Longevity FAQ: A beginner's guide to longevity research

Hi! I'm Laura Deming, and I run Longevity Fund. I spend a lot of time thinking about what could increase healthy human lifespan. This is my overview of the field for beginners. Feel free to send me any questions  about the below (just include name and affiliation).

Overview:

• Introduction:
  • Basic concepts in aging research
• Explanation:
  • Major areas of aging research
    • Caloric Restriction
    • Insulin/IGF
    • Parabiosis
    • Senescence
    • Autophagy
    • Hypothalamus
    • Reproductive System
    • Mitochondria
    • Sirtuins
• Data:
  • Comprehensive surveys of longevity
    • 95 things that make mice live longer
    • 70 drugs in the clinic that might make people live longer

As you get older, the chance that you will die goes up.

As you get older, the chance that you will die from certain diseases also goes up. 

Why does this happen? 

A simple explanation would be that, like an old car, you accumulate damage in a random fashion. 

However, there are many simple things that we can do to make animals live longer. Why? We don’t really know.

Eating less makes mice live longer.

Some genes, when mutated, make mice live longer,

A few drugs, approved for human use, also make mice live longer.

There are others - we will cover them below. 

So what is the study of aging?

I sum it up as the following: trying to figure out what kinds of damage accumulate with age, how to reverse that accumulation, and the search for switches that we could flip in human biology to increase lifespan.

Caloric Restriction

at a glance: eating less, in a variety of ways, can make you live longer - but is your body just using number of calories as a signal?

In the 1930s, investigators wanted to do an experiment to see if stunted growth rates during the Great Depression might impact lifespan. They tested this in rats by feeding them less food than they would normally eat. To their surprise, this actually made the rats live longer! This was a seminal discovery. For the first time, we changed the environment of an animal to make it live longer than it normally would. 

Since then, investigators have tried to uncover how this works. The effect depends on what genes you have, what you are eating and how much less you eat. If you take many genetically distinct mouse strains and put them on the same diet (cutting calories by ~40%), sometimes fewer than 1/5 of the mouse strains live longer. Diet composition also plays a role. Just decreasing protein or a specific amino acid, while keeping total calorie intake the same, can result in a lifespan extension in mice. Feeding mice a ketogenic diet also seems to help. Decreasing food intake by too much will result in starvation, so finding a diet that works can depend on the situation.

While long-term human studies are sparse, investigators have run two caloric restriction experiments in monkeys, one of which showed promising results for an increase in survival. To avoid the difficulty of continuous dieting, fasting ~8+ hours a day, or 5 days/month, or on a variety of different cycles might also be helpful. This is called intermittent fasting. Medically, intermittent fasting may aid recovery during chemotherapy. Some longevity-related pathways involve sensing amino acid levels, so it is possible that a specific biological process, not total calorie intake, controls the increase in lifespan.

Insulin/IGF

at glance: genetic pathways related to growth and insulin signaling are linked to aging

In papers published in 1983-1993, investigators introduced the concept that a gene could control lifespan. I got my start in science when one of the founders of this field, Cynthia Kenyon, agreed to let me work in her lab as a 12 year old kid. I'll always be grateful for her kindness and mentorship. Previously we'd known that caloric restriction could make animals live longer, but Kenyon and other scientists including Michael Klass, David Friedman and Tom Johnson found mutant genes that could make worms live longer. The gene that Kenyon found encoded a protein that is similar to insulin-like growth factor and insulin receptors in humans. In mice, mutating members of both of those pathways can increase lifespan. One of the longest-lived mouse mutants we have today is a dwarf mouse. In one study, people with similar dwarf mutations seemed to suffer less age-related disease than their non-mutated relatives.

I'm fascinated by the fact that many drugs which have been developed for diabetes, without any thought for their use elsewhere, turn out later to be relevant to aging. Good examples of this are metformin and FGF-21. Metformin is a small molecule used to treat Type 2 Diabetes, and FGF-21 is a protein in your blood that can increase lifespan in mice. We are still figuring out how the insulin/IGF pathway works, in particular what kinds of molecules might be driving the lifespan effect that we observe. 

Parabiosis

at a glance: young blood makes old mice healthier, but why?

Dracula wanted to drink young blood, but what does that have to do with aging? A paper published in the 70's showed that linking old and young female mice so that they share a bloodstream increased lifespan. Decades later, in 2005, scientists at Stanford showed that this procedure might help old muscle stem cells repair wounds. Then, in 2011, a succession of papers came out showing that this procedure and others like it (such as injecting young blood into old mice) made mice better at remembering things, and improved heart and muscle function with age. These discoveries increased excitement and interest in the field, and lead to a wave of startups. 

Investigators in the field have proposed many possible causes for this phenomenon. Proteins, small vesicles, or cells in the young mouse cleaning the blood of the old mouse might all be part of the effect. Many companies are trying to figure out whether there is a special protein or molecule involved. The big questions to resolve will be whether we can isolate a few key factors that are responsible for the parabiosis effect, and how many of the longevity-related phenotypes will translate to improve human health.

Senescence

at a glance: a fraction of your cells get older than the others, so we'd like to eliminate them

As you get old, so do your cells. But some of your cells get old in a way that is much worse than the others. You may have heard of a thing called telomerase. If you remember correctly, it's the thing that keeps the end of your DNA long enough that your cells can still divide. When one of your cells runs out of telomerase, it can't make many more copies of itself. If the cell sticks around, refuses to die even when it stops working, and starts secreting signals to the immune system, we call that a 'senescent cell'.

