a stereotypical TDP-43 proteinopathy in older adults, with or without coexisting hippocampal sclerosis pathology. LATE-NC is a common TDP-43 proteinopathy, associated with an amnestic dementia syndrome that mimicked Alzheimer's-type dementia in retrospective autopsy studies. LATE is distinguished from frontotemporal lobar degeneration with TDP-43 pathology based on its epidemiology (LATE generally affects older subjects), and relatively restricted neuroanatomical distribution of TDP-43 proteinopathy. In community-based autopsy cohorts, ∼25% of brains had sufficient burden of LATE-NC to be associated with discernible cognitive impairment. Many subjects with LATE-NC have comorbid brain pathologies, often including amyloid-β plaques and tauopathy. Given that the 'oldest-old' are at greatest risk for LATE-NC, and subjects of advanced age constitute a rapidly growing demographic group in many countries, LATE has an expanding but under-recognized impact on public health. For these reasons, a working group was convened to develop diagnostic criteria for LATE, aiming both to stimulate research and to promote awareness of this pathway to dementia. We report consensus-based recommendations including guidelines for diagnosis and staging of LATE-NC. For routine autopsy workup of LATE-NC, an anatomically-based preliminary staging scheme is proposed with TDP-43 immunohistochemistry on tissue from three brain areas, reflecting a hierarchical pattern of brain involvement: amygdala, hippocampus, and middle frontal gyrus. LATE-NC appears to affect the medial temporal lobe structures preferentially, but other areas also are impacted. Neuroimaging studies demonstrated that subjects with LATE-NC also had atrophy in the medial temporal lobes, frontal cortex, and other brain regions. Genetic studies have thus far indicated five genes with risk alleles for LATE-NC: GRN, TMEM106B, ABCC9, KCNMB2, and APOE. The discovery of these genetic risk variants indicate that LATE shares pathogenetic mechanisms with both frontotemporal lobar degeneration and Alzheimer's disease, but also suggests disease-specific underlying mechanisms. Large gaps remain in our understanding of LATE. For advances in prevention, diagnosis, and treatment, there is an urgent need for research focused on LATE, including in vitro and animal models. An obstacle to clinical progress is lack of diagnostic tools, such as biofluid or neuroimaging biomarkers, for ante-mortem detection of LATE. Development of a disease biomarker would augment observational studies seeking to further define the risk factors, natural history, and clinical features of LATE, as well as eventual subject recruitment for targeted therapies in clinical trials.

Prediction models for dementia and neuropathology in the oldest old: the Vantaa 85+ cohort study

Background

We developed multifactorial models for predicting incident dementia and brain pathology in the oldest old using the Vantaa 85+ cohort.

Methods

We included participants without dementia at baseline and at least 2 years of follow-up (N = 245) for dementia prediction or with autopsy data (N = 163) for pathology. A supervised machine learning method was used for model development, considering sociodemographic, cognitive, clinical, vascular, and lifestyle factors, as well as APOE genotype. Neuropathological assessments included β-amyloid, neurofibrillary tangles and neuritic plaques, cerebral amyloid angiopathy (CAA), macro- and microscopic infarcts, α-synuclein pathology, hippocampal sclerosis, and TDP-43.

Results

Prediction model performance was evaluated using AUC for 10 × 10-fold cross-validation. Overall AUCs were 0.73 for dementia, 0.64–0.68 for Alzheimer’s disease (AD)- or amyloid-related pathologies, 0.72 for macroinfarcts, and 0.61 for microinfarcts. Predictors for dementia were different from those in previous reports of younger populations; for example, age, sex, and vascular and lifestyle factors were not predictive. Predictors for dementia versus pathology were also different, because cognition and education predicted dementia but not AD- or amyloid-related pathologies. APOE genotype was most consistently present across all models. APOE alleles had a different impact: ε4 did not predict dementia, but it did predict all AD- or amyloid-related pathologies; ε2 predicted dementia, but it was protective against amyloid and neuropathological AD; and ε3ε3 was protective against dementia, neurofibrillary tangles, and CAA. Very few other factors were predictive of pathology.

Conclusions

Differences between predictors for dementia in younger old versus oldest old populations, as well as for dementia versus pathology, should be considered more carefully in future studies.

Electronic supplementary material

The online version of this article (10.1186/s13195-018-0450-3) contains supplementary material, which is available to authorized users.

