title: Reduced physiological complexity in robust elderly adults with the APOE epsilon4 allele.
abstract: BACKGROUND
  It is unclear whether the loss of physiological complexity during the aging process is due to genetic variations. The APOE gene has been studied extensively in regard to its relationship with aging-associated medical illness. We hypothesize that diminished physiological complexity, as measured by heart rate variability, is influenced by polymorphisms in the APOE allele among elderly individuals.
  
  
  RESULTS
  A total of 102 robust, non-demented, elderly subjects with normal functions of daily activities participated in this study (97 males and 5 females, aged 79.2+/-4.4 years, range 72-92 years). Among these individuals, the following two APOE genotypes were represented: epsilon4 non-carriers (n = 87, 85.3%) and epsilon4 carriers (n = 15, 14.7%). Multi-scale entropy (MSE), an analysis used in quantifying complexity for nonlinear time series, was employed to analyze heart-rate dynamics. Reduced physiological complexity, as measured by MSE, was significantly associated with the presence of the APOE epsilon4 allele in healthy elderly subjects, as compared to APOE epsilon4 allele non-carriers (24.6+/-5.5 versus 28.9+/-5.2, F = 9.429, p = 0.003, respectively).
  
  
  CONCLUSIONS
  This finding suggests a role for the APOE gene in the diminished physiological complexity seen in elderly populations.
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Cheng
authors.forename: Shih-Jen
authors.initials: SJ
authors.lastname: Tsai
authors.forename: Chen-Jee
authors.initials: CJ
authors.lastname: Hong
authors.forename: Albert C
authors.initials: AC
authors.lastname: Yang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics* / Q000502:physiology*; D000483:Alleles; D053327:Apolipoprotein E4 / Q000235:genetics*; D005260:Female; D005838:Genotype; D015577:Geriatric Assessment / Q000379:methods; D006339:Heart Rate; D006801:Humans; D008297:Male; D010827:Physiology
chemical_list: D053327:Apolipoprotein E4