Can severe coronavirus cause your IQ to fall or age brain by up to 10 years? Study claims it may be possible
There is growing evidence that some patients with severe coronavirus disease can develop a range of complications that may have lasting health effects. A research team now suggests that the worst-hit Covid-19 patients may suffer an IQ drop or that their brain could age by up to 10 years. Based on their findings, the authors write that even people who had recovered, including those no longer reporting symptoms, “exhibited significant cognitive deficits” when controlling for age, gender, education level, income, racial-ethnic group and pre-existing medical disorders. They were of “substantial effect size” for people who had been hospitalized, but also for mild but biologically confirmed cases who reported no breathing difficulty.
“There is evidence that Covid-19 may cause long term health changes past acute symptoms, termed ‘long Covid’. Our analyses of detailed cognitive assessment and questionnaire data from tens thousands of datasets, align with the view that there are chronic cognitive consequences of having Covid-19. Individuals who recovered from suspected or confirmed Covid-19 perform worse on cognitive tests in multiple domains than would be expected given their detailed age and demographic profiles. This deficit scales with symptom severity and is evident amongst those without hospital treatment,” says researchers in the study, which has been published as a pre-print and is yet to be peer-reviewed.
The team includes experts from Imperial College London, UK; University of Southampton, UK; University of Cambridge, UK; University of Chicago, US; and King’s College London, UK. They caution that these results “should act as a clarion call for more detailed research investigating the basis of cognitive deficits in people who have survived SARS-COV-2 infection.” According to the World Health Organization (WHO), coronavirus may increase the risk of long-term health problems. Body systems and organs that can be affected include the heart (damage to the heart muscle, heart failure), lungs (damage to lung tissue and restrictive lung failure), brain and the nervous system (loss of sense of smell, cognitive impairment such as memory and concentration), mental health (anxiety, depression, post-traumatic stress disorder and sleep disturbance), and musculoskeletal and others (such as pain in muscles and fatigue).
The findings
While case studies have revealed neurological problems in severely affected Covid-19 patients, there is little information regarding the nature and broader prevalence of cognitive problems post-infection or across the full spread of severity. Accordingly, for the current report, the investigators analyzed cognitive test data from 84,285 “Great British Intelligence Test” participants, who completed a questionnaire regarding suspected and biologically confirmed Covid-19 infection. “We analyzed data from 84,285 individuals who completed the full extended questionnaire to determine whether those who had recovered from Covid-19 showed objective cognitive deficits when performing tests of semantic problem solving, spatial working memory, selective attention and emotional processing; and whether the extent and/or nature of deficit related to the severity of respiratory symptoms as gauged by the level of medical assistance,” explains the team.
Among the participants, 60 reported being put on a ventilator, 147 were hospitalized without a ventilator, 176 required medical assistance at home for respiratory difficulties, 3,466 had respiratory difficulties and received no medical assistance, and 9,201 reported being ill without respiratory symptoms. The investigators noted learning deficit, drop in IQ, among other changes in Covid-19 survivors. Their analysis reveals that the worst-affected patients suffered the equivalent of an 8.5-point drop in their IQ.
“The scale of the observed deficits was not insubstantial. The 0.57 SD global composite score reduction for the hospitalized with ventilator sub-group was equivalent to the average 10-year decline in global performance between the ages of 20 to 70 within this dataset. It was larger than the mean deficit of 512 people who indicated they had previously suffered a stroke and the 1,016 who reported learning disabilities. For comparison, in a classic intelligence test, 0.57 SDs equates to an 8.5-point difference in IQ,” the findings state.
According to the authors, the findings provide converging evidence to support the hypothesis that Covid-19 infection likely has consequences for cognitive function that persist into the recovery phase. The observed performance deficits varied in scale depending on how severe the disease had been. Differences in other factors, such as age, underlying health conditions, or education, among others, could not explain the deficits.
The analysis suggests that while “semantic problem solving” was particularly reduced for people who had been put on a ventilator, it also showed a “significant scaled reduction” for other people who required a hospital visit. Visual attention showed similar scaled reductions in performance for all groups who required medical assistance. Spatial working memory appeared not to be significantly affected. People who have recovered from Covid-19 infection show “particularly pronounced problems in multiple aspects of higher cognitive or ‘executive’ function.”
“There was a significant main effect, with increasing degrees of cognitive underperformance relative to controls dependent on the level of medical assistance received for Covid-19 respiratory symptoms. People who had been hospitalized showed large-medium scaled global performance deficits dependent on whether they were versus were not put onto a ventilator. Those who remained at home (that is, without inpatient support) showed small statistically significant global performance deficits,” writes the team. They conclude, “A fuller understanding of the marked deficits that our study shows will enable better preparedness in the post-pandemic recovery challenges.”