There is a deadly link between Covid-19 and brain illnesses, a study published on Tuesday suggests.
The Global Consortium Study of Neurologic Dysfunction in Covid-19 says hospital patients with clinically diagnosed neurological signs are six times more likely to die than those without.
"Very early on in the pandemic it became apparent that a good number of people who were sick enough to be hospitalised also developed neurological problems," said Dr Sherry Chou, lead author and associate professor of critical care medicine, neurology and neurosurgery at the University of Pittsburgh School of Medicine and the University of Pittsburgh Medical Centre (UPMC).
"A year later we are still fighting an unknown invisible enemy and, like in any battle, we need intel – we have to learn as much as we can about neurological impacts of Covid-19 in patients who are actively sick and in survivors."
The study spans 133 adult patient sites in all regions across the globe bar Antarctica.
Among one group of 3,744 adult patients, 82 per cent had reported or clinically captured neurological symptoms.
Four out of 10 patients reported having headaches, and about three out of 10 said they lost their sense of smell or taste.
Of the clinically diagnosed syndromes, acute encephalopathy was most common, affecting nearly half of the patients, followed by coma (17 per cent) and strokes (6 per cent).
Despite early concern about the virus's ability to attack the brain causing swelling and meningitis, those events were very rare, occurring in less than one per cent of patients.
"Acute encephalopathy is by far the most common symptom that we see in the clinic," said Dr Chou.
"Those patients may be in an altered sensory state or have impaired consciousness, or they don't feel like themselves and act confused, delirious or agitated."
The study also found that having a pre-existing neurological condition of any kind – from brain, spinal cord and nerve diseases to chronic migraines, dementia or Alzheimer's disease – is the strongest predictor for developing Covid-related neurological complications, doubling the risk.
In addition, having any neurological symptoms related to the virus, regardless of their severity, increased the chances of death six-fold. And when patients beat the odds and recover, their long-term health outlook is still uncertain.
"Even if the pandemic is completely eradicated, we are still talking about millions of survivors who need our help," said Dr Chou.
"It is important to find out what symptoms and health problems those patients are facing, and there is still plenty of work for years to come."