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Long COVID and the Brain

A study underscores the role of inflammation in key brain cells.

Key points

  • Research suggests that tens of millions of people experience "long COVID," with many dealing with debilitating brain-related symptoms.
  • Inflammation in the brain has emerged as a major potential cause of long COVID brain symptoms.
  • Studies over the last few years indicate many potential drivers of brain issues in the context of the pandemic, some of which are non-infectious.
Source: mohamed_hassan/pixabay

As we enter the third year following COVID-19's global appearance, there remain some real and significant issues, especially surrounding the impact of the virus on the brains and bodies of many who contract it.

After an acute infection with the SARS-CoV-2 virus, many people experience long-term changes to their health. In fact, estimates are that over 65 million people around the world suffer from what has been called “long COVID.” Among the problems linked to long COVID are brain-specific issues like mental health conditions, fatigue, issues with sleeping, and cognitive impairment. These symptoms correlate with trouble performing basic activities like walking and paying bills.

The wide variety of brain-related issues linked to long COVID and the millions of people suffering from these problems have prompted researchers and the lay public alike to investigate how and why infection with COVID can influence the brain, as well as potential strategies to offset its effects.

Some possible contributors to damage within the brain include viral spread into the brain, inflammation associated with infection, metabolic challenges, microbiome changes, and damage to blood vessels. Yet it’s also important to highlight that many people may have experienced similar brain issues during the pandemic independent of infection, as a reflection of the stress, unhealthy eating, and lifestyle changes that occurred in the context of large-scale lockdown measures.

This speaks to the idea that certain brain symptoms thought to be due to COVID infection may in fact be better explained by other factors. To this end, some research finds that a sizable proportion of people attributing their symptoms to COVID may not have evidence of infection with the virus.

Recent research lends credence to the idea of brain inflammation as a driver of long COVID. In a March 2023 study published in Brain, Behavior, and Immunity, researchers studied the SARS-CoV-2 virus in animal models and found that the virus activated immune cells in the brain, increasing brain inflammation. Importantly, we now know that immune cells in the brain (called microglia) may have a role to play in mood, cognition, and much more. Specifically, activation of inflammatory microglia has been linked to increased risk for brain health conditions.

Likely, there are a number of different processes at play. Regardless of the drivers, a continued emphasis on finding solutions for people experiencing related brain issues is critical.

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