Midlife interventions are critical in prevention, delay, or improvement of Alzheimer's disease and vascular cognitive impairment and dementia

Activity-Induced Pain as a Predictor of Sedentary Behavior Among Midlife Adults

Purpose: Midlife adults have been estimated to spend over half of their waking time engaging in sedentary behavior, and greater sedentary behavior has been associated with a reduced likelihood of successful aging. Moreover, more than one-quarter of midlife adults report chronic pain, and there is reason to believe that pain may contribute to sedentary behavior among this population. The goal of these analyses was to test associations between self-reported increases in pain during activity and subsequent sedentary behavior among a sample of midlife adults with chronic pain. Methods: Participants included 200 midlife adults (age 50-64) who reported chronic pain and completed an online prospective survey. Activity-induced pain was assessed at baseline and total time spent engaging in sedentary behavior was assessed at baseline, 1-week, and 4-week follow-up assessments. Results: Activity-induced pain predicted greater sedentary behavior at 1-week (p < .05) and 4-week (p < .01) follow-up assessments, even after controlling for chronic pain intensity and baseline sedentary behavior. Conclusions: Activity-induced pain may represent an important mechanism underlying sedentary behavior among midlife adults with chronic pain, and programs designed to reduce sedentary behavior among this population may benefit from tailoring to account for the antithetical influence of activity-induced pain. Indeed, the current findings suggest that mitigating the extent to which pain increases during activity may be more important than reducing overall pain intensity when attempting to decrease sedentary behavior among this population. This and future work have the potential to inform the refinement of tailored interventions.

Early Chronic Stress Induced Changes within the Locus Coeruleus in Sporadic Alzheimer's Disease

Chronic exposure to stress throughout the lifespan has been the focus of many studies on Alzheimer's disease (AD) because of the similarities between the biological mechanisms involved in chronic stress and the pathophysiology of AD. In fact, the earliest abnormality associated with the disease is the presence of phosphorylated tau protein in locus coeruleus neurons, a brain structure highly responsive to stress and perceived threat. Here, we introduce allostatic load as a useful concept for understanding many of the complex, interacting neuropathological changes involved in the AD degenerative process. In response to chronic stress, aberrant tau proteins that begin to accumulate within the locus coeruleus decades prior to symptom onset appear to represent a primary pathological event in the AD cascade, triggering a wide range of interacting brain changes involving neuronal excitotoxicity, endocrine alterations, inflammation, oxidative stress, and amyloid plaque exacerbation. While it is acknowledged that stress will not necessarily be the major precipitating factor in all cases, early tau-induced changes within the locus coeruleus-norepinephrine pathway suggests that a therapeutic window might exist for preventative measures aimed at managing stress and restoring balance within the HPA axis.

Circulating serum metabolites as predictors of dementia: a machine learning approach in a 21-year follow-up of the Whitehall II cohort study

BACKGROUND

Age is the strongest risk factor for dementia and there is considerable interest in identifying scalable, blood-based biomarkers in predicting dementia. We examined the role of midlife serum metabolites using a machine learning approach and determined whether the selected metabolites improved prediction accuracy beyond the effect of age.

METHODS

Five thousand three hundred seventy-four participants from the Whitehall II study, mean age 55.8 (standard deviation (SD) 6.0) years in 1997-1999 when 233 metabolites were quantified using nuclear magnetic resonance metabolomics. Participants were followed for a median 21.0 (IQR 20.4, 21.7) years for clinically-diagnosed dementia (N=329). Elastic net penalized Cox regression with 100 repetitions of nested cross-validation was used to select models that improved prediction accuracy for incident dementia compared to an age-only model. Risk scores reflecting the frequency with which predictors appeared in the selected models were constructed, and their predictive accuracy was examined using Royston's R², Akaike's information criterion, sensitivity, specificity, C-statistic and calibration.

RESULTS

Sixteen of the 100 models had a better c-statistic compared to an age-only model and 15 metabolites were selected at least once in all 16 models with glucose present in all models. Five risk scores, reflecting the frequency of selection of metabolites, and a 1-SD increment in all five risk scores was associated with higher dementia risk (HR between 3.13 and 3.26). Three of these, constituted of 4, 5 and 15 metabolites, had better prediction accuracy (c-statistic from 0.788 to 0.796) compared to an age-only model (c-statistic 0.780), all p<0.05.

CONCLUSIONS

Although there was robust evidence for the role of glucose in dementia, metabolites measured in midlife made only a modest contribution to dementia prediction once age was taken into account.

Polyphenol-rich tart cherries (Prunus Cerasus, cv Montmorency) improve sustained attention, feelings of alertness and mental fatigue and influence the plasma metabolome in middle-aged adults: a randomised, placebo-controlled trial

Tart Montmorency cherries (MC) are a particularly rich source of anthocyanins and other polyphenols that have been shown to elicit antioxidant, anti-inflammatory and vasomodulatory actions. The current study aimed to determine the influence of chronic MC supplementation on cognitive function and mood. In a 3-month double-blinded, placebo-controlled parallel study, middle-aged adults (mean ± sd: 48 ± 6 years) were randomly assigned to either 30 ml twice daily of MC (n 25) or the same amount of an isoenergetic placebo (n 25). Cognitive function and mood were assessed before and after supplementation using a computerised cognitive task battery and visual analogue scales. Cerebral blood flow was also monitored by near-infrared spectroscopy during the task battery, and questionnaires were administered to determine subjective sleep and health status and plasma metabolomics were analysed before and after supplementation. After 3 months, the MC resulted in higher accuracy in digit vigilance (mean difference: 3·3, 95 % CI: 0·2, 6·4 %) with lower number of false alarms (mean difference: -1·2, 95 % CI: -2·0, -0·4) compared with the placebo. There was also a treatment effect for higher alertness (mean difference: 5·9, 95 % CI: 1·3, 10·5 %) and lower mental fatigue ratings (mean difference -9·5, 95 % CI: -16·5, -2·5 %) with MC. Plasma metabolomics revealed an increase in a number of amino acids in response to MC intake, but not placebo. These data suggest an anti-fatiguing effect of MC supplementation as well as the ability to improve sustained attention during times of high cognitive demand, this could be related to changes in amino acid metabolism.

Alzheimer Drug Trials: Combination of Safe and Efficacious Biologicals to Break the Amyloidosis-Neuroinflammation Vicious Cycle

Late-onset Alzheimer’s disease (LOAD) is a long-enduring neurodegenerative disease that progresses for decades before the symptoms of cognitive decline and loss of executive function are measurable. Amyloid deposits among other pathological changes, tau hyperphosphorylation, synapse loss, microglia and astroglia activation, and hippocampal atrophy are among the pathological hallmarks of the disease. These are present in the brain before memory complaints are reported and an AD diagnosis is made. The attempt to postpone or prevent the disease is becoming a more and more plausible goal because new early electrophysiological, cognitive, blood-based, and imaging-based diagnostics are being brought forward at the same time as the first anti-amyloid antibody is about to be approved. In view of known contributions of neuroinflammation to the pathology of LOAD, we should not focus solely on anti-amyloid therapies and ignore the interactive neuroinflammatory component of AD. Our belief is that it would be more rewarding to start clinical trials using combination therapies that are based on approved, safe, and efficacious anti-neuroinflammatory agents such as anti-interleukin-1 signaling agents in combination with the anti-amyloid antibodies that have been shown to be safe in multiyear trials. The proposal is that we should administer these two classes of safe biologicals to symptom-free individuals in midlife who are identified as having a high-risk-for-Alzheimer’s-disease using “precision medicine.”

Epidemiology of Alzheimer’s disease and other dementias: rising global burden and forecasted trends

Background: The burden associated with Alzheimer’s disease is recognized as one of the most pressing issues in healthcare. This study aimed to examine the global and regional burden of Alzheimer’s disease and related dementias. Methods: Epidemiological data from the latest Global Burden of Disease (GBD) dataset were analysed to determine the prevalence, incidence and mortality rates from 1990 to 2019 for 204 countries and world regions. This dataset derives estimates for health metrics by collating primary data from research studies, disease registries and government reports. Temporal forecasting was conducted using the GBD Foresight tool. Results: An estimated 0.7% of the global population has dementia, translating to 51.6 million people worldwide. The total number of persons affected has more than doubled from 1990 to 2019. Dementia metrics showed a continuous increase in prevalence, incidence, mortality, and disability adjusted life years (DALYs) rates worldwide during the last three decades. Japan has the highest prevalence (3,079 cases per 100,000), followed by Italy, Slovenia, Monaco, Greece and Germany. The prevalence is higher in high-income regions such as Western Europe compared to Asia and Africa. However, total number of affected individuals is substantial in South and East Asian regions, in particular China, Japan and India. Dementia related deaths are projected to increase from the current 2.4 million per year to 5.8 million by 2040. Women are more likely to be affected by dementia than men. Age-standardized rates have not changed indicating possible stability of risk factors. Conclusions: Alzheimer’s disease and other dementias are rising rapidly and will more than double in mortality burden over the next 20 years. The tremendous burden in high- and middle-income countries can potentially overwhelm communities and health systems. Urgent measures are needed to allocate funding and provide residential care for affected persons.

Mid age APOE ε4 carriers show memory-related functional differences and disrupted structure-function relationships in hippocampal regions

Carriers of the APOE e4 allele are at higher risk of age-related cognitive decline and Alzheimer’s disease (AD). The underlying neural mechanisms are uncertain, but genotype differences in medial temporal lobe (MTL) functional activity and structure at mid-age might contribute. We tested 16 non-e4 and 16 e4 carriers (aged 45–55) on a subsequent memory task in conjunction with MRI to assess how hippocampal volume (from T1 structural) and microstructure (neurite orientation-dispersion, from NODDI) differs by genotype and in relation to memory encoding. No previous study has investigated APOE effects on hippocampal microstructure using NODDI. Recall performance did not differ by genotype. A genotype by condition interaction in left parahippocampus indicated that in e4 carriers activity did not differentiate subsequently remembered from forgotten words. Hippocampal volumes and microstructure also did not differ by genotype but hippocampal volumes correlated positively with recognition performance in non-e4 carriers only. Similarly, greater hippocampal neurite orientation-dispersion was linked to better recall but only in non-e4s. Thus, we suggest that mid-age e4 carriers show a breakdown of normal MTL activation and structure-performance relationships. This could reflect an inability to utilise compensatory mechanisms, and contribute to higher risk of cognitive decline and AD in later life.

Canine Cognitive Dysfunction: Pathophysiology, Diagnosis, and Treatment

Canine cognitive dysfunction (CCD) is the canine analog of human Alzheimer disease (AD). The pathophysiology of CCD/AD is multifaceted. CCD is common in aged (>8 years) dogs, affecting between 14% and 35% of the pet dog population. Apparent confusion, anxiety, disturbance of the sleep/wake cycle, and decreased interaction with owners are all common clinical signs of CCD. Although there is no cure for CCD, several proven effective therapeutic approaches are available for improving cognitive ability and maintaining a good quality of life; instituting such therapies early in the disease course is likely to have the greatest positive clinical effect.