title: Advanced paternal and grandpaternal age and schizophrenia: a three-generation perspective.
abstract: BACKGROUND
  Advanced paternal age has been linked with an increased risk of schizophrenia in the offspring. If age-related de novo mutations in the male germ line underlie this association, grandpaternal and paternal age would both be expected to influence the risk of schizophrenia. The aim of the current study was to explore the links between both paternal and grandpaternal age with respect to the risk of schizophrenia in a large, national register-based cohort.
  
  
  METHODS
  We linked the Swedish Multi-Generation and Hospital Discharge Registers and compared parents' ages at offspring birth for 20,582 schizophrenia-affected and 100,176 non-affected individuals. Grandparents' ages at the birth of the parent were compared between 2511 affected and 15,619 non-affected individuals. The risk of schizophrenia was examined with logistic regression when the predictor variable (parent or grandparent age) varied across age strata.
  
  
  RESULTS
  After adjusting for maternal age, birth year and proband sex, we confirmed that offspring of older fathers had an increased risk of schizophrenia. Compared to those with paternal age 20-24years, those with fathers >55years had a two-fold increased risk of schizophrenia. With respect to grandparent age, older maternal (but not paternal) grandfather age was associated with an increased risk of schizophrenia. Compared to maternal grandfather age 20-24years, those with maternal grandfathers >55years had a significantly increased risk of schizophrenia (adjusted odds ratio and 95% confidence intervals; 2.79, 1.71-4.56). The pattern of results was essentially unchanged when we examined male and female probands separately.
  
  
  CONCLUSIONS
  This is the first study to report an association between grandpaternal age and risk of schizophrenia. The selective effect of advanced maternal grandfather age suggests that the biological mechanisms involving the X-chromosome may differentially contribute to the association between paternal age and offspring risk of schizophrenia.
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors: Emma M
authors: EM
authors: Frans
authors: John J
authors: JJ
authors: McGrath
authors: Sven
authors: S
authors: Sandin
authors: Paul
authors: P
authors: Lichtenstein
authors: Abraham
authors: A
authors: Reichenberg
authors: Niklas
authors: N
authors: Långström
authors: Christina M
authors: CM
authors: Hultman
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D005192:Family Health; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010290:Parents; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology* / Q000235:genetics*; D012737:Sex Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult