The global outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the causative pathogen of coronavirus disease 2019 (COVID-19) – has already claimed more than 2.96 million lives worldwide. And while COVID-19 is mild or asymptomatic for the vast majority, followed by a full recovery in most cases, a significant minority of those with symptomatic infection have exhibited a host of sequelae, from pulmonary to gastrointestinal complications. The increasing emergence of neurological and psychiatric complications, in many cases months after infection, is an area of particular concern.
A new study by researchers at Oxford University examines neurological and psychiatric outcomes in recovered COVID-19 patients six months post-infection. Their findings have been published in The Lancet Psychiatry journal.
Previous studies reported that several individuals, who had recovered from coronavirus infections, have developed neurological disorders. Scientists have been exploring if similar outcomes are possible in SARS-CoV-2 recovered patients and have found a positive correlation between COVID-19 and neurological disorders. They have been successful in identifying the mechanism behind such occurrence. Another line of study has shown the existence of psychiatric sequelae, such as mood and anxiety disorders linked to COVID-19 three months post-infection.
Scientists have identified the need for large-scale and robust data for a longer period that would help quantify the consequences of COVID-19 on brain health. The present study used electronic health records to study the emergence of neurological and psychiatric disorders in patients who have recovered from COVID-19 disease. Electronic data on patients six months following the clinical diagnosis of COVID-19 infection were obtained. Researchers have also explored the connection between the severity of COVID-19 infection and associated health risks. The disease's severity was gauged in terms of admission to the intensive therapy unit (ITU) and development of encephalopathy.
The present research conforms with previous conclusions regarding the increased risk of neurological and psychiatric disorders in COVID-19 recovered patients. Researchers have estimated the incidence and risk of these outcomes in patients who had COVID-19 and have compared the result with similar cohorts of patients with other medical conditions.
This study included 236,379 patients who were diagnosed with COVID-19. Scientists revealed that a relative risk of incidence and hazard ratios (HRs) of neurological and psychiatric disorders were higher for people who suffered from severe COVID-19 infection. The incidence of a neurological or psychiatric diagnosis, six months post-infection, was found to be 33.62% (95% CI 33.17–34.07), with 12.84% (12.36–13.33) being diagnosed for the first time. For patients admitted to ITU, 46.42% (44.78–48.09) of individuals were diagnosed with neurological or psychiatric disorders six months after the disease. Among these individuals, 25.79% (23.50–28.25) had no history of these diseases.
Neurological and psychiatric disorders were also found in patients who did not require hospitalization. Researchers believe that this could be owing to the viral invasion of the central nervous system, hypercoagulable states, and neural effects of the immune response.
The possibility of cerebrovascular events, such as intracranial hemorrhage and ischaemic stroke, is enhanced due to COVID-19. Researchers found the prevalence of ischaemic stroke in one in ten patients with encephalopathy. A similar incidence was recorded for patients who recovered from influenza. Previous research has suggested a relationship between COVID-19 and dementia, which was supported by the data used in this study. In the whole COVID-19 cohort, researchers reported that 2.66% of aged patients (older than 65 years) and 4.72% of patients with encephalopathy were diagnosed with dementia for the first time, within six months of having COVID-19. Researchers also reported that parkinsonism might be a delayed outcome, 0.11% (0.08–0.14). Some of the other incidences of disease were also evaluated, for example, intracranial hemorrhage 0.56% (0.50–0.63), ischaemic stroke 2.10% (1.97–2.23), anxiety disorder 17.39% (17.04–17.74), etc.
In comparison to the existing reports, the current research showed a significantly increased risk of psychotic disorders. Such a difference in result may be owing to the larger sample size and a longer timeline of the study. Insomnia was found to be closely related to COVID-19; however, such association was absent in individuals who suffered from influenza or other respiratory tract infections. Further, scientists revealed that in comparison with neurological disorders, psychiatric disorders showed a weaker relationship with the markers of COVID-19 severity in terms of incidence or HRs.
Although the findings of this study are extremely reliable and strong, they have some weaknesses. Some of the data obtained from the electronic health records included data that had no validation of diagnoses, and minimal information regarding any socioeconomic factors was present. These data would affect the incidence estimations. The researchers were skeptical regarding the analyses that included individuals who developed encephalopathy. This is because, among the hospitalized patients, around 11% received this diagnosis, which was far less than the expected number of cases. Further, some biased data could develop an error; for instance, some of the patients in the comparison cohorts might have developed COVID-19 symptoms later, which would lead to an underestimation of HRs.