Caffeine Consumption and Dementia: Are Lewy Bodies the Link?

Sleep disorders and risk of alzheimer's disease: A two-way road

Substantial sleep impairment in patients with Alzheimer's disease (AD) is one of the emerging points for continued efforts to better understand the disease. Individuals without cognitive decline, an important marker of the clinical phase of AD, may show early alterations in the sleep-wake cycle. The objective of this critical narrative review is to explore the bidirectional pathophysiological correlation between sleep disturbances and Alzheimer's Disease. Specifically, it examines how the disruption of sleep homeostasis in individuals without dementia could contribute to the pathogenesis of AD, and conversely, how neurodegeneration in individuals with Alzheimer's Disease might lead to dysregulation of the sleep-wake cycle. Recent scientific results indicate that sleep disturbances, particularly those related to impaired glymphatic clearance, may act as an important mechanism associated with the genesis of Alzheimer's Disease. Additionally, amyloid deposition and tau protein hyperphosphorylation, along with astrocytic hyperactivation, appear to trigger changes in neurotransmission dynamics in areas related to sleep, which may explain the onset of sleep disturbances in individuals with AD. Disruption of sleep homeostasis appears to be a modifiable risk factor in Alzheimer's disease. Whenever possible, the use of non-pharmacological strategies becomes important in this context. From a different perspective, additional research is needed to understand and treat the dysfunction of the sleep-wake cycle in individuals already affected by AD. Early recognition and correction of sleep disturbances in this population could potentially mitigate the progression of dementia and improve the quality of life for those with AD.

Association of caffeine consumption with cerebrospinal fluid biomarkers in mild cognitive impairment and Alzheimer's disease: A BALTAZAR cohort study

INTRODUCTION

We investigated the link between habitual caffeine intake with memory impairments and cerebrospinal fluid (CSF) biomarkers in mild cognitive impairment (MCI) and Alzheimer's disease (AD) patients.

METHODS

MCI (N = 147) and AD (N = 116) patients of the Biomarker of AmyLoid pepTide and AlZheimer's diseAse Risk (BALTAZAR) cohort reported their caffeine intake at inclusion using a dedicated survey. Associations of caffeine consumption with memory impairments and CSF biomarkers (tau, p-tau181, amyloid beta 1-42 [Aβ1-42], Aβ1-40) were analyzed using logistic and analysis of covariance models.

RESULTS

Adjusted on Apolipoprotein E (APOE ε4), age, sex, education level, and tobacco, lower caffeine consumption was associated with higher risk to be amnestic (OR: 2.49 [95% CI: 1.13 to 5.46]; p = 0.023) and lower CSF Aβ1-42 (p = 0.047), Aβ1-42/Aβ1-40 (p = 0.040), and Aβ1-42/p-tau181 (p = 0.020) in the whole cohort.

DISCUSSION

Data support the beneficial effect of caffeine consumption to memory impairments and CSF amyloid markers in MCI and AD patients.

HIGHLIGHTS

We studied the impact of caffeine consumption in the BALTAZAR cohort. Low caffeine intake is associated with higher risk of being amnestic in MCI/AD patients. Caffeine intake is associated with CSF biomarkers in AD patients.

Habitual Coffee, Tea, and Caffeine Consumption, Circulating Metabolites, and the Risk of Cardiometabolic Multimorbidity

CONTEXT

Cardiometabolic multimorbidity (CM) is an increasing public health concern. Previous observational studies have suggested inverse associations between coffee, tea, and caffeine intake and risks of individual cardiometabolic diseases; however, their associations with CM and related biological markers are unknown.

METHODS

This prospective study involved 172 315 (for caffeine analysis) and 188 091 (tea and coffee analysis) participants free of any cardiometabolic diseases at baseline from the UK Biobank; 168 metabolites were measured among 88 204 and 96 393 participants. CM was defined as the coexistence of at least 2 of the following conditions: type 2 diabetes, coronary heart disease, and stroke.

RESULTS

Nonlinear inverse associations of coffee, tea, and caffeine intake with the risk of new-onset CM were observed. Compared with nonconsumers or consumers of less than 100 mg caffeine per day, consumers of moderate amount of coffee (3 drinks/d) or caffeine (200-300 mg/d) had the lowest risk for new-onset CM, with respective hazard ratios (95% CIs) of 0.519 (0.417-0.647) and 0.593 (0.499-0.704). Multistate models revealed that moderate coffee or caffeine intake was inversely associated with risks of almost all developmental stages of CM, including transitions from a disease-free state to single cardiometabolic diseases and subsequently to CM. A total of 80 to 97 metabolites, such as lipid components within very low-density lipoprotein, histidine, and glycoprotein acetyls, were identified to be associated with both coffee, tea, or caffeine intake and incident CM.

CONCLUSION

Habitual coffee or caffeine intake, especially at a moderate level, was associated with a lower risk of new-onset CM and could play important roles in almost all transition phases of CM development. Future studies are warranted to validate the implicated metabolic biomarkers underlying the relation between coffee, tea, and caffeine intake and CM.

Genome-wide association studies of coffee intake in UK/US participants of European ancestry uncover cohort-specific genetic associations

Coffee is one of the most widely consumed beverages. We performed a genome-wide association study (GWAS) of coffee intake in US-based 23andMe participants (N = 130,153) and identified 7 significant loci, with many replicating in three multi-ancestral cohorts. We examined genetic correlations and performed a phenome-wide association study across hundreds of biomarkers, health, and lifestyle traits, then compared our results to the largest available GWAS of coffee intake from the UK Biobank (UKB; N = 334,659). We observed consistent positive genetic correlations with substance use and obesity in both cohorts. Other genetic correlations were discrepant, including positive genetic correlations between coffee intake and psychiatric illnesses, pain, and gastrointestinal traits in 23andMe that were absent or negative in the UKB, and genetic correlations with cognition that were negative in 23andMe but positive in the UKB. Phenome-wide association study using polygenic scores of coffee intake derived from 23andMe or UKB summary statistics also revealed consistent associations with increased odds of obesity- and red blood cell-related traits, but all other associations were cohort-specific. Our study shows that the genetics of coffee intake associate with substance use and obesity across cohorts, but also that GWAS performed in different populations could capture cultural differences in the relationship between behavior and genetics.

Tea, coffee, and caffeine intake and risk of dementia and Alzheimer's disease: a systematic review and meta-analysis of cohort studies

Background: Limited and conflicting evidence exists for the associations between tea, coffee, and caffeine intake and risk of dementia and Alzheimer's disease (AD). This meta-analysis aimed to elucidate these associations and quantify potential dose-response relationships. Methods: PubMed, EMBASE, and Web of Science were searched up to 11 June 2024 for cohort studies. Random effects models were used to calculate pooled relative risks (RRs) and 95% confidence intervals (CIs), with the dose-response relationship assessed using restricted cubic splines. The Grading of Recommendations Assessment Development and Evaluation (GRADE) tool was used to assess the risk of bias. Results: Our analysis encompassed 38 cohorts, totalling 751 824 participants and 13 017 dementia and 17 341 AD cases. For dementia, compared with the lowest category, the pooled RRs (95% CI) in the highest category of tea, coffee, and caffeine were 0.84 (0.74-0.96, n = 6), 0.95 (0.87-1.02, n = 9), and 0.94 (0.70-1.25, n = 5), with all rated as low certainty in GRADE. For AD, the pooled RRs (95% CI) in the highest category of tea, coffee, and caffeine compared to the lowest category were 0.93 (0.87-1.00, n = 6), 1.01 (0.90-1.12, n = 10), and 1.34 (1.04-1.74, n = 2), with certainty ratings of low, low, and very low, respectively. Dose-response analysis indicated a non-linear relationship between coffee intake (Poverall = 0.04 and Pnonlinear = 0.01) and dementia risk, showing the protective association of risk of dementia with 1 to 3 cups per day of coffee intake. There is a linear association between tea intake and risk of dementia, with a significantly decreased risk of dementia for each 1 cup per day increase in tea consumption (0.96, 95% CI 0.94-0.99, Poverall = 0.01 and Pnonlinear = 0.68). Conclusion: Increased tea consumption was associated with a decreased risk of dementia and AD, and a non-linear relationship was found between coffee and dementia, supporting public health recommendations for dementia prevention.

