title: Interaction of Apolipoprotein E Genotypes, Lifestyle Factors and Future Risk of Dementia-Related Mortality: The Cohort of Norway (CONOR).
abstract: OBJECTIVE
  Our aims were two-fold: firstly, to investigate the association and interaction between apolipoprotein E (ApoE), lifestyle risk factors and dementia-related mortality and, secondly, to examine if using dementia-related mortality yielded comparable risk estimates for the ApoE genotypes as reported in studies using a clinical dementia diagnosis as the end point.
  
  
  METHODS
  We used a nested case-control study with 561 cases drawn from dementia deaths in the Cohort of Norway (CONOR) and 584 alive controls.
  
  
  RESULTS
  ApoE ε4 carriers were at increased risk of dementia-related mortality compared to noncarriers [odds ratio (OR) 2.46, 95% confidence interval (CI) 1.93-3.13], and ε4 homozygotes were at particularly high risk (OR 7.86, 95% CI 3.80-13.8), while the ε2 type was associated with a lower risk. The highest risk of dementia-related mortality was found among ε4 carriers with more lifestyle risk factors (ε4 carriers who were smokers, hypertensive, physically inactive and diabetics) versus ε4 noncarriers without lifestyle risk factors (OR 15.4, 95% CI 4.37-52.4). The increased risk was additive, not multiplicative.
  
  
  CONCLUSIONS
  Ensuring a healthy lifestyle is important to be able to prevent dementia in populations at large, but especially for ε4 carriers. Using dementia mortality gives comparable results for the ApoE-dementia association as studies using clinical dementia diagnoses.
authors.affiliation: Department of Community Medicine, Institute of Health and Society, University of Oslo, Oslo, Norway.
authors.forename: Bjørn Heine
authors.initials: BH
authors.lastname: Strand
authors.forename: Tor Atle
authors.initials: TA
authors.lastname: Rosness
authors.forename: Knut
authors.initials: K
authors.lastname: Engedal
authors.forename: Per
authors.initials: P
authors.lastname: Magnus
authors.forename: Astrid Liv Mina
authors.initials: AL
authors.lastname: Bergem
authors.forename: Henrik
authors.initials: H
authors.lastname: Schirmer
authors.forename: Espen
authors.initials: E
authors.lastname: Bjertness
authors.forename: Gun Peggy
authors.initials: GP
authors.lastname: Knudsen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D053329:Apolipoprotein E2 / Q000235:genetics*; D053327:Apolipoprotein E4 / Q000235:genetics*; D016022:Case-Control Studies; D015331:Cohort Studies; D003704:Dementia / Q000453:epidemiology / Q000235:genetics / Q000401:mortality*; D005260:Female; D005838:Genotype; D006801:Humans; D008019:Life Style; D008297:Male; D009664:Norway / Q000453:epidemiology; D016017:Odds Ratio; D012307:Risk Factors
chemical_list: D053329:Apolipoprotein E2; D053327:Apolipoprotein E4