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# COVID-19 and later cognitive impairment and dementia by vaccination status in England
- URL: https://www.coios.me/covid-19-and-later-cognitive-impairment-and-dementia-by/
- Published: 2026-11-03T13:12:57.000Z
- Updated: 2026-11-03T16:33:58.000Z
- Description: Dementia diagnoses rose sharply in the month after COVID-19, and cognitive impairment stayed raised for up to 4 years.
- Author: Daniel Ryan
- Tags: Health today, Dementia, Infection and pandemics, What linked data reveals, United Kingdom, #preprint, #refines, #item, #source-2026-11, #score-72

Researchers studied neurodegenerative and neurological disorders after COVID-19 in 18.3 million adults in English GP records on OpenSAFELY-TPP. Pre-vaccination, vaccinated and unvaccinated cohorts were followed up to 5.5 years, comparing incidence after COVID-19 with before or without it. In weeks 0-4 after COVID-19, adjusted hazard ratios for dementia were 5.05 pre-vaccination, 2.05 vaccinated and 8.69 unvaccinated. In hospitalised patients, cognitive impairment ratios up to 4 years later were 1.49 pre-vaccination, 1.27 vaccinated and 1.55 unvaccinated. The long-term dementia ratio for hospitalised unvaccinated patients, 1.48, was uncertain, as its confidence interval reached 1.00.

*Why it is interesting: The early excess in dementia diagnoses was much smaller in vaccinated people. Recorded cognitive impairment stayed raised for up to 4 years after hospitalisation with COVID-19.*

Source

[medRxiv, 1 November 2026](https://doi.org/10.64898/2026.10.30.26366919?ref=coios.me)

Paper

Association of COVID-19 with neurodegenerative and neurological disorders in vaccinated and unvaccinated people

Authors

Mason H, Zou M, Eyles E, Coronado JIC, Madley-Dowd P, Al Arab M et al.

DOI

10.64898/2026.10.30.26366919

Type

Preprint

Design

Retrospective cohort in linked English primary and secondary care records (OpenSAFELY-TPP), 18.3 million adults, three cohorts by vaccination status, up to 5.5 years follow-up, 2020-2025

Verdict

Refines prior evidence

Driver

[Dementia](https://www.coios.me/d-dementia/)

Driver

[Infection and pandemics](https://www.coios.me/d-infectious-disease/)

Driver

[What linked data reveals](https://www.coios.me/d-linked-data/)

Abstract — the authors' own words, CC BY

Introduction:

COVID-19 has been linked to neuropathology, neurological symptoms, and diagnoses of neurological illnesses. Evidence regarding the long-term impact of COVID-19 on neurodegenerative and neurological disorders is still limited. Methods:

We investigated associations of COVID-19 with neurodegenerative and neurological disorders by vaccination status in both hospitalised patients and the general population in the largest and longest study to date. We used OpenSAFELY-TPP to access linked electronic health records from 18.3 million adults registered with English GPs. We defined three cohorts with up to 5.5 years follow-up: pre-vaccination (exposed to COVID-19 January 2020-June 2021), and vaccinated and unvaccinated (exposed June-December 2021). We estimated adjusted hazard ratios (aHRs) comparing the incidence of cognitive impairment and dementia after diagnosis of COVID-19 with before or without COVID-19\. We also studied Parkinson's disease, restless leg syndrome, rapid eye movement sleep disorder, motor neuron disease, multiple sclerosis, and migraine. Results:

Incidence of most outcomes was elevated during weeks 0-4 after COVID-19 (cognitive impairment/dementia aHRs; pre-vaccination: 4.02 (3.74-4.32)/5.05 (4.63-5.52), vaccinated: 2.24 (2.05-2.45)/2.05 (1.77-2.37), unvaccinated: 4.38 (3.45-5.55)/8.69 (6.13-12.32)). Incidence remained elevated up to 4 years after COVID-19, especially in those hospitalised with COVID-19 (cognitive impairment/dementia aHRs; pre-vaccination: 1.49 (1.35-1.64)/ 1.39 (1.21-1.60), vaccinated: 1.27 (1.04-1.54)/1.32 (1.02-1.71), unvaccinated: 1.55 (1.11-2.16)/1.48 (1.00-2.20)). Conclusion:

Incidence of cognitive impairment and dementia were elevated shortly after COVID-19\. Incidence of cognitive impairment remained elevated in the longer term, particularly among unvaccinated individuals and/or those hospitalised with COVID-19\. These patients may require additional assessment during routine care to evaluate persistent or new cognitive concerns.