Memory and concentration problems are common in long-COVID and the impact on the future health of affected individuals, and of society in general, should be recognised and taken more seriously say researchers.

In two papers, published in the journal Frontiers in Aging Neuroscience, researchers from the University of Cambridge have reported some of the first findings from the  COVID and Cognition study – an online cross-sectional longitudinal study investigating cognition post-COVID-19.

In the ongoing study the symptoms of 181 long-COVID patients (130 women) were monitored over 18 months – the majority of patients having suffered COVID-19 infection at least 6 months before the study began, with very few being hospitalised. These patients were compared with 185 other participants (118 women) who had not had COVID-19 infection.

Study participants were recruited between October 2020 and March 2021, when the Alpha variant and the original form of SARS-CoV-2 was circulating in the population.

Long-COVID Neurological Symptoms Predict Poor Cognitive Performance

In the first paper the researchers explored the characteristics of those individuals who had experienced COVID-19 infection, and those who had not, and the factors that predicted ongoing symptoms and self-reported cognitive deficits. In the second paper the researchers assessed memory, language, and executive function through cognitive testing.

The researchers found that of the 181 participants self-reporting having long-COVID:

• 78% reported difficulty concentrating

• 69% reported brain fog

• 68% reported forgetfulness

• 60% reported problems finding the right word in speech

Participants performed multiple tasks to assess their decision-making and memory – including remembering words in a list, and remembering two images that appeared together. Those who had suffered COVID-19 infection were found to have a consistent pattern of ongoing memory problems, with long-COVID sufferers performing worse on cognitive tests, and problems being more pronounced in those with more severe ongoing symptoms.

The authors said that “severity of initial illness is a significant predictor of the presence and severity of ongoing symptoms”, and that “some symptoms during the initial illness may be more common in those that have more severe ongoing symptoms”.

They explained that “neurological/psychiatric and fatigue/mixed symptoms during the initial illness, and neurological, gastrointestinal, and cardiopulmonary/fatigue symptoms during the ongoing illness, predicted experience of cognitive symptoms”.

They highlighted that those with severe ongoing symptoms were “significantly more likely to have experienced limb weakness during the initial illness than those that recovered”. Also that their findings “strongly suggest that experiences of neurological symptoms during the initial illness are significant predictors of self-reported cognitive impairment”.

In addition, they said that memory deficits in those who had experienced COVID-19 infection increased with the severity of self-reported ongoing symptoms, and that “fatigue/mixed symptoms during the initial illness and ongoing neurological symptoms were predictive of cognitive performance”.

To help understand the cause of the cognitive issues, the researchers investigated other symptoms that might be linked. They found that people who experienced fatigue and neurological symptoms, like dizziness and headache, during their initial illness were more likely to have cognitive symptoms later on. They also found that those who were still experiencing neurological symptoms were particularly impaired on cognitive tests.

Long-COVID Sufferers Not Taken Seriously

The study also found that even among those not admitted to hospital, people who had worse initial symptoms of COVID-19 were more likely to have a variety of ongoing symptoms (including nausea, abdominal pain, chest tightness and breathing issues) weeks or months later, and those symptoms were likely to be more severe than in people whose initial illness was mild.

Of concern was that “half of the patients in the study reported difficulties in getting medical professionals to take their symptoms seriously”, the authors said, suggesting that this might be because “cognitive symptoms do not get the same attention as lung problems or fatigue”.

The Office for National Statistics estimates that 10-25% of COVID-19 sufferers go on to have some degree of chronic illness. “This is important evidence that when people say they’re having cognitive difficulties post-COVID, these are not necessarily the result of anxiety or depression,” said Dr Muzaffer Kaser, a researcher in the University of Cambridge’s Department of Psychiatry and consultant psychiatrist at Cambridgeshire and Peterborough NHS Foundation Trust, who was involved in the study. “The effects are measurable – something concerning is happening.”

He added: “It’s important that people seek help if they’re concerned about any persistent symptoms after COVID infection.”

Severe Ongoing Long-COVID Symptoms Linked to Inability to Work

Long-COVID “urgently needs to be taken more seriously”, said Dr Lucy Cheke, a researcher in the University of Cambridge’s Department of Psychology and senior author of the paper. She added that the impact on the working population “could be huge”.

The researchers found that people over 30 were more likely to have severe ongoing symptoms than younger people. They highlighted that 75% of those with severe ongoing symptoms of long-COVID reported long periods of being unable to work.

“Memory difficulties can significantly affect people’s daily lives, including the ability to do their jobs properly,” said Dr Kaser.

Dr Cheke pointed out: “People think that long-COVID is ‘just’ fatigue or a cough, but cognitive issues are the second most common symptom – and our data suggest this is because there is a significant impact on the ability to remember.”

The researchers emphasise that for the benefit of individuals with long-COVID, and for society in general, it is important “to be able to prevent, predict, identify and treat issues associated with long-COVID”.

The authors explained that their study currently has no data on long-COVID associated with the Delta or Omicron variants of coronavirus, although a new cohort is now being recruited to test this.