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Background: Meta-analyses of observational studies on the effect of dairy on cognitive function have yielded inconclusive results, potentially due to unmeasured confounding. To avoid the no-unmeasured confounding assumption, we used lactase persistence genetic variant as an instrumental variable, for which the CC genotype is associated with lower lactase production and, consequently, lower dairy consumption. We used it to assess the effect of long-term consumption of total and non-fermented dairy on cognitive function. Methods: We included 43,836 individuals over 55 years old with genotyping, dietary data, and cognitive function measurements from three population-based studies: CoLaus|PsyCoLaus (Switzerland), the Rotterdam Study (the Netherlands) and the Canadian Longitudinal Study on Aging (CLSA - Canada). We performed a one-sample Mendelian randomization using two-stage least-squares regression. First, we estimated total and non-fermented dairy consumption by T-allele frequency. Second, we used the estimated dairy consumption in linear regression models on general cognition, assessed by the Mini-Mental State Examination (MMSE) and the Mental Alternation Test, executive function, verbal fluency, verbal learning, and memory. Results: Per T-allele, total dairy intake and non-fermented was 24.8 and 15.3 g/day higher in PsyCoLaus, 57.9 and 49.8 g/day in the Rotterdam Study, and 0.31 and 0.29 times/day in CLSA, respectively. We found no association between the genetically predicted difference and the MMSE in PsyCoLaus and the Rotterdam Study. However, lactase persistent individuals scored 3.4 (95% CI 2.1− 4.7) and 3.5 (95% CI 2.3–4.7) points more in the Mental Alternation Test for total and fermented dairy, respectively, in CLSA. Similarly, lactase persistent participants in CLSA had higher verbal fluency, verbal learning and executive function, but no differences were found in the other cohorts. Such inconsistencies might stem from different FFQs across cohorts and consumption ranges. Nonetheless, the generally small magnitude of effect sizes may suggest that there is no real effect between total or non-fermented dairy intake and cognitive function. Conclusion: The evidence for a causal effect of dairy consumption on general cognitive function is weak, consistent with previous results from classic analysis from observational studies. Interventions targeting dairy are unlikely to have a relevant effect on cognitive function. [ABSTRACT FROM AUTHOR]

Introduction: We determined associations of total and regional adiposity with incident dementia among older adults. Methods: Within the population‐based Rotterdam Study, adiposity was measured as total, android, and gynoid fat mass using dual‐energy X‐ray absorptiometry in 3408 men and 4563 women, every 3 to 6 years between 2002 and 2016. Incident dementia was recorded until 2020. Results: Higher adiposity measures were associated with a decreased risk of dementia in both sexes. After excluding the first 5 years of follow‐up, only the association of gynoid fat among women remained significant (hazard ratio 0.85 [95% confidence interval 0.75–0.97] per standard deviation increase). No major differences in trajectories of adiposity measures were observed between dementia cases and dementia‐free controls. Discussion: Higher total and regional fat mass related to a decreased risk of dementia. These results may be explained by reverse causality, although a protective effect of adiposity cannot be excluded. Highlights: Total and regional adiposity were assessed using dual‐energy X‐ray absorptiometry scans in 7971 older adults.All adiposity measures were associated with a decreased risk of dementia.The results suggest a beneficial effect of gynoid fat on the risk of dementia in women.Reverse causation and competing risk may explain these inverse associations. [ABSTRACT FROM AUTHOR]

Background: Air pollution is a well-established risk factor for several adverse health outcomes, but the specific molecular mechanisms, particularly those involving metabolic processes, remain incompletely understood., Objective: To evaluate associations between long-term air pollutant exposure and circulating plasma metabolites in two sub-cohorts of the population-based Rotterdam Study., Methods: We analyzed data from 1455 participants of sub-cohort I (mean age 76.9 years, 58% female, 2002-2004) and 1061 participants from sub-cohort III (mean age 62.6 years, 56% female, 2012-2014). Mean annual exposure to fine particulate matter (PM 2.5 ), black carbon, nitrogen dioxide, and ozone (measured both annually and in warm seasons only) were estimated at residential addresses using land use regression models. Plasma metabolites were