title: Neural basis for the relationship between frequency of going outdoors and depressive mood in older adults.
abstract: Low frequency of going outdoors (e.g. being homebound) is associated with depressive mood; however, the underlying neural mechanism of this association is unclear. We therefore investigated the neural substrate involved in the relationship between frequency of going outdoors and depressive mood using positron emission tomography (PET), focusing on the frontal lobe and the limbic system.
  
  
  
  One hundred fifty-eight community-dwelling older adults aged 65-85 years underwent PET with18F-fluorodeoxyglucose to evaluate regional cerebral metabolic rates of glucose normalized in reference to cerebellar glucose metabolic value (normalized-rCMRglc) in six regions of interest. We also assessed depressive mood, frequency of going outdoors, and potential covariates. Depressive mood was assessed using the Geriatric Depression Scale (GDS).
  
  
  
  The proportion of participants who reported low frequency of going outdoors (LG, every 2-3 days or less) was 36.1%. The LG group showed significantly higher GDS scores than those who reported high (once a day or more) frequency of going outdoors. A multiple linear regression analysis adjusted for potential covariates showed higher GDS scores were associated with lower normalized-rCMRglc in the ventrolateral prefrontal and orbitofrontal cortices. Adjusting for frequency of going outdoors, the association between GDS score and normalized-rCMRglc in the orbitofrontal cortex was attenuated.
  
  
  
  Our results suggest that the orbitofrontal cortex may mediate the relationship between low frequency of going outdoors and depressive mood among community-dwelling older adults. These findings may help disentangle the role of going outdoors in regulating brain function to improve and/or maintain mental health among community-dwelling older adults. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan.|Research Team for Social Participation and Community Health, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo, Japan.|Research Fellow of the Japan Society for the Promotion of Science, Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Sakurai
authors.affiliation: Research Team for Social Participation and Community Health, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Research Team for Social Participation and Community Health, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Fujiwara
authors.affiliation: Research Team for Social Participation and Community Health, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Yasunaga
authors.affiliation: Research Team for Social Participation and Community Health, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo, Japan.
authors.forename: Rumi
authors.initials: R
authors.lastname: Takeuchi
authors.affiliation: Research Team for Social Participation and Community Health, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo, Japan.
authors.forename: Yoh
authors.initials: Y
authors.lastname: Murayama
authors.affiliation: Research Team for Social Participation and Community Health, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo, Japan.
authors.forename: Kimi Estela Kobayashi
authors.initials: KEK
authors.lastname: Cuya
authors.affiliation: Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kanosue
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ishii
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003863:Depression / Q000378:metabolism*; D004777:Environment; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D005625:Frontal Lobe / Q000378:metabolism*; D006801:Humans; D008019:Life Style; D008032:Limbic System / Q000378:metabolism*; D008297:Male; D015999:Multivariate Analysis; D049268:Positron-Emission Tomography; D012044:Regression Analysis
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: FDG-PET; depressive mood; older adults; orbitofrontal cortex; physical activity