July 25, 2013
Rapamycin Does Not Slow Aging In Mice

Rapamycin, a drug that has been found to increase max life expectancy in mice, has drawn interest from researchers in hopes that the drug slows the aging process. But some German researchers find that rapamycin works by suppressing tumors.

Bonn, Germany, July 25, 2013 – The drug rapamycin is known to increase lifespan in mice. Whether rapamycin slows down aging, however, remains unclear. A team of researchers from the German Center for Neurodegenerative Diseases (DZNE) and the Helmholtz Zentrum München has now found that rapamycin extends lifespan - but its impact on aging itself is limited. The life-extending effect seems to be related to rapamycin’s suppression of tumors, which represent the main causes of death in these mouse strains. The findings are reported in the current issue of the “Journal of Clinical Investigation” (published online on July 25, 2013).

Of course tumor suppression is a good thing. But a general slowing of the aging process would have greater utility for extending human life expectancy. An even better method to deal with aging: repair and replace aged tissue.

The rapamycin discovery in 2009 seemed like a big deal at the time.

. In 2009, US scientists discovered another effect: Mice treated with rapamycin lived longer than their untreated counterparts. “Rapamycin was the first drug shown to extend maximal lifespan in a mammalian species. This study has created quite a stir,” says Ehninger.

Rapamycin's seems to change metrics of aging traits via mechanisms that do not involve a slowing of the aging process.

Together with scientists from the Helmholtz Zentrum München and other colleagues, Ehninger’s group investigated if rapamycin influences aging in mice. The results are sobering: “Our results indicate that rapamycin extends lifespan, but it has only limited effects on the aging process itself,” is Ehninger’s summary of the findings. “Most aging traits were not affected by rapamycin treatment. Although we did observe positive effects on some aging traits, such as memory impairments and reduced red blood cell counts, our studies showed that similar drug effects are also seen in young mice, indicating that rapamycin did not influence these measures by slowing aging, but rather via other, aging-independent, mechanisms.”

Cancer is my biggest death fear. But you might be surprised to learn (as I was just now when I did the calculation) that out of the 2,468,435 people who died in the United States in 2010 only 23.2% died from cancer.

  • Heart disease: 597,689
  • Cancer: 574,743
  • Chronic lower respiratory diseases: 138,080
  • Stroke (cerebrovascular diseases): 129,476
  • Accidents (unintentional injuries): 120,859
  • Alzheimer's disease: 83,494
  • Diabetes: 69,071
  • Nephritis, nephrotic syndrome, and nephrosis: 50,476
  • Influenza and Pneumonia: 50,097
  • Intentional self-harm (suicide): 38,364

Note the third place position for respiratory diseases as well as the ninth place position for flue and pneumonia. Infections kill people whose immune systems have gotten too old and feeble.

An aged immune system also probably boosts the risk of cancer by because old immune cells are less able to attack and kill aged abnormal cells that are at increased risk of going cancerous. Methods to rejuvenate the immune system would cut both cancer and infectious disease deaths.

Share |      Randall Parker, 2013 July 25 10:00 PM 


Comments
Nick G said at July 26, 2013 2:29 PM:

Plus, of course, if you don't smoke your cancer risk is probably 50% as high as the overall average mortality rate.

Cancer statistics look very different if you weight them by mortality, rather than incidence - lung cancer is very hard to treat.

Brett Bellmore said at July 27, 2013 12:13 PM:

But there are potential life extension techniques whose downside is *promoting* tumors, (Lengthening telomeres.) so maybe it would still be useful as a way of taking away their disadvantage in this respect?

Da55id said at July 29, 2013 10:29 AM:

regarding long term immune system overuse due to frequent flu and colds, one can reduce these incidents dramatically by simply keeping one's environment at 50% relative humidity. I have done this successfully and have not had any illness for 4 years in a row. 50% humidity is the standard for operating rooms as it is the best level for humans and the worst for pathogens of ALL kinds (known).

Randall Parker said at August 1, 2013 9:17 PM:

Nick G,

Good point. the average non-smoker death from cancer is even lower than those figures indicate. I'm still scared of cancer though.

Da55id,

I can see how you can control humidity in your home? But how about at work? That's got to be the far risk source for getting sick, no? I guess it depends on who you live with and your work environment.

Da55id said at August 2, 2013 6:52 PM:

true. I telework so I have greater control of my environment - but like anything related to health and longevity if it's important enough a way can be found. The key problem to avoid is extremes. Commercial aircraft cabin RH is between 15 and 19 percent - perfect breeding grounds for pathogens - our lungs get dessicated and allow the beasties to build a home while we're in our seat belts. Cars in winter have a similar problem with rh around 31 percent. Work places are usually not as bad as these. It's not a fluke that so many folks get ill 3 days after an air trip. Interestingly, the new dreamliner is the first commercial aircraft that controls humidity since carbon fibre doesn't oxidize like aluminum in most aircraft. As long as you can keep things between 40 and 60 percent you should be ok at work.

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