title: Body mass and white matter integrity: the influence of vascular and inflammatory markers.
abstract: High adiposity is deleteriously associated with brain health, and may disproportionately affect white matter integrity; however, limited information exists regarding the mechanisms underlying the association between body mass (BMI) and white matter integrity. The present study evaluated whether vascular and inflammatory markers influence the relationship between BMI and white matter in healthy aging. We conducted a cross-sectional evaluation of white matter integrity, BMI, and vascular/inflammatory factors in a cohort of 138 healthy older adults (mean age: 71.3 years). Participants underwent diffusion tensor imaging, provided blood samples, and participated in a health evaluation. Vascular risk factors and vascular/inflammatory blood markers were assessed. The primary outcome measure was fractional anisotropy (FA) of the genu, body, and splenium (corpus callosum); exploratory measures included additional white matter regions, based on significant associations with BMI. Regression analyses indicated that higher BMI was associated with lower FA in the corpus callosum, cingulate, and fornix (p<.001). Vascular and inflammatory factors influenced the association between BMI and FA. Specifically, BMI was independently associated with the genu [β=-.21; B=-.0024; 95% CI, -.0048 to -.0000; p=.05] and cingulate fibers [β=-.39; B=-.0035; 95% CI,-.0056 to -.0015; p<.001], even after controlling for vascular/inflammatory risk factors and blood markers. In contrast, BMI was no longer significantly associated with the fornix and middle/posterior regions of the corpus callosum after controlling for these markers. Results partially support a vascular/inflammatory hypothesis, but also suggest a more complex relationship between BMI and white matter characterized by potentially different neuroanatomic vulnerability.
authors.affiliation: University of California, San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Brianne Magouirk
authors.initials: BM
authors.lastname: Bettcher
authors.forename: Christine M
authors.initials: CM
authors.lastname: Walsh
authors.forename: Christa
authors.initials: C
authors.lastname: Watson
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Miller
authors.forename: Ralph
authors.initials: R
authors.lastname: Green
authors.forename: Nihar
authors.initials: N
authors.lastname: Patel
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Miller
authors.forename: John
authors.initials: J
authors.lastname: Neuhaus
authors.forename: Kristine
authors.initials: K
authors.lastname: Yaffe
authors.forename: Joel H
authors.initials: JH
authors.lastname: Kramer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D015992:Body Mass Index; D003337:Corpus Callosum / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000150:complications; D006973:Hypertension / Q000150:complications; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects