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What Hamsters with Long COVID Can Teach Us About Brain Fog and Fatigue

You know that feeling when you’re exhausted for no reason, your brain feels like it’s wrapped in fog, and even simple tasks seem overwhelming? For people with long COVID, that’s daily life. And now, a new study with hamsters might help explain why.

Researchers found that hamsters infected with COVID-19 (yes, hamsters can get it too) showed signs of persistent infection in their brainstems—long after the virus was gone from their lungs. These little furballs also started acting differently: less active, less interested in their usual hamster activities (like running on wheels or exploring), and showing changes in their genes linked to neurodegeneration. Sound familiar?

It’s not a perfect match for humans, of course. We’re not giant hairless hamsters. But it’s a clue. If the virus can linger in the brainstem—the control center for things like breathing, sleep, and mood—it could explain some of the lingering fatigue, depression, and brain fog people report.

The study also found changes in genes related to dopamine and serotonin, two chemicals that affect mood and motivation. That might be why some long COVID patients feel like they’re fighting an invisible wall every day.

So what does this mean for us? For one, it reinforces that long COVID isn’t “all in someone’s head” in the dismissive sense—it might literally be in their head, in their brain tissue. And it could point researchers toward better treatments, like therapies that target these lingering effects.

For now, if you or someone you know is dealing with long COVID, this study is a small but important piece of the puzzle. It’s a reminder that recovery isn’t just about lungs—it’s about the brain too.