Brain fog might be a bigger deal than you think.

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Could confusion be a sign of COVID-19? A new study in JAMA Network Open makes the case for this. The study, published on November 19, found that 28% of older COVID-19 patients at seven US emergency departments were in a confused mental state, which put them at higher risk of an intensive care unit (ICU) stay and death.

When the research team at Massachusetts General Hospital analyzed the records of 817 COVID-19 patients age 65 and older, confusion—aka, delirium—was the sixth most common symptom, and it was a primary symptom in 16% of patients. Also, 37% of the patients with delirium had none of the most typical symptoms of COVID-19, such as fever or shortness of breath.

A previous COVID-19 study, published in the New England Journal of Medicine, backed up the connection. The study estimated that the rate of delirium among ICU patients with COVID was 65%, thought this symptom may be heightened by the isolation imposed in the ICU to limit coronavirus spread.

What kind of confusion (delirium) is a potential COVID-19 symptom?

The Cleveland Clinic defines delirium as "sudden confusion or a sudden change in mental status." The person may appear disoriented or distracted, and they may have difficulty thinking clearly or paying attention. While it's perfectly normal to have occasional awareness and memory issues as you get older, delirium is much more serious, requiring treatment and even hospitalization.

Delirium shouldn't be confused with dementia—although there is a certain amount of overlap, and dementia is a risk factor for delirium. According to the Mayo Clinic, delirium is typically caused by acute illness or drug toxicity and is temporary and often reversible. On the other hand, dementia is usually caused by anatomic changes in the brain, has slower onset, and is generally chronic or progressive.

Confusion as a COVID-19 symptom seems to strike elderly adults more often

Confusion can be a sign of COVID-19, particularly in elderly people, Charulatha Nagar, MD, a neurologist at Northwestern Medicine Lake Forest Hospital in Lake Forest, Illinois, tells Health. This doesn't come as a huge surprise to Dr. Nagar. Although COVID-19 is a new disease, she points out that reports of neurological symptoms during previous coronavirus epidemics can provide a roadmap for potential neurological complications, due to many shared characteristics in this family of viruses.

A growing body of coronavirus research reports that COVID-19 patients are presenting with a range of neurological issues including dizziness, headache, and hypogeusia and hyposmia (a loss of taste and smell), as well as more serious manifestations including polyneuropathy (peripheral nerve damage) and encephalitis (inflammation of the brain).

However, Dr. Nagar notes that potential neurological symptoms of COVID-19 and the disordered physiological processes behind them haven't yet been fully established. In other words, we still don't know what the exact connection is.

"COVID-19 can present itself in many different forms, which is the challenge," says Dr. Nagar. "Plus, being elderly or immunocompromised, or having various other medical conditions, are risk factors in themselves."

What to do if you detect confusion in someone who might have COVID-19

Although the Centers for Disease Control (CDC) doesn't include delirium or confusion in its list of reported COVID-19 symptoms, it does cite "new confusion" as an emergency warning sign for the disease. Per the agency's advice, if you detect this in someone, you should call 911 or call ahead to your local emergency facility, explaining that you are seeking care for a person who may have COVID-19.

However, the authors of the JAMA study don't think the CDC advice goes far enough. They have called for the agency to revise its guidance to include delirium as an important coronavirus symptom.

"Many centers use the CDC guidance to prioritize screening, testing, and evaluation of presenting patients," they wrote. "By continuing to exclude delirium as a known presenting symptom of COVID-19, many cases will be missed or diagnoses delayed, as is already happening on a wide scale, particularly in older adults."

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDCWHO, and their local public health department as resources.

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