What happens when you get rid of these cells? Some animals that age faster than normal have a lot of these 'senescent cells' and are good experimental models in which to ask that question. In 2011, a group from the Mayo Clinic cleared out many of the senescent cells in one of those animal models, and found that the resulting mice were healthier in old age (among other things, they did not get cataracts and bent spines, which typically emerge in old age). In 2016, the same investigators found that getting rid of senescent cells in normal mice made them live a longer healthy lifespan. Knocking out senescent cells is tricky, because they don't have many unique identifiers. Companies are working to either find things empirically that kill senescent cells, or figure out specific mechanisms by which to try to destroy them.

Autophagy

at a glance: the garbage disposal unit of the cell worsens with age, improving it might increase healthy lifespan

Your body makes a lot of junk, on the molecular level, and cells need to clean this up. Just increasing the expression of one protein that helps to clean up this junk was enough to make mice live ~17% longer. Cells recycle old proteins and other molecules into a big vesicle, called a lysosome. It contains many proteins, and their job is to chop up old cell parts that it engulfs. Genes for proteins that do work in the lysosome are mutated in diseases such as Parkinson's. So improving this process has immediate relevance to neurodegenerative disease. As the lysosome gets older, more junk builds up in it that it cannot degrade. Finding ways to make more lysosomes, or help lysosomes degrade junk, may be interesting therapeutic avenues to pursue. 

Hypothalamus

at a glance: a surprising number of things can increase lifespan when only changed in the brain tissue

Changing something just in the brain can be enough to make a mouse live longer. If the hypothalamus thinks it is too warm, for example, it can decrease the core body temperature of a mouse, resulting in a slightly longer lifespan. Changing the level of a variety of genes in a brain-specific way can also make a mouse live longer.We know that the hypothalamus makes something called growth hormone releasing hormone (GHRH), which is in charge of, well, releasing growth hormone. Growth hormone appears to be closely tied to lifespan, so the hypothalamus could be an important control point. One interesting question is how much you can affect the lifespan of a whole organism by just making changes to the brain.

Reproductive System

at a glance: removing the ability to reproduce can increase lifespan

10 years ago, one of the first projects I worked on was trying to understand a weird fact about reproduction in worms. If you take little worms and get rid of their gonads (I know, it's weird), they live ~60% longer than normal. But this only works if you get rid of the stuff inside (sperm/eggs - these worms are hermaphrodites, which means they carry around both). If you get rid of the whole thing, lifespan goes back to normal.

This isn't restricted to worms. From court records of Korean eunuchs, the eunuchs tend to live longer than their contemporaries by 14-19 years. Some people have tried to do things such as transplant young ovaries into old mice, to see if that helps (it might add a bit to lifespan). There are also many reports showing that when you make things live longer, fertility goes down. There might be a tradeoff (fertility takes away resources that could be used for something else), or a signal coming from the reproductive system that tries to hold up aging if it is damaged.

Mitochondria

at a glance: mitochondrial mutations impact lifespan in counterintuitive ways

You may have heard mitochondria referred to as the 'powerhouses' of the cell. It's funny, they do literally run like a dam generating hydroelectric power! - They pump protons (positively charged particles) one way, then use them as they slide back to run a kind of motor that makes a small energetic molecule used by many entities in the cell. One concept that comes up when people talk about mitochondria is 'oxidative stress' - the idea that if molecules are very reactive (say they have oxygen, acquire some extra electrons, and now want to discharge them onto other molecules), they are likely to interfere with a lot of other molecules in the cell that should be left to their own devices.

Weirdly, the story has turned on its head over time. It's true that it is bad to pump an animal full of reactive oxygen species, and that you can make a mouse live longer by increasing the level of proteins that are supposed to clean up mitochondria. But you can also mutate things that should be helping the mitochondria, and end up increasing lifespan! It's counterintuitive, and one hypothesis is that a little bit of stress is good because it forces your cells to put up their defenses and ramp up production of molecules that neuter the reactive oxygen species. But we don't really know. 

Sirtuins

at a glance: sirtuins can change DNA and increase lifespan

Sirtuins add tags to the structural protein balls that DNA wraps around. It sounds odd, but think of yarn wrapping around a cardboard tube. When they add tags to the DNA yarn ball, it changes how the DNA is folded and expressed. So one of their actions is to control what genes do.

Sirtuins were first discovered to increase lifespan in yeast, and seem to also do so in worms, flies and mice. They depend on NAD to do their job, so when you see people talking about NR or other precursors of NAD, you can think about them as also helping the sirtuins do their job. You can extend lifespan a little bit in mice by giving them NR in old age. 

[That's all for this part for now - I'm planning to add to the above, as time allows. There's lots more to talk about!]

To give some context for the field, I thought it would be fun to do a more comprehensive survey. Below are virtually all the things we've seen that might improve mouse lifespan, listed in order of citations/year. 

I think some of the papers on the bottom of the list are actually pretty cool and might have been given a short shrift

(Methodology - I took all papers that had a demonstrated mouse lifespan effect, extracted the key lifespan figure, and in cases where the text didn't list actual median or other lifespan used a virtual pixel ruler to count the pixels to the median point. Allow for some standard deviation of error accordingly!).