Neuropathology and cognitive performance in self-reported cognitively healthy centenarians

With aging, the incidence of neuropathological hallmarks of neurodegenerative diseases increases in the brains of cognitively healthy individuals. It is currently unclear to what extent these hallmarks associate with symptoms of disease at extreme ages. Forty centenarians from the 100-plus Study cohort donated their brain. Centenarians self-reported to be cognitively healthy at baseline, which was confirmed by a proxy. Objective ante-mortem measurements of cognitive performance were associated with the prevalence, distribution and quantity of age- and AD-related neuropathological hallmarks. Despite self-reported cognitive health, objective neuropsychological testing suggested varying levels of ante-mortem cognitive functioning. Post-mortem, we found that neuropathological hallmarks related to age and neurodegenerative diseases, such as Aβ and Tau pathology, as well as atherosclerosis, were abundantly present in most or all centenarians, whereas Lewy body and pTDP-43 pathology were scarce. We observed that increased pathology loads correlated across pathology subtypes, and an overall trend of higher pathology loads to associate with a lower cognitive test performance. This trend was carried especially by the presence of neurofibrillary tangles (NFTs) and granulovacuolar degeneration (GVD) and to a lesser extent by Aβ-associated pathologies. Cerebral Amyloid Angiopathy (CAA) specifically associated with lower executive functioning in the centenarians. In conclusion, we find that while the centenarians in this cohort escaped or delayed cognitive impairment until extreme ages, their brains reveal varying levels of disease-associated neuropathological hallmarks, some of which associate with cognitive performance.

Biomarkers for Early Diagnosis of Alzheimer's Disease in the Oldest Old: Yes or No?

In recent years, many efforts have been spent to identify sensitive biomarkers able to improve the accuracy of Alzheimer's disease (AD) diagnosis. Two different workgroups (NIA-AA and IWG) included cerebrospinal fluid (CSF) and neuroimaging findings in their sets of criteria in order to improve diagnostic accuracy as well as early diagnosis. The number of subjects with cognitive impairment increases with aging but the oldest old (≥85 years of age), the fastest growing age group, is still the most unknown from a biological point of view. For this reason, the aim of our narrative mini-review is to evaluate the pertinence of the new criteria for AD diagnosis in the oldest old. Moreover, since different subgroups of oldest old have been described in scientific literature (escapers, delayers, survivors), we want to outline the clinical profile of the oldest old who could really benefit from the use of biomarkers for early diagnosis. Reviewing the literature on biomarkers included in the diagnostic criteria, we did not find a high degree of evidence for their use in the oldest old, although CSF biomarkers seem to be still the most useful for excluding AD diagnosis in the "fit" subgroup of oldest old subjects, due to the high negative predictive value maintained in this age group.

Functional segregation loss over time is moderated by APOE genotype in healthy elderly

We investigated the influence of the apolipoprotein E-ɛ4 allele (APOE-ɛ4) on longitudinal age-related changes in brain functional connectivity (FC) and cognition, in view of mixed cross-sectional findings. One hundred and twenty-two healthy older adults (aged 58-79; 25 APOE-ɛ4 carriers) underwent task-free fMRI scans at baseline. Seventy-eight (16 carriers) had at least one follow-up (every 2 years). Changes in intra- and internetwork FCs among the default mode (DMN), executive control (ECN), and salience (SN) networks, as well as cognition, were quantified using linear mixed models. Cross-sectionally, APOE-ɛ4 carriers had lower functional connectivity between the ECN and SN than noncarriers. Carriers also showed a stronger age-dependent decrease in visuospatial memory performance. Longitudinally, carriers had steeper increase in inter-ECN-DMN FC, indicating loss of functional segregation. The longitudinal change in processing speed performance was not moderated by APOE-ɛ4 genotype, but the brain-cognition association was. In younger elderly, faster loss of segregation was correlated with greater decline in processing speed regardless of genotype. In older elderly, such relation remained for noncarriers but reversed for carriers. APOE-ɛ4 may alter aging by accelerating the change in segregation between high-level cognitive systems. Its modulation on the longitudinal brain-cognition relationship was age-dependent.

Consumption of pomegranates improves synaptic function in a transgenic mice model of Alzheimer's disease

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterized by extracellular plaques containing abnormal Amyloid Beta (Aβ) aggregates, intracellular neurofibrillary tangles containing hyperphosphorylated tau protein, microglia-dominated neuroinflammation, and impairments in synaptic plasticity underlying cognitive deficits. Therapeutic strategies for the treatment of AD are currently limited. In this study, we investigated the effects of dietary supplementation of 4% pomegranate extract to a standard chow diet on neuroinflammation, and synaptic plasticity in APPsw/Tg2576 mice brain. Treatment with a custom mixed diet (pellets) containing 4% pomegranate for 15 months ameliorated the loss of synaptic structure proteins, namely PSD-95, Munc18-1, and SNAP25, synaptophysin, phosphorylation of Calcium/Calmodulin Dependent Protein Kinase IIα (p-CaMKIIα/ CaMKIIα), and phosphorylation of Cyclic AMP-Response Element Binding Protein (pCREB/CREB), inhibited neuroinflammatory activity, and enhanced autophagy, and activation of the phophoinositide-3-kinase-Akt-mammalian target of rapamycin signaling pathway. These neuroprotective effects were associated with reduced β-site cleavage of Amyloid Precursor Protein in APPsw/Tg2576 mice. Therefore, long-term supplementation with pomegranates can attenuate AD pathology by reducing inflammation, and altering APP-dependent processes.

MH84 improves mitochondrial dysfunction in a mouse model of early Alzheimer's disease

BACKGROUND

Current approved drugs for Alzheimer's disease (AD) only attenuate symptoms, but do not cure the disease. The pirinixic acid derivate MH84 has been characterized as a dual gamma-secretase/proliferator activated receptor gamma (PPARγ) modulator in vitro. Pharmacokinetic studies in mice showed that MH84 is bioavailable after oral administration and reaches the brain. We recently demonstrated that MH84 improved mitochondrial dysfunction in a cellular model of AD. In the present study, we extended the pharmacological characterization of MH84 to 3-month-old Thy-1 AβPPSL mice (harboring the Swedish and London mutation in human amyloid precursor protein (APP)) which are characterized by enhanced AβPP processing and cerebral mitochondrial dysfunction, representing a mouse model of early AD.

METHODS

Three-month-old Thy-1 AβPPSL mice received 12 mg/kg b.w. MH84 by oral gavage once a day for 21 days. Mitochondrial respiration was analyzed in isolated brain mitochondria, and mitochondrial membrane potential and ATP levels were determined in dissociated brain cells. Citrate synthase (CS) activity was determined in brain tissues and MitoTracker Green fluorescence was measured in HEK293-AβPPwt and HEK293-AβPPsw cells. Soluble Aβ1-40 and Aβ1-42 levels were determined using ELISA. Western blot analysis and qRT-PCR were used to measure protein and mRNA levels, respectively.

RESULTS

MH84 reduced cerebral levels of the β-secretase-related C99 peptide and of Aβ40 levels. Mitochondrial dysfunction was ameliorated by restoring complex IV (cytochrome-c oxidase) respiration, mitochondrial membrane potential, and levels of ATP. Induction of PPARγ coactivator-1α (PGC-1α) mRNA and protein expression was identified as a possible mode of action that leads to increased mitochondrial mass as indicated by enhanced CS activity, OXPHOS levels, and MitoTracker Green fluorescence.

CONCLUSIONS

MH84 modulates β-secretase processing of APP and improves mitochondrial dysfunction by a PGC-1α-dependent mechanism. Thus, MH84 seems to be a new promising therapeutic agent with approved in-vivo activity for the treatment of AD.

Of Energy and Entropy: The Ineluctable Impact of Aging in Old Age Dementia

Alzheimer’s disease (AD) represents the most common form of dementia among older age subjects, and despite decades of studies, the underlying mechanisms remain unresolved. The definition of AD has changed over the past 100 years, and while early-onset AD is commonly related to genetic mutations, late-onset AD is more likely due to a gradual accumulation of age-related modifications. “Normal brain aging” and AD may represent different pathways of successful or failed capability to adapt brain structures and cerebral functions. Cellular senescence and age-related changes (ARCs) affecting the brain may be considered as biologic manifestations of increasing entropy, a measure of disorder. Late-onset AD may be regarded as the final effect of a reduced energy production, due to exhausted mitochondria, and an increased entropy in the brain. This unique trajectory enables a bioenergetics-centered strategy targeting disease-stage specific profile of brain metabolism for disease prevention and treatment.