measured by Metabolon Inc., using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry. Cross-sectional associations between each air pollutant and 940 metabolites were determined using linear regression models. Benjamini-Hochberg false discovery rate (FDR) was utilized to control for multiple testing. Enrichment analysis was performed on statistically significant associated metabolites to identify significant metabolic pathways (p-value <0.05)., Results: In sub-cohort I, PM 2.5 , black carbon, nitrogen dioxide, annual ozone and ozone in warm season were statistically significantly associated with, respectively, 63, 30, 20, 31, and 41 metabolites (FDR <0.05) mostly belonging to lipid and amino acid sub-classes, and unannotated metabolites. Sphinganine, X - 16576 and 2-pyrrolidinone displayed statistically significant associations across all five air pollutants. In sub-cohort III, black carbon, nitrogen dioxide and ozone in warm seasons were associated with a single unannotated metabolite (X - 24970), and annual ozone with two unannotated metabolites (X - 24970 and X - 24306). Enriched pathways identified in sub-cohort I included pyrimidine metabolism and steroid hormone biosynthesis., Conclusions: Our study revealed associations of long-term air pollutant exposure with several metabolites and enrichment of two pathways, which are known to be involved in the adrenal and reproductive system and cell metabolism., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Studies have correlated living close to major roads with Alzheimer's disease (AD) risk. However, the mechanisms responsible for this link remain unclear., Methods: We exposed olfactory mucosa (OM) cells of healthy individuals and AD patients to diesel emissions (DE). Cytotoxicity of exposure was assessed, mRNA, miRNA expression, and DNA methylation analyses were performed. The discovered altered pathways were validated using data from the human population-based Rotterdam Study., Results: DE exposure resulted in an almost four-fold higher response in AD OM cells, indicating increased susceptibility to DE effects. Methylation analysis detected different DNA methylation patterns, revealing new exposure targets. Findings were validated by analyzing data from the Rotterdam Study cohort and demonstrated a key role of nuclear factor erythroid 2-related factor 2 signaling in responses to air pollutants., Discussion: This study identifies air pollution exposure biomarkers and pinpoints key pathways activated by exposure. The data suggest that AD individuals may face heightened risks due to impaired cellular defenses., Highlights: Healthy and AD olfactory cells respond differently to DE exposure. AD cells are highly susceptible to DE exposure. The NRF2 oxidative stress response is highly activated upon air pollution exposure. DE-exposed AD cells activate the unfolded protein response pathway. Key findings are also confirmed in a population-based study., (© 2024 The Author(s). Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Background: Consumption of more plant-based foods is gaining popularity, but the role of healthy versus unhealthy plant-based diets in cardiovascular disease (CVD) risk remains inconclusive., Objectives: We investigated associations of plant-based diet indices (PDIs) with incident CVDs in a prospective cohort study and conducted an updated meta-analysis., Methods: We included 3507 men and 5345 women of the population-based Rotterdam Study. Multivariable Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs) for CVD, coronary heart disease (CHD) and stroke per SD increment of an overall PDI, healthy PDI (hPDI) and unhealthy PDI (uPDI), among men and women separately. We combined our findings with previously published effect estimates in an updated meta-analysis., Results: We documented 2015 CVD cases (1231 CHD and 952 stroke) during 107,290 person-years follow-up. Among men, the PDI and hPDI were associated with a 7 % (HR 0.93, 95 % CI 0.87-0.99) and 8 % (HR 0.92, 95 % CI 0.86-0.98) lower CVD risk. Among women, there was evidence suggesting a U-shaped association of the PDI with stroke (p non-linearity  < 0.01). In meta-analyses including up to 43,067 incident CVD cases among 359,740 participants from nine studies, the PDI and hPDI, were associated with a lower CVD riskand the uPDI with a higher CVD risk (pooled HRs [95 % CI], per SD, PDI: 0.94 [0.91-0.97], I 2  = 50.4 %; hPDI: 0.94 [0.91-0.98], I 2  = 74.7 %; uPDI: 1.03 [1.01-1.06], I 2  = 49.0 %)., Conclusions: Our findings support recommendations to consume relatively more healthy plant-based foods for CVD prevention. Potential differences by sex and non-linear associations warrant further investigation., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier Inc.)

