Those who recovered from COVID-19 retain changes in brain function

In a recent study published in The Lancet Regional Health – Western Pacific, a team of researchers from China and the Netherlands used resting-state functional magnetic resonance imaging (rs-fMRI) to study the long-term impact of COVID-19 on brain function based on reports of persistent neurological, cognitive and psychiatric symptoms in people recovering from the disease.

Although global medical efforts have helped contain the spread of the COVID-19 pandemic, there is significant evidence that a significant proportion of people who recover from SARS-CoV-2 infection experience long-term sequelae of the disease (long COVID) or post-COVID syndrome.

Symptoms of long COVID are varied and affect a wide range of organ systems. While the most common symptoms are fatigue, shortness of breath, and post-exertional malaise, people with post-COVID syndrome also report cognitive, neurological, and psychiatric symptoms such as brain fog, anxiety, inability to concentrate, sleep disturbances, and depression.

Studies have confirmed deficits in certain areas of cognitive function as long-term consequences of SARS-CoV-2 infections.

Research also shows that people infected with the original SARS-CoV-2 strain or the alpha variant and requiring hospitalization experienced greater cognitive deficits compared to other COVID-19 patients.

However, the mechanisms or pathophysiology of neuropsychiatric or cognitive deficits in patients with long COVID remain unclear.

The present study aims to understand the long-term cognitive, neurological and psychiatric impact of COVID-19 and brain changes in long COVID patients two years after SARS-CoV-2 infection using rs-fMRI.

The study included adults aged 18 to 65 years, including people previously infected with SARS-CoV-2, as well as healthy controls.

Classification of a participant as a COVID-19 survivor required medical records confirming the diagnosis, whereas healthy control participants were defined as individuals with no history or medical record of a positive PCR or antigen test for SARS-CoV-2.

Individuals with current neurological or psychiatric illnesses, stroke or brain injury, pregnant or lactating women, and individuals with metal or electronic implants, claustrophobia, or other contraindications to MRI were excluded.

A variety of data were collected, including demographic characteristics such as age, gender, and education level, as well as information on comorbidities, smoking status, history of mental disorders, COVID-19 vaccination status, length of hospitalization, and time between COVID-19 diagnosis and follow-up.

The Cognitive Impairment Questionnaire was used to assess cognitive function, and memory tasks were used to assess working memory.

Additional questionnaires were used to assess mental and physical health, fatigue, symptoms of depression, anxiety, insomnia severity, symptoms of post-traumatic stress disorder (PTSD), and self-reported symptoms of headache, dizziness, and taste and smell disturbances. The MRI scanner provided brain scans of varying thickness and angles.

The study found that people who experienced mild to moderate and severe to critical acute symptoms during SARS-CoV-2 infection had significantly more cognitive complaints of mental fatigue and cognitive impairment compared to healthy control participants.

However, no significant differences in cognitive complaints were observed between people with mild to moderate COVID-19 symptoms and those with severe to critical symptoms.

Moreover, the two groups of COVID-19 survivors and the control group showed similar performance on the Montreal Cognitive Assessment, as well as on tasks assessing working memory and simple reaction time.

However, the incidence of psychiatric symptoms such as depression, insomnia, PTSD, anxiety, and taste and smell disturbances was higher in the two groups of COVID-19 survivors compared to the control group.

Furthermore, rs-fMRI results showed that among people recovering from COVID-19, the amplitude of low-frequency oscillations was significantly higher in the right inferior temporal gyrus, left putamen, and right globus pallidus, and lower in the left superior temporal gyrus and right superior parietal gyrus.

Regional homogeneity values were also lower in the left postcentral gyrus, right precentral gyrus, left calcarine sulcus, and left superior temporal gyrus in COVID-19 survivors.

Low regional homogeneity values in the left superior temporal gyrus were also correlated with lower cognitive fatigue questionnaire scores and higher mental fatigue.

Overall, the results showed that long COVID patients continue to experience persistent cognitive symptoms, as well as neurological and psychiatric complaints, and show changes in the brain even two years after recovery from SARS-CoV-2 infection.

The study reported changes in brain function across multiple regions that may contribute to long-term cognitive complaints in long COVID patients.