Alzheimer's & dementia : the journal of the Alzheimer's AssociationMar 2, 2026

Higher rates of mild memory and thinking problems in long COVID patients

Updated Jun 28, 2026

Abstract

Essence

Long COVID was linked to a markedly higher incidence of mild cognitive impairment, including AD-related MCI.

Evidence

In a 260-person observational cohort followed for 4.4 years, MCI incidence was 27% in Long-COVID versus 5% in recovered-COVID and 1% in COVID-negative controls, with a higher hazard of MCI for Long-COVID patients (HR 3.93).

Caveat

The study is observational with a modest sample, so it shows association rather than proving Long-COVID causes MCI.

Simplified

INTRODUCTION: Though brain fog is common in Long-coronavirus disease 2019 (Long-COVID), the incidence of mild cognitive impairment (MCI) is unknown.

METHODS: In an observational cohort study, recovered COVID-positive, Long-COVID, and COVID-negative subjects underwent blinded evaluation using National Alzheimer's Coordinating Center (NACC) and National Institute on Aging (NIA) -Alzheimer's Association diagnostic criteria for dementia and MCI. The cumulative incidence of MCI was calculated for each group, and the hazard of MCI was compared between groups.

RESULTS: Among 260 subjects, the cumulative incidence of MCI over 4.4 years was higher with Long-COVID (27%) versus recovered-COVID (5%) or COVID-negative status (1%). There was a higher hazard of MCI for patients with Long-COVID compared to those without (hazard ratio [HR] 3.93, 95% confidence interval [CI] 1.86-8.31, p < 0.001), and specifically for the Alzheimer's disease (AD) -related MCI subtype (HR 3.20, 95% confidence interval [CI] 1.14-9.00, p = 0.027).

DISCUSSION: The cumulative incidence and adjusted hazard of MCI (and specifically AD-related MCI) at 4.4 years was significantly higher among Long-COVID patients compared to recovered-COVID and COVID-negative controls.

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Higher rates of mild memory and thinking problems in long COVID patients

Abstract

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