title: Interleukin-6, age, and corpus callosum integrity.
abstract: The contribution of inflammation to deleterious aging outcomes is increasingly recognized; however, little is known about the complex relationship between interleukin-6 (IL-6) and brain structure, or how this association might change with increasing age. We examined the association between IL-6, white matter integrity, and cognition in 151 community dwelling older adults, and tested whether age moderated these associations. Blood levels of IL-6 and vascular risk (e.g., homocysteine), as well as health history information, were collected. Processing speed assessments were administered to assess cognitive functioning, and we employed tract-based spatial statistics to examine whole brain white matter and regions of interest. Given the association between inflammation, vascular risk, and corpus callosum (CC) integrity, fractional anisotropy (FA) of the genu, body, and splenium represented our primary dependent variables. Whole brain analysis revealed an inverse association between IL-6 and CC fractional anisotropy. Subsequent ROI linear regression and ridge regression analyses indicated that the magnitude of this effect increased with age; thus, older individuals with higher IL-6 levels displayed lower white matter integrity. Finally, higher IL-6 levels were related to worse processing speed; this association was moderated by age, and was not fully accounted for by CC volume. This study highlights that at older ages, the association between higher IL-6 levels and lower white matter integrity is more pronounced; furthermore, it underscores the important, albeit burgeoning role of inflammatory processes in cognitive aging trajectories.
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Brianne M
authors.initials: BM
authors.lastname: Bettcher
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Christa L
authors.initials: CL
authors.lastname: Watson
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Walsh
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Iryna V
authors.initials: IV
authors.lastname: Lobach
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: John
authors.initials: J
authors.lastname: Neuhaus
authors.affiliation: Rutgers University, Department of Nutritional Sciences, New Brunswick, New Jersey, United States of America; University of California Davis Medical Center, Department of Pathology and Laboratory Medicine, Sacramento, California, United States of America.
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Miller
authors.affiliation: University of California Davis Medical Center, Department of Pathology and Laboratory Medicine, Sacramento, California, United States of America.
authors.forename: Ralph
authors.initials: R
authors.lastname: Green
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Nihar
authors.initials: N
authors.lastname: Patel
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Shubir
authors.initials: S
authors.lastname: Dutt
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Edgar
authors.initials: E
authors.lastname: Busovaca
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Rosen
authors.affiliation: University of California San Francisco, Department of Psychiatry, Neurology, and Epidemiology and Biostatistics, San Francisco, California, United States of America.
authors.forename: Kristine
authors.initials: K
authors.lastname: Yaffe
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Miller
authors.affiliation: University of California San Francisco, Neurology Department, Memory and Aging Center, San Francisco, California, United States of America.
authors.forename: Joel H
authors.initials: JH
authors.lastname: Kramer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D016880:Anisotropy; D003337:Corpus Callosum / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D016014:Linear Models; D008297:Male; D008875:Middle Aged
chemical_list: D015850:Interleukin-6