Prediction to prevention in Alzheimer's disease and dementia

A change in social participation affects cognitive function in middle-aged and older Chinese adults: analysis of a Chinese longitudinal study on aging (2011-2018)

Background

One of the biggest challenges facing older adults is cognitive decline and social participation has always been considered a protective factor. However, it is not clear whether social participation predicts cognitive function in this population, rather than depressive symptoms, self-reported health, and activities of daily life, with sufficient capacity to detect unique effects.

Methods

This study included adults aged 45 and above in China (N = 5,258) who participated in a large national older adult health survey and provided data from 2011, 2013, 2015, and 2018. The unique associations between the predictors of social participation and cognitive function over time and context were evaluated in the Latent Growth Model (LGM).

Results

Among the 5,258 participants in our study, an overall cognitive decline was observed. Social participation predicts two dimensions of cognitive function, with a degree of impact comparable to depressive symptoms, self-reported health, and activities of daily life. Among them, social participation exhibits a noteworthy prognostic impact on episodic memory during the same period. The regression coefficient is approximately 0.1 (p < 0.05) after controlling other mixed variables (depressive symptoms, self-reported health, and activities of daily life). In contrast, social participation is also a significant predictor of mental intactness in the same period, with a regression coefficient of 0.06 (p < 0.05), even if all mixed variables are controlled.

Conclusion

Over time, the correlation strength of social participation is comparable to other recognized cognitive function prediction indicators, indicating that promoting social participation among middle-aged and older Chinese adults is a meaningful way to improve cognitive function degradation, which has important policy and practical significance.

Design, synthesis and biological evaluation of naringenin carbamate derivatives as potential multifunctional agents for the treatment of Alzheimer's disease

A series of naringenin derivatives were designed and synthesized as multifunctional anti-Alzheimer's disease (AD) agents. The results showed that these derivatives displayed moderate-to-good acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities at the micromolar range (IC₅₀, 12.91 ~ 62.52 μM for AChE and 0.094 ~ 13.72 μM for BuChE). Specifically, compound 1 showed the highest inhibitory activity against BuChE with the IC₅₀ value of (0.094 ± 0.0054) μM. A Lineweaver-Burk plot and molecular docking studies demonstrated that 1 targeted both the catalytically active site (CAS) and the peripheral anion site (PAS) of BuChE. Besides, all derivatives showed excellent hydroxyl free radicals (·OH) scavenging ability than vitamin C and cyclic voltammetry results displayed that 1 could effectively scavenge superoxide anion radical (·O₂^-). In addition, compound 1 displayed good metal chelating properties and had anti-Aβ aggregation activities. Therefore, compound 1 might be the potential anti-AD agent for further developments.

Enhancing Dementia Education and Cognitive Screening in A Haitian Population: A Faith-based Approach

Ethnically diverse Americans experience 1.8-2.5 times higher risk of developing Alzheimer's disease than Whites (Mayeda, et al., 2016), yet cognitive screening is not routinely conducted among Haitian American communities. Dementia risk awareness is beneficial for improving management of chronic illness and behaviors that impact risk of cognitive decline. A quasiexperimental paired samples t-test design was employed to test the effectiveness of an educational intervention among 50 older faith- based Haitian adults using the Basic Knowledge of Alzheimer's Disease (BKAD) scale, cognitive screening using the Cognitive State Test (COST), and referrals to a local memory/wellness center. A significant difference was seen in knowledge scores: pre-test (M = 18.5, SD = 3.12) and post-test (M = 23.1, SD = 2.42); conditions t(41.9) = -9.5, p = .000. All of those who volunteered for screening completed follow-up neuropsychological evaluations. Outreach to faith-based settings is suggested as an avenue for improving dementia knowledge and detection.

Good problems to have? Policy and societal implications of a disease-modifying therapy for presymptomatic late-onset Alzheimer's disease

In the United States alone, the prevalence of AD is expected to more than double from six million people in 2019 to nearly 14 million people in 2050. Meanwhile, the track record for developing treatments for AD has been marked by decades of failure. But recent progress in genetics, neuroscience and gene editing suggest that effective treatments could be on the horizon. The arrival of such treatments would have profound implications for the way we diagnose, triage, study, and allocate resources to Alzheimer's patients. Because the disease is not rare and because it strikes late in life, the development of therapies that are expensive and efficacious but less than cures, will pose particular challenges to healthcare infrastructure. We have a window of time during which we can begin to anticipate just, equitable and salutary ways to accommodate a disease-modifying therapy Alzheimer's disease. Here we consider the implications for caregivers, clinicians, researchers, and the US healthcare system of the availability of an expensive, presymptomatic treatment for a common late-onset neurodegenerative disease for which diagnosis can be difficult.

The power of weak ties in preserving cognitive function: a longitudinal study of older Chinese adults

Objectives: Characterized by infrequent contact, low emotional intensity, and limited intimacy, weak ties are found to be associated with better subjective well-being and other health outcomes. Drawing on the theory of weak ties and the convoy model of social relations, this paper aims to examine the association between weak ties and cognitive function among older adults in China.Methods: We used multilevel growth modeling to analyze panel data for adults aged 60 years and over (N = 2,650) selected from the China Health and Retirement Longitudinal Study (CHARLS, 2011-2015). Weak ties were measured based on the frequency of social activity participation and the number of social activities.Results: Weekly or irregular social activity participation in at least one social activity was significantly associated with better mental status and memory. The number of participated social activities was also significantly and positively associated with mental status and memory. After controlling for age, gender, marital status, educational attainment, geographic residence, household expenditures, and health conditions (i.e., depressive symptoms and self-reported health), we found that participation in a greater number of social activities protected memory from declining by 4% for every 2 years (p < 0.001).Conclusion: These findings suggest that social interactions with peripheral members of a diverse social network may help prevent cognitive decline for older Chinese adults. Greater attention on weak ties might yield practical implications for non-pharmacological dementia prevention and health promotion for the general older population.