For fun, I then took the list and matched the entries to drugs in the clinic. Part of the below might be outdated (companies sometimes take a long time to update on trial progress), but it's an interesting representation of the number of things in play that have a non-zero chance of having some impact on lifespan (would guess it to be pretty small in almost all cases though). Methodology is similar - just used clinicaltrials.gov to try to hunt down relevant trials and molecules, or googling generally. 

Thanks to Patrick Collison, Daniel Gross, Elad Gil and Nate Sauder for encouraging me to put this up, and Nathaniel Horwitz for major editorial help.

Those curves you saw up top (illustrating metformin or eating less increasing lifespan) were generated by the following equation. It's ubiquitous in aging biology, and allows you to draw lifespan curves when, for example,  some of the population could be censored.

 d_i is the number of events at time i

n_i is the total individuals at risk at time i.

References

Table 1: 95 things that make mice live longer

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5. Kanfi, Y., Naiman, S., Amir, G., Peshti, V., Zinman, G., Nahum, L., … Cohen, H. Y. (2012). The sirtuin SIRT6 regulates lifespan in male mice. Nature, 483(7388), 218–21. doi:10.1038/nature10815
6. Martin-Montalvo, A., Mercken, E. M., Mitchell, S. J., Palacios, H. H., Mote, P. L., Scheibye-Knudsen, M., … de Cabo, R. (2013). Metformin improves healthspan and lifespan in mice. Nature Communications, 4. doi:10.1038/ncomms3192
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14. Brandhorst, S., Choi, I. Y., Wei, M., Cheng, C. W., Sedrakyan, S., Navarrete, G., … Longo, V. D. (2015). A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan. Cell Metabolism, 22(1), 86–99. http://doi.org/10.1016/j.cmet.2015.05.012
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16. Satoh, A., Brace, C. S., Rensing, N., Cliften, P., Wozniak, D. F., Herzog, E. D., … Imai, S.-I. (2013). Sirt1 Extends Life Span and Delays Aging in Mice through the Regulation of Nk2 Homeobox 1 in the DMH and LH. Cell metabolism, 18(3), 416–30. doi:10.1016/j.cmet.2013.07.013
17. Mitchell, S. J., Martin-Montalvo, A., Mercken, E. M., Palacios, H. H., Ward, T. M., Abulwerdi, G., … De Cabo, R. (2014). The SIRT1 activator SRT1720 extends lifespan and improves health of mice fed a standard diet. Cell Reports, 6(5), 836–843. http://doi.org/10.1016/j.celrep.2014.01.031
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19. Pyo, J.-O., Yoo, S.-M., Ahn, H.-H., Nah, J., Hong, S.-H., Kam, T.-I., … Jung, Y.-K. (2013). Overexpression of Atg5 in mice activates autophagy and extends lifespan. Nature communications, 4, 2300. doi:10.1038/ncomms3300
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30. Ortega-Molina, A., Efeyan, A., Lopez-Guadamillas, E., Muñoz-Martin, M., Gómez-López, G., Cañamero, M., … Serrano, M. (2012). Pten positively regulates brown adipose function, energy expenditure, and longevity. Cell metabolism, 15(3), 382–94. doi:10.1016/j.cmet.2012.02.001
31. Hofmann, J. W., Zhao, X., De Cecco, M., Peterson, A. L., Pagliaroli, L., Manivannan, J., … Sedivy, J. M. (2015). Reduced expression of MYC increases longevity and enhances healthspan. Cell, 160(3), 477–488. http://doi.org/10.1016/j.cell.2014.12.016
32. Zhang, Y., Xie, Y., Berglund, E. D., Coate, K. C., He, T. T., Katafuchi, T., … Mangelsdorf, D. J. (2012). The starvation hormone, fibroblast growth factor-21, extends lifespan in mice. eLife, 1, e00065. doi:10.7554/eLife.00065
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35. Harrison, D. E., Strong, R., Allison, D. B., Ames, B. N., Astle, C. M., Atamna, H., … Miller, R. a. (2013). Acarbose, 17-α-estradiol, and nordihydroguaiaretic acid extend mouse lifespan preferentially in males. Aging Cell, (October), n/a–n/a. doi:10.1111/acel.12170
36. Harrison, D. E., Strong, R., Allison, D. B., Ames, B. N., Astle, C. M., Atamna, H., … Miller, R. a. (2013). Acarbose, 17-α-estradiol, and nordihydroguaiaretic acid extend mouse lifespan preferentially in males. Aging Cell, (October), n/a–n/a. doi:10.1111/acel.12170
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38. Mercken, E. M., Mitchell, S. J., Martin-Montalvo, A., Minor, R. K., Almeida, M., Gomes, A. P., … de Cabo, R. (2014). SRT2104 extends survival of male mice on a standard diet and preserves bone and muscle mass. Aging Cell, 13(5), 787–796. http://doi.org/10.1111/acel.12220
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51. Anisimov, V., Popovich, I. G., Zabezhinski, M. A., Egormin, P. A., Yurova, M. N., Semenchenko, A. V., … Khaitsev, N. V. (2015). Sex differences in aging, life span and spontaneous tumorigenesis in 129/Sv mice neonatally exposed to metformin http://www.tandfonline.com/doi/pdf/10.4161/15384101.2014.973308. Cell Cycle, 14(1), 46–55. http://doi.org/10.4161/15384101.2014.973308
52. Sun, L. Y., Spong, a., Swindell, W. R., Fang, Y., Hill, C., Huber, J. a., … Bartke, a. (2013). Growth hormone-releasing hormone disruption extends lifespan and regulates response to caloric restriction in mice. eLife, 2, e01098–e01098. doi:10.7554/eLife.01098
53. Hu, D., Cao, P., Thiels, E., Chu, C. T., Wu, G.-Y., Oury, T. D., & Klann, E. (2007). Hippocampal long-term potentiation, memory, and longevity in mice that overexpress mitochondrial superoxide dismutase. Neurobiology of learning and memory, 87(3), 372–84. doi:10.1016/j.nlm.2006.10.003
