Health Talk | How real is cognitive impairment in Covid survivors?

Researchers investigated cognitive changes over two-and-a-half years among 1,245 individuals aged 60 years or older who survived the infection

The overall incidence of cognitive impairment among Covid-19 survivors aged 60 years and older was 19.1% at two-and-a-half years after infection, according to a new analysis published in Nature, which highlights the emerging evidence that suggests neurological and other post-acute sequelae of Covid-19 can persist beyond or develop following SARS-CoV-2 infection.

An illustration of the novel coronavirus seen next to a health care worker at a Covid-19 testing centre in New Delhi on October 28. (Sanchit Khanna / HT Photo)

For the Nature study, the researchers investigated cognitive changes over a period of two-and-a-half years among 1,245 individuals aged 60 years or older who survived infection with the original SARS-CoV-2 strain in Wuhan, China, and 358 uninfected spouses.

“We show that the overall incidence of cognitive impairment among older Covid-19 survivors was 19.1% at 2.5 years after infection and hospitalisation,” said researchers in the paper.

According to the paper, cognitive decline primarily manifested in individuals with severe Covid-19 during the initial year of infection, after which the rate of decline decelerated. Severe Covid-19, cognitive impairment at six months and hypertension were associated with long-term cognitive decline. These findings reveal the long-term cognitive trajectory of the disease and underscore the importance of post-infection cognitive care for Covid-19 survivors.

A lot of Covid-19 survivors have experienced what they loosely call brain fog.

Apart from respiratory symptoms, the most frequent symptoms post Covid-19 that people have complained of are related to brain health, which includes cognitive and mental symptoms. The debate on the long-term effects of Covid-19 is a burning one and several studies are being conducted globally to look at the disease impact and establish a correlation.

Earlier, in February this year, The Lancet also published a multicentre cross-sectional study on how long Covid-19 is associated with severe cognitive slowing.

“We identified pronounced cognitive slowing in patients with post covid conditions (PCC), which distinguished them from age-matched healthy individuals who previously had symptomatic Covid-19 but did not manifest PCC. Cognitive slowing was evident even on a 30-s task measuring simple reaction time (SRT), with patients with PCC responding to stimuli ∼3 standard deviations slower than healthy controls. 53.5% of patients with PCC's response speed was slower than 2 standard deviations from the control mean, indicating a high prevalence of cognitive slowing in PCC,” read the Lancet paper.

While there is data at hand that seems to suggest changes in cognitive function, it is still short-term data. As researchers also admit in both papers that the long-term trajectories of cognitive change after a Covid-19 infection remain unclear, it will be crucial to see what facts the long-range data throw up in the future.

Rhythma Kaul, national deputy editor, health, analyses the impact of the most significant piece of news this week in the health sector