Benchmarking machine learning models for late-onset alzheimer's disease prediction from genomic data

BACKGROUND

Late-Onset Alzheimer's Disease (LOAD) is a leading form of dementia. There is no effective cure for LOAD, leaving the treatment efforts to depend on preventive cognitive therapies, which stand to benefit from the timely estimation of the risk of developing the disease. Fortunately, a growing number of Machine Learning methods that are well positioned to address this challenge are becoming available.

RESULTS

We conducted systematic comparisons of representative Machine Learning models for predicting LOAD from genetic variation data provided by the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. Our experimental results demonstrate that the classification performance of the best models tested yielded ∼72% of area under the ROC curve.

CONCLUSIONS

Machine learning models are promising alternatives for estimating the genetic risk of LOAD. Systematic machine learning model selection also provides the opportunity to identify new genetic markers potentially associated with the disease.

Genetic risk of dementia mitigated by cognitive reserve: A cohort study

OBJECTIVE

We investigated whether cognitive reserve modifies the risk of dementia attributable to apolipoprotein ε4 (APOE-ε4), a well-known genetic risk factor for dementia.

METHODS

We followed 2,556 cognitively intact participants aged ≥60 years from the ongoing prospective community-based Swedish National Study on Aging and Care in Kungsholmen (SNAC-K). Dementia was ascertained through clinical and neuropsychological assessments and diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria. Structural equation modeling was used to generate a cognitive reserve indicator from 4 previously validated contributors: early life education, midlife substantive work complexity, late life leisure activities, and late life social networks. Cox proportional hazard models estimated dementia risk in relation to cognitive reserve indicator. The interaction between the cognitive reserve indicator and APOE-ε4 was assessed on multiplicative and additive scales.

RESULTS

After an average of 6.3 years (range = 2.1-10.7) of follow-up, 232 dementia cases were ascertained. Relative to individuals in the lowest tertile of cognitive reserve indicator, those with moderate and high reserve were at a reduced risk of dementia. There was no multiplicative interaction between APOE-ε4 status and cognitive reserve indicator (p = 0.113). Additive interaction was statistically significant. Relative to APOE-ε4 carriers with low cognitive reserve, ε4 carriers with high reserve had a reduced risk of dementia (hazard ratio [HR] = 0.28, 95% confidence interval [CI] = 0.13-0.59). The magnitude of risk reduction was similar in ε4 noncarriers with a high cognitive reserve indicator (HR = 0.24, 95% CI = 0.15-0.40).

INTERPRETATION

Lifelong engagement in reserve-enhancing activities attenuates the risk of dementia attributable to APOE-ε4. Promoting cognitive reserve might be especially effective in subpopulations with high genetic risk of dementia. ANN NEUROL 2019.

Implications of sleep disturbance and inflammation for Alzheimer's disease dementia

Nearly half of all adults older than 60 years of age report sleep disturbance, as characterised either by reports of insomnia complaints with daytime consequences, dissatisfaction with sleep quality or quantity, or the diagnosis of insomnia disorder. Accumulating evidence shows that sleep disturbance contributes to cognitive decline and might also increase the risk of Alzheimer's disease dementia by increasing β-amyloid burden. That sleep disturbance would be a candidate risk factor for Alzheimer's disease might seem surprising, given that disturbed sleep is usually considered a consequence of Alzheimer's disease. However, a bidirectional relationship between sleep and Alzheimer's disease is supported by advances in our understanding of sleep disturbance-induced increases in systemic inflammation, which can be viewed as an early event in the course of Alzheimer's disease. Inflammation increases β-amyloid burden and is thought to drive Alzheimer's disease pathogenesis. Improved understanding of the mechanisms linking sleep disturbance and Alzheimer's disease risk could facilitate the identification of targets for prevention, given that both sleep disturbance and inflammatory activation might be modifiable risk factors for Alzheimer's disease.

TGF-β1 Restores Hippocampal Synaptic Plasticity and Memory in Alzheimer Model via the PI3K/Akt/Wnt/β-Catenin Signaling Pathway

Alzheimer's disease (AD) is the most common neurodegenerative disturbances. Dysfunction of synaptic plasticity and decline in cognitive functions are the most prominent features of AD, but the mechanisms of pathogenesis have not been well elucidated. In this paper, transforming growth factor-β1 (TGF-β1) was found to be reduced in the hippocampus of AD mouse which was accompanied by impaired pine density, synaptic plasticity, and memory function. Hippocampal injection of TGF-β1 rescued the AD-induced memory function impairment. In addition, TGF-β1 ameliorated synaptic plasticity and increased synaptic plasticity-associated protein expression including Arc, NR2B, and PSD-95 in mouse model of AD. Furthermore, we demonstrated that Akt/Wnt/β-catenin pathway protein expression in the hippocampus was suppressed in a mouse model of AD and TGF-β1 significantly enhanced the phosphorylation Akt, GSK3β, and increased the nuclear β-catenin. These results indicate that TGF-β1activates PI3K/Akt/Wnt/β-catenin signaling in mouse model of AD, which is important for promoting synaptic plasticity related to memory function. More importantly, suppression of PI3K/Akt/Wnt/β-catenin pathway compromised the beneficial effects of TGFβ1 in Alzheimer's model. Hence, TGF-β1 shows protective effect on neurons, which might be through the PI3K/Akt/Wnt/β-catenin signaling pathway, serving as a potential target in AD pathology.