How Many Years Does the Brain Age After COVID? What We Know About COVID-19 and Dementia Risk

A longitudinal study published in 2025 by the UK Biobank reported changes in Alzheimer's disease-related biomarkers, such as a decrease in the Aβ42:Aβ40 ratio and an increase in pTau-181, following COVID-19 infection. These changes were more pronounced in individuals with severe cases or hypertension, although causality has not been established. Meanwhile, a meta-analysis combining 15 studies with approximately 26.4 million participants estimated that the risk of developing new-onset dementia increased by about 49% after COVID-19, with the effect being more pronounced in those aged 65 and older and lasting for 24 months. On social media, practical advocates calling for strengthened prevention measures coexist with cautious voices emphasizing the need to consider biases and comparison groups. In summary, a balanced approach of "neither over-fearing nor underestimating" is deemed appropriate, with increased importance placed on vaccination, lifestyle management, and early consultation for the elderly and those with underlying health conditions.