title: Low testosterone and the risk of dementia in elderly men: Impact of age and education.
abstract: OBJECTIVE
  The objective of this study was to examine the association of plasma estradiol and testosterone with risk for dementia in elderly men.
  
  
  METHODS
  Within the population based Three-City study, including 3650 men age 65 years and older, a case-cohort design was set up after 4-years of follow-up. Baseline plasma levels of total 17-β estradiol (Total-E2), total testosterone (total-T) and bioavailable testosterone (bio-T) were measured for all cases of incident dementia (n=105) and for a random sample of the cohort (n=413). Cox regression models were used to estimate multivariate steroid sex hormone-associated hazard ratios (HR) and 95% confidence intervals of dementia.
  
  
  RESULTS
  There was a reverse J-shaped relationship between total-T and risk for dementia (P=.007). Compared with the median tertile, the HRs associated with total-T in the lower and upper tertile were increased (HR, 2.33; P=.026; HR, 1.9, P=.126; respectively). Low bio-T was associated with a greater risk for dementia (HR for one standard deviation of decreasing log(bio-T), 1.29; 95% confidence interval, 1.03-1.62). An interaction was found between bio-T and age (P<.0001), and bio-T and education (P=.044). Risk for dementia associated with low bio-T was greater in older men (80 years or older) than in younger men (younger than 80 years; HR, 3.11; P=.011 vs. HR, 1.07, P=.715, respectively) and in men with high level of education compared with those with low level of education (HR, 2.32; P=.0002 vs. HR, 0.95; P=.790, respectively). No significant association was found between Total-E2 and dementia.
  
  
  CONCLUSIONS
  Low levels of testosterone are associated with a risk for dementia in elderly men. The association between low bio-T and dementia may be more relevant to men 80 years or older and men with a high level of education.
authors.affiliation: Inserm, CESP Centre for research in Epidemiology and Population Health, UMR-S1018, Hormones and Cardiovascular Disease, Villejuif, France; Université Paris Sud 11, Kremlin-Bicêtre, France. Electronic address: laure.carcaillon@inserm.fr.
authors.forename: Laure
authors.initials: L
authors.lastname: Carcaillon
authors.affiliation: Hôpital Bicêtre, APHP, Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie, Kremlin-Bicêtre, France; Inserm UMR-S693, Université Paris Sud 11, Kremlin-Bicêtre, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Brailly-Tabard
authors.affiliation: Inserm U1061, F-34093, Montpellier, France.
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Ancelin
authors.affiliation: Inserm U708, Neuroepidemiology, Bordeaux, France; Université Victor Segalen Bordeaux2, Bordeaux, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Tzourio
authors.affiliation: Université Victor Segalen Bordeaux2, Bordeaux, France; Inserm U897, Epidemiology and Neuropsychology of Brain Aging, Bordeaux, France.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Foubert-Samier
authors.affiliation: Université Victor Segalen Bordeaux2, Bordeaux, France; Inserm U897, Epidemiology and Neuropsychology of Brain Aging, Bordeaux, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Dartigues
authors.affiliation: Hôpital Bicêtre, APHP, Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie, Kremlin-Bicêtre, France; Inserm UMR-S693, Université Paris Sud 11, Kremlin-Bicêtre, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Guiochon-Mantel
authors.affiliation: Inserm, CESP Centre for research in Epidemiology and Population Health, UMR-S1018, Hormones and Cardiovascular Disease, Villejuif, France; Université Paris Sud 11, Kremlin-Bicêtre, France.
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Scarabin
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003704:Dementia / Q000097:blood* / Q000453:epidemiology*; D004522:Educational Status; D004958:Estradiol / Q000097:blood; D005500:Follow-Up Studies; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D004958:Estradiol
keywords: Cohort study; Dementia; Elderly men; Estradiol; Testosterone