Covid-19 patients still have a slightly increased risk of some psychiatric and neurological problems two years after infection. This is what British researchers report in the journal “The Lancet Psychiatry” after evaluating the medical records of 1.28 million Covid 19 patients and a similar number of people with another respiratory disease.
The University of Oxford team led by Paul Harrison and Maxime Taquet used data from the US, UK, Spain, Bulgaria, Australia, India, Malaysia and Taiwan. During the comparison, the researchers made sure that the group of Covid patients and the control group with other respiratory diseases were very similar in terms of age, gender, ethnic origin and other characteristics. The Covid diseases were diagnosed between January 2020 and April 2022.
The results initially contradict the suspicion that Covid can cause long-term mood disorders. "It is good news that the excess of depression and anxiety diagnoses in the wake of Covid-19 is short-lived and not seen in children," Harrison said in a statement from his university.
Accordingly, mood disorders were at the same level as in the control group 43 days after the Covid diagnosis, and this was the case for anxiety disorders after 58 days. The scientists did not find an increased occurrence of such disorders in the age group under 18 years.
However, the study in Covid-19 patients indicates a slightly higher risk of clouded consciousness (brain fog), dementia, psychotic flare-ups and epilepsy even at the end of the two-year follow-up period. Calculated per 10,000 patients, there were 640 cases of impaired consciousness in the Covid group of 18 to 64 year olds, while there were 550 cases in the control group. In the over 64-year-olds, there were 450 cases of dementia in 10,000 Covid patients, in the control group there were 330 cases.
Researchers also looked at the effects of the alpha, delta and omicron coronavirus variants. Compared to the alpha variant, the delta variant showed an increased risk of ischemic stroke, epilepsy, impaired consciousness, insomnia and anxiety disorders. In the case of the omicron variant, there were therefore hardly any differences to the delta variant, but the death rate was lower.
"The results shed new light on the longer-term consequences for people's mental health and brain after a Covid-19 infection," says Taquet. However, the authors acknowledge that because of the database, Covid cases with little or no symptoms may be underrepresented.
It also did not take into account when the neurological or psychiatric diseases were first diagnosed and how severe the cases were. The team also admits that information about Covid diseases or vaccinations against the corona virus could be missing in the patient files, which could distort the results.
Jonathan Rogers and Glyn Lewis of University College London, who were not involved in the study, write in a comment, also in The Lancet Psychiatry: "This is the first study to attempt to explain some of the disparity in persistent neurological and psychiatric aspects of Covid-19 in a large data set.” Some clinical features require further examination.
The study is particularly relevant because of the enormous number of patients, the control group and the long observation period of two years, says Peter Berlit, Secretary General of the German Neurological Society (DGN). However, the validity is limited by the fact that the severity of the respiratory diseases in the control group was not taken into account.
The study does not show an increased risk of dementia in Covid patients. "It is known that latent dementia often becomes manifest as a result of a serious event, such as Covid-19 disease, without there being a causal connection," emphasizes the neurologist.