54. Yang, X., Doser, T. A., Fang, C. X., Nunn, J. M., Janardhanan, R., Zhu, M., … Ren, J. (2006). Metallothionein prolongs survival and antagonizes senescence-associated cardiomyocyte diastolic dysfunction : role of oxidative stress. FASEB. doi:10.1096/fj.05
55. Xu, J., Gontier, G., Chaker, Z., Lacube, P., Dupont, J., & Holzenberger, M. (2014). Longevity effect of IGF-1R+/- mutation depends on genetic background-specific receptor activation. Aging Cell, 13(1), 19–28. http://doi.org/10.1111/acel.12145
56. Matheu, A., Maraver, A., Collado, M., Garcia-Cao, I., Cañamero, M., Borras, C., … Serrano, M. (2009). Anti-aging activity of the Ink4/Arf locus. Aging Cell, 8(2), 152–161. http://doi.org/10.1111/j.1474-9726.2009.00458.x
57. Junnila, R. K., Duran-Ortiz, S., Suer, O., Sustarsic, E. G., Berryman, D. E., List, E. O., & Kopchick, J. J. (2016). Disruption of the GH receptor gene in adult mice increases maximal lifespan in females. Endocrinology, 157(12), 4502–4513. http://doi.org/10.1210/en.2016-1649
58. Cargill, S. L., Carey, J. R., Müller, H.-G., & Anderson, G. (2003). Age of ovary determines remaining life expectancy in old ovariectomized mice. Aging cell, 2(3), 185–90.
59. Gates, A. C., Bernal-Mizrachi, C., Chinault, S. L., Feng, C., Schneider, J. G., Coleman, T., … Semenkovich, C. F. (2007). Respiratory uncoupling in skeletal muscle delays death and diminishes age-related disease. Cell metabolism, 6(6), 497–505. doi:10.1016/j.cmet.2007.10.010)
60. Conover, C. a, Bale, L. K., Mader, J. R., Mason, M. a, Keenan, K. P., & Marler, R. J. (2010). Longevity and age-related pathology of mice deficient in pregnancy-associated plasma protein-A. The journals of gerontology. Series A, Biological sciences and medical sciences, 65(6), 590–9. doi:10.1093/gerona/glq032
61. López-Domínguez, J. A., Ramsey, J. J., Tran, D., Imai, D. M., Koehne, A., Laing, S. T., … McDonald, R. B. (2015). The Influence of Dietary Fat Source on Life Span in Calorie Restricted Mice. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 70(10), 1181–1188. http://doi.org/10.1093/gerona/glu177
62. Enns, L. C., Morton, J. F., Treuting, P. R., Emond, M. J., Wolf, N. S., Dai, D.-F., … Ladiges, W. C. (2009). Disruption of protein kinase A in mice enhances healthy aging. PloS one, 4(6), e5963. doi:10.1371/journal.pone.0005963
63. Mendias, C. L., Bakhurin, K. I., Gumucio, J. P., Shallal-Ayzin, M. V., Davis, C. S., & Faulkner, J. A. (2015). Haploinsufficiency of myostatin protects against aging-related declines in muscle function and enhances the longevity of mice. Aging Cell, 14(4), 704–706. http://doi.org/10.1111/acel.12339
64. Nojima, A., Yamashita, M., Yoshida, Y., Shimizu, I., Ichimiya, H., Kamimura, N., … Minamino, T. (2013). Haploinsufficiency of akt1 prolongs the lifespan of mice. PloS one, 8(7), e69178. doi:10.1371/journal.pone.0069178
65. Du, W. W., Yang, W., Fang, L., Xuan, J., Li, H., Khorshidi, A., … Yang, B. B. (2014). miR-17 extends mouse lifespan by inhibiting senescence signaling mediated by MKP7. Cell Death and Disease, 5(7), e1355. http://doi.org/10.1038/cddis.2014.305
66. Spindler, S. R., Mote, P. L., Lublin, A. L., Flegal, J. M., Dhahbi, J. M., & Li, R. (2015). Nordihydroguaiaretic acid extends the lifespan of drosophila and mice, increases mortality-related tumors and hemorrhagic diathesis, and alters energy homeostasis in mice. Journals of Gerontology - Series A Biological Sciences and Medical Sciences, 70(12), 1479–1489. http://doi.org/10.1093/gerona/glu190
67. Canaan, A., DeFuria, J., Perelman, E., Schultz, V., Seay, M., Tuck, D., … Weissman, S. M. (2014). Extended lifespan and reduced adiposity in mice lacking the FAT10 gene. Proceedings of the National Academy of Sciences, 111(14), 5313–5318. http://doi.org/10.1073/pnas.1323426111
68. Bobkova, N. V., Evgen’ev, M., Garbuz, D. G., Kulikov, A. M., Morozov, A., Samokhin, A., … Nudler, E. (2015). Exogenous Hsp70 delays senescence and improves cognitive function in aging mice. Proceedings of the National Academy of Sciences, 112(52), 16006–16011. http://doi.org/10.1073/pnas.1516131112
69. Borrás, C., Monleón, D., Grueso, R. L., Gambini, J., Orlando, L., Pallardó, F. V, … Mora, J. F. De. (2011). RasGrf1 deficiency delays dging i n mice, 3(3), 262–276.
70. Lopez-Mejia, I. C., De Toledo, M., Chavey, C., Lapasset, L., Cavelier, P., Lopez-Herrera, C., … Tazi, J. (2014). Antagonistic functions of LMNA isoforms in energy expenditure and lifespan. EMBO Reports, 15(5), 529–539. http://doi.org/10.1002/embr.201338126
71. Wu, C.-Y., Chen, Y.-F., Wang, C.-H., Kao, C.-H., Zhuang, H.-W., Chen, C.-C., … Tsai, T.-F. (2012). A persistent level of Cisd2 extends healthy lifespan and delays aging in mice. Human molecular genetics, 21(18), 3956–68. doi:10.1093/hmg/dds210
72. Spindler, S. R., Mote, P. L., Li, R., Dhahbi, J. M., Yamakawa, A., Flegal, J. M., … Lublin, A. L. (2013). β 1-Adrenergic receptor blockade extends the life span of Drosophila and long-lived mice. doi:10.1007/s11357-012-9498-3
73. Spindler, S. R., Mote, P. L., Li, R., Dhahbi, J. M., Yamakawa, A., Flegal, J. M., … Lublin, A. L. (2013). β 1-Adrenergic receptor blockade extends the life span of Drosophila and long-lived mice. doi:10.1007/s11357-012-9498-3
