People with dementia are not more likely than their same-age peers to develop severe COVID-19 or die from the disease — but they are more likely to experience delirium, according to a new study.

Investigators followed the clinical outcomes of patients in New York City who were hospitalized with COVID-19 during the first wave of the pandemic. A greater proportion of patients with dementia died, but this mortality rate was due to factors other than dementia, including age and comorbidities, reported James Noble, M.D., associate professor of neurology at Columbia University. But one unmistakable difference among the patients was a greater incidence of delirium in those with dementia, he said.

Delirium was found in more than 36% of hospitalized patients with dementia versus less than 12% of those without dementia. Notably, patients with dementia and COVID-19 also were less likely to report subjective symptoms such as shortness of breath, muscle aches, chills, nausea, or headaches compared with patients without dementia. This may have been due to relatively poor awareness or memory, Noble said.

The findings are in line with the many calls Noble, a geriatrician, and his colleagues said they have received from caregivers during the pandemic. Their patients’ caregivers have noted sudden development of confusion and delirium, even in dementia patients with only mild COVID-19 symptoms, he said. “[W]e realized delirium might be an unrecognized symptom of COVID-19 in this population.”

In any case, the results suggest that clinicians may need to look beyond conventional symptoms associated with COVID-19 and recognize delirium as a common sign of infection, Noble concluded. He and his colleagues join the ranks of other geriatricians who recently have advocated for more attention to this symptom.

The study was published in the Journal of Alzheimer’s Disease.