scholarly journals Association between alcohol consumption and Alzheimer’s disease: A Mendelian randomization Study

2017 ◽  
Author(s):  
Shea J. Andrews ◽  
Alison Goate ◽  
Kaarin J. Anstey
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Alcohol Consumption ◽  
Alcohol Dependence ◽  
Alcohol Intake ◽  
Mendelian Randomization ◽  
Age Of Onset ◽  
Moderate Alcohol Consumption ◽  
Causal Association ◽  
Study Designs

AbstractINTRODUCTIONObservational studies have suggested that light-moderate alcohol consumptions decreases the risk of Alzheimer’s disease, but it is unclear if this association is causal.METHODSTwo-sample Mendelian randomization (MR) analysis was used to examine whether alcohol consumption, alcohol dependence or Alcohol Use Disorder Identification Test (AUDIT) scores were causally associated with the risk of Late Onset Alzheimer’s disease (LOAD) or Alzheimer’s disease age of onset survival (AAOS). Additionally, γ-glutamyltransferase levels were included as a positive control.RESULTSThere was no evidence of a causal association between alcohol consumption, alcohol dependence or AUDIT and LOAD. Alcohol consumption was associated with an earlier AAOS and increased γ-glutamyltransferase blood concentrations. Alcohol dependence was associated with a delayed AAOS.DISCUSSIONMR found robust evidence of a causal association between alcohol consumption and an earlier AAOS, but not alcohol intake and LOAD risk. The protective effect of alcohol dependence is potentially due to survivor bias.Research in ContextSystematic ReviewThe authors reviewed the literature using online databases (e.g. PubMed). Previous research links light-moderate alcohol consumption to a decreased risk of Alzheimer’s disease (AD), however, prior studies based on observational study designs may be biased due to unmeasured confounders influencing both alcohol consumption and AD risk.InterpretationWe used a two-sample Mendelian randomization (MR) approach to evaluated the causal relationship between alcohol intake and AD. MR uses genetic variants as proxies for environmental exposures to provide an estimate of the causal association between an intermediate exposure and a disease outcome. MR found evidence of a causal association between alcohol consumption and an earlier AD age of onset, suggesting that light-moderate alcohol consumption does not reduce risk of Alzheimer’s disease.Future DirectionsFuture studies should use alterative study designs and account for additional confounders when evaluating the causal relationship between alcohol consumption and AD.HighlightsWe evaluated causal relationships between alcohol intake and Alzheimer’s diseaseAlcohol consumption is causally associated with an earlier Alzheimer’s age of onsetNo evidence of causal assocations between alcohol intake and Alzheimer’s risk

scholarly journals Evidence of a Causal Association Between Cancer and Alzheimer’s Disease: a Mendelian Randomization Analysis

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sahba Seddighi ◽  
Alexander L. Houck ◽  
James B. Rowe ◽  
Paul D. P. Pharoah
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mendelian Randomization ◽  
Observational Evidence ◽  
Inverse Association ◽  
Causal Association ◽  
Lower Odds ◽  
Genetic Predictors ◽  
Log Odds ◽  
Randomization Analysis

Abstract While limited observational evidence suggests that cancer survivors have a decreased risk of developing Alzheimer’s disease (AD), and vice versa, it is not clear whether this relationship is causal. Using a Mendelian randomization approach that provides evidence of causality, we found that genetically predicted lung cancer (OR 0.91, 95% CI 0.84–0.99, p = 0.019), leukemia (OR 0.98, 95% CI 0.96–0.995, p = 0.012), and breast cancer (OR 0.94, 95% CI 0.89–0.99, p = 0.028) were associated with 9.0%, 2.4%, and 5.9% lower odds of AD, respectively, per 1-unit higher log odds of cancer. When genetic predictors of all cancers were pooled, cancer was associated with 2.5% lower odds of AD (OR 0.98, 95% CI 0.96–0.988, p = 0.00027) per 1-unit higher log odds of cancer. Finally, genetically predicted smoking-related cancers showed a more robust inverse association with AD than non-smoking related cancers (OR 0.95, 95% CI 0.92–0.98, p = 0.0026, vs. OR 0.98, 95% CI 0.97–0.995, p = 0.0091).

scholarly journals Mendelian randomization to evaluate the effect of plasma vitamin C levels on the risk of Alzheimer’s disease

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Haijie Liu ◽  
Yan Zhang ◽  
Yang Hu ◽  
Haihua Zhang ◽  
Tao Wang ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Vitamin C ◽  
Cognitive Performance ◽  
Large Scale ◽  
Mendelian Randomization ◽  
Plasma Vitamin ◽  
Causal Association ◽  
Uk Biobank ◽  
Gwas Dataset

Abstract Objective Until now, observational studies have explored the impact of vitamin C intake on Alzheimer’s disease (AD) risk, however, reported ambiguous findings. To develop effective therapies or prevention, the causal link between vitamin C levels and AD should be established. Methods Here, we selected 11 plasma vitamin C genetic variants from a large-scale plasma vitamin C GWAS dataset (N = 52,018) as the potential instrumental variables. We extracted their corresponding summary statistics from large-scale IGAP clinically diagnosed AD GWAS dataset (N = 63,926) and UK Biobank AD proxy phenotype GWAS dataset (N = 314,278), as well as two UK Biobank subgroups including the maternal AD group (27,696 cases of maternal AD and 260,980 controls) and paternal AD group (14,338 cases of paternal AD and 245,941 controls). We then performed a Mendelian randomization (MR) study to evaluate the causal association between plasma vitamin C levels and the risk of AD and AD proxy phenotype. Meanwhile, we further verified these findings using a large-scale cognitive performance GWAS dataset (N = 257,841). Results In IGAP, we found no significant causal association between plasma vitamin C levels and the risk of AD. In UK Biobank, we found that per 1 SD increase in plasma vitamin C levels (about 20.2 μmol/l) was significantly associated with the reduced risk of AD proxy phenotype (OR = 0.93, 95% CI 0.88–0.98, P = 7.00E−03). A subgroup MR analysis in UK Biobank indicated that per 1 SD increase in plasma vitamin C levels could significantly reduce the risk of AD proxy phenotype in the maternal AD group (OR = 0.89, 95% CI 0.84–0.94, P = 7.29E−05), but not in the paternal AD group (OR = 1.02, 95% CI 0.92–1.12, P = 7.59E−01). The leave-one-out permutation further showed that the SLC23A1 rs33972313 variant largely changed the precision of the overall MR estimates in all these four GWAS datasets. Meanwhile, we did not observe any significant causal effect of plasma vitamin C levels on the cognitive performance. Conclusion We demonstrated that there may be no causal association between plasma vitamin C levels and the risk of AD in people of European descent. The insistent findings in clinically diagnosed AD and AD proxy phenotype may be caused by the phenotypic heterogeneity.

scholarly journals An Updated Mendelian Randomization Analysis of the Association Between Serum Calcium Levels and the Risk of Alzheimer’s Disease

2021 ◽  
Vol 12 ◽  
Author(s):  
Yuchen Shi ◽  
Ruifei Liu ◽  
Ying Guo ◽  
Qiwei Li ◽  
Haichun Zhou ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Serum Calcium ◽  
Large Scale ◽  
Mendelian Randomization ◽  
Causal Association ◽  
Cognitively Normal ◽  
Gwas Dataset ◽  
Weighted Median ◽  
Normal Controls

It has been a long time that the relationship between serum calcium levels and Alzheimer’s disease (AD) remains unclear. Until recently, observational studies have evaluated the association between serum calcium levels and the risk of AD, however, reported inconsistent findings. Meanwhile, a Mendelian randomization (MR) study had been conducted to test the causal association between serum calcium levels and AD risk, however, only selected 6 serum calcium SNPs as the instrumental variables. Hence, these findings should be further verified using additional more genetic variants and large-scale genome-wide association study (GWAS) dataset to increase the statistical power. Here, we conduct an updated MR analysis of the causal association between serum calcium levels and the risk of AD using a two-stage design. In discovery stage, we conducted a MR analysis using 14 SNPs from serum calcium GWAS dataset (N = 61,079), and AD GWAS dataset (N = 63,926, 21,982 cases, 41,944 cognitively normal controls). All four MR methods including IVW, weighted median, MR-Egger, and MR-PRESSO showed a reduced trend of AD risk with the increased serum calcium levels. In the replication stage, we performed a MR analysis using 166 SNPs from serum calcium GWAS dataset (N = 305,349), and AD GWAS dataset (N = 63,926, 21,982 cases, 41,944 cognitively normal controls). Only the weighted median indicated that genetically increased serum calcium level was associated with the reduced risk of AD. Hence, additional studies are required to investigate these findings.

Effects of a History of Heavy Alcohol Consumption on Alzheimer's Disease

1993 ◽  
Vol 163 (3) ◽  
pp. 358-363 ◽  
Author(s):  
Jules Rosen ◽  
Angela Colantonio ◽  
James T. Becker ◽  
Oscar L. Lopez ◽  
Steven T. Dᴇkosky ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Alcohol Consumption ◽  
Psychiatric Symptoms ◽  
Age Of Onset ◽  
Excessive Alcohol Consumption ◽  
Heavy Alcohol ◽  
Heavy Alcohol Consumption ◽  
History Of ◽  
One Year

Neuropsychological and psychiatric evaluations were made of 39 subjects with possible Alzheimer's disease and a history of excessive alcohol consumption (AD + ETOH), who had been abstinent or had drunk minimally for at least three months before evaluation, and 225 patients with probable Alzheimer's disease (PAD) of comparable age, years of education, and baseline global impairment. At baseline, there were no significant differences between the groups in terms of age of onset of dementia, neuropsychological test scores, or current behavioural or psychiatric symptoms. One year later, no differences in rates of decline between 20 abstinent AD + ETOH patients and 88 PAD subjects could be shown. Thus, past heavy alcohol consumption does not appear to modify the presentation of dementia of the Alzheimer's type, nor does it modify progression over a one-year interval.

scholarly journals Role of Alcohol Drinking in Alzheimer’s Disease, Parkinson’s Disease, and Amyotrophic Lateral Sclerosis

2020 ◽  
Vol 21 (7) ◽  
pp. 2316 ◽  
Author(s):  
Bin Peng ◽  
Qiang Yang ◽  
Rachna B Joshi ◽  
Yuancai Liu ◽  
Mohammed Akbar ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyotrophic Lateral Sclerosis ◽  
Alcohol Consumption ◽  
Environmental Factors ◽  
Neurodegenerative Diseases ◽  
Alcohol Intake ◽  
Heavy Alcohol ◽  
Heavy Alcohol Consumption ◽  
Lateral Sclerosis

Neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS), increase as the population ages around the world. Environmental factors also play an important role in most cases. Alcohol consumption exists extensively and it acts as one of the environmental factors that promotes these neurodegenerative diseases. The brain is a major target for the actions of alcohol, and heavy alcohol consumption has long been associated with brain damage. Chronic alcohol intake leads to elevated glutamate-induced excitotoxicity, oxidative stress and permanent neuronal damage associated with malnutrition. The relationship and contributing mechanisms of alcohol with these three diseases are different. Epidemiological studies have reported a reduction in the prevalence of Alzheimer’s disease in individuals who drink low amounts of alcohol; low or moderate concentrations of ethanol protect against β-amyloid (Aβ) toxicity in hippocampal neurons; and excessive amounts of ethanol increase accumulation of Aβ and Tau phosphorylation. Alcohol has been suggested to be either protective of, or not associated with, PD. However, experimental animal studies indicate that chronic heavy alcohol consumption may have dopamine neurotoxic effects through the induction of Cytochrome P450 2E1 (CYP2E1) and an increase in the amount of α-Synuclein (αSYN) relevant to PD. The findings on the association between alcohol consumption and ALS are inconsistent; a recent population-based study suggests that alcohol drinking seems to not influence the risk of developing ALS. Additional research is needed to clarify the potential etiological involvement of alcohol intake in causing or resulting in major neurodegenerative diseases, which will eventually lead to potential therapeutics against these alcoholic neurodegenerative diseases.