74. Miskin, R., & Masos, T. (1997). Transgenic mice overexpressing urokinase-type plasminogen activator in the brain exhibit reduced food consumption, body weight and size, and increased longevity. The Journal of Gerontology: Biological Science, 52(2), B118–B124. http://doi.org/10.1093/gerona/52A.2.B118
75. Harper, J. M., Wilkinson, J. E., & Miller, R. a. (2010). Macrophage migration inhibitory factor-knockout mice are long lived and respond to caloric restriction. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 24(7), 2436–42. doi:10.1096/fj.09-152223
76. Singh, S. P., Niemczyk, M., Saini, D., Sadovov, V., Zimniak, L., & Zimniak, P. (2010). Disruption of the mgsta4 gene increases life span of C57BL mice. Journals of Gerontology - Series A Biological Sciences and Medical Sciences, 65(1), 14–23. http://doi.org/10.1093/gerona/glp165
77. List, E. O., Berryman, D. E., Ikeno, Y., Hubbard, G. B., Funk, K., Comisford, R., … Kopchick, J. J. (2015). Removal of growth hormone receptor (GHR) in muscle of male mice replicates some of the health benefits seen in global GHR-/-mice. Aging, 7(7), 500–512.
78. Doze, V. A., Papay, R. S., Goldenstein, B. L., Gupta, M. K., Collette, K. M., Nelson, B. W., … Perez, D. M. (2011). Long-Term ␣ 1A -Adrenergic Receptor Stimulation Improves Synaptic Plasticity , Cognitive Function , Mood , and Longevity, 80(4), 747–758. doi:10.1124/mol.111.073734.Norepinephrine
79. Wu, S., Li, Q., Du, M., Li, S.-Y., & Ren, J. (2007). Cardiac-specific overexpression of catalase prolongs lifespan and attenuates ageing-induced cardiomyocyte contractile dysfunction and protein damage. Clinical and experimental pharmacology & physiology, 34(1-2), 81–7. doi:10.1111/j.1440-1681.2007.04540.x
80. Zhang, S. Q., Cai, W. J., Huang, J. H., Wu, B., Xia, S. J., Chen, X. L., … Shen, Z. Y. (2015). Icariin, a natural flavonol glycoside, extends healthspan in mice. Experimental Gerontology, 69, 226–235. http://doi.org/10.1016/j.exger.2015.06.020
81. Takeda, T., & Tanabe, H. (2016). Lifespan and reproduction in brain-specific MIR-29-knockdown mouse. Biochemical and Biophysical Research Communications, 471(4), 454–458. http://doi.org/10.1016/j.bbrc.2016.02.055
82. Kawahara, M., & Kono, T. (2010). Longevity in mice without a father. Human reproduction (Oxford, England), 25(2), 457–61. doi:10.1093/humrep/dep400
83. Andersen, J. B., Li, X. L., Judge, C. S., Zhou, A., Jha, B. K., Shelby, S., … Hassel, B. A. (2007). Role of 2-5A-dependent RNase-L in senescence and longevity, (October 2006), 3081–3088. doi:10.1038/sj.onc.1210111
84. De Luca, G., Ventura, I., Sanghez, V., Russo, M. T., Ajmone-Cat, M. A., Cacci, E., … Calamandrei, G. (2013). Prolonged lifespan with enhanced exploratory behavior in mice overexpressing the oxidized nucleoside triphosphatase hMTH1. Aging cell, 12(4), 695–705. doi:10.1111/acel.12094
85. Streeper, R. S., Grueter, C. a, Salomonis, N., Cases, S., Levin, M. C., Koliwad, S. K., … Farese, R. V. (2012). Deficiency of the lipid synthesis enzyme, DGAT1, extends longevity in mice. Aging, 4(1), 13–27.
86. Hoeflich, A., Reyer, A., Ohde, D., Schindler, N., Brenmoehl, J., Spitschak, M., … Wolf, E. (2016). Dissociation of somatic growth, time of sexual maturity, and life expectancy by overexpression of an RGD-deficient IGFBP-2 variant in female transgenic mice. Aging Cell, 15(1), 111–117. http://doi.org/10.1111/acel.12413
87. Conover, C. A., Bale, L. K., & Marler, R. J. (2015). Pregnancy-associated plasma protein-A deficiency improves survival of mice on a high fat diet. Experimental Gerontology, 70, 131–134. http://doi.org/10.1016/j.exger.2015.08.007
88. Takahashi, K., Noda, Y., Ohsawa, I., Shirasawa, T., & Takahashi, M. (2014). Extended lifespan, reduced body size and leg skeletal muscle mass, and decreased mitochondrial function in clk-1 transgenic mice. Experimental Gerontology, 58, 146–153. http://doi.org/10.1016/j.exger.2014.08.003
89. Redmann, S. M., & Argyropoulos, G. (2006). AgRP-deficiency could lead to increased lifespan. Biochemical and Biophysical Research Communications, 351(4), 860–864. http://doi.org/10.1016/j.bbrc.2006.10.129
90. Kovina, M. V, Zuev, V. a, Kagarlitskiy, G. O., & Khodarovich, Y. M. (2013). Effect on lifespan of high yield non-myeloablating transplantation of bone marrow from young to old mice. Frontiers in genetics, 4(August), 144. doi:10.3389/fgene.2013.00144
91. Shytikov, D., Balva, O., Debonneuil, E., Glukhovskiy, P., & Pishel, I. (2014). Aged mice repeatedly injected with plasma from young mice: a survival study. BioResearch Open Access, 3(5), 226–32. http://doi.org/10.1089/biores.2014.0043
92. Markovich, D., Ku, M.-C., & Muslim, D. (2011). Increased lifespan in hyposulfatemic NaS1 null mice. Experimental Gerontology.
93. Vereczki, V., Mansour, J., Pour-Ghaz, I., Bodnar, I., Pinter, O., Zelena, D., … Chinopoulos, C. (2016). Cyclophilin D regulates lifespan and protein expression of aging markers in the brain of mice. Mitochondrion, 34, 115–126. http://doi.org/10.1016/j.mito.2017.03.003
94. Bale, L. K., West, S. A., & Conover, C. A. (2017). Inducible knockdown of pregnancy-associated plasma protein-A gene expression in adult female mice extends life span. Aging Cell, 1–3. http://doi.org/10.1111/acel.12624
95. Grieb, B. C., Boyd, K., Mitra, R., & Eischen, C. M. (2016). Haploinsufficiency of the Myc regulator Mtbp extends survival and delays tumor development in aging mice, 8(10), 590–602.

