A new study suggests that Long COVID may cause changes in the brain that resemble early processes seen in Alzheimer’s disease.
Researchers found that people with lingering neurological symptoms after COVID-19 infection showed physical changes in a key brain structure, along with blood markers commonly linked to dementia.
The study was led by scientists at NYU Langone Health and published in Alzheimer’s & Dementia.
The research focused on the choroid plexus, a small but important structure deep in the brain.
The choroid plexus produces cerebrospinal fluid, which cushions the brain and helps remove waste. It also forms a protective barrier between the blood and the brain and plays a key role in regulating inflammation.
Using advanced MRI scans, the team discovered that patients with Long COVID had a choroid plexus that was about 10% larger than that of people who had fully recovered from COVID-19.
At the same time, blood flow through this structure was reduced.
These changes were not just structural. The researchers also found that a larger choroid plexus was linked to higher levels of proteins in the blood that are associated with Alzheimer’s disease. One of these proteins, called pTau217, tends to increase as Alzheimer’s worsens.
Another marker, glial fibrillary acidic protein, rises when there is brain injury or inflammation.
Cognitive testing revealed subtle differences as well. On the Mini-Mental State Exam, a common 30-point test used to assess memory and thinking skills, patients with larger choroid plexuses scored on average 2% lower than others.
While this difference may seem small, it suggests that the brain changes may already be affecting cognitive function.
The study included 179 participants. Among them were 86 people with neurological symptoms of Long COVID, 67 people who had recovered from COVID-19 without lasting symptoms, and 26 individuals who had never been infected.
Researchers believe the brain changes may be driven by ongoing immune activity. After a COVID infection, the immune system can remain activated for months in some individuals. This chronic inflammation may cause thickening of blood vessel walls in the choroid plexus, along with scar-like tissue buildup. These changes could reduce blood supply and interfere with the production of cerebrospinal fluid.
If the choroid plexus does not function properly, waste products may accumulate in the brain, and the protective barrier between blood and brain may weaken. Over time, this could increase the risk of cognitive decline.
The scientists emphasize that more research is needed. They plan to follow patients over time to determine whether these brain changes predict future memory problems or dementia. Larger, long-term studies will help clarify whether the choroid plexus alterations are a cause of cognitive symptoms or simply a consequence of them.
With millions of people worldwide affected by Long COVID, understanding these brain changes may be critical for identifying those at risk and developing targeted treatments.
