Models, Statistical

Publication Title: 
Mechanisms of Ageing and Development

Accessible and readily utilized software, tables and approximation formulae have been developed to estimate power and sample size for studies of time to event (survival times) when the survival times are assumed to be exponential. These methods can markedly misestimate power when the distribution is Weibull and not exponential. The Weibull distribution with increasing hazard is common in aging research, especially when the whole life span of the subjects is of interest.

Author(s): 
Heo, M.
Faith, M. S.
Allison, D. B.
Publication Title: 
Annals of the New York Academy of Sciences

Little effort has been directed toward studying the relationship between morbidity and mortality at exceptional ages, perhaps for no better reason than it has been difficult to do given available data resources. Two study innovations/adjustments are required to adequately represent count data with reports of health from aged sample persons. These design features are oversampling of the exceptional group and linkage to detailed administrative reports. The National Long-Term Care Survey (NLTCS) has made it possible to study health and functioning in the context of exceptional longevity.

Author(s): 
Corder, Larry S.
Publication Title: 
Biometrics

In the Georgia Centenarian Study (Poon et al., Exceptional Longevity, 2006), centenarian cases and young controls are classified according to three categories (age, ethnic origin, and single nucleotide polymorphisms [SNPs] of candidate longevity genes), where each factor has two possible levels. Here we provide methodologies to determine the minimum sample size needed to detect dependence in 2 x 2 x 2 tables based on Fisher's exact test evaluated exactly or by Markov chain Monte Carlo (MCMC), assuming only the case total L and the control total N are known.

Author(s): 
Dai, Jianliang
Li, Li
Kim, Sangkyu
Kimball, Beth
Jazwinski, S. Michal
Arnold, Jonathan
Georgia Centenarian Study
Publication Title: 
The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences

BACKGROUND: Most survival studies of the elderly population have set their baselines for first examinations between 60 and 80 years. The rapidly increasing numbers of exceptionally old persons call for knowledge about determinants of exceptional survival. METHODS: The Swedish Centenarian Study followed 100 centenarians from the age of 100 to death of the entire cohort, by age 111 years. A biomedical, psychological, and social multivariate survival analysis was performed based on factors identified as important in earlier studies of older adults.

Author(s): 
Hagberg, Bo
Samuelsson, Gillis
Publication Title: 
Science (New York, N.Y.)

Human senescence patterns-late onset of mortality increase, slow mortality acceleration, and exceptional longevity-are often described as unique in the animal world.

Author(s): 
Bronikowski, Anne M.
Altmann, Jeanne
Brockman, Diane K.
Cords, Marina
Fedigan, Linda M.
Pusey, Anne
Stoinski, Tara
Morris, William F.
Strier, Karen B.
Alberts, Susan C.
Publication Title: 
PloS One

Like most complex phenotypes, exceptional longevity is thought to reflect a combined influence of environmental (e.g., lifestyle choices, where we live) and genetic factors. To explore the genetic contribution, we undertook a genome-wide association study of exceptional longevity in 801 centenarians (median age at death 104 years) and 914 genetically matched healthy controls.

Author(s): 
Sebastiani, Paola
Solovieff, Nadia
Dewan, Andrew T.
Walsh, Kyle M.
Puca, Annibale
Hartley, Stephen W.
Melista, Efthymia
Andersen, Stacy
Dworkis, Daniel A.
Wilk, Jemma B.
Myers, Richard H.
Steinberg, Martin H.
Montano, Monty
Baldwin, Clinton T.
Hoh, Josephine
Perls, Thomas T.
Publication Title: 
Molecular Psychiatry

General intelligence is a robust predictor of important life outcomes, including educational and occupational attainment, successfully managing everyday life situations, good health and longevity. Some neuronal correlates of intelligence have been discovered, mainly indicating that larger cortices in widespread parieto-frontal brain networks and efficient neuronal information processing support higher intelligence. However, there is a lack of established associations between general intelligence and any basic structural brain parameters that have a clear functional meaning.

Author(s): 
Penke, L.
Maniega, S. MuÒoz
Bastin, M. E.
ValdÈs Hern·ndez, M. C.
Murray, C.
Royle, N. A.
Starr, J. M.
Wardlaw, J. M.
Deary, I. J.
Publication Title: 
Aging Cell

Comparative biogerontology evaluates cellular, molecular, physiological, and genomic properties that distinguish short-lived from long-lived species. These studies typically use maximum reported lifespan (MRLS) as the index with which to compare traits, but there is a general awareness that MRLS is not ideal owing to statistical shortcomings that include bias resulting from small sample sizes. Nevertheless, MRLS has enough species-specific information to show strong associations with many other species-specific traits, such as body mass, stress resistance, and codon usage.

Author(s): 
Moorad, Jacob A.
Promislow, Daniel E. L.
Flesness, Nate
Miller, Richard A.
Publication Title: 
Aging Cell

Biomarkers of aging are essential to predict mortality and aging-related diseases. Paradoxically, age itself imposes a limitation on the use of known biomarkers of aging because their associations with mortality generally diminish with age. How this pattern arises is, however, not understood. With meta-analysis we show that human leucocyte telomere length (TL) predicts mortality, and that this mortality association diminishes with age, as found for other biomarkers of aging.

Author(s): 
Boonekamp, Jelle J.
Simons, Mirre J. P.
Hemerik, Lia
Verhulst, Simon
Publication Title: 
PloS One

Like most complex phenotypes, exceptional longevity is thought to reflect a combined influence of environmental (e.g., lifestyle choices, where we live) and genetic factors. To explore the genetic contribution, we undertook a genome-wide association study of exceptional longevity in 801 centenarians (median age at death 104 years) and 914 genetically matched healthy controls.

Author(s): 
Sebastiani, Paola
Solovieff, Nadia
Dewan, Andrew T.
Walsh, Kyle M.
Puca, Annibale
Hartley, Stephen W.
Melista, Efthymia
Andersen, Stacy
Dworkis, Daniel A.
Wilk, Jemma B.
Myers, Richard H.
Steinberg, Martin H.
Montano, Monty
Baldwin, Clinton T.
Hoh, Josephine
Perls, Thomas T.

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