Table 2: 70 things in the clinic that might make people live longer

1. http://www.accessdata.fda.gov/drugsatfda_docs/label/2012/021106s031lbl.pdf
2. https://clinicaltrials.gov/ct2/show/NCT02089334
3. Chen, T., Hogan, S., Conley, G., Pazmany, C., Wu, Q.-L., McNeil, G. L., … Sexton, D. J. (2007). Discovery and characterization of human antibody inhibitors of pregnancy-associated plasma protein-A. Biological chemistry, 388(5), 507–12. doi:10.1515/BC.2007.058, Mikkelsen, J. H., Gyrup, C., Kristensen, P., Overgaard, M. T., Poulsen, C. B., Laursen, L. S., & Oxvig, C. (2008). Inhibition of the proteolytic activity of pregnancy-associated plasma protein-A by targeting substrate exosite binding. The Journal of biological chemistry, 283(24), 16772–80. doi:10.1074/jbc.M802429200
4. Vikram, A., & Jena, G. (2010). S961, an insulin receptor antagonist causes hyperinsulinemia, insulin-resistance and depletion of energy stores in rats. Biochemical and biophysical research communications, 398(2), 260–5. doi:10.1016/j.bbrc.2010.06.070, Schäffer, L., Brand, C. L., Hansen, B. F., Ribel, U., Shaw, A. C., Slaaby, R., & Sturis, J. (2008). A novel high-affinity peptide antagonist to the insulin receptor. Biochemical and biophysical research communications, 376(2), 380–3. doi:10.1016/j.bbrc.2008.08.151
5. https://clinicaltrials.gov/ct2/show/NCT03041701
6. http://clinicaltrials.gov/ct2/show/NCT00791544
7. http://clinicaltrials.gov/ct2/results?term=cixutumumab&Search=Search
8. http://www.astellas.com/en/ir/library/pdf/2q2014_rd_en.pdf (Page 12), http://www.firstwordpharma.com/node/363806#axzz2o4na47BE
9. http://clinicaltrials.gov/ct2/show/NCT01721577, http://www.axelar.se/docs/Axelar_PR13%20Results%20clinical%20study%20I-II%202011-09-26%20EN.pdf
10. http://clinicaltrials.gov/ct2/show/NCT00673049, Ma, H., Zhang, T., Shen, H., Cao, H., & Du, J. (2013). The Adverse Events Profile of anti-IGF-1R Monoclonal Antibodies in Cancer Therapy. British journal of clinical pharmacology. doi:10.1111/bcp.12228
11. http://clinicaltrials.gov/ct2/show/NCT01779336
12. http://clinicaltrials.gov/ct2/results/displayOpt?flds=a&flds=b&flds=f&flds=n&flds=o&submit_fld_opt=on&term=biib022&show_flds=Y, http://meeting.ascopubs.org/cgi/content/abstract/28/15_suppl/2612
13. http://clinicaltrials.gov/ct2/results/displayOpt?flds=a&flds=b&flds=f&flds=n&flds=o&submit_fld_opt=on&term=rg1507&show_flds=Y, Bagatell, R., Herzog, C. E., Trippett, T. M., Grippo, J. F., Cirrincione-Dall, G., Fox, E., … Gore, L. (2011). Pharmacokinetically guided phase 1 trial of the IGF-1 receptor antagonist RG1507 in children with recurrent or refractory solid tumors. Clinical cancer research : an official journal of the American Association for Cancer Research, 17(3), 611–9. doi:10.1158/1078-0432.CCR-10-1731
14. http://clinicaltrials.gov/ct2/results?term=dalotuzumab&Search=Search, Atzori, F., Tabernero, J., Cervantes, A., Prudkin, L., Andreu, J., Rodríguez-Braun, E., … Baselga, J. (2011). A phase I pharmacokinetic and pharmacodynamic study of dalotuzumab (MK-0646), an anti-insulin-like growth factor-1 receptor monoclonal antibody, in patients with advanced solid tumors. Clinical cancer research : an official journal of the American Association for Cancer Research, 17(19), 6304–12. doi:10.1158/1078-0432.CCR-10-3336
15. El-Ami, T., Moll, L., Carvalhal Marques, F., Volovik, Y., Reuveni, H., & Cohen, E. (2013). A novel inhibitor of the insulin/IGF signaling pathway protects from age-onset, neurodegeneration-linked proteotoxicity. Aging cell, 1–10. doi:10.1111/acel.12171
16. Annunziata, M., Grande, C., Scarlatti, F., Deltetto, F., Delpiano, E., Camanni, M., … Granata, R. (2010). The growth hormone-releasing hormone (GHRH) antagonist JV-1-36 inhibits proliferation and survival of human ectopic endometriotic stromal cells (ESCs) and the T HESC cell line. Fertility and sterility, 94(3), 841–9. doi:10.1016/j.fertnstert.2009.03.093
17. Siejka, A., Schally, A. V, Block, N. L., & Barabutis, N. (2010). Antagonists of growth hormone-releasing hormone inhibit the proliferation of human benign prostatic hyperplasia cells. The Prostate, 70(10), 1087–93. doi:10.1002/pros.21142
18. http://www.accessdata.fda.gov/drugsatfda_docs/label/2003/19667scm044_Sandostatin_lbl.pdf
19. http://www.accessdata.fda.gov/drugsatfda_docs/label/2012/200677lbl.pdf
20. http://www.accessdata.fda.gov/drugsatfda_docs/label/2010/019667s058,021008s023lbl.pdf
21. http://clinicaltrials.gov/ct2/show/NCT00640757
