title: Shared genetic variance between obesity and white matter integrity in Mexican Americans.
abstract: Obesity is a chronic metabolic disorder that may also lead to reduced white matter integrity, potentially due to shared genetic risk factors. Genetic correlation analyses were conducted in a large cohort of Mexican American families in San Antonio (N = 761, 58% females, ages 18-81 years; 41.3 ± 14.5) from the Genetics of Brain Structure and Function Study. Shared genetic variance was calculated between measures of adiposity [(body mass index (BMI; kg/m(2)) and waist circumference (WC; in)] and whole-brain and regional measurements of cerebral white matter integrity (fractional anisotropy). Whole-brain average and regional fractional anisotropy values for 10 major white matter tracts were calculated from high angular resolution diffusion tensor imaging data (DTI; 1.7 × 1.7 × 3 mm; 55 directions). Additive genetic factors explained intersubject variance in BMI (heritability, h (2) = 0.58), WC (h (2) = 0.57), and FA (h (2) = 0.49). FA shared significant portions of genetic variance with BMI in the genu (ρG = -0.25), body (ρG = -0.30), and splenium (ρG = -0.26) of the corpus callosum, internal capsule (ρG = -0.29), and thalamic radiation (ρG = -0.31) (all p's = 0.043). The strongest evidence of shared variance was between BMI/WC and FA in the superior fronto-occipital fasciculus (ρG = -0.39, p = 0.020; ρG = -0.39, p = 0.030), which highlights region-specific variation in neural correlates of obesity. This may suggest that increase in obesity and reduced white matter integrity share common genetic risk factors.
authors.affiliation: Department of Family Medicine, Madigan Army Medical Center Tacoma, WA, USA ; Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine Baltimore, MD, USA.
authors.forename: Elena A
authors.initials: EA
authors.lastname: Spieker
authors.affiliation: Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine Baltimore, MD, USA ; Department of Physics, University of Maryland Baltimore, MD, USA ; South Texas Diabetes and Obesity Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Kochunov
authors.affiliation: Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine Baltimore, MD, USA.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Rowland
authors.affiliation: Department of Psychiatry, Yale University New Haven, CT, USA ; Olin Neuropsychiatry Research Center, Institute of Living Hartford, CT, USA.
authors.forename: Emma
authors.initials: E
authors.lastname: Sprooten
authors.affiliation: Department of Psychiatry, Yale University New Haven, CT, USA ; Department of Clinical Neurosciences, Oxford Centre for Functional MRI of the Brain, University of Oxford Oxford, UK.
authors.forename: Anderson M
authors.initials: AM
authors.lastname: Winkler
authors.affiliation: Department of Psychiatry, University of Texas Health Science Center at San Antonio San Antonio, TX, USA.
authors.forename: Rene L
authors.initials: RL
authors.lastname: Olvera
authors.affiliation: South Texas Diabetes and Obesity Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Almasy
authors.affiliation: South Texas Diabetes and Obesity Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Duggirala
authors.affiliation: Research Imaging Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Fox
authors.affiliation: South Texas Diabetes and Obesity Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA.
authors.forename: John
authors.initials: J
authors.lastname: Blangero
authors.affiliation: Department of Psychiatry, Yale University New Haven, CT, USA ; Olin Neuropsychiatry Research Center, Institute of Living Hartford, CT, USA ; Research Imaging Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Glahn
authors.affiliation: South Texas Diabetes and Obesity Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA.
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Curran
keywords: Mexican American; diffusion tensor imaging; fractional anisotropy; genetics; genotype; obesity; white matter