Dementia Increases COVID-19 Mortality But Less Than Previously Suspected

From almost the beginning of the COVID-19 pandemic, those with cognitive limitations have been considered at much higher risk of severe outcomes than others. A new study confirmed the association but also found that the risk isn’t as great as assumed early in the pandemic with a different virus strain and no vaccines. Here is more information.

FRANKFURT, GERMANY – Does a dementia diagnosis increase the risk of dying from COVID-19? An answer from German researchers offers both good and bad news.

While an association was found, it was not as strong as previous studies had suggested. The issue might have been that most of the research had been conducted during the first months of the COVID-19 pandemic, according to the current authors who reported their findings in the Journal of Alzheimer’s Disease.

Their goal was to confirm the association of dementia diagnosis with the risk of mortality as a result of COVID-19 among patients treated in several large hospitals in Germany over an extended period of time during the pandemic.

“It is possible that the effects of dementia on COVID-19 mortality may have changed over time, especially after vaccines became available and were broadly administered and as different variants of SARS-CoV-2 evolved,” explained Karel Kostev, PhD, from the Department of Epidemiology of the IQVIA, “In view of these factors, it is important to conduct studies that include patients diagnosed with COVID-19 across a long time period of the pandemic.

The retrospective study notes that dementia has been identified as a major predictor of mortality associated with COVID-19. The study team used anonymized data from 50 hospitals in Germany; included were patients with a confirmed COVID-19 diagnosis hospitalized between March 11, 2020, and July 20, 2022.

Defined as the main outcome of the study was the association of mortality during inpatient stays with a dementia diagnosis. The researchers from the Asklepios hospital group focused on 28,311 patients diagnosed with COVID-19, of which 11.3% had a diagnosis of dementia.

“Prior to matching, 26.5% of dementia patients and 11.5% of non-dementia patients died; the difference decreased to 26.5% of dementia versus 21.7% of non-dementia patients within the matched pairs (n = 3,317),” they reported. “This corresponded to an increase in the risk of death associated with dementia (OR = 1.33; 95% CI: 1.16–1.46) in the univariate regression conducted for matched pairs.”

The study concluded that, while dementia was associated with COVID-19 mortality, the association was weaker than in previously published studies. “Further studies are needed to better understand whether and how pre-existing neuropsychiatric conditions such as dementia may impact the course and outcome of COVID-19,” the authors advised.

In the multivariable logistic regression, dementia was associated with an 84% (OR=1.84; 95% CI: 1.52–2.24) increase in the risk of death. In the univariate logistic regression conducted for matched pairs, dementia was associated with a 33% (OR=1.33; 95% CI: 1.16–1.53) increase in the risk of death.

“Dementia was associated with an increased mortality risk, but the association was weaker than that reported in the majority of previous publications,” Marc Axel Wollmer, MD, director of the department of Gerontopsychiatry from the Asklepios Hospital Nord-Ochsenzoll in Hamburg, explained. “To the best of the authors' knowledge, this is one of the first studies to have investigated the association between dementia and COVID-19 mortality using data collected for more than two years and applying two different statistical methods in parallel.”

The authors of the study also note that “although SARS-CoV-2 has changed over time and vaccination has greatly improved the prognosis of individuals who contract COVID-19 in general, further studies are needed to identify, prevent, and treat risk factors for mortality of this disease.”

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