Ever since 2009, it has been known that the drug rapamycin
extends the lifespan of mice. The journal
Science identified this discovery as
one of the top 10 research breakthroughs for that year. The news was all the more exciting because
rapamycin already has FDA approval for other uses.
So researchers want to know just how rapamycin extends the
lifespan. Does it actually slow the entire
aging process? Or does it just slow down
certain diseases, such as cancer?
New research testing the effects of rapamycin on mice suggests that the drug probably does not slow
the aging process itself. It does slow
the development of cancer and a few other diseases. But rapamycin is no fountain of youth. In fact, if it were used just by itself to
extend the lifespan of human beings, it might merely draw out the aging
process. In other words, it might extend
the lifespan but not extend the healthspan.
Photo: Public domain through Wikimedia. Thanks to Rama.
The research was conducted by a team led by Dan Ehninger and his colleagues at the German Center for Neurodegenerative Diseases. It is published in the August 2013 issue of The Journal of Clinical Investigation, which is freely available online. In addition to the research article, the
journal is publishing an expert commentary that warns about any drug that
brings an increase in lifespan that “is accompanied by more disability and
disease and a greater loss of physiological functions, i.e., a reduced quality
of life.” By itself, rapamycin could do
just that.
On the bright side, the new study shows even more
conclusively that rapamycin extends the lifespan of mice by the equivalent of
almost a decade of human life. It also
provides a small benefit for cognitive function. So despite the mixed results, the journal
commentary advocates clinical trials involving human patients, perhaps those
with dementia. According to the journal
article, the research supports “the feasibility of clinical trials to study the
efficacy of rapamycin in treating diseases of the elderly, especially those
that are debilitating and for which no current treatment is known, such as
Alzheimer’s disease and other neurodegenerative diseases.”
Advocates of anti-aging research will see this new study as
something of a set-back, but it is not likely to slow down basic work in the
field. Opponents of anti-aging research
are likely to renew their warnings about the prospect of more years of
declining health. Any effort to enhance our
humanity, whether it is by increasing cognitive ability or extending the
lifespan, is always accompanied by a down-side, by side effects so costly that true
enhancement is impossible. The warning
is serious, but advocates of human enhancement are not likely to be
convinced.
The research article is entitled “Rapamycin Extends Murine
Lifespan but Has Limited Effects on Aging.”
The commentary is entitled “Rapamycin, Anti-aging, and Avoiding the Fate
of Tithonus.” Both are available free to
the public in the August 2013 issue of The Journal of Clinical Investigation.
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