Development of White Cabbage, Coffee, and Red Onion Extracts as Natural Phosphodiesterase-4B (PDE4B) Inhibitors for Cognitive Dysfunction: In Vitro and In Silico Studies

Human cognition fundamentally depends on memory. Alzheimer's disease exhibits a strong correlation with a decline in this factor. Phosphodiesterase-4 B (PDE4B) plays a crucial role in neurodegenerative disorders, and its inhibition is one of the promising approaches for memory enhancement. This study aimed to identify secondary metabolites in white cabbage, coffee, and red onion extracts and identify their molecular interaction with PDE4B by in silico and in vitro experiments. Crushed white cabbage and red onion were macerated separately with ethanol to yield respective extracts, and ground coffee was boiled with water to produce aqueous extract. Thin layer chromatography (TLC)-densitometry was used to examine the phytochemicals present in white cabbage, coffee, and red onion extracts. Molecular docking studies were performed to know the interaction of test compounds with PDE4B. TLC-densitometry analysis showed that chlorogenic acid and quercetin were detected as major compounds in coffee and red onion extracts, respectively. In silico studies revealed that alpha-tocopherol (binding free energy (∆Gbind) = -38.00 kcal/mol) has the strongest interaction with PDE4B whereas chlorogenic acid (∆Gbind = -21.50 kcal/mol) and quercetin (∆Gbind = -17.25 kcal/mol) exhibited moderate interaction. In vitro assay showed that the combination extracts (cabbage, coffee, and red onion) had a stronger activity (half-maximal inhibitory concentration (IC50) = 0.12 ± 0.03 µM) than combination standards (sinigrin, chlorogenic acid, and quercetin) (IC50 = 0.17 ± 0.03 µM) and rolipram (IC50 = 0.15 ± 0.008 µM). Thus, the combination extracts are a promising cognitive enhancer by blocking PDE4B activity.

Dietary factors and Alzheimer's disease risk: a Mendelian randomization study

BACKGROUND

Prior observational research has investigated the association between dietary patterns and Alzheimer's disease (AD) risk. Nevertheless, due to constraints in past observational studies, establishing a causal link between dietary habits and AD remains challenging.

METHODS

Methodology involved the utilization of extensive cohorts sourced from publicly accessible genome-wide association study (GWAS) datasets of European descent for conducting Mendelian randomization (MR) analyses. The principal analytical technique utilized was the inverse-variance weighted (IVW) method.

RESULTS

The MR analysis conducted in this study found no statistically significant causal association between 20 dietary habits and the risk of AD (All p > 0.05). These results were consistent across various MR methods employed, including MR-Egger, weighted median, simple mode, and weighted mode approaches. Moreover, there was no evidence of horizontal pleiotropy detected (All p > 0.05).

CONCLUSION

In this MR analysis, our finding did not provide evidence to support the causal genetic relationships between dietary habits and AD risk.

Habitual coffee consumption and risk of dementia in older persons: modulation by CYP1A2 polymorphism

Higher coffee consumption has been associated with reduced dementia risk, yet with inconsistencies across studies. CYP1A2 polymorphisms, which affects caffeine metabolism, may modulate the association between coffee and the risk of dementia and Alzheimer's disease (AD). We included 5964 participants of the Three-City Study (mean age 74 years-old), free of dementia at baseline when they reported their daily coffee consumption, with available genome-wide genotyping and followed for dementia over a median of 9.0 (range 0.8-18.7) years. In Cox proportional-hazards models, the relationship between coffee consumption and dementia risk was modified by CYP1A2 polymorphism at rs762551 (p for interaction = 0.034). In multivariable-adjusted models, coffee intake was linearly associated with a decreased risk of dementia among carriers of the C allele only ("slower caffeine metabolizers"; HR for 1-cup increased [95% CI] 0.90 [0.83-0.97]), while in non-carriers ("faster caffeine metabolizers"), there was no significant association but a J-shaped trend toward a decrease in dementia risk up to 3 cups/day and increased risk beyond. Thus, compared to null intake, drinking ≥ 4 cups of coffee daily was associated with a reduced dementia risk in slower but not faster metabolizers (HR [95% CI] for ≥ 4 vs. 0 cup/day = 0.45 [0.25-0.80] and 1.32 [0.89-1.96], respectively). Results were similar when studying AD and another CYP1A2 candidate polymorphism (rs2472304), but no interaction was found with CYP1A2 rs2472297 or rs2470893. In this cohort, a linear association of coffee intake to lower dementia risk was apparent only among carriers of CYP1A2 polymorphisms predisposing to slower caffeine metabolism.

