Diet as a Risk Factor for Cognitive Decline in African Americans and Caucasians with a Parental History of Alzheimer's Disease: A Cross-Sectional Pilot Study Dietary Patterns

Somatic comorbidity and the progression of cognitive impairment

Background

There are usually multiple factors underlying dementia in old age. Somatic comorbidity is one important element that influences the progression of cognitive impairment.

Objective

The goal of this study was to assess the relationship between the progression of cognitive impairment and the presence and severity of comorbidities based on a four-year observation.

Material

Out of 128 patients from the Clinic for Outpatients in Gdansk, who were recruited into the study based on the criteria of the Working Group on Mild Cognitive Impairment, a total of 93 participants completed the four-year observation. Only the data from participants who completed the full period of observations were analysed. The mean age of the group was M = 75.93 (SD = 9.43). The level of progression of cognitive impairment was measured using the Clinical Dementia Rating Scale - Sum of Boxes, the severity of comorbidities was measured using the modified Cumulative Illness Rating Scale, and, additionally, at the time of inclusion in the study, participants were assessed using the MMSE scale and the Activity Scale, and sociodemographic data were collected. The Generalized Estimating Equations method was employed to fit a marginal model for analyzing the data collected in a repeated measures design. The tested model elucidated the role of the overall severity of comorbidities in explaining the progression of cognitive impairment, while controlling for everyday activity and basic demographic variables.

Results

During the four-year observation, a significant decline in cognitive function (B = 1.86, p < 0.01) was observed in the examined sample. The statistical analysis revealed that individuals with higher overall severity of comorbidities exhibited significantly more pronounced progression of cognitive impairment over time. Regarding particular comorbidities, metabolic diseases were found to be associated with a poorer prognosis (rho = 0.41, p < 0.05). Furthermore, a time physical activity interaction was identified as predicting cognitive impairment, indicating that individuals who were more physically active at the beginning of the study exhibited significantly less pronounced progression of cognitive impairment over the course of the 4 years.

Conclusion

This study suggests the important roles of comorbidities and physical activity for the prognosis of mild cognitive impairment.

Effect of nutrition in Alzheimer's disease: A systematic review

Background and objective

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by declining cognitive ability. Currently, there are no effective treatments for this condition. However, certain measures, such as nutritional interventions, can slow disease progression. Therefore, the objective of this systematic review was to identify and map the updates of the last 5 years regarding the nutritional status and nutritional interventions associated with AD patients.

Study design

A systematic review.

Methods

A search was conducted for randomized clinical trials, systematic reviews, and meta-analyses investigating the association between nutritional interventions and AD published between 2018 and 2022 in the PubMed, Web of Science, Scopus, and Cochrane Library databases. A total of 38 studies were identified, of which 17 were randomized clinical trials, and 21 were systematic reviews and/or meta-analyses.

Results

The results show that the western diet pattern is a risk factor for developing AD. In contrast, the Mediterranean diet, ketogenic diet, and supplementation with omega-3 fatty acids and probiotics are protective factors. This effect is significant only in cases of mild-to-moderate AD.

Conclusion

Certain nutritional interventions may slow the progression of AD and improve cognitive function and quality of life. Further research is required to draw more definitive conclusions.

Blood pressure and Alzheimer's disease: A review of meta-analysis

Background

Alzheimer's disease (AD) is a neurological disorder of unknown cause, resulting in the death of brain cells. Identifying some of the modifiable risk factors for AD could be crucial for primary prevention and could lead to a reduction in the incidence of AD.

Objective

This study aimed to perform a meta-meta-analysis of studies in order to assess the effect of blood pressure (BP) on the diagnosis of AD.

Method

The search was restricted to meta-analyses assessing high systolic BP (SBP) and diastolic BP (DBP) and AD. We applied the PRISMA guidelines.

Results

A total of 214 studies were identified from major databases. Finally, five meta-analyses (52 studies) were analyzed in this review. Results confirm that high SBP is associated with AD. The exploration of parameters (sex, age, study design, region, and BP measurements) shows that only region significantly moderates the relationship between BP and AD. Asian people are those whose SBP levels >140 mmHg are associated with AD. BP is associated with AD in both people aged ≤65 years and those aged ≥65 years and in cross-sectional and longitudinal studies. In the case of DBP, only women are at a higher risk of AD, particularly when its levels are >90.

Conclusion

SBP is associated with both cerebrovascular disease and AD. Therefore, future studies should use other uncontrolled factors, such as cardiovascular diseases, diabetes, and stroke, to explain the relationship between SBP and AD.

