Cold temperatures prolong life

TLDR: Mild cold exposure helps clear diseased proteins to prolong life (at least in worm and cell culture models). 

We’ve all been told to take a cold shower at some point. I’ve taken a few in my life, but odds are it was because one of my siblings used all the hot water.

Why? Does it do anything? Do cold temperatures somehow help your body?

A lot of science points towards yes. Brief exposure to chilly but bearable temperatures makes several species live longer. It’s a lot harder to test in humans (think 1-month experiment vs 70 years), but there might be some credibility behind the pop science “get cold to live longer” claims.

For obvious reasons, figuring out how to slow down aging is a hot research topic.

Growing old is one of the single biggest risk factors for getting diseases. Particularly, getting neurodegenerative diseases like Alzheimer's that involve proteins building up in your brain.

One of the open secrets in the medical field is that we just don’t know how many treatments work. Especially new treatments. We typically figure it out eventually, but sometimes we just accept that things work before figuring out why.

A good example is the active ingredient in Tylenol: acetaminophen. We have no idea why it stops pain.

That’s currently how a lot of aging research works. Particularly on things like cold therapy. There’s decent evidence that it works, but we don’t know why.

This week’s paper takes a step toward understanding how being cold makes some species live longer.

Specifically, the authors wanted to know if our body’s way of cleaning up debris was affected by the cold. The proteasome is our body’s system to recycle proteins into their amino acid building blocks. It plays an important role in keeping our bodies going.

When we age, the proteasome stops working well. It slows down and lets protein debris build-up. It’s not a coincidence that many age-related neurological diseases involve protein accumulation.

Conveniently, the proteasome is consistent across nearly all eukaryotes. That means me, you, and a worm have very similar proteasomes. Scientists take advantage of this to study how the proteasome works in worms. To start this study, worms were exposed to slightly cold temperatures and the authors observed how the proteasome reacted.

They found that the proteasome gene psme-3 was activated in the cold and let the worms live longer than usual. When psme-3 was turned off, the worms didn’t live any longer in the cold vs at their normal temperature.

Next, the authors looked to see if cold temperatures could help with proteins that build-up in Huntington’s disease, a rare neurodegenerative disorder. They found that colder temperatures decreased the amount of protein accumulation and helped prevent motor deficits.

They did a similar study looking at ALS proteins and once again saw that cold temperatures help prevent build-up. Together, these two experiments show that mild cold exposure can fairly dramatically prevent disease protein debris from accumulating.

This is great for the worms, but does it translate to people? It does indeed, at least in cell culture.

There are cell culture versions of many human diseases that we use better understand how they work and how best to fight them. Both Huntington’s and ALS have cell culture models that mimic the protein accumulation typically seen in human diseases.

For both of these models, the authors cultured their cells at normal “body temperature” conditions and then 1ºC colder. This small difference led to less disease protein accumulation and less cell death.

You can see this in the ALS cell culture model. The red in the image represents dying cells. It’s a bit hard to tell the difference from the pictures, but the graph on the right shows the same data. The percentage of dying cells is much lower when the temperature is 36ºC (red) compared to the normal 37ºC (black).

Apparently being a little chilly isn’t a bad thing. I still not going to take cold showers, but I’m excited to see where aging research takes us.

See you next week for more science,

Neil

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