Background: Targeting effective strategies to prevent cognitive decline is key in the aging population. Some diets have been linked to a slower cognitive decline, potentially through reducing inflammation. We aimed at determining the effect of inflammatory dietary patterns (IDPs) on cognitive function in three population-based cohorts., Methods: In this longitudinal study, we analyzed data from the Canadian Longitudinal Study of Aging, CoLaus|PsyCoLaus and Rotterdam Study. Our analytical sample included participants over 55 years old with baseline data on cognition, dietary intake, and inflammatory markers. IDPs were derived for each cohort using reduced rank regression to reflect maximal variation in three inflammatory markers. We calculated scores of consumption of the IDPs, higher scores indicating more IDP consumption. We used inverse probability of treatment and censoring weights in the marginal structural models to estimate associations of higher versus lower quarters of consumption of an IDP on general cognition (Mini-Mental State Evaluation) and four cognitive domains (memory, verbal fluency, verbal learning and processing speed and executive function) during at least 3 years of follow-up., Results: We included 10,366 participants (mean age 68) followed-up for a mean of 5 years. Diet explained between 1 and 2% of the variation of the inflammatory markers. There were no differences in general cognition when comparing the highest to the lowest quarter of consumption of IDPs among the three cohorts. Mean differences for the four cognitive domains were of small magnitude across cohorts and not clinically relevant., Conclusion: Diet explained low variation in inflammatory markers. Consuming IDPs was not associated with mean differences in general or domain-specific cognitive function., Competing Interests: Conflict of interest The authors report that there are no disclosures relevant to this publication., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Introduction: Air pollution is a significant contributor to morbidity and mortality globally and has been linked to an increased risk of dementia. Previous studies within the Betula cohort in Northern Sweden have demonstrated associations between air pollution and dementia, as well as distinctive metabolomic profiles in dementia patients compared to controls. This study aimed to investigate whether air pollution is associated with quantitative changes in metabolite levels within this cohort, and whether future dementia status would modify this association., Methods: Both short-term and long-term exposure to air pollution were evaluated using high spatial resolution models and measured data. Air pollution from vehicle exhaust and woodsmoke were analyzed separately. Metabolomic profiling was conducted on 321 participants, including 58 serum samples from dementia patients and a control group matched for age, sex, and education level, using nuclear magnetic resonance spectroscopy., Results: No statistically significant associations were found between any metabolites and any measures of short-term or long-term exposure to air pollution. However, there were trends potentially suggesting associations between both long-term and short-term exposure to air pollution with lactate and glucose metabolites. Notably, these associations were observed despite the lack of correlation between long-term and short-term air pollution exposure in this cohort. There were also tendencies for associations between air pollution from woodsmoke to be more pronounced in participants that would later develop dementia, suggesting a potential effect depending on urban/rural factors., Discussion: While no significant associations were found, the trends observed in the data suggest potential links between air pollution exposure and changes in lactate and glucose metabolites. These findings provide some new insights into the link between air pollution and metabolic markers in a low-exposure setting. However, addressing existing limitations is crucial to improve the robustness and applicability of future research in this area. The pronounced associations in participants who later developed dementia may indicate an influence of urban/rural factors, warranting further investigation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Raza, Öhman, Kanninen, Jalava, Zeng, de Crom, Ikram and Oudin.)

A higher body mass at older age has been linked to a lower risk of dementia. This unexpected trend may be explained by age-related lean mass depletion, or methodological issues such as the long preclinical phase of dementia or competing risks. Focusing on preclinical markers of dementia may overcome these issues. Between 2002 and 2005, body composition and plasma total-tau, neurofilament light chain (NfL), amyloid-β40, and amyloid-β42 were measured in 3408 dementia-free participants from the population-based Rotterdam Study. The cross-sectional associations between body composition and plasma markers were determined using linear regression models. Whole body and fat mass, but not lean mass, were positively associated with total-tau, while all these measures were inversely associated with NfL. Apart from an inverse association between lean mass and amyloid-β40, body composition measures were not associated with plasma amyloid-β. Our findings suggest distinct effects of body composition on neurodegeneration., Competing Interests: The authors declare no conflicts of interest. Author disclosures are available in the supporting information., (© 2024 The Authors. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring published by Wiley Periodicals, LLC on behalf of Alzheimer's Association.)

