COVID-19 and the Brain: What MRI Scans Reveal About Lasting Changes

A systematic review published in the journal Cerebral Cortex in March 2026 has drawn together findings from 49 separate brain imaging studies and the picture it paints is consistent: COVID-19 is associated with measurable structural and functional changes in the brain, particularly in regions involved in memory, emotion and attention. For anyone who has experienced "brain fog" or other lingering cognitive symptoms after COVID-19, this research offers one of the clearest pictures yet of what might be happening underneath those symptoms.

What the researchers actually did

This wasn't a single new brain-scanning study. It was a systematic review, meaning the authors, led by researchers including Li Chen and Xueling Suo, searched PubMed, Embase and Web of Science for existing MRI studies comparing COVID-19 patients with healthy controls, then synthesised the results across all 49 studies to identify which brain regions came up as abnormal most consistently. This kind of review carries more weight than any single study alone, since a pattern that shows up repeatedly across dozens of independent research groups is far less likely to be a one-off finding. The full review, titled "Widespread structural and functional brain alterations in COVID-19: a systematic review of MRI studies", was published in the journal Cerebral Cortex.

Which parts of the brain were most affected

Two areas stood out consistently across the studies reviewed. The insula, a region tucked deep within the brain that plays a role in emotional processing and bodily awareness, was the most frequently implicated grey matter region. The thalamic radiation, a bundle of white matter nerve fibres connecting the thalamus to the rest of the brain, was the most frequently implicated white matter tract. Deep subcortical structures, including the thalamus itself, were particularly likely to show abnormalities compared with other brain regions.

What "structural" and "functional" changes actually mean

Structural changes refer to physical differences in brain tissue that MRI can detect, such as altered grey matter volume or abnormal water movement along white matter nerve fibres, which can indicate that the protective coating around those fibres has been affected. Functional changes refer to how different brain regions activate and communicate with each other, measured while patients rest or perform tasks such as working memory exercises. The review found both types of change, with some patients showing altered brain activation patterns during memory tasks even when their actual performance on the task looked normal, suggesting the brain may be working harder or recruiting additional resources to achieve the same result.

The link to brain fog and other symptoms

The limbic system, a network of deep structures including the insula, hippocampus and amygdala, showed connectivity changes particularly often across the studies reviewed. Because this network plays a central role in regulating emotion and memory, disruptions here have been linked to some of the clinical symptoms commonly reported after COVID-19, including anxiety, low mood and post-traumatic stress symptoms, alongside the memory and concentration difficulties often described as brain fog. This gives researchers a plausible biological basis for symptoms that, until relatively recently, were difficult to explain or measure objectively.

Who this research applies to

The 49 studies reviewed included a mix of patients: some hospitalised with severe COVID-19, others who had relatively mild infections and some scanned months after their initial illness as part of long COVID research. This variation is actually one of the review's more notable findings, since it suggests brain changes weren't limited only to the most severe cases. That said, the studies differed in their methods, patient populations and how long after infection scans were taken, which makes it difficult to say precisely how common these changes are, or exactly how long they persist, across the wider population of people who've had COVID-19.

What this doesn't tell us

It's worth being clear about the limits of this kind of research. A systematic review of existing MRI studies can identify consistent patterns, but it can't establish with certainty that COVID-19 directly causes permanent brain damage in every case, nor can it tell us what proportion of people go on to develop lasting symptoms. Most of the underlying studies are observational and correlational rather than designed to prove causation. MRI differences also don't always translate into noticeable day to day symptoms. Many people recover fully from COVID-19 with no lasting cognitive effects at all.

Why this matters for long COVID research

For people living with long COVID symptoms such as brain fog and persistent fatigue, findings like these matter because they help validate symptoms that can otherwise be hard to explain to others, or even to healthcare professionals unfamiliar with the condition. Having an objective, imaging-based basis for these symptoms may also help guide future research into treatment and rehabilitation approaches, rather than leaving patients with a diagnosis based on symptoms alone.

What to do if you're experiencing ongoing cognitive symptoms

If you've noticed persistent memory problems, difficulty concentrating or other cognitive changes since having COVID-19, it's worth raising this with your GP rather than assuming it's something you have to live with indefinitely. The NHS long COVID pathway can involve referral to specialist services. Simple strategies such as pacing your activity, prioritising sleep and breaking tasks into smaller steps can also genuinely help manage day to day symptoms while any underlying recovery continues.

A quick recap

A major 2026 review of 49 brain imaging studies found consistent structural and functional changes in the brains of COVID-19 patients, particularly in regions linked to memory, emotion and attention. It offers a plausible biological explanation for brain fog and related long COVID symptoms, though it can't tell us exactly how common these changes are or how long they last in any individual case. If you're dealing with ongoing cognitive symptoms after COVID-19, this research is a reason to take them seriously and seek support, not a reason to assume the worst.

Frequently asked questions

Does this mean COVID-19 causes permanent brain damage?

Not necessarily. The review found measurable differences between COVID-19 patients and healthy controls on brain scans, but it can't establish how permanent these changes are for any individual and many people recover fully with no lasting symptoms at all.

Were these changes only found in severe COVID-19 cases?

No. The 49 studies reviewed included patients with both severe and mild infections and brain changes were reported across this range, though the studies varied too much in design to say precisely how risk differs by severity.

Can brain fog after COVID-19 be treated?

There's no single specific treatment for brain fog itself, but pacing activity, prioritising good sleep and support through NHS long COVID services can help many people manage symptoms while recovery continues.

How long after infection were these brain scans taken?

This varied considerably across the 49 studies, from scans taken shortly after acute infection to those conducted months later as part of long COVID research, which is one of the reasons the review can't give a precise timeline for how long changes persist.

Should I get a brain scan if I've had COVID-19?

Routine brain scanning isn't recommended for everyone who's had COVID-19. If you're experiencing persistent or worsening neurological symptoms, your GP can assess whether further investigation, including imaging, is appropriate for your specific situation.