Neuropathological and transcriptomic characteristics of the aged brain

As more people live longer, age-related neurodegenerative diseases are an increasingly important societal health issue. Treatments targeting specific pathologies such as amyloid beta in Alzheimer’s disease (AD) have not led to effective treatments, and there is increasing evidence of a disconnect between traditional pathology and cognitive abilities with advancing age, indicative of individual variation in resilience to pathology. Here, we generated a comprehensive neuropathological, molecular, and transcriptomic characterization of hippocampus and two regions cortex in 107 aged donors (median = 90) from the Adult Changes in Thought (ACT) study as a freely-available resource (http://aging.brain-map.org/). We confirm established associations between AD pathology and dementia, albeit with increased, presumably aging-related variability, and identify sets of co-expressed genes correlated with pathological tau and inflammation markers. Finally, we demonstrate a relationship between dementia and RNA quality, and find common gene signatures, highlighting the importance of properly controlling for RNA quality when studying dementia.

Alzheimer's Disease-Related Dementias Summit 2016: National research priorities

Goal 1 of the National Plan to Address Alzheimer's Disease is to prevent and effectively treat Alzheimer disease and Alzheimer disease-related dementias by 2025. To help inform the research agenda toward achieving this goal, the NIH hosts periodic summits that set and refine relevant research priorities for the subsequent 5 to 10 years. This proceedings article summarizes the 2016 Alzheimer's Disease-Related Dementias Summit, including discussion of scientific progress, challenges, and opportunities in major areas of dementia research, including mixed-etiology dementias, Lewy body dementia, frontotemporal degeneration, vascular contributions to cognitive impairment and dementia, dementia disparities, and dementia nomenclature.

Age-related white matter integrity differences in oldest-old without dementia

Aging is known to have deleterious effects on cerebral white matter, yet little is known about these white matter alterations in advanced age. In this study, 94 oldest-old adults without dementia (90-103 years) underwent diffusion tensor imaging to assess relationships between chronological age and multiple measures of integrity in 18 white matter regions across the brain. Results revealed significant age-related declines in integrity in regions previously identified as being sensitive to aging in younger-old adults (corpus callosum, fornix, cingulum, external capsule). For the corpus callosum, the effect of age on genu fractional anisotropy was significantly weaker than the relationship between age and splenium fractional anisotropy. Importantly, age-related declines in white matter integrity did not differ in cognitively normal and cognitively impaired not demented oldest-old, suggesting that they were not solely driven by cognitive dysfunction or preclinical dementia in this advanced age group. Instead, white matter in these regions appears to remain vulnerable to normal aging processes through the 10th decade of life.

Cancer-Incidence, prevalence and mortality in the oldest-old. A comprehensive review

Chronic health conditions are commonplace in older populations. The process of aging impacts many of the world's top health concerns. With the average life expectancy continuing to climb, understanding patterns of morbidity in aging populations has become progressively more important. Cancer is an age-related disease, whose risk has been proven to increase with age. Limited information is published about the epidemiology of cancer and the cancer contribution to mortality in the 85+ age group, often referred to as the oldest-old. In this review, we perform a comprehensive assessment of the most recent (2011-2016) literature on cancer prevalence, incidence and mortality in the oldest-old. The data shows cancer prevalence and cancer incidence increases until ages 85-89, after which the rates decrease into 100+ ages. However the number of overall cases has steadily increased over time due to the rise in population. Cancer mortality continues to increase after age 85+. This review presents an overview of plausible associations between comorbidity, genetics and age-related physiological effects in relation to cancer risk and protection. Many of these age-related processes contribute to the lowered risk of cancer in the oldest-old, likewise other certain health conditions may "protect" from cancer in this age group.

Late-Onset Alzheimer Disease

The oldest-old represent the fastest growing segment of society, and the risk of developing dementia continues to increase with advancing age into the 9th and 10th decades of life. The most common form of dementia in the oldest-old is Alzheimer disease (AD), although there are often mixed pathologies contributing to dementia in addition to amyloid plaques and neurofibrillary tangles. Diagnosing AD in the oldest-old is challenging due to cognitive and physical changes associated with aging. Treatment remains supportive, with current approved medications able to provide modest symptomatic benefit but unable to slow the progression of disease.

Clinical characteristics and outcomes of the oldest old people with type 2 diabetes - perspective from a tertiary diabetes center in Thailand

BACKGROUND

Advance in medicine has led to an increase in life expectancy of elderly diabetic patients especially on the growing population called the "oldest old", those in their mid-80s upwards. The aim of this study is to describe clinical characteristics and outcomes of "oldest old" patients in a specialized diabetes center.

METHODS

A retrospective review was conducted on medical records of type 2 diabetes who were older than 85 years at Theptarin hospital from September 2014 to August 2015.

