Wednesday, July 08, 2009

CR, Reproduction and Exercise

The latest issues of Journal of Gerontology: Biological Sciences and Medical Sciences (see here) have a interesting mix of articles that reveal how complex the aging process is and the different interventions that can impact health and longevity. I will briefly note three here.

This study examines the impact calorie restriction has on mice during different periods of their lifespan. Here is the abstract:

Life span can be extended in rodents by restricting food availability (caloric restriction [CR]) or by providing food low in methionine (Meth-R). Here, we show that a period of food restriction limited to the first 20 days of life, via a 50% enlargement of litter size, shows extended median and maximal life span relative to mice from normal sized litters and that a Meth-R diet initiated at 12 months of age also significantly increases longevity. Furthermore, mice exposed to a CR diet show changes in liver messenger RNA patterns, in phosphorylation of Erk, Jnk2, and p38 kinases, and in phosphorylation of mammalian target of rapamycin and its substrate 4EBP1, HE-binding protein 1 that are not observed in liver from age-matched Meth-R mice. These results introduce new protocols that can increase maximal life span and suggest that the spectrum of metabolic changes induced by low-calorie and low-methionine diets may differ in instructive ways.

A second study examines the hypothesis that late female fertility and slow somatic aging may be promoted by the same genetic variants. Here is the abstract:

Women giving birth at advanced reproductive ages in natural fertility conditions have been shown to have superior postmenopausal longevity. It is unknown whether improved survival is more likely among relatives of late-fertile women. This study compares survival past age 50 of men with and without a late-fertile sister in two populations: Utahns born in 1800–1869 identified from the Utah Population Database and Québec residents born in 1670–1750 identified from the Programme de recherche en démographie historique. Male survival was greater for those with, rather than without, a sister reproducing after age 45, particularly among men with at least three sisters (Utah rate ratio [RR] = .801, 95% CI = 0.687–0.940; Quebec RR = .786, 95% CI = 0.664–0.931). Survival of wives was unaffected by whether their husbands had a late-fertile sister, suggesting a weak influence of unmeasured socioenvironmental factors. These results support the hypothesis that late female fertility and slow somatic aging may be promoted by the same genetic variants.
And finally this study compares the impact physical activity has for end-of-life care. Here is the abstract:

Background: Little is known about the early predictors of need for care in late life. The purpose of this study was to investigate whether physical activity from midlife onward was associated with hospital and long-term care in the last year of life.

Methods: We studied a decedent population of 846 persons aged 66–98 years at death, who, on average 5.8 years prior to death, had participated in an interview about their current and earlier physical activity. Data on the use of care in the last year of life are register-based data and complete.

Results: Men needed on average 96 days (SD 7.0) and women 138 days (SD 6.2) of inpatient care in the last year of life. Among men, the risk for all-cause hospital care in the last year of life was higher for those who had been sedentary since midlife (adjusted incidence rate ratio [IRR] 1.98, 95% confidence interval [CI] 1.14–3.42) compared with those who had been consistently physically active, whereas use of long-term care did not correlate with physical activity history. Among women, the risk for long-term care was higher for those who had been sedentary (IRR 2.03, 95% CI 1.28–3.21) or only occasionally physically active (IRR 1.60, 95% CI 1.06–2.43), than for those who had been consistently active from midlife onward, whereas use of hospital care did not correlate with physical activity history.

Conclusion: People who had been physically active since midlife needed less end-of-life inpatient care but patterns differed between men and women.