Background & Aims: Inflammation is involved in the pathogenesis of cataract, age-related macular degeneration (AMD), and possibly open-angle glaucoma (OAG). We assessed whether the inflammatory potential of diet (quantified using the dietary inflammatory index; DII) affects the incidence of these common blinding age-related eye diseases. Serum inflammation markers were investigated as possible mediators., Methods: Participants aged >45 years were selected from the prospective, population-based Rotterdam Study. From 1991 onwards, every 4-5 years, participants underwent extensive eye examinations. At baseline, blood samples and dietary data (using food frequency questionnaires) were collected. The DII was adapted based on the data available. Of the 7436 participants free of eye diseases at baseline, 4036 developed incident eye diseases during follow-up (cataract = 2895, early-intermediate AMD = 891, late AMD = 81, OAG = 169)., Results: The adapted DII (aDII) ranged from -4.26 (i.e., anti-inflammatory) to 4.53 (i.e., pro-inflammatory). A higher aDII was significantly associated with increased inflammation. A higher neutrophil-lymphocyte ratio (NLR) was associated with an increased risk of cataract and AMD. Additionally, complement component 3c (C3c) and systemic immune-inflammation index (SII) were associated with increased risks of cataract and late AMD, respectively. Every point increase in the aDII was associated with a 9% increased risk of cataract (Odds ratio [95% confidence interval]: 1.09 [1.04-1.14]). The NLR and C3c partly mediated this association. We also identified associations of the aDII with risk of AMD (early-intermediate AMD, OR [95% CI]: 1.11 [1.03-1.19]; late AMD, OR [95% CI]: 1.24 [1.02-1.53]). The NLR partly mediated these associations. The aDII was not associated with OAG., Conclusions: A pro-inflammatory diet was associated with increased risks of cataract and AMD. Particularly the NLR, a marker of subclinical inflammation, appears to be implicated. These findings are relevant for patients with AMD and substantiate the current recommendations to strive for a healthy lifestyle to prevent blindness., Competing Interests: Conflicts of interest CCWK: Consultant – Bayer, Laboratoires Théa, Novartis., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Nitric oxide is a free radical that can be produced from dietary nitrate and positively affects cardiovascular health. With cardiovascular health playing an important role in the etiology of dementia, we hypothesized a link between dietary nitrate intake and the risk of dementia., Objectives: This study aimed to find the association of total, vegetable, and nonvegetable dietary nitrate intake with the risk of dementia and imaging markers of vascular brain health, such as total brain volume, global cerebral perfusion, white matter hyperintensity volume, microbleeds, and lacunar infarcts., Methods: Between 1990 and 2009, dietary intake was assessed using food-frequency questionnaires in 9543 dementia-free participants (mean age, 64 y; 58% female) from the prospective population-based Rotterdam Study. Participants were followed up for incidence dementia until January 2020. We used Cox models to determine the association between dietary nitrate intake and incident dementia. Using linear mixed models and logistic regression models, we assessed the association of dietary nitrate intake with changes in imaging markers across 3 consecutive examination rounds (mean interval between images 4.6 y)., Results: Participants median dietary nitrate consumption was 85 mg/d (interquartile range, 55 mg/d), derived on average for 81% from vegetable sources. During a mean follow-up of 14.5 y, 1472 participants developed dementia. A higher intake of total and vegetable dietary nitrate was associated with a lower risk of dementia per 50-mg/d increase [hazard ratio (HR): 0.92; 95% confidence interval (CI): 0.87, 0.98; and HR: 0.92; 95% CI: 0.86, 0.97, respectively] but not with changes in neuroimaging markers. No association between nonvegetable dietary nitrate intake and the risk of dementia (HR: 1.15; 95% CI: 0.64, 2.07) or changes in neuroimaging markers were observed., Conclusions: A higher dietary nitrate intake from vegetable sources was associated with a lower risk of dementia. We found no evidence that this association was driven by vascular brain health., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Introduction: We determined associations of total and regional adiposity with incident dementia among older adults., Methods: Within the population-based Rotterdam Study, adiposity was measured as total, android, and gynoid fat mass using dual-energy X-ray absorptiometry in 3408 men and 4563 women, every 3 to 6 years between 2002 and 2016. Incident dementia was recorded until 2020., Results: Higher adiposity measures were associated with a decreased risk of dementia in both sexes. After excluding the first 5 years of follow-up, only the association of gynoid fat among women remained significant (hazard ratio 0.85 [95% confidence interval 0.75-0.97] per standard deviation increase). No major differences in trajectories of adiposity measures were observed between dementia cases and dementia-free controls., Discussion: Higher total and regional fat mass related to a decreased risk of dementia. These results may be explained by reverse causality, although a protective effect of adiposity cannot be excluded., Highlights: Total and regional adiposity were assessed using dual-energy X-ray absorptiometry scans in 7971 older adults. All adiposity measures were associated with a decreased risk of dementia. The results suggest a beneficial effect of gynoid fat on the risk of dementia in women. Reverse causation and competing risk may explain these inverse associations., (© 2022 The Authors. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Background: Exposure to air pollution has been suggested to increase the risk of dementia, but studies on this link often lack a detailed screening for dementia and data on important confounders., Objective: To determine the association of exposure to air pollution with the risk of dementia and cognitive decline in the population-based Rotterdam Study., Methods: Between 2009 and 2010, we determined air pollutant concentrations at participants residential addresses using land use regression models. Determined air pollutants include particulate matter <10μm (PM10) and <2.5μm (PM2.5), a proxy of elemental carbon (PM2.5 absorbance), nitrogen oxide (NOx), and nitrogen dioxide (NO2). As the individual air pollutant levels were highly correlated (r = 0.71-0.98), we computed a general marker covering all air pollutants based on a principal component analysis. We followed participants up for dementia until 2018 and determined cognitive performance during two subsequent examination rounds. Using Cox and linear mixed models, we related air pollution to dementia and cognitive decline., Results: Of the 7,511 non-demented participants at baseline, 545 developed dementia during a median follow-up of 7 years. The general marker of all air pollutants was not associated with the risk of dementia (hazard ratio [95% confidence interval]: 1.04 [0.95-1.15]), neither were the individual air pollutants. Also, the general marker of all air pollutants or the individual air pollutant levels were not associated with cognitive decline., Conclusion: In this study, we found no clear evidence for an association between exposure to air pollution and the risk of dementia or cognitive decline.