Life Course Adiposity and Alzheimer’s Disease: A Mendelian Randomization Study

2021 ◽  
pp. 1-10
Author(s):  
Xian Li ◽  
Yan Tian ◽  
Yu-Xiang Yang ◽  
Ya-Hui Ma ◽  
Xue-Ning Shen ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Life Course ◽  
Mendelian Randomization ◽  
Association Studies ◽  
Meta Analysis ◽  
Genome Wide Association Studies ◽  
Fat Percentage ◽  
Regression Methods ◽  
Weighted Median

Background: Several studies showed that life course adiposity was associated with Alzheimer’s disease (AD). However, the underlying causality remains unclear. Objective: We aimed to examine the causal relationship between life course adiposity and AD using Mendelian randomization (MR) analysis. Methods: Instrumental variants were obtained from large genome-wide association studies (GWAS) for life course adiposity, including birth weight (BW), childhood body mass index (BMI), adult BMI, waist circumference (WC), waist-to-hip ratio (WHR), and body fat percentage (BFP). A meta-analysis of GWAS for AD including 71,880 cases and 383,378 controls was used in this study. MR analyses were performed using inverse variance weighted (IVW), weighted median, and MR-Egger regression methods. We calculated odds ratios (ORs) per genetically predicted standard deviation (1-SD) unit increase in each trait for AD. Results: Genetically predicted 1-SD increase in adult BMI was significantly associated with higher risk of AD (IVW: OR = 1.03, 95% confidence interval [CI] = 1.01–1.05, p = 2.7×10–3) after Bonferroni correction. The weighted median method indicated a significant association between BW and AD (OR = 0.94, 95% CI = 0.90–0.98, p = 1.8×10–3). We also found suggestive associations of AD with WC (IVW: OR = 1.03, 95% CI = 1.00–1.07, p = 0.048) and WHR (weighted median: OR = 1.04, 95% CI = 1.00–1.07, p = 0.029). No association was detected of AD with childhood BMI and BFP. Conclusion: Our study demonstrated that lower BW and higher adult BMI had causal effects on increased AD risk.

scholarly journals Circulating biomarkers of immunity and inflammation, risk of Alzheimer’s disease, and hippocampal volume: a Mendelian randomization study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lana Fani ◽  
Marios K. Georgakis ◽  
M. Arfan Ikram ◽  
M. Kamran Ikram ◽  
Rainer Malik ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mendelian Randomization ◽  
Hippocampal Volume ◽  
Cd4 Count ◽  
European Ancestry ◽  
Monocyte Count ◽  
Circulating Biomarkers ◽  
Lymphocyte Ratio ◽  
Immune Biomarkers

AbstractThe aim of this study was to explore the association between genetically predicted circulating levels of immunity and inflammation, and the risk of Alzheimer’s disease (AD) and hippocampal volume, by conducting a two-sample Mendelian Randomization Study. We identified 12 markers of immune cells and derived ratios (platelet count, eosinophil count, neutrophil count, basophil count, monocyte count, lymphocyte count, platelet-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, CD4 count, CD8 count, CD4-to-CD8 ratio, and CD56) and 5 signaling molecules (IL-6, fibrinogen, CRP, and Lp-PLA2 activity and mass) as primary exposures of interest. Other genetically available immune biomarkers with a weaker a priori link to AD were considered secondary exposures. Associations with AD were evaluated in The International Genomics of Alzheimer’s Project (IGAP) GWAS dataset (21,982 cases; 41,944 controls of European ancestry). For hippocampal volume, we extracted data from a GWAS meta-analysis on 33,536 participants of European ancestry. None of the primary or secondary exposures showed statistically significant associations with AD or with hippocampal volume following P-value correction for multiple comparisons using false discovery rate < 5% (Q-value < 0.05). CD4 count showed the strongest suggestive association with AD (odds ratio 1.32, P < 0.01, Q > 0.05). There was evidence for heterogeneity in the MR inverse variance-weighted meta-analyses as measured by Cochran Q, and weighted median and weighted mode for multiple exposures. Further cluster analyses did not reveal clusters of variants that could influence the risk factor in distinct ways. This study suggests that genetically predicted circulating biomarkers of immunity and inflammation are not associated with AD risk or hippocampal volume. Future studies should assess competing risk, explore in more depth the role of adaptive immunity in AD, in particular T cells and the CD4 subtype, and confirm these findings in other ethnicities.

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