Most everyone has heard of Alzheimer’s Disease, far too often because of personal experience with loved ones. Although everyone associates the disease with someone losing their memory (and rightfully so), a physiological hallmark of Alzheimers is insulin resistance, which is thought of as the state of not having enough insulin, for one reason or another.
Insulin is most commonly known for its role in regulating metabolism. Insulin however, does a whole host of other helpful things for our bodies, including the regulation of synaptic plasticity, being neuroprotective, acting on neuronal growth and survival, and has been proposed to regulate the gene expression required for the ability to consolidate long term memories. All of this alludes to the fact that if we don’t have enough insulin, as seen in Alzheimers, we have a problem.
What can we do?
Insulin resistance has been observed to occur due to an inhibited insulin signalling pathway and an overactive pathway that leads that resistance called mTOR1 (mammalian target of rapamycin). However, with a drug called Rapamycin, mTOR can be inhibited and insulin resistance is abolished. Now, this doesn’t solve Alzheimers, but it’s certainly a step in the right direction for treatment if nothing else.
Some researchers however are suggesting that rapamycin has additional beneficial effects than simply increasing insulin (although this still might be the mechanism, the benefits are broader than simply treating Alzheimers). One of the positive 
effects of rapamycin that was found was that, when intermittently administered, rapamycin led to stem cell regeneration. Considering some of the applications for stem cells, this is an amazing discovery that could have far reaching implications on the future of medicine. And that’s potentially just the tip of the iceberg. Because of the mTOR1 inhibition through rapamycin, it has been found that there is a decreased risk of cancer, since mTOR1 signaling can lead to cell proliferation. Tumor regression has also been observed to occur. It’s also been found that mTOR1 signalling sometimes leads to misfolded proteins. Using rapamycin, inhibiting mTOR1 led to greater autophagy and suppression of protein synthesis, which is important because this means that rapamycin can have neuroprotective effects in not just Alzheimers, but also Parkinson’s Disease and Huntington’s Disease.
One of the most interesting positive effects found from administration of rapamycin was its ability to increase the lifespan of rats that were treated with the drug. It does this through slowing down the aging process along with inhibiting metabolic or neoplastic diseases. This also potentially includes cancer, as regulating cell proliferation through the drug means that cancer cells can’t spread as rapidly, and cancer cells may also happen less in the first place.
Before we all start taking insulin, it’s important to remember however that one of the most consequential aspects of a drug’s effects and effectiveness is the dosage and how often its administration. With rapamycin, the appropriate ratios of both of these factors are still unknown as of yet, but research is being done to try decipher further how to access the perceived positive effects of the drug. It has been seen though that rapamycin doesn’t fully inhibit mTORC1 processes, and so a combination with another treatment would more effectively implement the positive effects of Rapamycin.
This being said, there are observed downsides, which shouldn’t ever be overlooked within any kind of drug treatment. Rapamycin has been sometimes seen to actually 
increase insulin resistance, but the mechanism for why this occurs is speculated to be known (inhibition of mTOR2). Other negative effects included increased hyperglycemia within type 2 diabetes mouse models, and the ability for tumors to start regrowing after treatment with rapamycin stopped.
To end on a positive note about rapamycin treatment, there are no known overdose deaths due, which could signify that the ability for researchers to manipulate administered dosage levels could be rather high. All in all, more research into the side-effects and anti-aging effects of rapamycin are needed, but some people even now think that rapamycin can be used as an effective anti-aging (or at least an anti-disease) drug with very few discovered side-effects.