RESULTS

During the study period, there were 143 oldest old diabetic patients who visited our hospital regularly. Of the 133 active follow-up patients (median time of follow-up 15 years, range 1-30 years), 70.7 % was female, the mean age of onset was 68.3 ± 11.5 years and duration of diabetes was 20.1 ± 11.1 years. According to the Charlson co-morbidity index (CCI), 35.3 % of patients were classified as having severe co-morbidities. The mean A1C, blood pressure, LDL were 6.7 ± 1.1 %, 132/65 mmHg and 80 ± 29 mg/dl respectively. 66.9 % of patients had tight glycemic control (A1C <7 %) while 12.0 % had poor control (A1C >8 %). Oral hypoglycemic agent (OHA) dual therapy was the most common treatment (26.3 %) followed by OHA monotherapy (22.6 %), insulin alone (19.5 %), diet therapy alone (12.7 %), and insulin plus OHA (8.3 %). Hypoglycemia was found in 10.5 % of patients in previous 12 months. Diabetic retinopathy, chronic kidney disease, cardiovascular disease, and stroke were presented in 23.4, 54.9, 15.8, 18.0 % of patients, respectively. Among patients whose received diabetic medications and resulted in very low level of A1C (A1C less than 6.0 %), only 20.0 % underwent deintensification.

CONCLUSIONS

Our results revealed that real-world clinical outcomes of extreme elderly diabetic patients were diverse and being too "aggressive" diabetes treatment with older patients did occur frequently. Decision making in older people with diabetes is complex as chronic co-morbidities are very common.

The Science of Vascular Contributions to Cognitive Impairment and Dementia (VCID): A Framework for Advancing Research Priorities in the Cerebrovascular Biology of Cognitive Decline

The World Health Organization reports that 47.5 million people are affected by dementia worldwide. With aging populations and 7.7 million new cases each year, the burden of illness due to dementia approaches crisis proportions. Despite significant advances in our understanding of the biology of Alzheimer's disease (AD), the leading dementia diagnosis, the actual causes of dementia in affected individuals are unknown except for rare fully penetrant genetic forms. Evidence from epidemiology and pathology studies indicates that damage to the vascular system is associated with an increased risk of many types of dementia. Both Alzheimer's pathology and cerebrovascular disease increase with age. How AD affects small blood vessel function and how vascular dysfunction contributes to the molecular pathology of Alzheimer's are areas of intense research. The science of vascular contributions to cognitive impairment and dementia (VCID) integrates diverse aspects of biology and incorporates the roles of multiple cell types that support the function of neural tissue. Because of the proven ability to prevent and treat cardiovascular disease and hypertension with population benefits for heart and stroke outcomes, it is proposed that understanding and targeting the biological mechanisms of VCID can have a similarly positive impact on public health.

Carotid atherosclerosis, cytomegalovirus infection, and cognitive decline in the very old: a community-based prospective cohort study

To investigate various risk factors of cognitive decline in the very old, we studied 494 subjects over 85 years old without diagnosis of dementia at baseline from the Tokyo Oldest Old Survey on Total Health, an ongoing, community-based cohort in Japan. Cognitive function was assessed at baseline and at 3-year follow-up using Mini-Mental State Examination (MMSE). Plasma samples were assayed for levels of cytomegalovirus (CMV) immunoglobulin G (IgG) antibodies, tumor necrosis factor-alpha, interleukin-6, and blood chemistry. Carotid artery plaques were measured using an ultrasonography. In the cross-sectional analyses using Tobit regression, individuals with high carotid artery plaque score (≥5.0) had MMSE scores that were 1.08 points lower compared to those with no plaque (95 % confidence interval (CI) -1.95 to -0.20; p = 0.016), adjusted for age, sex, and education. Individuals with CMV IgG titers in the highest quartile had MMSE scores that were 1.47 points lower compared to individuals in the lowest quartile (95 % CI -2.44 to -0.50; p = 0.003). CMV and carotid atherosclerosis showed evidence of an interaction, where the association between CMV and MMSE was present only in subjects with carotid artery plaque. In the longitudinal analyses using linear regression, carotid atherosclerosis, smoking, low grip strength, and poor activities of daily living (ADL) status were associated with faster cognitive decline, adjusted for age, sex, education, and baseline cognitive function. Our findings suggest that carotid atherosclerosis is consistently associated with low cognitive function in the very old and modifies the association between latent CMV infection and cognition.