title: Genetically predicted body mass index and Alzheimer's disease-related phenotypes in three large samples: Mendelian randomization analyses.
abstract: Observational research shows that higher body mass index (BMI) increases Alzheimer's disease (AD) risk, but it is unclear whether this association is causal. We applied genetic variants that predict BMI in Mendelian randomization analyses, an approach that is not biased by reverse causation or confounding, to evaluate whether higher BMI increases AD risk. We evaluated individual-level data from the AD Genetics Consortium (ADGC: 10,079 AD cases and 9613 controls), the Health and Retirement Study (HRS: 8403 participants with algorithm-predicted dementia status), and published associations from the Genetic and Environmental Risk for AD consortium (GERAD1: 3177 AD cases and 7277 controls). No evidence from individual single-nucleotide polymorphisms or polygenic scores indicated BMI increased AD risk. Mendelian randomization effect estimates per BMI point (95% confidence intervals) were as follows: ADGC, odds ratio (OR) = 0.95 (0.90-1.01); HRS, OR = 1.00 (0.75-1.32); GERAD1, OR = 0.96 (0.87-1.07). One subscore (cellular processes not otherwise specified) unexpectedly predicted lower AD risk.
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Shubhabrata
authors.initials: S
authors.lastname: Mukherjee
authors.affiliation: Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, CA, USA.
authors.forename: Stefan
authors.initials: S
authors.lastname: Walter
authors.affiliation: Department of Biology, Brigham Young University, Provo, UT, USA.
authors.forename: John S K
authors.initials: JSK
authors.lastname: Kauwe
authors.affiliation: Department of Radiology, Indiana University, Indianapolis, IN, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Saykin
authors.affiliation: Department of Neurology, Rush University, Chicago, IL, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Bennett
authors.affiliation: Group Health Research Institute, Seattle, WA, USA.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Larson
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Paul K
authors.initials: PK
authors.lastname: Crane
authors.affiliation: Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, CA, USA. Electronic address: mglymour@epi.ucsf.edu.
authors.forename: M Maria
authors.initials: MM
authors.lastname: Glymour
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications / Q000235:genetics*; D015992:Body Mass Index; D005260:Female; D005838:Genotype; D006801:Humans; D016014:Linear Models; D008297:Male; D057182:Mendelian Randomization Analysis; D009765:Obesity / Q000150:complications / Q000235:genetics; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012307:Risk Factors
keywords: Alzheimer's disease; Dementia; Mendelian randomization; Obesity