Increased incidence of mild cognitive impairment in long COVID patients, 2026, Frontera et al.

[SNT Gatchaman]

Increased incidence of mild cognitive impairment in long COVID patients

Spoiler: Authors

Jennifer A Frontera; Arjun V Masurkar; Rebecca A Betensky; Zariya Alvarez; Allal Boutajangout; Joshua Chodosh; Salma Hammam; Jessica Hunter; Li Jiang; Melanie Li; Jon Links; Karyn Marsh; Huize Pang; Floyd Silva; Sujata Thawani; Daria Vasilchenko; Alok Vedvyas; Amin Yakubov; Yulin Ge; Thomas Wisniewski

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 Alzheimers Coordinating Center (NACC) and National Institute on Aging (NIA) -Alzheimers 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

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3.93, 95% confidence interval [CI] 1.86–8.31, p < 0.001), and specifically for the Alzheimers 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.

HIGHLIGHTS
The cumulative incidence of mild cognitive impairment (MCI) was higher in Long-coronavirus disease 2019 (Long-COVID) compared to other groups.

The hazard of MCI was four-fold higher for Long-COVID subjects.

The hazard of Alzheimers disease related MCI was significantly higher with Long-COVID.

The hazard of MCI due to psychiatric illness did not differ between groups.

Web | DOI | PDF | Alzheimer's & Dementia | Open Access

 

[Eleanor]

Useful that they had pre-2020 data on subjects so they could compare pre and post illness cognitive performance. Also that they seem to have made a real effort to check covid-negative status for controls.

For anyone else looking for the raw numbers: 260 patients, median age of 70, of whom 113 had Long Covid. "Overall, MCI was diagnosed in 37 patients (14%) and dementia (AD type) was diagnosed in one (0.4%) Long-COVID patient."

 

[EndME]

Useful that they had pre-2020 data on subjects so they could compare pre and post illness cognitive performance

But as far as I can see they provide no information on how those results differed with the only reference being "Furthermore, 73% of our cohort underwent the same extensive neuropsychological battery and clinician interviews pre-pandemic and pre-COVID with documentation of normal cognitive and functional status at baseline." so there is seemingly no quantificantion on how for example the NACC UDS version 3 results differed rather than the assessment of the specialist differing which might be weighted by other things.

 

[rvallee]

Useful that they had pre-2020 data on subjects so they could compare pre and post illness cognitive performance. Also that they seem to have made a real effort to check covid-negative status for controls.

For anyone else looking for the raw numbers: 260 patients, median age of 70, of whom 113 had Long Covid. "Overall, MCI was diagnosed in 37 patients (14%) and dementia (AD type) was diagnosed in one (0.4%) Long-COVID patient."

This really needs to be considered alongside growing evidence of other infectious illnesses also leading to increases in cognitive problems, as well as evidence that some vaccines reduce them.

But it remains difficult to assess the true burden here when somehow medicine seems incapable of producing useful evaluations for brain fog, which is not the same as dementia. It's really hard to explain that when the impact is so dramatic on us.