22. http://clinicaltrials.gov/ct2/show/NCT00427193
23. http://www.accessdata.fda.gov/drugsatfda_docs/label/2010/021110s058lbl.pdf
24. http://www.accessdata.fda.gov/drugsatfda_docs/label/2011/022088s002s004s005s007s010s012lbl.pdf
25. http://www.accessdata.fda.gov/drugsatfda_docs/label/2010/022334s6lbl.pdf
26. http://www.drugs.com/nda/ridaforolimus_120606.html, http://www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials/drugs/oncologicdrugsadvisorycommittee/ucm296305.pdf
27. Pearce, L. R., Alton, G. R., Richter, D. T., Kath, J. C., Lingardo, L., Chapman, J., … Alessi, D. R. (2010). Characterization of PF-4708671, a novel and highly specific inhibitor of p70 ribosomal S6 kinase (S6K1). The Biochemical journal, 431(2), 245–55. doi:10.1042/BJ20101024
28. http://clinicaltrials.gov/ct2/show/NCT00937326, Venkatasubramanian, S., Noh, R. M., Daga, S., Langrish, J. P., Joshi, N. V, Mills, N. L., … Newby, D. E. (2013). Cardiovascular effects of a novel SIRT1 activator, SRT2104, in otherwise healthy cigarette smokers. Journal of the American Heart Association, 2(3), e000042. doi:10.1161/JAHA.113.000042
29. http://clinicaltrials.gov/ct2/show/NCT01416376
30. http://clinicaltrials.gov/ct2/show/NCT00678015
31. http://www.fda.gov/ohrms/dockets/ac/03/briefing/4012B1_03_Appd%201-Professional%20Labeling.pdf
32. http://www.accessdata.fda.gov/drugsatfda_docs/label/2008/020357s031,021202s016lbl.pdf
33. http://www.accessdata.fda.gov/drugsatfda_docs/label/2011/020482s024lbl.pdf
34. https://clinicaltrials.gov/ct2/show/NCT02531334
35. Ziegelbauer, K., Gantner, F., Lukacs, N. W., Berlin, A., Fuchikami, K., Niki, T., … Bacon, K. B. (2005). A selective novel low-molecular-weight inhibitor of IkappaB kinase-beta (IKK-beta) prevents pulmonary inflammation and shows broad anti-inflammatory activity. British journal of pharmacology, 145(2), 178–92. doi:10.1038/sj.bjp.0706176
36. Leung, C.-H., Chan, D. S.-H., Li, Y.-W., Fong, W.-F., & Ma, D.-L. (2013). Hit identification of IKKβ natural product inhibitor. BMC pharmacology & toxicology, 14(1), 3. doi:10.1186/2050-6511-14-3
37. https://clinicaltrials.gov/ct2/show/NCT02439216
38. Miller, S. C., Huang, R., Sakamuru, S., Shukla, S. J., Attene-, M. S., Shinn, P., … Austin, C. P. (2011). Signaling and their Mechanism of Action, 79(9), 1272–1280. doi:10.1016/j.bcp.2009.12.021.Identification
39. http://clinicaltrials.gov/ct2/show/NCT01869959
40. https://clinicaltrials.gov/ct2/show/NCT02097277?term=BMS-986036&rank=1
41. http://clinicaltrials.gov/ct2/show/NCT01442584
42. http://clinicaltrials.gov/ct2/show/NCT00545805
43. http://www.vitaminshoppe.com/p/nature-plus-niacinamide-1000-mg-90-tablets/nt-1308#.UrsRAGRDulo
44. https://chromadex.com/Ingredients/NIAGEN.html
45. https://clinicaltrials.gov/ct2/show/NCT03176628
46. http://www.amicusrx.com/preclinical.aspx
47. https://clinicaltrials.gov/ct2/show/NCT01590888
48. http://lysosomaltx.com
49. Braeunig, J. H., Schweda, F., Han, P.-L., & Seifert, R. (2013). Similarly potent inhibition of adenylyl cyclase by P-site inhibitors in hearts from wild type and AC5 knockout mice. PloS one, 8(7), e68009. doi:10.1371/journal.pone.0068009
50. http://clinicaltrials.gov/ct2/show/NCT01064492
51. Murray, A. J. (2008). Pharmacological PKA inhibition: all may not be what it seems. Science signaling, 1(22), re4. doi:10.1126/scisignal.122re4
52. http://clinicaltrials.gov/ct2/show/NCT01363141
53. http://clinicaltrials.gov/ct2/show/NCT00739687
54. http://clinicaltrials.gov/ct2/show/NCT00565318
55. http://www.carolustherapeutics.com
56. Al-Abed, Y., & VanPatten, S. (2011). MIF as a disease target: ISO-1 as a proof-of-concept therapeutic. Future medicinal chemistry, 3(1), 45–63. doi:10.4155/fmc.10.281
57. http://www.fda.gov/Drugs/DrugSafety/ucm225444.htm
58. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=021846
59. https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000032634
60. https://www.nature.com/articles/nbt0104-3
61. https://clinicaltrials.gov/ct2/show/NCT03268382
62. https://clinicaltrials.gov/ct2/show/NCT02545283
63. https://clinicaltrials.gov/ct2/show/NCT00779519
64. https://clinicaltrials.gov/ct2/show/NCT02974153
65. https://clinicaltrials.gov/ct2/show/NCT02959190
66. https://clinicaltrials.gov/ct2/show/NCT02483585
67. https://clinicaltrials.gov/ct2/show/NCT03303079
68. https://clinicaltrials.gov/ct2/show/NCT02310763
69. https://clinicaltrials.gov/ct2/show/NCT03039686
70. http://www.cypralis.com/aims/research-portfolio

