Scientists have sifted through a huge amount of research looking at how COVID-19 affects the brain and reached a worrying conclusion: there’s compelling evidence to suggest the coronavirus could bring a wave of cognitive decline, dementia, and Alzheimer’s diseases in years to come. In light of these initial workings, they're now looking to launch a global study to further dig into this possible link.
In the first few months of the pandemic, scientists quickly started to realize COVID-19 was far from a straightforward respiratory infection that causes a cough and a fever. From a loss of taste and smell to “brain fog” and memory problems, doctors have reported an array of neurological symptoms in COVID-19 patients, indicating the viral infection impacts the central nervous system. They have even discovered SARS-CoV-2 in the brains of people who have died from COVID-19.
The question is whether these effects on the brain could have any long-term implications down the line in terms of neurodegeneration and dementia.
In a new paper published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, a team of dementia experts put forward a “compelling case” that COVID-19 will have long-term effects on the brain and could potentially trigger dementia in some people. Based on their initial findings, they are launching a massive international study to understand the long-term neurological effects of this relatively new disease.
Their initial paper has looked at the evidence on how COVID-19 affects the brain, as well as over a century's worth of data on other viral infections, including SARS, MERS, and the 1918 “Spanish flu” pandemic.
"Since the flu pandemic of 1917 and 1918, many of the flu-like diseases have been associated with brain disorders,” Gabriel A. de Erausquin, lead author and professor of neurology at the University of Texas Health Science Center at San Antonio, said in a statement.
“[T]he under-recognized medical history of these viruses over the last century suggests a strong link to brain diseases that affect memory and behavior,” added Maria C Carrillo, PhD, study co-author and Alzheimer’s Association chief science officer.
The world has only known about COVID-19 for a little over a year, so there’s scant long-term evidence. However, there’s good reason to believe the novel disease can have an effect on memory. For one, SARS-CoV-2 is known to enter cells via receptors known as ACE2, which are found in the highest concentration in the olfactory bulb, the brain structure involved in the sense of smell, which perhaps explains the commonly reported loss of smell. Furthermore, the structure is also closely connected with the hippocampus, a brain structure involved in short-term memory.
“The trail of the virus, when it invades the brain, leads almost straight to the hippocampus,” explained Dr de Erausquin. “That is believed to be one of the sources of the cognitive impairment observed in COVID-19 patients. We suspect it may also be part of the reason why there will be an accelerated cognitive decline over time in susceptible individuals.”
While much of this remains (educated) speculation for now, many scientists and doctors are bracing for a surge of COVID-related dementia and brain damage in the coming years and decades. Hopefully, the researchers say, this new upcoming study will help to illuminate the path ahead.