A new study has suggested that long COVID—persistent symptoms following recovery from a SARS-CoV-2 infection—may share biological mechanisms with Alzheimer’s disease. Researchers led by experts from New York University found structural and molecular changes in the brain that could link the two conditions.
Enlargement of the Choroid Plexus Observed
The team reported that individuals experiencing long COVID symptoms showed a 10 per cent enlargement of the choroid plexus (ChP), a network of blood vessels that produces cerebrospinal fluid and cushions the brain. Importantly, the ChP also regulates immune responses, including inflammation and waste clearance within the brain.
Previous research has established that impaired waste clearance in the brain contributes to dementia, of which Alzheimer’s disease is the most common form. Furthermore, earlier studies have shown that SARS-CoV-2 can damage the cells lining blood vessels in the choroid plexus.
Published Evidence Links Structural and Molecular Changes
As reported by NDTV, the findings, published in Alzheimer’s & Dementia, revealed that long COVID patients exhibited choroid plexus enlargement along with reduced cerebral blood flow. The researchers also identified associations between ChP alterations and Alzheimer’s-related symptoms, as well as changes in plasma biomarkers.
Notably, increased ChP size correlated with elevated levels of blood proteins such as pTau217, a biomarker known to rise as Alzheimer’s disease progresses. Additionally, the team detected higher levels of glial fibrillary acidic protein (GFAP), which typically increases in response to brain injury.
Cognitive Impact Detected on Standard Testing
Beyond imaging and molecular findings, the study identified measurable cognitive differences. Patients with enlarged choroid plexus structures performed, on average, two per cent worse on the Mini-Mental State Examination (MMSE), a widely used 30-point screening tool that assesses memory and attention.
Yulin Ge, Professor of Radiology at NYU’s School of Medicine and senior author of the study, explained that prolonged immune reactions following initial COVID infection may cause swelling that damages the blood–cerebrospinal fluid barrier within the choroid plexus. He added that physical, molecular, and clinical evidence suggests that ChP enlargement could serve as an early warning sign of Alzheimer’s-like cognitive decline.
Inflammation and Vascular Remodelling Identified as Possible Mechanisms
The study evaluated 179 participants: 86 patients with neurological symptoms of long COVID, 67 individuals who recovered fully without lasting symptoms, and 26 people who never had COVID-19. All participants underwent brain MRI scans.
Researchers observed that structural changes in long COVID patients not only increased the overall volume of the choroid plexus but also reduced blood flow through its vessels. Although the exact mechanisms remain under investigation, the team proposed that chronic inflammation may trigger “vascular remodelling.” In this process, immune activation thickens the cellular layers lining blood vessels.
Moreover, inflammation may lead to stromal fibrosis—a buildup of scar-like tissue—that further restricts blood flow. Consequently, impaired perfusion of the ChP could reduce cerebrospinal fluid production, allow waste accumulation, and weaken the blood–cerebrospinal fluid barrier.
Need for Long-Term Follow-Up
Thomas Wisniewski, Professor of Neurology at NYU and co-senior author, emphasised the importance of longitudinal research. He stated that the team plans to follow patients over time to determine whether these brain changes can predict long-term cognitive decline.
He further noted that larger, extended studies are essential to clarify whether ChP alterations directly cause neurological symptoms or represent a consequence of underlying immune responses. Such clarity will help refine future treatment strategies.
Broader Concerns About COVID’s Lasting Impact
Symptoms of long COVID frequently include “brain fog,” difficulty concentrating, and cognitive slowing. Additionally, a separate study published in the European Heart Journal in August 2025 suggested that COVID-19 infection may accelerate vascular ageing by up to five years, with women appearing more affected than men.
Together, these findings underscore the potential long-term neurological and vascular consequences of COVID-19 and highlight the urgent need for continued research into its lasting effects on brain health.