According to the U.S. Centers for Disease Control and Prevention (CDC), about one in five adults have a health condition that might be related to having previously been infected with COVID-19. In addition to cardiovascular and respiratory conditions, blood clots and vascular issues, kidney failure, and musculoskeletal conditions, these individuals may also experience changes in their neurological and mental health conditions.
Researchers shared how their use of a special type of MRI revealed brain changes in patients up to 6 months after they have recovered from COVID-19 at the 2022 Radiological Society of North America (RSNA) annual meeting.
For their study, a team led by researchers at the Indian Institute of Technology used susceptibility-weighted imaging (SWI) to analyze the effects that COVID-19 has on the brain. Magnetic susceptibility "denotes how much certain materials, such as blood, iron and calcium, will become magnetized in an applied magnetic field," the authors noted in an RSNA statement summarizing the findings. "This ability aids in the detection and monitoring of a host of neurologic conditions including microbleeds, vascular malformations, brain tumors, and stroke."
The researchers also pointed out that group-level studies have not previously focused on COVID-19 changes in magnetic susceptibility of the brain, despite several case reports signaling such abnormalities. For this study, the authors sought to highlight this new aspect of the neurological effects of COVID-19 and report on the significant abnormalities seen in COVID survivors.
To that end, the investigators analyzed the susceptibility weighted imaging data of 46 COVID-recovered patients and 30 healthy controls. Imaging was done within 6 months of recovery. Fatigue, trouble sleeping, lack of attention, and memory issues were the most commonly reported symptoms among patients with long COVID, according to the researchers.
Changes in susceptibility values of brain regions may signal local compositional changes, researchers added, noting that susceptibilities might also reflect the presence of abnormal quantities of paramagnetic compounds, while lower susceptibility could be linked to abnormalities such as calcification or lack of paramagnetic molecules containing iron.
Overall, MRI results demonstrated that patients who had recovered from COVID-19 had "significantly higher susceptibility values in the frontal lobe and brain stem compared to healthy controls. The clusters obtained in the frontal lobe primarily show differences in the white matter."
Portions of the left orbital-inferior frontal gyrus (a key region for language comprehension and production) and right orbital-inferior frontal gyrus (associated with various cognitive functions including attention, motor inhibition and imagery, as well as social cognitive processes) and the adjacent white matter areas made up the frontal lobe clusters, the authors noted.
The researchers also saw a meaningful difference in the right ventral diencephalon region of the brain stem, a region associated with many crucial bodily functions, such as coordinating with the endocrine system to release hormones, relaying sensory and motor signals to the cerebral cortex, and regulating circadian rhythms.
The results point to serious long-term complications that the coronavirus may be causing, even months after recovery from the infection, according to the authors, who are also conducting a longitudinal study on the same patient cohort to determine whether these brain abnormalities persist over a longer span of time.
The increasing number of reports of mild to severe psychological, behavioral, and cognitive sequelae in COVID-19 "motivated the need for a neuroimaging-based study of these post-COVID symptoms," noted study co-author Sapna S. Mishra, a PhD candidate at the Indian Institute of Technology. "We wanted to see if there are any group-level changes in the MRI of these COVID survivors, which cannot be directly observed by radiologists in patient-level studies." SWI shows utility in uncovering brain changes in these patients, she noted.
"The SWI images represent maps of susceptibility differences of various compounds present in different brain tissue types," Mishra explained. "It is useful in detecting several pathologies and conditions such as cerebral microbleeds, microhemorrhages, vascular malformations, and so on, which makes it a viable modality for investigating the effects of coronavirus on the brain, as such abnormalities have been reported in autopsy case reports."
Looking ahead, "we need to integrate these results with the findings of other neuroimaging-based studies of COVID-19 done at a global scale with larger datasets," Mishra concluded. "Our study aims to contribute to this field and aid the medical community in its efforts to develop rehabilitative measures for post-COVID patients."
Mark McGraw is a contributing writer.