Genome-Wide Association Studies of Coffee Intake in UK/US Participants of European Ancestry Uncover Gene-Cohort Influences

Coffee is one of the most widely consumed beverages. We performed a genome-wide association study (GWAS) of coffee intake in US-based 23andMe participants (N=130,153) and identified 7 significant loci, with many replicating in three multi-ancestral cohorts. We examined genetic correlations and performed a phenome-wide association study across thousands of biomarkers and health and lifestyle traits, then compared our results to the largest available GWAS of coffee intake from UK Biobank (UKB; N=334,659). The results of these two GWAS were highly discrepant. We observed positive genetic correlations between coffee intake and psychiatric illnesses, pain, and gastrointestinal traits in 23andMe that were absent or negative in UKB. Genetic correlations with cognition were negative in 23andMe but positive in UKB. The only consistent observations were positive genetic correlations with substance use and obesity. Our study shows that GWAS in different cohorts could capture cultural differences in the relationship between behavior and genetics.

Effect of Daily Coffee Consumption on the Risk of Alzheimer's Disease: A Systematic Review and Meta-Analysis

Alzheimer's disease (AD) is a highly prevalent neurodegenerative disorder that affects millions of individuals globally. The identification of the lifestyle factors that potentially help prevent or postpone disease onset is of interest to the researchers. Although the study results are inconsistent, one such factor that has been extensively studied is coffee consumption. Therefore, this meta-analysis primarily aimed to investigate the effects of coffee consumption on the risk of AD. Pubmed, Embase, and Web of Science (Only Writing Web of Science is Fine) databases were searched for relevant studies with the keywords in various combinations, including "coffee", "caffeine", and "Alzheimer's disease". This meta-analysis included 11 studies. The relative risk (RR) with 95% confidence intervals (CI) was calculated to estimate the effect size. The study used the restricted maximum-likelihood method for a generic-inverse-variance analysis with random-effect (when heterogeneity, I2 > 50%) or fixed-effect (when heterogeneity, I2 < 50%) modeling. The study protocol has been registered at International Prospective Register of Systematic Reviews (CRD42023429016). Individuals that regularly consumed 1-2 cups and 2-4 cups coffee/day demonstrated a significantly lower risk of developing AD (1-2 cups/day: RR = 0.68, 95% CI = 0.54 to 0.83, I2 = 50.99%, p = 0.00 [the software used for analysis, shows the results of p value like this (0.00), I prefer not to change this as this is also fine]; 2-4 cups/day: RR = 0.79, 95% CI = 0.56 to 1.02, I2 = 71.79%, p = 0.00). However, individuals who consumed > 4 cups/day demonstrated an increased risk of developing AD (RR = 1.04, 95% CI = 0.91 to 1.17, I2 = 0.00%, p = 0.00). This meta-analysis indicates that limited (1-4 cups/day) daily coffee consumption reduces the risk of AD, whereas excessive consumption (> 4 cups/day) might increase the risk.

Caffeine intake improves the cognitive performance of patients with chronic kidney disease

Objective

Cognitive impairment is a common complication of chronic kidney disease (CKD). Caffeine intake has been reported to improve cognitive performance in several studies. However, whether the benefits of caffeine intake on cognitive function apply to patients with CKD remains unknown.

Methods

We performed a retrospective cross-sectional study based on the National Health and Nutrition Examination Survey (NHANES). The data of CKD subjects and non-CKD subjects from NHANES 2011−2014 were analyzed. Propensity score matching (PSM) was performed based on age, sex, diabetes, cancer, educational level, energy intake and protein intake to select subjects. The Consortium to Establish a Registry for Alzheimer’s Disease Word Learning Test (CERAD-WL), the CERAD Word List Recall Test (CERAD-DR), the Animal Fluency Test (AF) and the Digit Symbol Substitution Test (DSST) were used, whereby the occurrence of cognitive impairment was identified. Logistic regression models were performed to evaluate the association between caffeine intake and cognitive performance in CKD and non-CKD participants. Stratified analyses according to the stage of CKD and the urinary albumin/creatinine ratio levels were performed. Plot curves were then generalized to present a non-linear relationship, and the inflection point for each non-linear model was obtained by using a recursive algorithm.

Results

Cognitive impairment was more prevalent in CKD patients than in non-CKD subjects. For CKD patients, caffeine intake was associated with higher CERAD-WL, CERAD-DR, AF and DSST scores. For non-CKD subjects, caffeine intake was associated with higher DSST scores only. Subgroup analysis revealed that caffeine only benefited the cognitive function of patients with CKD stages 2 and 3. The analysis showed non-linear relationships of caffeine intake and cognitive function for both CKD and non-CKD subjects. The inflection point of caffeine intake for CKD patients was 279 mg/day.

Conclusion

The recommended dose of caffeine intake to improve the cognitive function of CKD patients is ≤279 mg/day.