Brain fog, a major symptom of long COVID

Brain fog, a term used to describe slow or sluggish thinking, can occur under many different circumstances.

For example, it can occur when someone is sleep-deprived or feeling unwell, or due to side effects from medicines that cause drowsiness. Brain fog can also occur following chemotherapy or a concussion.

In many cases, brain fog is temporary and gets better on its own. However, we don't really understand why brain fog happens after COVID-19, or how long these symptoms are likely to last.

But we do know that this form of brain fog can affect different aspects of cognition.

What is cognition?

Cognition refers to processes in the brain that we use to think, read, learn, remember, reason, and pay attention. Cognitive impairment is a reduction in your ability to perform one or more thinking skills.

Among people who were hospitalized for COVID, a wide range of problems with cognition have been reported. They include difficulties with

attention, which allows our brains to actively process information that is happening around us while simultaneously ignoring other details. Attention is like a spotlight on a stage during a show that allows performers to stand out from the background.

memory, the ability to learn, store, retain, and later retrieve information.

executive function, which includes more complex skills such as planning, focusing attention, remembering instructions, and juggling multiple tasks.

People struggling with the effects of long COVID may have noticeable problems with attention, memory, and executive function.

Studies report these issues both in people who were not hospitalized with COVID and in those who were, as well as in people who had severe cases. These findings raise some important questions about how COVID-19 infection affects cognition.

A recent study published by a group of German researchers suggests that even people who don't notice signs of cognitive impairment can have problems with memory and attention after recovering from a mild case of COVID-19.

Further research is needed to confirm whether attention and memory difficulties occur widely with COVID-19 infections — across all age groups and no matter how mild or severe the illness — and to consider other factors that might affect cognition. Better understanding of why some people have noticeable problems with attention and memory after having COVID and others do not may ultimately help guide care.

Recovery in memory within six months and improvement in attention within nine months of COVID infection was seen in this study, suggesting that some cognitive impairments with COVD, even if widespread, are potentially reversible.

Harvard Health Publishing

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