People hospitalised due to severe Covid-19 can experience cognitive decline that they would otherwise experience in 20 years of ageing, according to a new study.
The study, conducted in the United Kingdom, has been published in eClinicalMedicine, a journal published by The Lancet. An earlier study had found that “long Covid” can cause physical damage in the brain. The eClinicalMedicine’s study has noted that such brain damage can be a reason for the cognitive decline equivalent to 20 years of ageing that they found.
Unnatural cognitive decline is seen in several conditions, such as in dementia, but this study reported that the decline observed in Covid-19 is distinct from previously known declines.
Here is all you need to know about the research’s findings, how they add to our understanding of Covid-19, and what it means for people suffering from the disease.
What are research findings?
The study involved 46 people admitted to Addenbrooke's Hospital in Cambridge because of Covid-19 between March-July 2020. Sixteen of these people were on mechanical ventilators.
They were assessed through a testing tool called “Cognitron” six months after their infections on parameters such as memory, attention, reasoning, anxiety, depression, and post-traumatic stress disorder. The study found people’s verbal analogy was most affected. They were not able to find similarities between words.
“This mirrors anecdotal reports that suggest people post-infection are struggling to find the right word, and feeling like their brain is in slow motion,” noted science news website Science Alert.
“By comparing the patients to 66,008 members of the public, we were able to estimate that the magnitude of cognitive loss is similar on average to that sustained with 20 years of ageing, between 50 and 70 years of age,” said Adam Hampshire of Imperial College London and David Menon of University of Cambridge in an article in The Conversation.
Hampshire is the lead researcher of the study and Menon is a senior author. They added that such a cognitive decline is equivalent to losing ten IQ points.
What causes this cognitive decline?
The researchers have said that Covid-19 infection in itself would not be completely responsible for this.
Hampshire and Menon said, “Direct viral infection is possible, but unlikely to be a major cause. Instead, it is more likely that a combination of factors contributes, including inadequate oxygen or blood supply to the brain, blockage of large or small blood vessels because of clotting, and microscopic bleeds.”
The researchers also suggested that the immune system’s and body’s inflammatory response to the disease might cause this. This is supported by anecdotal evidence.
Hampshire and Menon noted that neurological effects were reduced when anti-inflammatory drugs were administered to patients, suggesting inflammation worsens the cognitive state.
Study adds to science of mental effects of Covid-19
It has been known for some time that Covid-19 can affect people’s minds. A study suggested that as many as 40 per cent of Covid-19 patients suffer from “long Covid”, which is defined as having symptoms of the disease after more than 12 weeks of testing negative.
Long Covid’s most distinguishable feature is “brain fog”. It’s an umbrella term used to refer to a range of cognitive issues such as developing an erratic memory where you forget things, lack of clarity of mind, poor concentration, inability to focus, and a persisting feeling of confusion, as earlier reported by Outlook.
This research quantifies the mental decline that Covid-19 causes and adds to the existing body of scientific literature on the subject.