Per-section references for longevity explanations

Caloric Restriction

• McCay, C. M., Crowell, M. F., & Maynard, L. A. (1935). The effect of retarded growth upon the length of life span and upon the ultimate body size one figure. The journal of Nutrition, 10(1), 63-79.
• Solon-Biet, S. M., McMahon, A. C., Ballard, J. W. O., Ruohonen, K., Wu, L. E., Cogger, V. C., … Simpson, S. J. (2014). The ratio of macronutrients, not caloric intake, dictates cardiometabolic health, aging, and longevity in ad libitum-fed mice. Cell Metabolism, 19(3), 418–430. http://doi.org/10.1016/j.cmet.2014.02.009
• Miller, R. A., Buehner, G., Chang, Y., Harper, J. M., Sigler, R., & Smith-wheelock, M. (2005). Methionine-deficient diet extends mouse lifespan , slows immune and lens aging , alters glucose , T4 , IGF-I and insulin levels , and increases hepatocyte MIF levels and stress resistance, (February), 119–125. doi:10.1111/j.1474-9726.2005.00152.x
• Newman, J. C., Covarrubias, A. J., Zhao, M., Yu, X., Gut, P., Ng, C. P., ... & Verdin, E. (2017). Ketogenic diet reduces midlife mortality and improves memory in aging mice. Cell metabolism, 26(3), 547-557.
• Liao, C.-Y., Rikke, B. a, Johnson, T. E., Diaz, V., & Nelson, J. F. (2010). Genetic variation in the murine lifespan response to dietary restriction: from life extension to life shortening. Aging cell, 9(1), 92–5. doi:10.1111/j.1474-9726.2009.00533.x
• Mattison, J. A., Colman, R. J., Beasley, T. M., Allison, D. B., Kemnitz, J. W., Roth, G. S., ... & Anderson, R. M. (2017). Caloric restriction improves health and survival of rhesus monkeys. Nature communications, 8.
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Insulin/IGF

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Parabiosis

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Senescence

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Autophagy

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Hypothalamus

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Reproductive System

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Mitochondria

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Sirtuins

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