👤 Anwar Mulugeta

Coffee is a widely consumed beverage, which has been extensively studied for its potential effects on health. We aimed to map genetic evidence for the effect of habitual coffee consumption on health. We searched PubMed, Embase, Cochrane Database of Systematic Reviews, Cumulative Index to Nursing and Allied Health Literature and two preprint repositories from inception to 30 September 2022, and included fifty-nine studies, spanning 160 disease or biomarker associations. We evaluated the articles for certainty of evidence using a modified GRADE tool and robustness of the associations by comparing Mendelian randomisation (MR) sensitivity analyses. Coffee consumption was associated with smaller grey matter brain volume in one study, and there was probable evidence for an increased risk of Alzheimer’s disease and younger age of onset of Huntington’s disease. MR studies provided probable evidence for an association with increased risk of oesophageal and digestive cancers, but protective effects for hepatocellular carcinomas and ovarian cancer. We found probable evidence for increased risk of type 2 diabetes mellitus, osteoarthritis, rheumatoid arthritis, menopausal disorders, glaucoma, higher total cholesterol, LDL-cholesterol and ApoB, and lowered risk of migraines, kidney disease and gallstone disease. Future studies should aim to understand underlying mechanisms of disease, expand knowledge in non-European cohorts and develop quality assessment tools for systematic reviews of MR studies. Show less

Sub-optimal metabolism is linked to dementia risk, yet metabolic traits rarely occur in isolation. Using data from 308,019 UK Biobank participants, we examined associations of six diverse metabolic subgroups (I-VI) - previously derived via a self-organising map (SOM) that captures patterns of co-occurring metabolic biomarker traits in the population - and 39 individual biomarkers, with incident all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD). Biomarker associations were assessed using both linear and nonlinear (restricted cubic spline) models. After adjusting for age, sex, socioeconomic, and lifestyle factors, subgroup analyses showed that participants in the two leanest and two most adipose subgroups had higher risk of dementia outcomes compared to others. Subgroups with high adiposity exhibited elevated VaD risk, which was linked to hypertension, hyperglycaemia, and liver stress (Subgroup II); inflammation, microalbuminuria, and low apolipoprotein A1 (III). For AD, the risk was elevated in the lean subgroups (IV, V), characterised by low body mass index (BMI), triglycerides, and urate, and high sex-hormone binding globulin; as well as for adipose Subgroup II. APOE-ε4 allele count had limited influence on dementia associations with metabolic subgroups and biomarkers. This marked metabolic heterogeneity in dementia risk suggests that metabolic profiling could inform targeted prevention strategies. Interpretation of these findings is supported by previously reported MRI profiles of the metabolic subgroups, providing biological context. Show less

This study aimed to explore the association between depression and body mass index (BMI), and to investigate whether genetic susceptibility to high BMI is different among individuals with or without depression. We used data on 251,125 individuals of white British ancestry from the UK Biobank. We conducted Mendelian randomization (MR) analysis to test for a causal association between depression and BMI using a major depressive disorder (MDD)-related genetic risk score (GRS We found observational and genetic evidence for an association between depression and BMI (MR beta: 0.09, 95% confidence interval [CI] 0.04-0.13). Further, the contribution of genetic risk to high BMI was higher among individuals with depression compared to controls. Carrying 10 additional BMI increasing alleles was associated with 0.24 standard deviation (SD; 95%CI 0.23-0.25) higher BMI among depressed individuals compared to 0.20 SD (95%CI 0.19-0.21) higher in controls, which corresponds to 3.4 kg and 2.8 kg extra weight for an individual of average height. Amongst the individual loci, the evidence for interaction was most notable for a variant near MC4R, a gene known to affect both appetite regulation and the hypothalamic-pituitary adrenal axis (p Genetic predisposition to high BMI was higher among depressed than to nondepressed individuals. This study provides support for a possible role of MC4R in the link between depression and obesity. Show less