title: The relative contributions of aging, health, and lifestyle factors to serum testosterone decline in men.
abstract: BACKGROUND
  Although it is known that serum testosterone (T) concentrations decline with age, the relative contributions of changes in health and lifestyle to that decline have not been adequately assessed.
  
  
  OBJECTIVE
  The objective of this study was to establish the relative importance of aging, health, and lifestyle in contributing to male T decline.
  
  
  METHODS
  A prospective cohort study of health and endocrine functioning in randomly selected men with a baseline visit (T1, 1987-1989) and two follow-up visits (T2, 1995-1997; T3, 2002-2004) was conducted.
  
  
  METHODS
  An observational study of men residing in greater Boston, Massachusetts, was conducted.
  
  
  METHODS
  Participants included 1667 men aged 40 to 70 at baseline; follow-up was conducted on 947 (57%) and 584 (35%) at T2 and T3, respectively.
  
  
  METHODS
  Main outcome measures included total serum T, calculated free T (FT), and SHBG.
  
  
  RESULTS
  There were substantial declines in total serum T and FT levels associated with aging alone. However, many health and lifestyle changes were associated with accelerated decline. A 4- to 5-kg/m2 increase in body mass index or loss of spouse was associated with declines in total serum T comparable to that associated with approximately 10 yr of aging. Results were similar for FT, but fewer factors were associated with SHBG after age was taken into account.
  
  
  CONCLUSIONS
  Both chronological aging and changes in health and lifestyle factors are associated with declines in serum T. Comorbidities and lifestyle influences may be as strongly associated with declining T levels as is aging itself over the short- to midterm. These results suggest the possibility that age-related hormone decline may be decelerated through the management of health and lifestyle factors.
authors.affiliation: New England Research Institutes, 9 Galen Street, Watertown, Massachusetts 02472, USA. ttravison@neriscience.com
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Travison
authors.forename: Andre B
authors.initials: AB
authors.lastname: Araujo
authors.forename: Varant
authors.initials: V
authors.lastname: Kupelian
authors.forename: Amy B
authors.initials: AB
authors.lastname: O'Donnell
authors.forename: John B
authors.initials: JB
authors.lastname: McKinlay
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood*; D001900:Boston / Q000453:epidemiology; D015331:Cohort Studies; D004703:Endocrine System / Q000502:physiology; D006304:Health Status; D006801:Humans; D007006:Hypogonadism / Q000453:epidemiology* / Q000378:metabolism*; D008019:Life Style; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000097:blood / Q000172:deficiency*
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone