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Pneumonia after Covid-19 Ups the Risk of Dementia

Monday, June 6th, 2022

There have been multiple reports of patients experiencing difficulties with their cognition after recovering from COVID-19[1]. Pneumonia has also previously been associated with the risk of a new diagnosis of dementia. However, a recent study has shown that adults who develop pneumonia after COVID-19 have a higher risk of a new diagnosis of dementia than other pneumonia patients.

A team of University of Missouri researchers pulled real world data from 1.4 billion medical encounters prior to July 31st 2021, across 110 healthcare facilities in the United States. They selected patients hospitalised with pneumonia for more than 24 hours. Among the 10,403 patients identified with COVID-19 pneumonia, 3% (312) developed new onset dementia.  This was compared to a control group of 10,403 patients with non-COVID related pneumonia.  This group developed dementia at a lesser rate of 2.5%. The average time between COVID-19 pneumonia and dementia onset was 182 days, based on recorded ICD-10 codes.[2]

Over 70s at Greatest Risk

This effect was strongest among people aged over 70, where the risk of dementia was 5% after non-Covid-19 pneumonia and 6.4% after Covid-19 pneumonia. These findings remained after controlling for demographic factors, plus numerous health conditions or procedures. Key lifestyle factors known to be associated with dementia were unavailable.

A Follow-up Dementia Screen for COVID-19 Patients

The study is observational, so we cannot be sure of causation. Moreover, information related to the severity of pneumonia or exactly how a diagnosis of dementia was reached, is rudimentary. At minimum, the findings suggest that COVID-19 patients may benefit from cognitive screening as part of their follow-up care. Further study would also help provide more reason as to why COVID-19 pneumonia might be associated with increased dementia risk.



[2] ICD-10 is the 10th version of the International Classification of Diseases (ICD) that has been used to classify diseases (internationally agreed codes for diseases containing the cause, manifestation, location, severity, and type of injury or disease symptoms). The current version is ICD-11.