Knowledge is Power OR Ignorance is Bliss?

We’ve all seen the popular headlines: Breaking News, Alzheimer’s Disease is Now Type III Diabetes! But what does the research actually say? 

Here is what we do know: Alzheimer’s is linked to insulin resistance, which is where the theory that the disease could be called type III diabetes comes from. But let’s back up and see exactly how related they are.

Neurofibrillary Tangles

When phosphorylation is increased or decreased, key signaling molecules for the insulin pathway are activated or inactivated. These include IRS, PI3K, Akt, and GSK-3β. These changes in the pathway can lead to insulin resistance, and overall insulin signaling dysfunction. Insulin resistance is the key way some research is connecting diabetes and Alzheimer’s. It leads to hyperphosphorylation of tau protein, which leads to neurofibrillary tangles [1].

Amyloid-β Plaques

Insulin resistance also can cause the formation and accumulation of amyloid-β plaques. Insulin competes with amyloid-β to be degraded by IDE and competes for binding sites on insulin receptors [1].

Neuroinflammation

Insulin resistance is interconnected with neuroinflammation, both of which are caused by pro-inflammatory cytokine release in the brain. Both can also lead to neurodegeneration. Additionally, neuroinflammation is thought to be another cause of amyloid-β plaque formation, further relating all of these factors [2].

Oxidative Stress

Insulin resistance is interconnected with oxidative stress as well. Insulin is known to boost, or worse, oxidative stress [1], and oxidative stress also can be a cause of insulin resistance [3].

Connection Alzheimer’s Disease

Neurofibrillary tangles and amyloid-β plaques have long been known to be key identifiers of Alzheimer’s. And, neuroinflammation and oxidative stress have been found to contribute to Alzheimer’s disease. Since insulin resistance has been connected to all of these factors, insulin resistance can be connected to Alzheimer’s disease [1].

Knowledge is Power

As we have seen, there are many ways in which insulin is related to Alzheimer’s disease, but it has not been definitively proven to be type III diabetes …yet. If this theory is further researched, and it turns out Alzheimer’s is type III diabetes, that could open the door for new research and treatment strategies. Diabetes medications or lifestyle changes could provide more options for Alzheimer’s patients and their families. People could learn about their lifestyle or genetic risk factors earlier, and have more time to gather information and make changes. If you have family members who have been diagnosed with Alzheimer’s, you could get tested, and make changes early on, that could potentially make a difference in the disease outcome. But would knowing you are at an increased risk for Alzheimer’s many decades down the road change your behaviors right now? Would more knowledge about how Alzheimer’s works in the brain, and how it’s connected to insulin and diabetes make you more likely to follow a doctor’s recommendations? What about if you knew the risk was in your family, but you didn’t know your own individual risk? Would you want to find more information? Would knowledge empower you to change your life?

Ignorance is Bliss

On the other hand, research shows that simply knowing genetic risk isn’t enough to change everyday behaviors [4]. Does this mean we need more education about how diseases work and why someone would need to make changes? Or is it that ignorance is bliss? Not knowing might allow you to not overthink, or stress out over something decades down the line.  Since there is no complete cure and only treatments to slow the progression of the disease, there is not much you can do, and that might leave someone feeling powerless.

Both?

We definitely should focus research on this new theory, knowledge is power after all. However, we also need to make sure each individual has been given the choice of what information or tests they want to pursue. Because ignorance is bliss, both can be true at the same time. I, for one, just hope we have enough research on this topic to make informed decisions when we are at the age of risk.

References

[1] Akhtar, A., & Sah, S. P. (2020). Insulin signaling pathway and related molecules: Role in neurodegeneration and Alzheimer’s disease. Neurochemistry International, 135. https://doi.org/10.1016/j.neuint.2020.104707 

[2] Vinuesa, A., Pomilio, C., Gregosa, A., Bentivegna, M., Presa, J., Bellotto, M., Saravia, F., & Beauquis, J. (2021). Inflammation and insulin resistance as risk factors and potential therapeutic targets for Alzheimer’s disease. Frontiers in Neuroscience, 15. https://doi.org/10.3389/fnins.2021.653651 

[3] Hurrle, S., & Hsu, W. H. (2017). The etiology of oxidative stress in insulin resistance. PubMed Central, 40(5), 257–262. https://doi.org/10.1016/j.bj.2017.06.007 

[4] Hollands, G. J., French, D. P., Griffin, S. J., Prevost, A. T., Sutton, S., King, S., & Marteau, T. M. (2016). The impact of communicating genetic risks of disease on risk-reducing health behavior: Systematic review with meta-analysis. BMJ, 352. https://doi.org/10.1136/bmj.i1102