Manipulation of the diet-microbiota-brain axis in Alzheimer's disease

Several studies investigating the pathogenesis of Alzheimer's disease have identified various interdependent constituents contributing to the exacerbation of the disease, including Aβ plaque formation, tau protein hyperphosphorylation, neurofibrillary tangle accumulation, glial inflammation, and the eventual loss of proper neural plasticity. Recently, using various models and human patients, another key factor has been established as an influential determinant in brain homeostasis: the gut-brain axis. The implications of a rapidly aging population and the absence of a definitive cure for Alzheimer's disease have prompted a search for non-pharmaceutical tools, of which gut-modulatory therapies targeting the gut-brain axis have shown promise. Yet multiple recent studies examining changes in human gut flora in response to various probiotics and environmental factors are limited and difficult to generalize; whether the state of the gut microbiota in Alzheimer's disease is a cause of the disease, a result of the disease, or both through numerous feedback loops in the gut-brain axis, remains unclear. However, preliminary findings of longitudinal studies conducted over the past decades have highlighted dietary interventions, especially Mediterranean diets, as preventative measures for Alzheimer's disease by reversing neuroinflammation, modifying the intestinal and blood-brain barrier (BBB), and addressing gut dysbiosis. Conversely, the consumption of Western diets intensifies the progression of Alzheimer's disease through genetic alterations, impaired barrier function, and chronic inflammation. This review aims to support the growing body of experimental and clinical data highlighting specific probiotic strains and particular dietary components in preventing Alzheimer's disease via the gut-brain axis.

Microbial-derived metabolites as a risk factor of age-related cognitive decline and dementia

A consequence of our progressively ageing global population is the increasing prevalence of worldwide age-related cognitive decline and dementia. In the absence of effective therapeutic interventions, identifying risk factors associated with cognitive decline becomes increasingly vital. Novel perspectives suggest that a dynamic bidirectional communication system between the gut, its microbiome, and the central nervous system, commonly referred to as the microbiota-gut-brain axis, may be a contributing factor for cognitive health and disease. However, the exact mechanisms remain undefined. Microbial-derived metabolites produced in the gut can cross the intestinal epithelial barrier, enter systemic circulation and trigger physiological responses both directly and indirectly affecting the central nervous system and its functions. Dysregulation of this system (i.e., dysbiosis) can modulate cytotoxic metabolite production, promote neuroinflammation and negatively impact cognition. In this review, we explore critical connections between microbial-derived metabolites (secondary bile acids, trimethylamine-N-oxide (TMAO), tryptophan derivatives and others) and their influence upon cognitive function and neurodegenerative disorders, with a particular interest in their less-explored role as risk factors of cognitive decline.

Lifestyle Factors Influencing Dietary Patterns of University Professors

The objectives of this study are to identify eating patterns of university professors and to assess the relationships among sociodemographic factors in relation to lifestyle and physical activity. It is a cross-sectional, descriptive-correlational, and observational study with a representative sample of 127 educators, which covers almost the total population of university professors belonging to one of the campuses of the University of Granada (Spain). Two eating patterns were identified a posteriori through explanatory factor analysis: a Western pattern characterised by the consumption of dairy products, eggs, meat, sausages, refined oils, and butter, sugar, processed baked goods, and sugar-containing beverages and alcoholic drinks, and a Mediterranean pattern based on olive oil, fish, fruits, nuts, vegetables, pulses, cereals, and honey, which explain the 20.102 and 17.411 of variance, respectively. Significant differences are observed between the two genders with respect to anthropometric characteristics (weight and size, p < 0.001 in both cases) and to nutritional status (p = 0.011). Origin (p = 0.022) and level of physical activity (p = 0.010) were significantly related to adherence to a Western diet pattern. In the case of the Mediterranean diet pattern, significant differences are observed according to the professors' type of bachelor's degree (p = 0.37). This study provides evidence on factors having an impact on adherence to eating patterns of professors of the University of Granada, and it suggests that programmes addressed to such groups should be developed to promote health.

Longitudinal associations between dietary quality and Alzheimer's disease genetic risk on cognitive performance among African American adults

Poor diet quality (DQ) is associated with poor cognition and increased neurodegeneration, including Alzheimer's disease (AD). We are interested in the role of DQ on cognitive functioning (by sex and increasing genetic risk for AD), in a sample of African American (AA) middle-aged adults. We analysed a sub-group of participants (about 55 % women; mean follow-up time of about 4·7 years) from the Healthy Aging in Neighborhoods of Diversity across the Life Span study with a genetic risk score for AD (hAlzScore). The Healthy Eating Index-2010, Dietary Approaches to Stop Hypertension and the mean adequacy ratio computed at baseline (2004-2009) and follow-up visits (2009-2013) were used to assess initial DQ and change over time. Linear mixed-effects regression models were utilised, adjusting for select covariates, selection bias and multiple testing. DQ change (ΔDQ) was associated with California Verbal Learning Test-List A - overall (0·15 (se 0·06), P = 0·008) and in women (0·21 (se 0·08), P = 0·006), at highest AD risk, indicating protective effects over time. Greater AD risk was longitudinally associated with poorer Clock Command Test scores in men. Poor DQ was positively and cross-sectionally associated with Trails B scores, but in women only. Better-quality diet was associated with a slower decline in verbal memory among AA women, with greater AD risk. Insufficient clinical evidence and/or mixed findings dictate that more studies are needed to investigate brain morphology and volume changes in relation to DQ in an at-risk population for AD, over time.