title: Stress hormones predict hyperbolic time-discount rates six months later in adults.
abstract: OBJECTIVE
  Stress hormones have been associated with temporal discounting. Although time-discount rate is shown to be stable over a long term, no study to date examines whether individual differences in stress hormones could predict individuals' time-discount rates in the relatively distant future (e.g., six month later), which is of interest in neuroeconomics of stress-addiction association.
  
  
  METHODS
  We assessed 87 participants' salivary stress hormone (cortisol, cortisone, and alpha-amylase) levels and hyperbolic discounting of delayed rewards consisting of three magnitudes, at the time-interval of six months. For salivary steroid assays, we employed a liquid chromatography/ mass spectroscopy (LC/MS) method. The correlations between the stress hormone levels and time-discount rates were examined.
  
  
  RESULTS
  We observed that salivary alpha-amylase (sAA) levels were negatively associated with time-discount rates in never-smokers. Notably, salivary levels of stress steroids (i.e., cortisol and cortisone) negatively and positively related to time-discount rates in men and women, respectively, in never-smokers. Ever-smokers' discount rates were not predicted from these stress hormone levels.
  
  
  CONCLUSIONS
  Individual differences in stress hormone levels predict impulsivity in temporal discounting in the future. There are sex differences in the effect of stress steroids on temporal discounting; while there was no sex defference in the relationship between sAA and temporal discounting.
authors.affiliation: Department of Behavioral Sciences, Hokkaido University, N.10, W.7, Kita-ku, Sapporo 060-0810, Japan. taikitakahashi@gmail.com
authors.forename: Taiki
authors.initials: T
authors.lastname: Takahashi
authors.forename: Mizuho
authors.initials: M
authors.lastname: Shinada
authors.forename: Keigo
authors.initials: K
authors.lastname: Inukai
authors.forename: Shigehito
authors.initials: S
authors.lastname: Tanida
authors.forename: Chisato
authors.initials: C
authors.lastname: Takahashi
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Mifune
authors.forename: Haruto
authors.initials: H
authors.lastname: Takagishi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Horita
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Yokota
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kameda
authors.forename: Toshio
authors.initials: T
authors.lastname: Yamagishi
mesh_terms: D000328:Adult; D000368:Aged; D002755:Choice Behavior; D003345:Corticosterone / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D007175:Impulsive Behavior / Q000378:metabolism / Q000523:psychology*; D007206:Individuality; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D008960:Models, Psychological; D012201:Reward; D012463:Saliva / Q000378:metabolism*; D012737:Sex Factors; D012907:Smoking; D011795:Surveys and Questionnaires / Q000706:statistics & numerical data; D013694:Temperament; D013997:Time Factors; D000516:alpha-Amylases / Q000378:metabolism*
chemical_list: D000516:alpha-Amylases; D003345:Corticosterone; D006854:Hydrocortisone